effects of different stretching modalities on the
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University of Texas at El Paso University of Texas at El Paso
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Open Access Theses & Dissertations
2021-05-01
Effects Of Different Stretching Modalities On The Antagonist And Effects Of Different Stretching Modalities On The Antagonist And
Agonist Muscles On Isokinetic Strength And Vertical Jump Agonist Muscles On Isokinetic Strength And Vertical Jump
Performance Performance
Samuel Montalvo University of Texas at El Paso
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EFFECTS OF DIFFERENT STRETCHING MODALITIES ON THE ANTAGONIST AND
AGONIST MUSCLES ON ISOKINETIC STRENGTH AND VERTICAL JUMP
PERFORMANCE
SAMUEL MONTALVO
Doctoral Program in Interdisciplinary Health Sciences
APPROVED:
Sandor Dorgo, Ph.D., Chair
Gabriel Ibarra-Mejía, M.D., Ph.D.
Jeffrey Eggleston, Ph.D.
Jeffrey McBride, Ph.D.
____________________________________
Stephen, L. Crites, Jr., Ph.D.
Dean of the Graduate School
Copyright ©
By
Samuel Montalvo
2021
Dedication
This work is dedicated to my parents, Sergio Montalvo and Elizabeth Montalvo, my sister
Elizabeth Montalvo de Solórzano, and my brother Sebastian Montalvo for their love and
continued support during my graduate studies and competitive career.
EFFECTS OF DIFFERENT STRETCHING MODALITIES ON THE ANTAGONIST AND
AGONIST MUSCLES ON ISOKINETIC STRENGTH AND VERTICAL JUMP
PERFORMANCE
by
SAMUEL MONTALVO, M.S., B.S., CSCS*D
DISSERTATION
Presented to the Faculty of the Graduate School of
The University of Texas at El Paso
in Partial Fulfillment
of the Requirements
for the Degree of
DOCTOR OF PHILOSOPHY
Interdisciplinary Health Science Program
THE UNIVERSITY OF TEXAS AT EL PASO
May 2021
v
Acknowledgments
I would like to express my deepest gratitude to my mentor Dr. Sandor Dorgo for his
mentorship and direction during my Ph.D. studies. I will forever be in debt with you. I would
also like to thank Dr. Gabriel Ibarra-Mejia for his continuous friendship, support, and
mentorship, Dr. Jeffrey Eggleston for his mentorship and assistance with biomechanical
equipment and analysis, and Dr. Jeffrey McBride for your mentorship and willingness to be part
of my Dissertation committee, your advice, and time were deeply appreciated it. To Matthew P.
Gonzalez, for his help on all of our research projects and his friendship all these years. To my
fitness research lab colleagues Martin Dietze-Hermosa, Nicolas Cubillos for also allowing me to
be part of their research projects and their friendship. To previous graduate students from the
Fitness Research Lab, Lizette Terrazas, Jeremy Perales, Fayon Gonzalez, and Lance Gruber for
allowing me to assist you with your graduate projects.
I would also like to express my gratitude to Dr. Alvaro Gurovich, Dr. Francisco Morales-
Acuña, Manuel Gomez, and Lisa Rodriguez for allowing me to be part of the Clinical Applied
Physiology lab and to Dr. Gabriel Ibarra-Mejia, and Dr. Daniel Conde for allowing me to also be
part of the Bio-Ergonomics Lab. I am grateful for all the teachings and experiences from your
laboratories. To my colleagues of the Interdisciplinary in Health Sciences Ph.D. program, Dr.
Juan Antonio Aguilera, Dr. Irma Yolanda Torres-Canayatch, Dr. Maria Fuentes, Dr. Fabricio
Saucedo, Dr. Amy Nava, and Dr. Isabel Latz for their friendship and support.
I would also like to thank Darlene Muguiro and Martha Losoya for all of their continued
support in administrative tasks. This work would have never been possible without your
continuous support. Thank you.
vi
Finally, I would like to thank all the donors and sponsors of the UTEP DODSON
foundation as this work was funded by The University of Texas at El Paso Dodson Research
Grant.
vii
Abstract
Warm-ups are essential components of all training sessions, sports, and physical activities.
Warm-ups are typically composed of a variety of stretches. Two stretching modalities that are
commonly performed before any physical activity are the static and dynamic stretching
modalities. Historically, static stretching has been used as a preferred stretching modality during
the warm-up period. However, research indicates that static stretching – if done prior to the
training session – may inhibit the expression of muscular strength, muscular activation, and
vertical jump height. On the contrary, dynamic stretching has been shown to improve the
expression of muscular strength, muscular activation, and vertical jump performance. In
addition, the effects of static stretching are modulated by the time under stretch, training history
of the individual, and pre-warm-up activities. More recently, static stretching of the antagonist
muscles has been shown to improve muscular strength and power of the agonist muscles during
knee extension and vertical jump. Moreover, we ought to expand on the previous results of
antagonist static stretching and explore if dynamic stretching of the agonist and static stretching
of the antagonist would improve muscular isokinetic strength, power, muscular activation, and
vertical jump performance. The purpose of this project was to explore the effects of static and
dynamic stretching under different configurations at the agonist (quadriceps and gastrocnemius)
and antagonist (hamstrings and tibialis anterior) muscular complex on isokinetic strength,
vertical jump height, and muscular activation (electromyography) of the lower body. A
randomized repeated measures within, and between subject’s design was utilized for this study.
Sixteen male subjects completed this study (n=16, trained=8, untrained=8) For every testing
session, subjects performed a general warm-up consisting of a 3-5-minute self-paced jog.
Following this, subjects performed a total of 9 conditions in a randomized order throughout nine
viii
testing sessions: 1) Baseline, 2) Static of Agonist, 3) Static of Antagonist, 4) Static of Agonist
and Antagonist, 5) Dynamic of Agonist, 6) Dynamic of Antagonist, 7) Dynamic of Agonist and
Antagonist, 8) Static of Agonist and Dynamic of Antagonist, and 9) Dynamic of Agonist and
Static of Antagonist. Subjects performed a series of stretches for each of these conditions in
separate sessions. Thereafter, subjects performed four repetitions of isokinetic knee extensions
and flexions. Finally, subjects performed five repetitions of the countermovement jump, squat
jump, and drop jump. A series of individual repeated measures ANOVA and Friedman tests for
non-parametric repeated measures data were utilized to determine the interaction of the
stretching conditions on isokinetic peak and mean torque, and power, electromyography, and
vertical jump performance. Results indicated a significant interaction on Isokinetic Peak Knee
Extension and Flexion Torque, Power, and Average Torque, with pairwise comparisons favoring
Dynamic stretching conditions. However, the analyses revealed no significant interactions for
muscular activation. Furthermore, there was no interaction on Vertical Jump Height. However,
there was a small worthwhile change favoring the dynamic of agonist and antagonist condition.
Therefore, it was concluded that the Dynamic of Agonist and Antagonist improves physical
performance in concordance with the previous literature. Moreover, results show that stretching
dynamically the agonist and the antagonist in a static manner also improves performance, with
no differences between these two stretching conditions. The Dynamic of Agonist and Static of
Antagonist can be an alternative to a Dynamic stretching of Agonist and Antagonist commonly
performed to improve isokinetic strength and vertical jump height. Future studies with athletes
from different sports are needed to extrapolate these results in different sport populations and
situations.
ix
Table of Contents
Acknowledgments........................................................................................................................... v
Abstract ......................................................................................................................................... vii
List of Tables ............................................................................................................................... xiii
List of Figures ............................................................................................................................. xvii
Chapter 1: Introduction ................................................................................................................... 1
1.1 Statement of the Research Problem ................................................................................. 2
1.2 Purpose of the Study ........................................................................................................ 2
1.3 Definition of terms ........................................................................................................... 3
1.3.1 Definition of Stretching ............................................................................................ 3
1.3.2 Definition of Muscular Strength ............................................................................... 4
1.3.3 Definition of Vertical Jump performance and Reactive Strength Index ................... 4
1.4 Hypotheses ....................................................................................................................... 4
Alternative Hypothesis: (H1) ................................................................................................... 5
1.5 Significance of the problem ............................................................................................. 5
Chapter 2: Review of the Literature................................................................................................ 7
1.6 Static Stretching ............................................................................................................... 7
1.7 Dynamic Stretching .......................................................................................................... 8
1.8 Antagonist Static Stretching ............................................................................................. 8
x
1.9 Conceptualization of Static and Dynamic stretching findings on Muscular Strength and
Power Performance ................................................................................................................... 14
1.10 Proposed Mechanisms .................................................................................................... 16
1.10.1 Increased Blood Flow, Heart Rate, Muscle, and Core Temperature ...................... 16
1.10.3 Muscle-Tendon Unit (MTU) Stiffness.................................................................... 17
1.10.4 Post-Activation Potentiation ................................................................................... 18
1.10.5 Muscular Architecture ............................................................................................ 20
1.10.6 Familiarization and Neural stimulation and inhibition ........................................... 22
1.10.7 Performance and Stretching .................................................................................... 22
1.10.8 Post-Activation Potentiation and Complex Training .............................................. 25
1.11 Plyometrics and the Stretch-Shortening Cycle............................................................... 26
1.11.1 The Mechanical Model ........................................................................................... 27
1.11.2 The Neurophysiological Model .............................................................................. 28
1.11.3 Evaluation of the Stretch-Shortening Cycle ........................................................... 29
1.11.4 Other evidence on the Stretch Shortening Cycle .................................................... 31
1.12 Measuring the Vertical Jump through Force Plates ....................................................... 33
1.13 Measuring Vertical Jump Considerations ...................................................................... 35
Chapter 3: Methodology ............................................................................................................... 37
1.14 Research Design ............................................................................................................. 37
Sample ....................................................................................................................................... 38
xi
1.15 Instrumentation............................................................................................................... 39
1.16 Procedures for Baseline and Stretching Conditions ....................................................... 49
1.17 Statistics and Data Analysis ........................................................................................... 50
Chapter 4: Results ......................................................................................................................... 54
1.18 Descriptives .................................................................................................................... 54
1.19 Data Normality ............................................................................................................... 54
1.20 Peak Torque Knee Extension and Flexion ..................................................................... 59
1.21 Average Power Extension and Flexion .......................................................................... 60
1.22 Average Peak Torque Extension and Flexion ................................................................ 60
1.23 Electromyography .......................................................................................................... 61
1.24 Vertical Jump ............................................................................................................... 100
Chapter 5: Discussion ................................................................................................................. 156
1.25 Isokinetic Strength........................................................................................................ 156
1.26 Electromyography during Isokinetic Testing ............................................................... 158
1.27 Vertical Jump Performance .......................................................................................... 159
1.28 Future Research Directions .......................................................................................... 165
1.29 Conclusion .................................................................................................................... 165
1.30 Practical Applications .................................................................................................. 166
References: .................................................................................................................................. 167
Appendix ..................................................................................................................................... 182
xii
1.31 Approval IRB Document ............................................................................................. 182
Vita .............................................................................................................................................. 185
xiii
List of Tables
Table 1. Summary of major findings of antagonist-stretching conditions.................................... 12
Table 2. Definitions of Kinematic temporal vertical jump parameters. Adopted and updated from
previous studies (Barker, Harry, & Mercer, 2018; McMahon, Suchomel, Lake, & Comfort, 2018;
Raymond et al., 2018). .................................................................................................................. 42
Table 3. Definitions of Kinetic parameters of vertical jump. Adopted and updated from previous
studies (Barker, Harry, & Mercer, 2018; McMahon, Suchomel, Lake, & Comfort, 2018;
Raymond et al., 2018). .................................................................................................................. 43
Table 4. A detailed description of the stretches performed during each stretching session. ........ 48
Table 5. Descriptives of Subjects.................................................................................................. 54
Table 6. Shapiro-Wilk test for assumptions of normality of data distribution. ............................ 59
Table 7. Descriptives of non-normalized raw data of Peak Torque Extension by BW by
stretching condition and by group................................................................................................. 64
Table 8. Descriptives of Normalized Peak Torque Extension by BW to Baseline values (%
MVC) by condition and by group. ................................................................................................ 65
Table 9. Effect size for pairwise comparisons of Peak Torque Extension / BW (% MVC). ........ 66
Table 10. Descriptives of non-normalized Peak Torque Flexion by BW (%) by group and
stretching condition. ...................................................................................................................... 69
Table 11. Normalized Peak Torque Flexion by BW (%) by group and stretching condition. ...... 70
Table 12. Descriptives of non-normalized Average Power Extension (W) by stretching condition.
....................................................................................................................................................... 73
Table 13. Normalized Average Power Extension (%MVC) by stretching condition. .................. 74
Table 14. Average Power (%MVC) Extension Effect Sizes and Pairwise comparisons. ............. 75
xiv
Table 15. Descriptives of non-normalized Average Knee Power Flexion (W) by stretching
condition. ...................................................................................................................................... 78
Table 16. Normalized Average Knee Power Flexion (W) by stretching condition. ..................... 79
Table 17. Average Power Knee Flexion (%MVC) Effect Sizes and Pairwise comparisons. ....... 80
Table 18. Average Peak Torque (N) values by Stretching Condition. ......................................... 83
Table 19. Normalized Average Peak Torque Extension (%MVC) by Baseline condition by
stretching condition. ...................................................................................................................... 84
Table 20. Effect Sizes for Average Peak Torque Extension by Stretching condition. ................. 85
Table 21. Non-normalized Average Peak Torque Knee Flexion by Stretching Condition. ......... 88
Table 22. Normalized Peak Torque Knee Flexion (%MVC) by stretching condition. ................. 89
Table 23. Vastus Lateralis (%MVC) activation by stretching condition. ..................................... 91
Table 24. Vastus Medialis Oblique (%MVC) activation by stretching condition. ....................... 93
Table 25. Rectus Femoris (%MVC) activation by stretching condition. ...................................... 95
Table 26. Bicepss Femoris (%MVC) activation by stretching condition. .................................... 97
Table 27. Semitendinosus (%MVC) activation by stretching condition. ..................................... 99
Table 28. Countermovement Jump Height (m) by stretching conditions and groups. ............... 104
Table 29. Normalized Countermovement Jump Height by stretching conditions and groups. .. 105
Table 30. Individual analysis of mean Vertical Jump Height (cm) via Smallest Worthwhile
Change ........................................................................................................................................ 106
Table 31. RSImod values for all subjects by stretching condition. ............................................ 108
Table 32. Normalized RSI values by stretching codition. .......................................................... 110
Table 33. Contact Time (s) values during the CMJ by stretching condition. ............................. 112
Table 34. Yielding time (s) values during CMJ by stretching condition and baseline. .............. 114
xv
Table 35. Braking time (s) values by stretching condition and baseline. ................................... 116
Table 36. Concentric time (s) values during the CMJ propulsive phase for each stretching
condition. .................................................................................................................................... 118
Table 37. Eccentric times (s) values by stretching condition. .................................................... 120
Table 38. Rate of Force Development (N/Kg/s) during the Yielding Phase of the CMJ by
stretching condition. .................................................................................................................... 122
Table 39. Rate of Force Development (N/Kg/s) during the Braking Phase of the CMJ by
stretching condition. .................................................................................................................... 124
Table 40. Rate of Force Development (N/Kg/s) during the Eccentric Phase of the CMJ by
stretching condition. .................................................................................................................... 126
Table 41. Rate of Force Development (N/Kg/s) of the Concentric Phase of the CMJ during the
stretching conditions. .................................................................................................................. 128
Table 42. Concentric Peak Force (N) of the CMJ by stretching condition................................. 130
Table 43. Time to peak force (s) values during the CMJ by stretching condition. ..................... 132
Table 44. Peak power (w/kg) values during the CMJ by stretching condition. .......................... 134
Table 45. Peak Velocity (m/s) of the CMJ by stretching condition. ........................................... 136
Table 46. Non-normalized Vertical Displacement Values during the CMJ by stretching
condition. .................................................................................................................................... 138
Table 47. Push-off Distance (cm) values by stretching condition. ............................................. 141
Table 48. Push-off Distance (%MVC) normalized by baseline values by stretching conditon. 142
Table 49. Effect size of Push-Off Distance (%MVC) by stretching condition. ......................... 143
Table 50. Non-Normalized SQJ (cm) values by stretching condition for all subjects and by
groups. ......................................................................................................................................... 146
xvi
Table 51. Normalized Values of SQJ by baseline values for all subjects and subsets by stretching
condition. .................................................................................................................................... 147
Table 52. Non-Normalized values for Depth Jump (DJ) by group and by stretching condition. 150
Table 53. Normalized Depth Jump values by baselinev values by group and stretching
conditions. ................................................................................................................................... 151
Table 54. Non-Normalized DJ values for all subjects and by groups by stretching condition. .. 154
Table 55. Normalized DJ values by baseline values by groups and stretching condition. ......... 155
xvii
List of Figures
Figure 1. Conceptualization of previous findings on vertical jump performance after specific
stretching protocol ........................................................................................................................ 15
Figure 2. Comparison of Mean Vertical Jump Height (cm) after Dynamic warm-up and Two
PAP protocols. .............................................................................................................................. 20
Figure 3. Ultrasonogram representation of the vastus lateralis (Ticinesi et al., 2017). ................ 21
Figure 4. Jump height values (cm) in the CMJ for baseline, ST, DY, ST+DY, and DY+ST
protocols. ....................................................................................................................................... 24
Figure 5. The Mechanical model; PEC = Parallel Elastic Component, SEC = Series Elastic
Component, CC = Contractile component (Haff & Triplett, 2015). ............................................. 28
Figure 6.The stretch reflex through the neurophysiological model (Haff & Triplett, 2015). ....... 29
Figure 7. A representation of the SSC muscular actions as suggested by Komi (1984). ............. 31
Figure 8. Variables that interplay to affect and produce an increased muscular force during
stretch-shortening cycle movements. ............................................................................................ 32
Figure 9. Representation of a representative uni-modal vertical jump height; left axis represents
vertical ground reaction force (N) in a blue line, primary right axis represents vertical velocity
(m/s) in yellow line, secondary right axis represent vertical displacement in red. ....................... 44
Figure 10. Illustration of the Static and Dynamic Stretches that were performed at the different
muscle groups. .............................................................................................................................. 46
Figure 11. Sample flowchart of the individual session within the proposed design..................... 50
Figure 12. Statistical decision tree for parametric and non-parametric data. ............................... 53
Figure 13. Distribution of Normalized Peak Torque Extension / BW (%MVC) by the stretching
conditions. ..................................................................................................................................... 55
xviii
Figure 14. Q-Q probability plot of Peak Torque Extension by the stretching conditions. ........... 56
Figure 15. Distribution of CMJ Height (m) by the stretching conditions. .................................... 57
Figure 16. Q-Q probability plot of CMJ height by the stretching conditions. .............................. 58
Figure 17. Interaction plot of Peak Torque Knee Extension by BW (%MVC). .......................... 62
Figure 18. Interaction plot of Peak Torque Knee Extension by BW (%MVC) by group............. 62
Figure 19. Normalized Peak Torque Knee Extension by BW (%MVC) by stretching condition
for all subjects. .............................................................................................................................. 63
Figure 20. Interaction plot of normalized peak torque flexion (%MVC) by stretching condition.
....................................................................................................................................................... 67
Figure 21. Interaction plot of normalized peak torque flexion (%MVC) by condition and group.
....................................................................................................................................................... 67
Figure 22. Peak torque flexion / BW normalized by baseline values (% MVC) by stretching
condition. ...................................................................................................................................... 68
Figure 23. Interaction plot for average power knee extension (%MVC) by stretching conditio . 71
Figure 24. Interaction plot for average power knee extension (%MVC) by period and group. ... 71
Figure 25. Average Knee Extension Power normalized by Baseline values (% MVC). .............. 72
Figure 26. Interaction plot for average power knee flexion (%MVC) by stretching condition. ... 76
Figure 27. Interaction plot for average power knee flexion (%MVC) by period and group. ....... 76
Figure 28. Average Knee Power Flexion (%MVC) by stretching condition. ............................... 77
Figure 29. Interaction Plot of Average Peak Torque Extension (%MVC) by stretching condition.
....................................................................................................................................................... 81
Figure 30. Interaction Plot of Average Peak Torque Extension (%MVC) by group and stretching
condition. ...................................................................................................................................... 81
xix
Figure 31. Boxplot of Average Peak Torque Extension (%MVC) by stretching condition. ....... 82
Figure 32. Interaction Plot of Average Peak Torque Knee Flexion (%MVC) by stretching
condition. ...................................................................................................................................... 86
Figure 33. Interaction Plot of Average Peak Torque Knee Flexion (%MVC) by stretching
condition and by group. ................................................................................................................ 86
Figure 34. Average Peak Torque Knee Flexion (%MVC) by Stretching Condition. ................... 87
Figure 35. Interaction plot for EMG (%MVC) of the Vastus Lateralis by period and group.Figure
36. EMG (%MVC) of the Vastus Lateralis by period and group. ................................................ 90
Figure 37. Interaction plot for EMG (%MVC) of the Vastus Medialis Oblique by period and
group. ............................................................................................................................................ 92
Figure 38. EMG (%MVC) of the Vastus Medialis Oblique by period and group. ....................... 92
Figure 39. Interaction plot for EMG (%MVC) of the rectus femoris oblique by period and group.
....................................................................................................................................................... 94
Figure 40. EMG (%MVC) of the rectus femoris by period and group. ........................................ 94
Figure 41. Interaction plot for EMG (%MVC) of the Bicepss femoris by period and group. ...... 96
Figure 42. EMG (%MVC) of the Bicepss femoris by period and group. ..................................... 96
Figure 43. Interaction plot for EMG (%MVC) of the semitendinosus by period and group. ....... 98
Figure 44. EMG (%MVC) of the semitendinosus by period and group. ...................................... 98
Figure 45. Interaction plot of normalized CMJ height (%MVC) by period and group.
Figure 46. Boxplot of normalized CMJ height (%MVC) for all subjectsFigure 47. Boxplot of
non-normalized Countermovement Jump Height (cm) by stretching condition. ....................... 102
Figure 48. boxplot of RSImod values for all stretching conditions. ........................................... 107
Figure 49. RSImod normalized by baseline condition by stretching condition. ......................... 109
xx
Figure 50. Boxplot of CMJ Contact time (s) by stretching conditions. ...................................... 111
Figure 51. Boxplot of Yielding time (s) during CMJ by stretching condition and baseline....... 113
Figure 52.Boxplot of Braking time (s) during CMJ by stretching condition and baseline. ........ 115
Figure 53. Boxplot of Concentric (Propulsive phase) time (s) during each stretching condition.
..................................................................................................................................................... 117
Figure 54. Boxplot of eccentric time (s) values by stretching condition. ................................... 119
Figure 55. Rate of Force Development during the Yielding Phase by stretching condition. ..... 121
Figure 56. Rate of Force Development (N/Kg/s) of the Braking Phase of the CMJ during the
stretching conditions. .................................................................................................................. 123
Figure 57. Rate of Force Development (N/Kg/s) of the Eccentric Phase of the CMJ during the
stretching conditions. .................................................................................................................. 125
Figure 58. Rate of Force Development (N/Kg/s) of the Concentric Phase of the CMJ during the
stretching conditions. .................................................................................................................. 127
Figure 59. Concentric Peak Force (N) of the CMJ by stretching condition. .............................. 129
Figure 60. Time to peak force (s) during the CMJ by stretching condition................................ 131
Figure 61. Peak power (w/kg) during the CMJ by stretching condition. .................................... 133
Figure 62. Peak velocity (m/s) of the CMJ by stretching condition. .......................................... 135
Figure 63. Vertical Displacement (Depth) of the Center of Mass (cm) during the CMJ by
stretching condition. .................................................................................................................... 137
Figure 64. Interaction plot of Push-off Distance (%MVC) by stretching condition for all subjects.
..................................................................................................................................................... 139
Figure 65. Interaction plot of Push-off Distance (%MVC) by stretching condition by group. .. 139
Figure 66. Boxplot of Push-Off Distance (%MVC) by stretching condition. ............................ 140
xxi
Figure 67. Interaction plot of normalzied SQJ for all subjects by stretching condition. ........... 144
Figure 68. Interaction Plot of SQJ by trained and untrained subjects by stretching condition. .. 144
Figure 69. Boxplot of SQJ normalized values (%MVC) for each stretching condition. ............ 145
Figure 70. Interaction plot of DJ for all subjects by stretching conditions. ................................ 148
Figure 71. Interaction plot of DJ for trained and untrained groups by stretching conditions. .... 148
Figure 72. Boxplot of normalized Depth Jump (DJ) by baseline values by stretching condition.
..................................................................................................................................................... 149
Figure 73. Interaction plot of RSI for all subjects by stretching condition. ................................ 152
Figure 74. Interaction plot of RSI by training status by stretching condition............................. 152
Figure 75. Boxplot of normalized RSI values (%MVC) by baseline values by stretching
condition. .................................................................................................................................... 153
1
Chapter 1: Introduction
A warm-up is an essential – and most necessary – component of any sport, fitness, or
physical activity-related training session. A well-designed warm-up, based on solid scientific
principles, has been shown to improve faster muscle contraction of the agonist and relaxation of
the antagonist muscles (Samson et al., 2012), improve overall strength and muscular power
through increased body temperature (Bergh & Ekblom, 1979), increase rate of force
development and reaction time (Dalrymple et al., 2010), improve psychological preparedness (de
Oliveira & Rama, 2016), enhance metabolic reactions (de Weijer et al., 2003), improve vertical
jump performance (Montalvo & Dorgo, 2019), and reduce the likelihood of injury (Peck et al.,
2014).
The goal of a warm-up is to prepare the individual for the main physical activity or sport.
Ideally, the warm-up session is composed of two subcomponents: a general warm-up and a
specific warm-up (Peck et al., 2014). The general warm-up is usually composed of a light-jog or
walk, whereas, the specific warm-up typically includes stretching activities. Typically, two
stretching modalities are used during the specific warm-up period: static or dynamic. A static
stretch is a muscular elongation performed at slow and constant velocity until a desired joint
angle position is reached; the new stretched position is then held for 15 to 30 seconds (Peck et
al., 2014). Previously, static stretching has been shown to improve the range of movement
(ROM) (Di Cagno et al., 2009). Dynamic stretching is a more functional stretching modality,
whose primary aim is to resemble the movements of the activity to be performed (Mann, DP., &
Jones, MT., 1999). Dynamic stretching is a continuous and active muscular elongation in where
– and in contrast to static stretching – there is no relaxation of the muscle or position to be held
(Dallas et al., 2014; Enoka, 2008). Dynamic stretching has been shown to improve muscular
2
power, strength, jumping abilities, and muscular activation through surface EMG, and ROM in
volleyball (Dalrymple et al., 2010a), football (Holt & Lambourne, 2008), baseball (Frantz &
Ruiz, 2011), soccer (Turki-Belkhiria et al., 2014), gymnastics (Montalvo & Dorgo, 2019), and
recreational athletes (Peck et al., 2014). More recently, studies have shown dynamic stretching to
be more effective than static stretching in measures of strength, power, and speed (McGowan,
Pyne, Thompson, & Rattray, 2015). Finally, and in contrast to dynamic stretching, static
stretching has been shown to have a greater effect on flexibility than dynamic stretching if done
after the training session, but not as a part of the warm-up session (Dallas et al., 2014).
Furthermore,
The effects of antagonist static stretching have been previously studied, with findings
indicating that it is a viable option to improve agonist muscular contraction (Maia et al., 2014;
McBride et al., 2007; Miranda et al., 2015; Sandberg et al., 2012). However, its benefits have
been only shown to be on athletic and highly active recreational subjects. Moreover, it is
unknown if the effects found on antagonist stretching can be magnified if they are performed in
conjunction with static or dynamic agonist stretching. Furthermore, the mechanical changes from
the muscular system are also unknown. Additionally, it is unknown if these findings are specific
to individual training history.
1.1 Statement of the Research Problem
Currently, there are contradictory and inconclusive finding on the utilization of static and
dynamic stretching, or their combination on isokinetic strength, muscular activation, and vertical
jump performance.
1.2 Purpose of the Study
3
The purpose of this project is to determine the effects of different stretching protocols on
isokinetic strength, vertical jump performance, reactive strength index, and muscular activation
of the lower leg.
1.3 Definition of terms
In this sub-section, the concepts and terms that are related to this project will be defined.
More specifically, the characteristics of “Stretching”, “Strength”, “Muscular Power”, and
“Reactive Strength Index” as they relate to human sports performance.
1.3.1 Definition of Stretching
Stretching can be defined as the ability of the muscle to be elongated without tearing or
breaking. Stretching can be sectioned into four major modalities: Static, Dynamic, Ballistic, and
Proprioceptive Neuromuscular Facilitation (PNF). Static stretching is defined as a stretch in
where the muscular elongation of the desired angle is sustained for more than 15 seconds to
more-less 1 minute. Dynamic stretching is defined as a continuous and dynamic elongation of
the muscles, where the primary aim of these stretching exercises is to mimic the movements to
be used during the sport or physical activity. Ballistic stretching is defined as a bounce-like
elongation of the muscles, in where the desired angle is reached, and continuously performing a
bounce-like motion between that position and few degrees before that. Finally, PNF is defined as
a method of elongation in where a stretching position is achieved and then a muscular
contraction; PNF has two methods, contract-relax-agonist-contract (CRAC) method, and
contract-relax methods. For the purpose of this Dissertation, only static and dynamic stretching
will be used as these methods are commonly used as part of the warm-up period prior to the sport
or physical activity to be performed.
4
1.3.2 Definition of Muscular Strength
Muscular Strength in the context of sport-performance can be defined as the ability of a
single or multiple muscle groups to exert a force against an external resistance (Hamill &
Derrick, 2015). Newton’s second law indicates that F = m·a, where F = to the applied force
measured in newtons (N), m = mass of the external resistance measured kilograms (kg), and a =
acceleration of the external resistance measured in meters per second2 (m • s-2). However, due to
the inherent nature of this project, we will refer to strength as the maximal weight an individual
can lift during a barbell squat (1RM).
1.3.3 Definition of Vertical Jump performance and Reactive Strength Index
Vertical Jump performance is regarded as a test of explosive performance (Papaiakovou,
2013). Vertical jump height can be obtained by the individual’s velocity at take-off, through
flight-time, impulse-momentum theorem, and displacement of the center of mass through motion
capture (Dalrymple et al., 2010; Moir, 2008). With take-take off velocity being one of the most
common methods to estimate vertical jump height, as follows:
JH = 𝑇𝑎𝑘𝑒𝑜𝑓𝑓 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦2
2∗𝑔𝑟𝑎𝑣𝑖𝑡𝑦
The Reactive Strength Index (RSI) is a measure used to evaluate stretch-shortening cycle
activity through plyometric exercises in sports (Ebben & Petushek, 2010a). Typically, RSI is
measured using a plyometric box of around 12 inches or 30 cm using Depth Jumps as a primary
exercise. Upon the subject completes a Depth Jump, then the following calculation is used to
estimate RSI (McMahon, Lake, & Comfort, 2018)
RSI = Contact time during the vertical jump / Jump Height
1.4 Hypotheses
5
Null Hypothesis: (HƟ)
Dynamic stretching of the agonist and antagonist muscles does not improve isokinetic
peak knee torque extension, power, muscle activation of the lower leg, and vertical jump height
to a greater degree than a static stretching condition.
Alternative Hypothesis: (H1)
Dynamic stretching of the agonist and antagonist muscles improves isokinetic peak knee
torque extension, power, muscle activation of the lower leg, and vertical jump height to a greater
degree than a static stretching condition.
Null Hypothesis: (HƟ)
Dynamic stretching of the agonist muscles followed by a static stretching of the
antagonist muscle does improves isokinetic peak knee torque extension, power, muscle
activation of the lower leg, and vertical jump height to a greater degree than a static stretching
condition.
Alternative Hypothesis: (H2)
Dynamic stretching of the agonist muscles followed by a static stretching of the
antagonist muscle improves isokinetic peak knee torque extension, power, muscle activation of
the lower leg, and vertical jump height to a greater degree than a static stretching condition.
1.5 Significance of the problem
Stretching is an essential component of every warm-up and training session. Finding the
most appropriate stretching protocol could promote minor acute improvements in strength,
power, and speed. Empirically, it has been known that individuals that are stronger or exhibit
greater abilities to produce force have greater probabilities to be successful in sports or physical
6
acitivities. Thus, minor acute increases seen from a good solid stretching protocol could – in
theory – result in greater physical performance. Furthermore, athletes and sports enthusiasts who
are competitively active look to get minimal advantage when it comes to physiological
performance. Inefficient training methodologies coupled with technical flaws can lead to these
individuals not reaching their goals, thus, discovering the best practices could lead to improving
the chances of these individuals to achieve their goals.
7
Chapter 2: Review of the Literature
The purpose of this chapter is to review relevant literature on static and dynamic
stretching modalities and their effects on strength, power, range of motion, vertical jump height,
speed, muscular activation, and methods to measures vertical jump performance. In addition, this
chapter aims to review previous literature on antagonist stretching and provide a theoretical
background for the proposed study of this Dissertation.
1.6 Static Stretching
Static stretching is defined as a slow-paced stretching at a constant velocity that is
performed until the desired angle is reached, and then this desired position is held for 15 to 30
seconds (Beedle et al., 2008). Historically, and for many years, static stretching has been a
desired pre and post stretching routine; this position has been changing through recent years, and
static stretching is now a preferred stretching modality post-exercise. Static stretching has been
shown to improve the range of motion (ROM) (Samson et al., 2012). A recent meta-analysis
determined that static stretching inhibits maximal muscular performance using a compilation of
104 studies with 61 data points for strength, 12 for power, and 57 for explosive performance
(Simic et al., 2013). Often, statistic stretching has been believed to reduce the risk of injury in
many sports. However, this has been to be proven to be minimal, to about a 5% reduction in risk
of injury (Andersen, 2005). Moreover, a recent review of the literature also points out that short-
duration static stretching can induce no changes or little changes (1 to 2 %) in muscular strength
and power, whereas in longer duration static stretching can impair strength and power up to 4.0-
7.5% (Chaabene et al., 2019); this highlights the importance of time duration during the static
stretching and its negative effects. Furthermore, it has been found that static stretching improves
8
ROM better than any other stretching modality, however, it also inhibits muscular power, force,
torque, and overall explosive performance.
1.7 Dynamic Stretching
Contrary to static stretching, dynamic stretching is a more functional stretching modality,
which primary aim is to resemble the movement of the activity to be performed (Mann, DP., &
Jones, MT., 1999). Dynamic stretching is a continuous and active muscular elongation in where
– and in contrast to static stretching – there is no relaxation of the muscle or position to be held
(Dallas et al., 2014) Dynamic stretching has been shown to improve muscular power, strength,
jumping abilities, and ROM (Peck et al., 2014) in volleyball (Dalrymple et al., 2010a), football
(Holt & Lambourne, 2008), baseball (Frantz & Ruiz, 2011), soccer (Turki-Belkhiria et al., 2014),
and recreational athletes (Gogte et al., 2017). More recently, studies have shown dynamic
stretching to be more effective than static stretching in measures of strength, power, and speed
(McGowan et al., 2015). Finally, static stretching has been shown to have a greater effect on
flexibility than dynamic stretching if done after the training session but not as a part of the warm-
up session (Dallas et al., 2014).
1.8 Antagonist Static Stretching
In previous years, antagonist stretching has gained some attention (Latash, 2018; Miranda
et al., 2015; Sandberg et al., 2012; Serefoglu et al., 2017). The antagonist muscles are opposite
muscles to the primary movers. For any action to occur – meaning muscular contraction of the
agonist or acting muscles – the antagonist must relax or reduce its activation. Moreover, any
activity of the antagonist while the agonist muscles are in action will impede and/or slow down
the muscular action of the agonist. In other words, there seems to be an inverse relationship
9
between the antagonist and agonist muscles when the agonist muscles are in action. Previous
studies on antagonist stretching are summarized in Table 1.
Recently, it has been proposed that static stretching inhibits muscular action in several
ways: relaxation of the muscle and decreased muscular stiffness (Evetovich et al., 2003; Kubo et
al., 2001), decreased muscular activity, decreasing motor unit activation, potential muscle
damage due to the duration of the stretch, and increase the rate of fatigue (Beedle et al., 2008).
Furthermore, the central idea of performing static stretching of the opposite muscles revolves in
that, if it’s possible to further diminish the activation and increasing the relaxation of the
opposite (antagonist) muscles, this will lead to greater muscular activation of the agonist
muscles. This idea was early explored in a study where the researchers aimed to study the effect
of stretching on agonist-antagonist muscle activity and muscle force output during single and
multiple joint isometric contractions (McBride et al., 2007). Using 3 sets of 30sec of static
stretching of the Quadriceps Femoris muscles (agonists), it was found that the antagonist muscles
(Biceps Femoris) activation decreased similarly to the agonist muscles. In addition, it was
observed that the rate of force development also decreased, and it was concluded that these
decrements in muscle force capabilities, lasted up to 16 min after the stretching intervention
(McBride et al., 2007).
The idea of only stretching statically the antagonist muscles was later explored in a study
using a 30s static stretch of the hip flexors and dosiflexors for 3 times with 20 second rests
between stretches (Sandberg et al., 2012). Results showed that static stretching of the antagonist
improved Fast KE during the isokinetic strength test, with improved Vertical Jump, and Power
when compared to a non-stretching trial. These results are of great importance, as they support
10
the theoretical idea that antagonist inhibition could lead to greater activation of the agonist
muscles (Sandberg et al., 2012).
In addition to acute effects observed after antagonist stretching, this stretching modality
has been also used during inter-rest periods to enhance muscular contraction of the agonist
during the work period. For example, a study observed an increased number of repetitions using
intra-res static stretching. During the rowing exercise, there was increased activation of the
latissimus dorsi during exercise using a 40s static stretch of the horizontal adductor muscles at
inter-resting periods (Miranda et al., 2015). Similarly, another study Miranda, De Freitas Maia,
Andadre Pax, & Acosta (2015) also observed increased repetitions using intra-rest antagonist
stretching (Miranda et al., 2015). Using one set of 40s stretching of the pectoralis major, it was
observed an increased muscle activity of the latissimus dorsi and Bicepss brachii during the
seated row exercises.
Opposing previous findings on agonist stretching, another study found that neither a static
or dynamic stretching of the antagonist effect isokinetic peak torque or EMG activities
(Serefoglu et al., 2017). In this study, 4 conditions were studies: 1) static stretching of the
agonists, 2) static stretching of the antagonist, 3) dynamic stretching of the agonists, and 4)
dynamic stretching of the antagonists. The negative findings of the antagonist group can be
partially attributed to the co-activation of the muscles. That is, during a dynamic movement there
is a co-activation of both muscles: the agonist and antagonists (Latash, 2018). It was suggested
that this co-activation is necessary to provide movement and energy efficiency. This means that
during the dynamic or static stretching regardless of stretching modality, the effects of each
condition transferred to the antagonist muscles due to the co-activation effect, however, this does
not explain why there were no differences in the static or dynamic agonists groups. Furthermore,
11
it is also to notice that a single stretching modality per muscle group was used, and the
combination of stretching modalities on the agonist-antagonist complex was not studied in this
study. Furthermore, we aim to fill the gap in this area by studying static and dynamic stretching
on the agonist-antagonist complex and combining these modalities by inducing dynamic
stretching of the agonists and static of the antagonists.
Finally, there is supporting data regarding the use of static stretching on the antagonist
muscles. Although the mechanisms for which static stretching diminishes muscular activation of
the antagonist muscles are unknown are possible explanations for this observable effect. As
previously mentioned, it has been observed that static stretching creates a relaxation of the
muscle with decreased muscular stiffness (Evetovich et al., 2003; Kubo et al., 2001), decreased
muscular activity, and motor unit activation, and creates muscle damage due to the duration and
magnitude of the stretch, while increasing fatigue (Beedle et al., 2008).
To date, several steps need to be taken before data on agonist stretching and stretching
modalities is conclusive. Furthermore, the proposed experiments aim to explore the differences
between different stretching modalities and the use of combined static and dynamic stretching.
Also, it is important to study the differences between physically active and trained individuals.
Finally, it will be also of interest to study how muscular architecture could explain the effects
seen after a stretching session.
12
Table 1. Summary of major findings of antagonist-stretching conditions.
Author Title Population Design stretching condition Outcome
McBridge,
Deane, &
Nimphius
(2007)
Effect of stretching on agonist-
antagonist muscle activity and
muscle force output during
single and multiple joint
isometric contractions
8 males
(21.4 ± 0.7
yrs.) active
college
males
Single Session,
10 min rest
between
conditions
3 sets of 33s stretch of
the quads (total of
270s); reps were
separated by 30s rest
and sets by 3 min
Reduced rate of
force development in
the isometric squat
and isometric knee
extension and
reduced peak force
in the isometric knee
extension
Sandberg et
al., (2012)
Acute Effects of Antagonist
Stretching on Jump Height,
Torque, and
Electromyography of Agonist
Musculature
16 men
(22.5 ± 4.9
yrs.) active
college
males
Within-group
design. Two
conditions: 60
degrees/sec and
300 degrees/sec
30s for 3 times with 20
second rests between
stretches of the hip
flexors and dosiflexors
Improved Fast KE
(8.6%), Vertical
Jump (2.1%), and
Power (1%)
Paz, Maia,
Whinchenster,
& Miranda
(2013)
Strength performance
parameters and muscle
activation adopting two
antagonist stretching methods
before and between sets
15 (35.1 ±
2.3 yrs.)
Resistance
trained men
Randomized
cross over design
(within groups).
Three groups: 1)
Traditional (T),
Antagonist static (AS), and
Antagonist PNF
(APNF)
Traditional: 3 sets reps
to failure followed by
2-min passive rest
interval. AS: The
researcher applied 1
set of 40s static stretch
of the horizontal
adductor muscles
followed by exercise.
APNF: one set of 40s
(6sec of isometric by 4
sec of relaxing) of the
horizontal adductor
muscles followed by
row exercise.
Increased number of
repetitions for the
static stretching
groups. Increased
Latissimus dorsi for
the static stretching
and PNF groups
compared to the
traditional set
13
Author Title Population Design stretching condition Outcome
Miranda, De
Freitas Maia,
Andadre Pax,
& Acosta
(2015)
Acute Effects
of Antagonist Static Stretching
in the Inter-Set Rest Period on
Repetition Performance and
Muscle Activation
10 men
(22.4 ± 0.9
yrs.) with
2.8 ± 0.9
yrs. of
experience
Randomized
crossover. Two
groups: 1)
passive recovery
(PR) and 2)
Antagonist
stretching (AS)
PR: 3 reps to failure of
seated row (SR), with
2min rest interval. SA:
one set of 40s
stretching of the
pectoralis major
followed by one set of
SR at inter-rest
Increased repetitions.
Increased muscle
activity of the
latissimus dorsi and
Bicepss brachii
(Wakefield &
Cottrell,
2015)
Changes in Hip Flexor Passive
Compliance Do Not Account
for Improvement In Vertical
Jump Performance After Hip
Flexor Static Stretching
15 men
(24.1 ± 2.4
yrs.)
Blocked Random
Design. Three
groups: Control,
3 conditions: No
stretch (control), Hip
Flexor Stretch (HFS)
and Hip Extensor
Stretch (HES)
HFS condition
increased vertical
jump about 1.36% ±
0.96 when compared
to CON and 1.74% ±
0.65 HES
Serefoglu,
Sekir, Gur, &
Akova (2017)
Effects of Static and
Dynamic Stretching on the
Isokinetic Peak Torques and
Electromyographic Activities
of the Antagonist Muscles
20
recreationall
y trained
males (24.8
± 2.8)
Randomized
blocked design. 5
groups: 1)
control, 2) static
of the
Quadriceps
Femoris, 3) static
of the
hamstrings, 4)
dynamic of the
Quadriceps
Femoris, and 6)
dynamic of the
hamstrings
Static stretching: four
times for 30sec with
20-30 seconds
between repetitions.
Dynamic stretching: 2
seconds contraction,
four times slowly, then
15 times as quickly
and powerful as
possible. Rest interval
between sets was 20-
30sec
Static or Dynamic
stretching of the
antagonist does not
affect isokinetic peak
torque or EMG
activities of the
agonist muscles
14
1.9 Conceptualization of Static and Dynamic stretching findings on Muscular Strength and
Power Performance
As described in the previous two sub-sections, static and dynamic stretching have been
extensively been studies, more specifically, it is apparent that dynamic stretching benefits
muscular power in a greater capacity than static stretching. In addition, static stretching appears
to affect positively muscular power in the vertical jump. However, it is unknown how the
combination of these modalities, using static and dynamic stretching at the agonist-antagonist
complex would affect muscular power through the vertical jump (figure 1).
15
Figure 1. Conceptualization of previous findings on vertical jump performance after specific stretching protocol
16
1.10 Proposed Mechanisms
Currently, there are no unified theories that support the benefits of either static or
dynamic stretching. However, static and dynamic stretching have different effects on the
neuromuscular and physiological systems. These effects can be explained by the
following factors: Neural adaptations increased blood flow and heart rate along with
increased muscle and core temperature, changes in the muscle-tendon unit stiffness, post-
activation activation, and changes in muscle architecture. The following section aims to
answer the above questions shortly and concisely.
1.10.1 Increased Blood Flow, Heart Rate, Muscle, and Core Temperature
The dynamic nature of the dynamic stretch, which is composed of active fast – in
a controlled manner – movements, allows for the heart rate and overall blood flow to
increase, and as in result, muscular and core temperature increases. On the contrary,
static stretching involves holding a position statically for a period of time (> 30 seconds),
which results in little to no effects on heart rate and body temperature. In an early study,
compare the heart rate and temperature of dynamic and static stretching. Results indicate
heart rate and core temperature to be significantly higher in the dynamic group when
compared to the static group (Fletcher, 2010). Also, muscle temperature has been shown
to influence positively jumping and sprint performance (Bergh & Ekblom, 1979; Mohr et
al., 2004).
1.10.2 Neural Adaptations to Stretching
Increases in muscular performance through stretching protocols can be explained
by neural changes through motor unit activations and/or reflex sensitivity (Condon &
Hutton, 1987). Neural changes can be observable through Electromyography (as
17
described in question 2 of this document). Increased neural conduction has been
attributed to be an effect of increased body temperature (Dallas et al., 2014).
Furthermore, it has been suggested that due to the muscular relaxation that is inherent of
the static stretching, there is a decreased Hoffman reflexes (H-reflexes) (Condon &
Hutton, 1987). H-reflexes are a measurement of muscle excitability, thus, any alteration
of these structures would affect muscular performance (Moore & Hutton, 1980). Finally,
there appears that there is no research on neural adaptations and dynamic stretching
(Page, 2012), although it could be hypothesized that the dynamic nature – contrary to the
static stretching – of rapid, but controlled, a muscular contraction would not have the
similar effects on H-reflexes as observed in the static stretching. More research needs to
be performed in this area.
1.10.3 Muscle-Tendon Unit (MTU) Stiffness
A secondary mechanism through which stretching might affect performances is
through the Muscle-Tendon Unit (MTU) stiffness. Due to the increased body
temperature, there is a decrease in muscular viscosity (Fletcher & Monte-Colombo,
2010), which leads to decreased MTU resistance, resulting in less resistance by the
working muscles and greater increases in the Range of Motion (ROM) (Opplert &
Babault, 2018). Furthermore, it has been found that greater muscular and tendon stiffness
leads to greater muscular force and power as stiffer muscle/tendons provide a greater
mechanical resistance during contraction (Massey et al., 2017). Thus, any decreases in
MTU stiffness could potentially lead to decreased muscular force. However, these
studies have been correlational and/or are long term interventions (Brumitt & Cuddeford,
2015). Finally, if dynamic stretching increases ROM by decreasing muscular viscosity
18
and MTU stiffness, then there would also be a decrease in force capabilities, but dynamic
stretching has been shown to improve force, power, and speed (Dallas et al., 2014;
Opplert & Babault, 2018). There is an apparent need for more studies in this area to
answer this question.
1.10.4 Post-Activation Potentiation
Post-Activation Potentiation can be defined as the acute improvement of speed,
power, and strength that are the resultant of a previous maximum voluntary contraction in a
biomechanically similar paired activity. Researchers have attempted to explain PAP through
various physiological mechanisms. Currently, there are two possible mechanisms believed to
generate a PAP effect: (1) Increased phosphorylation of the myosin heavy chain (Hamada et
al., 2000; Rixon et al., 2007); and (2) increased H-reflex activity from the nervous system
(Hodgson et al., 2005). The first theory involves increased phosphorylation of the myosin
regulatory light chain during a maximum voluntary contraction (MVC). The phosphorylation
of the myosin chain allows the actin and myosin binding to be more responsive to the
calcium ions released from the sarcoplasmic reticulum, which leads to several microcellular
events that ultimately lead to enhanced force muscle production at the structural level of
muscle (Hamada et al., 2000). The greater the muscle activation, the greater the duration of
calcium ions in the sarcoplasm, hence, the greater the phosphorylation of the myosin light
chain protein (Rixon et al., 2007). As a result, faster contraction rates and faster rates of
tension develop (Chiu et al., 2003). The second theory involves Hoffmann Reflex (H-
Reflex). The H-reflex is an excitation of a spinal reflex elicited by the Group Ia afferent
muscle nerves; these are specialized nerves conducting impulses to the muscle. It is theorized
19
that the PAP intervention enhances the H-reflex, thus increasing the efficiency and rate of the
nerve impulses to the muscle (Hodgson et al., 2005).
Multiple methods have been used to induce PAP; methods include the use of
weights, boxes, sleds, and resistance bands. The most common method is complex
training, where the individual uses heavy-load exercises followed by an explosive
movement (Seitz & Haff, 2016). Furthermore, dynamic stretching has also been shown to
improve muscular performance (Dallas et al., 2014). In addition, one of our latest
projects aimed to observe the effects of two PAP methods and a dynamic stretching
protocol on vertical jump height. 19 Kinesiology students participated in this randomized
blocked design study. The final analysis through an ANOVA with repeated measures
indicates that a dynamic warm-up potentiates the vertical jump height significantly,
although not as high as the other PAP protocols (Figure 2). As PAP is dependent on the
intensity of the muscular contraction prior to the explosive movement, perhaps the two
modalities that utilized heavier loads induced greater vertical jump effects than just a
dynamic warm-up (De La Torre, 2019). However, it is to notice that the effects of
dynamic warm-up vs no warm-up are evident and significant.
20
Figure 2. Comparison of Mean Vertical Jump Height (cm) after Dynamic warm-up and Two
PAP protocols.
1.10.5 Muscular Architecture
Ultrasonography has been used as method to study in-vivo muscular architecture. This
non-invasive technique allows for the measurement of pennation angle, fascicle length, cross
sectional area, and aponeurosis (Figure 3). The ultrasonography technique has been shown to be
an effective and reliable when compared to MRI measures and has a great intra-reliability; the
validity and reliability for the vastus lateralis has previously been shown to be moderately-high
(Pennation angles: ICC = 0.51–1.00, CV = 0.0–7.5%, SEM = 0.2–1.2°, and SEM% = 5.0–10.9%
and fascicle lengths: ICC = 0.62–0.99, CV = 0.0–6.8%, SEM = 0–17 mm, and SEM% = 4.3–
21
14.2%) (Chleboun et al., 2007; Chleboun et al., 2001); validity and reliability for the medial head
of the gastrocnemius also showed to be high (Pennation angles: CMC = 0.87–0.90, ICC = 0.85–
1.00, CV = 0.0–9.8%, and SEM = 0.2° and fascicle lengths: CMC = 0.93–0.95, ICC = 0.81–
0.99, r = 0.96, CV = 0.0–9.8%, and SEM = 0 mm) (Aggeloussis et al., 2010).
Figure 3. Ultrasonogram representation of the vastus lateralis (Ticinesi et al., 2017).
Dynamic stretching has been shown to improve performance through several
Static stretching has been shown to reduce pennation angle and increase fascicle length
on the agonist muscles. In short, fascicles are a bundle-like structure of skeletal muscle
fibers that are surrounded by a connective tissue known as perimysium. It is well
established that the length of the muscle fibers is strongly correlated to the shortening
velocity of the muscle fibers. A recent study found that a chronic static stretching
program does not alter muscle architecture (pennation angle, fiber length, muscle
thickness, and fascicle displacement) on the Biceps Femoris and vastus lateralis (e Lima
22
et al., 2015). In addition, and to a great surprise, a recent study on the dynamic stretching
on the plantar flexors also saw no changes in muscular architecture but only in tendon
tissues (Samukawa et al., 2011). Contrary to the previously reported, a recent study on
the Biceps Femoris using passive stretching found that fascicle length and the muscle-
tendon unit do change when the hip is flexed at least at 45 degrees (Fukutani & Kurihara,
2015). Furthermore, data appears to be limited in this area and the authors conclude that
different muscle groups should be investigated. The experimental part of this study aims
to study if muscular architecture changes with static or dynamic stretching, but a greater
volume (5 repetitions of 30 seconds per muscle group), than 3 repetitions as the previous
studies reported. Also, we will also be aiming to study the effects of stretching on the
antagonist to observe –if any- changes in muscular architecture.
1.10.6 Familiarization and Neural stimulation and inhibition
Another theory that might account for the positive changes are that dynamic stretching
creates a familiarization effect through induced neural stimulation and inhibition. One of the
reasons for this is that dynamic stretching is performed with a close replication of the sport
movements or physical activity to be performed. Furthermore, due to this dynamic interaction
between the movements, it is believed that the muscle spindles are stimulated, causing an
increased muscle reflex activity, which leads to greater muscular force production. Also, it
hypothesized that with increased muscle spindle activity there would be an inhibition of the
Golgi tendon, which would facilitate greater force capabilities of the muscle (Opplert &
Babault, 2018).
1.10.7 Performance and Stretching
23
Dynamic stretching has been shown to improve muscular power, strength, jumping
abilities, and ROM (Peck et al., 2014) in volleyball (Dalrymple et al., 2010), football (Holt &
Lambourne, 2008), baseball (Frantz & Ruiz, 2011), soccer (Turki-Belkhiria et al., 2014),
gymnastics (Montalvo & Dorgo, 2019), and recreational athletes (Gogte et al., 2017). More
recently, studies have shown dynamic stretching to be more effective than static stretching in
measures of strength, power, and speed (McGowan et al., 2015). In contrast to dynamic
stretching, static stretching has been shown to have a greater effect on flexibility than dynamic
stretching if done after the training session but not as a part of the warm-up session (Dallas et al.,
2014). In addition to the latest mentioned in the effects of dynamic stretching, recently, previous
work from our lab, researched the effects of static, dynamic, and mixed –static and dynamic-
warm-up protocols on vertical jump height using college-age gymnasts. In this randomized
blocked design, gymnasts performed a general warm-up consisting of a 5-minute self-paced jog,
followed by either a static, dynamic, static + dynamic, or dynamic + static stretching protocol.
Gymnasts performed all of the stretching protocols. The non-parametric equivalent to the
ANOVA with repeated measures, Friedman’s test, and the Dunn post-hoc test revealed that the
Dynamic stretching protocol was more effective than any other warm-up protocol to enhance
vertical jump height with college Gymnasts (Figure 4) (Montalvo & Dorgo, 2019).
24
Figure 4. Jump height values (cm) in the CMJ for baseline, ST, DY, ST+DY, and DY+ST
protocols.
It is evident –through the support of research findings- that dynamic stretching improves
several fitness components if done before the exercise or physical activity as part of the warm-up
session. On the contrary, static stretching appears to be suited for the end of the training session.
Furthermore, limited research on the antagonist, using static stretching, indicates potential
inhibition of muscular force and power. Moreover, one of the aims of this current study is to
determine the effects of antagonist static stretching and agonist dynamic stretching on isokinetic
strength, vertical jump (muscular power), and reactive strength index. This can be explained
through changes in muscular architecture (pennation angle and fascicle length).
25
1.10.8 Post-Activation Potentiation and Complex Training
In short, Post-Activation Potentiation (PAP) is the acute effect of increased physical
performance that is the resultant of a high force maximal voluntary contraction. The effects of
PAP have been early studied in animal and human skeletal muscle (Hodgson et al., 2005). More
recently, several reviews have described PAP effects and its application to sports (Chiu et al.,
2003; Hodgson et al., 2005). In the same lines, meta-analysis has looked upon the differences in
protocols (i.e. reps, sets, intensity, volume, gender, age, training status, etc.) and have shown that
PAP produces a reliable effect in athletes and non-athletes (Seitz & Haff, 2016). Explosive
movements during warm-ups have shown to increase power, due to the induced effect of PAP
(Baker, 2003). The effects of PAP have not only been restricted to laboratory and practice
settings but can be used before competition as well (Tillin & Bishop, 2009). To date, the exact
biological mechanism of PAP has not been defined; however, two major theories might explain
PAP: The first theory involves increased phosphorylation of the myosin regulatory light chain
during a maximum voluntary contraction (MVC). The phosphorylation of the myosin chain
allows the actin and myosin binding to be more responsive to the calcium ions released from the
sarcoplasmic reticulum, which leads to several of microcellular events that ultimately lead to
enhanced force muscle production at the structural level of muscle (Hamada et al., 2000). The
greater the muscle activation, the greater the duration of calcium ions in the sarcoplasm, hence,
the greater the phosphorylation of the myosin light chain protein (Rixon et al., 2007). As a result,
faster contraction rates and faster rates of tension develop (Chiu et al., 2003). The second theory
involves Hoffmann Reflex (H-Reflex). The H-reflex is an excitation of a spinal reflex elicited by
the Group Ia afferent muscle nerves; these are specialized nerves conducting impulses to the
muscle. It is theorized that the PAP intervention enhances the H-reflex, thus increasing the
efficiency and rate of the nerve impulses to the muscle (Hodgson et al., 2005).
26
Recently, the work of Seitz and Haff (2016) reviewed and produced a meta-analysis on the
factors that modulate PAP. This analysis consisted of a review of 47 studies and 135 or
participants per study, which gave a total of 1954 participants overall. The findings of this study
indicated that there is a small effect size (ES = 0.29) on vertical jump, throw (ES = 0.26), and
upper-bod ballistic (ES = 0.23) induced by PAP activities. PAP showed a moderate effect on
sprint (ES = 0.51) speed. In the methods used to induce a PAP effect, Plyometrics showed a
medium effect (ES = 0.47), high intensity conditioning activities (ES = 0.41), moderate-intensity
activities (ES = 0.19), and Isometric activities (ES = 0.09). Within rest periods after a PAP
induced activity, longer rest periods showed a medium effect (ES = 0.44 and 0.49) and shorter
rest periods showed a small effect (ES = 0.17) indicating that individual benefit the most from
longer rest periods after a maximal voluntary contraction or heavily loaded exercise. It was also
found that multiple sets showed a medium effect (ES = 0.69), while single sets (ES = 0.24).
Lastly, it was found that activities that were close to 1RM showed a medium effect (ES = 0.51),
whereas, a small effect was found on sub-maximal (ES = 0.34) loads (Hodgson et al., 2005; Seitz
& Haff, 2016)
1.11 Plyometrics and the Stretch-Shortening Cycle
Plyometrics are an exercise methodology where a pre-stretch of the muscles is utilized to
improve muscular performance. Plyometrics rely on the pre-muscular stretch observed in the
eccentric muscular action to store kinetic energy and utilizes this energy to produce a greater
concentric muscular action. This phenomenon is known as the Short Shortening Cycle (SSC).
The SSC is composed of three basic phases: eccentric, amortization, and concentric.
Furthermore, the SSC is explained by two primary models: 1) The mechanical model, and 2) the
neurophysiological model.
27
1.11.1 The Mechanical Model
The mechanic model is a theoretical model that explains the interaction of the
contractile proteins (Actin and Myosin), a series of elastic components (SEC), and the parallel
elastic component of the muscle (epimysium, perimysium, endomysium, and sarcolemma)
during plyometrics (Haff & Triplett, 2015). During a vertical jump, the subject descends into a
half squat position; the descending portion of the squat results in an eccentric action of the
Quadriceps Femoris, Gluteals, and ankle muscles and musculotendinous junctions. During
such a stage, kinetic energy is stored in muscles. After the eccentric motion of the squat, this
kinetic energy is released through a series of elastic components to increase the force through
the contractile proteins (actin and myosin). Concurrently to the activity of the elastic
components and contractile proteins, there is also a passive increased (minimal) force that is
resultant of the parallel elastic components within the muscles (Haff & Triplett, 2015). To take
advantage of this model, the eccentric motion of the jump needs to be as quick as possible,
otherwise, the kinetic energy stored within the muscles would be dissipated as heat and there
will not be an increase in plyometric activity through the mechanical model (Figure 5).
28
Figure 5. The Mechanical model; PEC = Parallel Elastic Component, SEC = Series Elastic
Component, CC = Contractile component (Haff & Triplett, 2015).
1.11.2 The Neurophysiological Model
The neurophysiological model explains the potentiation generated on the agonist
muscles by the use of the tendo-muscular stretch reflex (Haff & Triplett, 2015). This reflex is
involuntary and is only responsive to the external stimulus provided by the gravity and the pre-
stretch of the muscle. The primary organ dedicated to this potentiation activity are the muscle
spindles; these organs are proprioceptive organs sensitive to the magnitude, intensity, and
magnitude of the muscular stretch. During a muscular stretch, the muscle spindles are
stimulated, and in consequence, there is an increased stretch reflex (Haff & Triplett, 2015).
Subsequently, a signal is sent to the spinal cord through the type 1a nerve fibers. After
synapsing with the alpha motor neurons in the spinal cord, the electrical impulse travels back to
the muscle fibers and causes an involuntary flexible muscle action, which enhances muscular
force/power (Figure 6). Both, the mechanical and neurophysiological models provide a
29
theoretical frame that explains how plyometrics increase muscular power output, however, the
degree to how each individual contributes to the overall picture of plyometric power it is
unknown.
Figure 6.The stretch reflex through the neurophysiological model (Haff & Triplett, 2015).
Finally, previous reports indicate that jumping activities that rely on the use of SSC
through a pre-stretch might improve between 18-20% and 20-30%, and 2-4 cms in the
countermovement jump (Van Hooren & Zolotarjova, 2017). Thus, it is of great importance to
add plyometric training to any sport that relies on a pre-stretch of the muscles prior to the
muscular performance. Furthermore, evidence suggests that adding plyometric training in
conjunction with other exercise modalities, such resistance training can improve substantially
Rate of Force Development (RFD), speed, and muscular power (McKinlay et al., 2018).
1.11.3 Evaluation of the Stretch-Shortening Cycle
SSC can be observed using multiple methods. One of these methods is the Reactive
Strength Index (RSI); the RSI is calculated as follows: RSI = Jump Height / Contact Time. This
30
method involves the use of a box, from where a Depth Jump is performed (Ebben & Petushek,
2010). The depth jump can be performed from multiple boxes to find the greatest RSI; previous
reports have shown the use of multiple boxes height, typically of 30, 45, 60, and 75 cm. A
secondary method involves using the Countermovement Jump (CMJ) height – the Squat Jump
(SQJ) height. The third method also involves the CMJ and SQJ and is calculated as follows: % of
pre-stretch augmentation = ([CMJ – SQJ] * SQJ-1) * 100 (Malisoux et al., 2006). The last two
methods can be done without the use of force plates as no ground reaction forces are part of the
equations, while on the contrary, the RSI requires the use of force plates and/or motion capture to
estimate contact time. Furthermore, because of practicability, and because one of the variables of
interest in the proposed Dissertation project is to determine the interaction of the agonist-
antagonist is necessary to perform and analyze of ground reaction forces. Thus, it will be ideal,
and more practical, to estimate RSI from the ground reaction forces for the proposed
Dissertation.
In conclusion, plyometric activity is seen in sports that involves running and jumping in a
cyclical and/or acyclical manner. Plyometrics enhance the muscular power output generated by
the neurophysiological and mechanical models previously laid out; power can also be generated
at a lower speed with little or no plyometric activity. For example, the clean and jerk seen in
weightlifting use no plyometric activity as there is no pre-stretching of the agonist muscles and
relies mostly on muscular power to achieve the desired lift. Recently, the reactive strength index
(RSI) has been developed and used to provide a measure of the reactive strength elicited by
plyometric activity (Haff & Triplett, 2015). Research has shown the advanced and trained
individuals elicit greater RSI scores than untrained individuals (Kipp et al., 2016). One of the
metrics to be obtained in this project is the RSI. Combined with the overall power output
31
produced by a vertical jump, I seek to observe is there is a change of the RSI after different
stretching protocols due to increased plyometric activity.
1.11.4 Other evidence on the Stretch Shortening Cycle
One of the arguments for the previous biomechanical terms to describe the SSC phases as
eccentric, amortization, concentric, is that for the mechanical term of eccentric motion indicates
that there is muscular contraction during the eccentric motion. Moreover, movements that rely on
the SSC do not have the same characteristics as previously described, as they have a
preactivation phase, stretch, and then a shortening phase (Figure 7) (Komi, 1984). Besides, the
previous models do still apply, however, and for this reason, the previous biomechanical terms
appear to be misleading (Nicol et al., 2006).
Figure 7. A representation of the SSC muscular actions as suggested by Komi (1984).
SSC activity is dependent on a pre-stretch, in where mechanical energy is stored within
the muscle-tendon unit and then released to create a forceful shortening muscular contraction.
The magnitude of the SSC has been studied using muscular isometric contractions. For example,
previous research induced a pre-stretch of the muscles using electrical stimulation of the muscles
32
to find the residual force enhancement (RFE) (Seiberl et al., 2015). This study tested electrically
stimulated muscular pre-stretch, an active (dynamic) stretch, and an isometric contraction at
different join angles of the adductor pollicis muscle; results found that RFE is a significant
contributor to the increased force that is observable after a pre-stretch of the muscles during
active shortening (in an isometric contraction). Previously, other measures – along with RFE –
have been found to influence the observable increased force due to SSC movements: 1) Muscle-
tendon activation dynamics, 2) stretch reflex, and 3) storage and release of the elastic energy
(Figure 8) (Gerrit Jan van Ingen Schenau, 1997).
Figure 8. Variables that interplay to affect and produce an increased muscular force during
stretch-shortening cycle movements.
Further work needs to be done to account for other unexplained variables. For example,
even though in vivo testing of muscular activation and forces has been done, there appears to be
a lack of evidence on the influence of SSC and changes in muscular architecture. As previously
stated, pennation angle, fascicle length, and cross-sectional area of the muscle can all influence
33
muscular force (Blazevich et al., 2006). Thus, if the pre-stretch created by gravity causes an
effect on the mechanical properties of the muscular architecture, we could account for part of the
missing links in the knowledge of SSC. An earlier study looked at the changes in muscular
architecture after an exhaustive stretch-shortening protocol; the group performed 100 single
depth jump from an optimal box height followed by a series of rebounding exercise to a
submaximal height representing 70% of their maximal performance. Results indicate that
exhaustive SSC exercises lead to a decrease in fascicle length within 2hrs to 2 days after the
exercises and increases in muscle thickness 2 days after the SSC exercises (Ishikawa et al.,
2006). However, aside from this study, no study appears to be done on the muscular architecture
immediately after or during SSC exercises.
1.12 Measuring the Vertical Jump through Force Plates
Currently, there multiple ways to estimate vertical jump height, these methods include
motion capture, force plates, vertec, jump mats, photoelectric cell devices, video applications,
bar velocity, inertial measuring units, and/or measuring tapes (Buckthorpe et al., 2012; Castagna
et al., 2013; Dias et al., 2011; Garcia-Ramos et al., 2015; Glatthorn et al., 2011; Hatze, 1998;
Leard et al., 2007; Montalvo et al., 2021). Generally, motion capture and force plates are
considered to be the gold standard and/or criterion devices for validity purposes (Hatze, 1998).
Usually, when using motion capture, a single marker is placed in the sacrum; to estimate vertical
jump height, the total displacement of the marker can be computed from the standing position of
the subject minus the maximum displacement of the marker, resulting in the total displacement
of the center of mass. In addition, force plates can be utilized to estimate vertical jump height
using different methods: flight-time, the velocity of the center of mass or take-off velocity, the
work-energy momentum method, the impulse-momentum method, and adding the center of mass
34
to the take-off velocity method (TOV) (Hamill & Derrick, 2015; Linthorne, 2001). The flight-
time method utilizes the time in where the individual is suspended in time to calculate vertical
jump height.
And can be calculated as follows:
Jump Height = 𝐺𝑟𝑎𝑣𝑖𝑡𝑦∗ 𝐹𝑙𝑖𝑔ℎ𝑡 𝑇𝑖𝑚𝑒2
8
Additionally, the velocity of the center of the mass method involves the use of Velocity
of the Center of Mass (vCOM) at take-off, and is calculated as follows:
Vertical Jump Height from vCOM = 𝑇𝑎𝑘𝑒𝑜𝑓𝑓−𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦2
2∗𝐺𝑟𝑎𝑣𝑖𝑡𝑦
Similar to the previous method, a more accurate method to estimate vertical jump height
involves adding vertical displacement of the center of mass before take-off to the height
calculated using TOV (TOV+s). Displacement of the COM can be found by double integration
of the vertical forces (Moir, 2008).
The impulse-momentum method can be obtained by calculating the impulse of the jump
and using the previously described formula for vCOM. Because jump impulse is obtained as
Jump Impulse = m(vf –vi), and by substituting m (body mass), and obtaining jump impulse, one
can obtain velocity (Vf = final velocity, Vi = initial velocity which is zero) (Eagles & Lovell,
2016). Furthermore, jump impulse can be obtained as follows:
Jump Impulse = Totalimp - BWimp
And by the integration of the forces and time, body impulse (BWimp) and Total Impulse
(Totalimp) can be obtained as follows:
BWimp = Bodyweight*time to take off
And,
Totalimp = impulse at take off
35
Then, take-off velocity can be obtained by Jump impulse divided by the individual’s overall
mass. Thereafter, the calculation described previously (Vertical Jump Height from vCOM) can
be utilized to obtain jump height.
Finally, the work-energy method uses an integration of forces over displacement to obtain
changes in kinetic energy, which results in an estimation of the vertical jump. These methods
have been compared and contrasted. Methods have shown good reliability and agreement
(Eagles & Lovell, 2016; Komi, 1984, 1990; Moir, 2008). Findings indicate that TOV+s method
results in greater jump heights as compared to the flight-time method or vCOM (TOV), and as in
result, the authors suggest to simply use the vCOM method (Moir, 2008). Furthermore,
displacement of the COM through motion capture and force plate vertical jump estimation has
also been compared. The comparison between force plate calculations and motion capture usage
to estimate vertical jump showed no statistical differences between the methods. However, the
authors do state that extreme care must be taken when obtaining data as any errors in the
measuring could result in marginal final estimates of the vertical jump height (Eagles & Lovell,
2016).
1.13 Measuring Vertical Jump Considerations
Some considerations need to be kept in mind when performing a vertical jump using the
force plates. First, individuals must land with their knees fully extended. Landing with knees
bent will cause individuals will obtain greater flight-times, thus, greater vertical jump height.
Second, proper calibration and weight as any errors in these can also overestimate or
underestimate calculations from the ground reaction forces. Third, and finally, filtering of the
kinetic data must be properly performed as any errors in the signal could add estimate errors to
the computed vertical jump height.
36
Force plates can provide vertical ground reaction forces that are useful for strength and
conditioning coaches. Previously, greater eccentric activity during the vertical jump has been
correlated with greater concentric muscular activation and greater vertical jump height (Toumi et
al., 2004). Thus, analyzing the force-velocity curve through the vertical jump through the use of
force plates can provide insightful information to appropriately determine to individualize
training consideration for the athletes. Aside from estimating vertical jump height, force plates
can be utilized to assess plyometric activity efficiency from the reactive strength index (RSI).
Usually, RSI is computed from Contact time/Jump Height (Ebben & Petushek, 2010). RSI has
gained a lot of interest in recent years; this is primarily due to that it allows for the evaluation of
the stretch-shortening cycle through plyometric activity.
Finally, in this Dissertation, force plates will be used to estimate RSI and to observe
activity during the eccentric and concentric portions of the countermovement jump and depth
jumps. Kinetic data from the force plates will provide insight into the force generated by the co-
activation of the muscles and the interaction between eccentric and concentric forces.
Furthermore, because we are looking at a total vertical jump height as one of the variables in the
proposed research project, motion capture will be used as the primary method to estimate vertical
jump height. Moreover, and as previously stated, ground reaction force data from the force plate
will be utilized to determine and analyze eccentric-concentric movement interaction through the
multiple jumps.
37
Chapter 3: Methodology
1.14 Research Design
A randomized repeated measures, between and within subject’s design was used for this
study. Subjects participated in a single baseline session and 8 randomly selected experimental
stretching conditions: 1) Static of Agonist, 2) Static of Antagonist, 3) Static of Agonist and
Antagonist, 4) Dynamic of Agonist, 5) Dynamic of Antagonist, 6) Dynamic of Agonist and
Antagonist, 7) Dynamic of Agonist and Static of Antagonist, and 8) Static of Agonist and
Dynamic Antagonist. To simplify the wording of each condition, Static was condensed as “ST”
and Dynamic as “DY”, similarly, Agonist was simplified as (AG) and Antagonist was simplified
as (ANT). Giving this the following acronyms for each condition: 1) Static of Agonist (“ST
AG”), 2) Static of Antagonist (“ST ANT”), 3) Static of Agonist and Antagonist (“ST AG ANT”),
4) Dynamic of Agonist (“DY AG”), 5) Dynamic of Antagonist (“DY ANT”), 6) Dynamic of
Agonist and Antagonist (“DY AG ANT”), 7) Dynamic of Agonist and Static of Antagonist (“DY
AG ST ANT”), and 8) Static of Agonist and Dynamic Antagonist (“ST AG DY ANT”).
Briefly, all subjects went through a baseline (no-stretching) session, in where they
performed isokinetic knee extension and flexion test with electromyography on the right leg for
all subjects, followed by vertical jump testing on a dual-force platform. Thereafter, subjects
performed 8 different stretching conditions in random order. Each session consisted of a 5-
minute self-paced jog on a treadmill as part of the general warm-up, followed by the
experimental stretching condition, then isokinetic knee extension and flexion test with
electromyography, and finalizing with vertical jump testing on a dual force platform.
38
Sample
The proposed sample was a total of 24 male individuals. However, given the COVID-19
pandemic, only 16 male subjects were able to complete all stretching sessions (n = 16; trained =
8, untrained = 8). Participants were classified into trained and untrained groups by the following
criteria: 1) if participants have been and were currently participating in a plyometric training
program, sport, or resistance training program for the past 2 years, they were considered
“trained”, otherwise they were considered “untrained”, and 2) an arbitrary threshold of 30 cm
was selected to distinguish between trained and untrained participants, with those achieving a
countermovement jump grater than 30cm being considered as “trained” and those with less than
a 30cm jump height as “untrained”. A priori sample was conducted on G*Power 3.1.9.7
following previous research stretching studies; for example, a previous study on knee extension
strength found an effect size of d = 0.857 between no stretch and dynamic stretching, indicating
that a total of 15 subjects were necessary to find a power greater than 0.80 (Su et al., 2017).
Along these lines, our previous work comparing different stretching modalities and
configurations found an effect size of d = 0.817 when comparing baseline to dynamic stretching
and an effect size of d = 0.828 when comparing static stretching and dynamic stretching on
vertical jump height, indicating that a total of at least 11 subjects would be necessary to find a
power greater than 0.81 (Montalvo & Dorgo, 2019). Subjects were recruited from the
Kinesiology program at the University of Texas at El Paso and members of the community.
Recruited subjects met the inclusion criteria, while subjects were excluded from participation if
they met any of the exclusion criteria:
39
Inclusion Criteria
Subjects’ age ranged from 18 to 35yrs old. Subjercts were currently or previously
enrolled (independently or under a training program) in a resistance training program. They must
have at least 2 years of resistance training experience. Subjects had to be able to jump at least
20cm.
Exclusion Criteria
Subjects over the age of 18 and younger than 35 were excluded. Subjects who presented
any type of musculoskeletal or neurological injury were not allowed to participate in this study.
Since the vertical jump is an advanced skill, and to account for neuromuscular patterns that
might influence the jumps of untrained individuals, we excluded sedentary individuals and males
who jump less than 20cm. A normal drop in glucose that is inherent to any exercise is expected,
thus, and for safety reasons, we will exclude individuals with metabolic disease. Finally, because
of the inherent nature of exercise activities and the abrupt changes that might exist in cardiac
output during extraneous exercise, we will exclude any individual with cardiac problems.
This study was approved by the Institutional Review Board at the University of Texas at
El Paso (IRB: 1376857-3) (See Appendix A).
1.15 Instrumentation
Electromyography
An 8 NORAXON EMG system was utilized to observe the muscular activity of the
antagonist and agonist muscles. The subject’s skin was be prepared prior placing the electrodes;
all hair was shaved, the skin was prepared with sandpaper, and then cleaned with alcohol. Seven
EMG sensors were placed on the following muscles: Vastus Lateralis, Vastus Medialis, Rectus
40
femoris, Semitendinosus, Biceps Femoris, Gastrocnemius, and Tibialis Anterior. Data were
collected and analyzed on the Myomusle Noraxon software. Data were processed by a
Butterworth filter; a 10 Hz low pass and a 500 Hz high pass filter will be used. Data were then
rectified and then smoothed by Root Mean Square (RMS). Finally, peak amplitude (uV) and
mean amplitude (uV) of the Rectus Femoris (RF), Vastus Lateralis (VL), Vastus Medialis (VM),
Biceps Femoris, (BF) Gastrocnemius (GS), and Tibialis Anterior (TA) muscles were reported.
Electrode was placed at 50% of the distance of the insertion and origin, at the belly of each
muscle.
Normalization
To compare EMG values and isolate independent muscles as much as possible, we
performed Maximal Voluntary Contractions (MVC). Since we are utilizing EMG measures
during dynamic movements (isotonic and isokinetic), values were be normalized to changes from
baseline to any of the stretching conditions.
Force Plates
Vertical ground reaction forces (vGRF) data from the force platforms were imported into
Matlab (R2020b; The MathWorks, Inc., Natick, MA) for data processing. Data were filtered by a
4th order Butterworth digital filter with a low-pass set at 50-Hz; the cut-off frequency was
selected after a visual analysis of the force signal via a Fast-Fourier Transform. Body mass was
obtained using the average of one second while subjects remained still before jumping, while
take-off and landing thresholds were selected as five times the standard deviations of the flight
vGRF over an epoch (time window) of 30 milliseconds, as used in previous investigations
(McMahon et al., 2018; Owen et al., 2014). Thereafter, kinetic and kinematic variables were
41
obtained through forward dynamics by numerical integration using the trapezoidal rule
(McMahon et al., 2018). In short, vertical acceleration was obtained by using Newton’s second
law of motion (Force (N) = subject’s mass (kg) * acceleration (m/s2). Velocity was obtained as
the integral of velocity with respect to time. Lastly, the vertical displacement of the center of
mass was obtained by the integration of velocity with respect to time (Barker et al., 2018). The
start of the unweighing phase was defined when the subject’s mass dropped below five standard
deviations of the subject’s weight calculated – 30 milliseconds; the braking phase was defined as
the lowest velocity achieved, and the propulsion phase was defined to the first instance in where
positive vertical velocity was achieved (McMahon et al., 2018) as shown in Figure 9.
Assessed kinematic variables included velocity and time of the various CMJ variables,
and kinetic variables included peak and mean force, rate of force development, peak and mean
power, rate of power development, and impulse. All calculations and definitions for these
computed variables have been described in detail elsewhere (J. J. McMahon, Lake, & Comfort,
2018; Rago et al., 2018). Vertical jump height was obtained using the impulse-momentum
method (Linthorne, 2001), where total impulse (integration of force * time) is subtracted from
the subject's body weight resulting in jump impulse. Then, take-off velocity was obtained as the
derivative of jump impulse and the subject’s mass.
Thus, VJH was computed as: 𝑇𝑎𝑘𝑒−𝑜𝑓𝑓 𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦2
2∗𝐺𝑟𝑎𝑣𝑖𝑡𝑦
42
Table 2. Definitions of Kinematic temporal vertical jump parameters. Adopted and updated from
previous studies (Barker, Harry, & Mercer, 2018; McMahon, Suchomel, Lake, & Comfort, 2018;
Raymond et al., 2018).
Variables Unit Definition
Kinematic Related Parameters
Total contraction
time s Time duration from the start of the jump until take-off.
Eccentric
duration s
Time duration of the eccentric phase; the period between the
end of the unloading and the braking phases.
Concentric
duration s
Time duration of the concentric phase period between the end
of the braking phase and takeoff.
Time to peak
force s Time period between the start of the jump and peak force
Flight time s Time period of zero force, corresponding to noncontact with
the floor
Peak velocity m∙s−1 The highest velocity achieved during the concentric phase
Take off
Velocity m/s Velocity at takeoff
Minimum
velocity m∙s−1 The lowest velocity achieved during the eccentric phase
Jump height m Highest height achieved during the jump using the impulse-
momentum theory.
43
Table 3. Definitions of Kinetic parameters of vertical jump. Adopted and updated from previous
studies (Barker, Harry, & Mercer, 2018; McMahon, Suchomel, Lake, & Comfort, 2018;
Raymond et al., 2018).
Kinetic Related Parameters
Total impulse N∙s−1 Force exerted concentrically multiplied by the time
taken concentrically
I = F∆ * T∆
Relative net impulse N∙s∙kg−1 Total impulse / bodyweight
Jump impulse N∙s−1 Total impulse – bodyweight impulse
Peak force N∙kg−1 Relative maximum force achieved during the
concentric phase
Mean force N∙kg−1 Relative average force of the concentric phase
Peak power W∙kg−1
Maximum rate of
eccentric force
development
W∙s−1∙kg−1 Relative maximum force increase within a 30 ms
window during the eccentric phase (from the end of
the unloading phase to the end of the braking phase).
Maximum rate of
concentric force
development
W∙s−1∙kg−1 Relative maximum force increase within a 30 ms
window during the concentric phase (from the end of
the braking phase to takeoff).
Maximum rate of force
development during the
Unload phase
N∙s−1∙kg−1 Relative maximum rate of force development during
the Unload phase.
Maximum rate of force
development during the
of Yielding phase
N∙s−1∙kg−1 Relative maximum rate of force development during
the Yielding phase.
Maximum rate of force
development during the
of Braking phase
N∙s−1∙kg−1 Relative maximum rate of force development during
the Braking phase.
Force at zero velocity N∙kg−1 Relative force exerted at the end of the yielding
phase, where the body achieves zero velocity.
44
Figure 9. Representation of a representative uni-modal vertical jump height; left axis represents vertical ground reaction force (N) in a
blue line, primary right axis represents vertical velocity (m/s) in yellow line, secondary right axis represent vertical displacement in
red.
45
Isokinetic Dynamometer Strength Testing
The BIODEX system 3 was used to measure peak torque (n-m) and total work (j) during
knee extension and knee flexion. The work speed was set at 60 degrees/sec, as this protocol has
been previously been used to assess sub-maximal strength (Batista et al., 2007). A 4 repetition
sub-maximal test of knee extension and flexion was used to test for peak torque and work. This
protocol has been shown to have great test-retests reliability on peak torque (ICC, r = 0.95) and
work (ICC, r = 0.96) in healthy adult subjects (Feiring, Ellenbecker, & Derscheid, 1990).
Static Stretching
The unilateral static stretch lasted 1 minute for 3 repetitions for 5 sets; the subject
alternated each leg with no rest for a total volume of 6 repetitions between both joints. The
sequence of stretching was as follows: hip extensors, hip flexors, knee extensors, knee flexors,
plantar flexors, dorsiflexors. Figure 10, 2nd column, illustrates the chosen static stretching
exercises performed by the participants.
Dynamic Stretching
Stretching of the muscles was performed dynamically with no hold during the stretch.
The dynamic stretch was performed for 10 repetitions for 3 sets; a total of 30 repetitions were
performed. The sequence of stretching will be as follows: hip extensors, hip flexors, knee
extensors, knee flexors, plantar flexors, dorsiflexors. Figure 10, 3rd column, illustrates the chosen
dynamic stretching exercises performed by the participants.
46
Muscle Group Static Stretch Dynamic Stretch
Hip Flexors
Hip Extensors
Knee Flexors
Knee Extensors
Dorsiflexor
Plantar Flexor
Figure 10. Illustration of the Static and Dynamic Stretches that were performed at the different
muscle groups.
47
The sequence of Stretching Modalities
In the case of combined modalities, such as in the dynamic of agonist and static of
antagonist muscles, the dynamic stretching were be performed first. As stated previously, static
stretching was performed to create an inhibitory action of the action of the muscle, and dynamic
stretching to potentiate and active muscles by increasing temperature, excitation of the motor
neurons and nervous system, and creating an overall potentiating effect of the muscles (Lorenz,
2011). It was proposed to perform dynamic stretching first, and static stretching second, as
performing the dynamic stretching after the static stretching might create a potentiating effect of
the overall joint – including agonists and antagonist muscles – thus, creating a confounding
effect. A detailed section of each stretching modality, sequence and type is represented in table
(4).
48
Table 4. A detailed description of the stretches performed during each stretching session.
Dynamic of the Agonist + Static of the Antagonist
Muscle Group Muscle Action Stretching Type Time under Contraction Sets Repetitions Rest Between Sets-Reps
Quadriceps
Femoris Agonist Dynamic 0 sec 3 10 10 seconds
Hamstring Antagonist Static 1 minute 5 3 30 seconds
Gastrocnemius Agonist Dynamic 0 sec 3 10 10 seconds
Tibialis Anterior Antagonist Static 1 minute 5 3 30 seconds
Static of the Antagonist
Muscle Group Muscle Action Stretching Type Time under Contraction Sets Repetitions Rest Between Sets-Reps
Hamstring Agonist Static 1 minute 5 3 30 seconds
Tibialis Anterior Antagonist Static 1 minute 5 3 30 seconds
Dynamic of the Agonist
Muscle Group Muscle Action Stretching Type Time under Contraction Sets Repetitions Rest Between Sets-Reps
Quadriceps
Femoris Agonist Dynamic 0 sec 3 10 10 seconds
Hamstring Antagonist Static 1 minute 3 3 30 seconds
Gastrocnemius Agonist Dynamic 0 sec 3 10 10 seconds
Tibialis Anterior Antagonist Static 1 minute 3 3 30 seconds
49
1.16 Procedures for Baseline and Stretching Conditions
Before the start of any procedures, a consent form and a brief explanation of the
procedures was given to the subjects. On the first day, anthropometric measures (Height, Weight,
Body Fat %, Lean Muscle Mass, and Bone Mineral Density) were taken. Following this, and for
every stretching experimental condition, subjects performed a 3-5 minute of self-paced jogging
on a standard treadmill. Thereafter, subjects proceeded to a randomly selected stretching
experimental condition, wherein in the case of the baseline condition, there was no stretching
condition. Following each stretching experimental condition, the subject’s skin was prepared as
previously described. EMG was placed on the right leg for all individuals. The PI and an
experienced research assistant placed all of the EMG sensors in an approximated time of 2-3
minutes. Individuals then proceeded to perform 2 sets of 4 Isokinetic knee extensions at 60
deg/sec for each leg, followed by 5 repetitions of the CMJ, SQJ, and DJ in random order (Figure
10).
50
Figure 11. Sample flowchart of the individual session within the proposed design.
1.17 Statistics and Data Analysis
Processed data were imported into the open-source RStudio (version 1.3.959, RStudio,
Boston, MA, USA) for data analysis using R statistical language with the ggplot and ggpurb
publication-ready package being used for data visualization; the package “psych” was utilized
for Descriptives of the data, “tidiverse” package was utilized for data structures, “rstatix”
package was utilized for analysis of repeated measures ANOVA, and “ARTool” was utilized for
the non-parametric aligned ranks transformation repeated measures ANOVA. Descriptives from
the isokinetic dynamometer, EMG, and Force Plate data were obtained using the “Psych”
package; descriptives were presented as mean, standard deviation (sd), median, trimmed mean
(trimmed; mean after the removal of the upper and lower 10% values to estimate central
tendency), median absolute deviation (mad; to estimate the variability of the data), min, max,
range, skew (skewness; a measure of the asymmetry of the distribution of the data), kurtosis
General Warm-Up
Assigned Stretching Protocol
EMG Placement
Isokinetic Strength Testing
Vertical Jump Testing
•CMJ
•SQJ
•DJ
51
(description of the shape of the tails of the distribution) and standard error (se). Jump data were
analyzed as the mean of three trials and the maximum performance of three trials. Intra-subject
reliability was assessed through a two-way mixed model Intra-Class Correlation Coefficient
(ICC2k) (Atkinson & Nevill, 1998; Cormack, Newton, McGuigan, & Doyle, 2008; Haynes,
Bishop, Antrobus, & Brazier, 2018). Assumptions of data normality were assessed through the
five methods: 1) Q-Q plots (quantile-quantile plots), 2) Density plots, 3) Skewness (Data normal
was set between 1 and -1), 4) Kurtosis (Data normality was set between 3 [“platykurtic”] and – 3
[“leptokurtic”]), and 5) Shapiro-Wilk test. Individual repeated-measures analysis of variance
(RM-ANOVA) was utilized when assumptions of normality were met, otherwise, the aligned
ranks transformation ANOVA (ART-ANOVA) for non-parametric repeated measures test was
conducted (Wobbrock et al., 2011). When individual repeated-measures analysis of variance
(RM-ANOVA) was conducted, the Mauchly’s test for sphericity was performed to determine
data sphericity, thereafter the Greenhouse-Geiser sphericity correction was applied if sphercicity
was violated. Results of RM-ANOVA and ART-ANOVA were reported by the F distribution (F-
test) in where the first value indicates the degrees of freedom (DFn) and the second value
indicates the denominator (DFd), the p-value, and the effect size as partial eta squared (ηp2). The
magnitude of the ηp2 was interpreted as 0.01-0.05 as small, 0.06-0.13 as moderate, and > 0.14 as
large. If there was a significant main or time interaction, pairwise comparisons were conducted
using paired t-tests for RM-ANOVA or Wilcoxon signed-rank tests on paired samples for ART-
ANOVA with a Fisher’s Least Significant Difference (LSD) correction. Additionally, Cohen’s D
effect sizes with a Hedge’s g correction were applied when appropriated, and computed as
follows: mean of pretest values – mean of posttest values / weighted pooled standard deviation
(Bernards, Sato, Haff, & Bazyler, 2017; Hedges, 1981) for parametric data. When the ART-
52
ANOVA test was conducted, Wilcoxon signed-rank sum paired tests were conducted with a
Fisher’s Least Significant Difference (LSD) correction for pairwise comparisons. Then, the
effect size was computed as follows: r = z statistic / square root of the sample size (N). The
magnitude of all pairwise effect sizes were interpreted according to the Hopkins scale (Hopkins,
2003) as trivial = 0–0.2 small = 0.2–0.6, moderate = 0.6–1.2, large = 1.2–2.0, and very large =
2.0–4.0, and nearly perfect >4.0. Data were represented as mean and standard deviation along
with 95% confidence intervals (95% CI) for each of the variables of interest. Finally, the smallest
worthwhile change was computed ([SWC = 0.2 * between subjects baseline standard
deviation]*100) (Hopkins et al., 1999). Statistical significance was set at an alpha level of 0.05
for all analyzes. Significant p-values were reported as * for > 0.05, ** for > 0.01, and *** >
0.001.
53
Figure 12. Statistical decision tree for parametric and non-parametric data.
54
Chapter 4: Results
1.18 Descriptives
Subjects' age, height, weight, BMI, and BF% are delineated in Table 6. No differences
between training status (untrained vs trained) were found for Age, Height, Weight, or BMI (p <
0.05).
Table 5. Descriptives of Subjects.
Group n Age
(yrs.)
Height
(m)
Weight
(kg)
BMI
(kg/m2)
All 16 24.31±3.53 1.75±0.08 77.48±10.29 25.14±1.61
Untrained 8 24.75±3.42 1.77±0.08 79.94±10.87 25.43±1.15
Trained 8 23.88±3.59 1.73±0.08 75.02±9.03 24.85±1.92
1.19 Data Normality
Data normality was assessed through visual distribution, QQ-plots, skewness, kurtosis, and
the Shapiro-Wilk Test. All data violated assumptions of normality. Figure 12 shows Peak Torque
Knee extension (%MVC) in where only DY ANT followed a gaussian distribution (normal) with
the rest of the conditions following a gamma distribution (slightly skewed). Further analysis with
QQ-plots on Figure 13 also showed DY AG, and DY AG ANT also not following a normal
distribution for Peak Torque Knee extension (%MVC). Similarly, for Vertical Jump Height (m)
in Figure 14, only the DY AG ANT, DY AG, and DY AG ST ANT followed a Gaussian
distribution, whereas the rest followed a gamma distribution (skewed). Analysis of the QQ-plot
also showed that the ST AG DY ANT, DY AG ST ANT, and DY AG did not follow a normal
distribution (Figure 15). Finally, in Table 5, the Shapiro-Wilk test showed that the ST AG was
signifcinatly different from a normal distribution for Peak Torque Knee extension (%MVC), and
55
ST AG DY ANT was also different from a normal distribution for CMJ (m) height. All variables
followed a similar pattern, thus, it was decided to follow the non-parametric analysis as
presented in the decision tree in figure 11.
Figure 13. Distribution of Normalized Peak Torque Extension / BW (%MVC) by the stretching
conditions.
56
Figure 14. Q-Q probability plot of Peak Torque Extension by the stretching conditions.
57
Figure 15. Distribution of CMJ Height (m) by the stretching conditions.
58
Figure 16. Q-Q probability plot of CMJ height by the stretching conditions.
59
Table 6. Shapiro-Wilk test for assumptions of normality of data distribution.
Peak Torque Knee Extension Jump Height (m)
Condition W statistic P-value W statistic P-value
ST AG 0.884 0.04* 0.85 0.15
ST ANT 0.917 0.15 0.87 0.02*
ST AG ANT 0.908 0.10 0.90 0.10
DY AG 0.902 0.08 0.78 0.00*
DY ANT 0.954 0.54 0.88 0.04*
DY AG ANT 0.888 0.05 0.93 0.33
ST AG DY ANT 0.953 0.53 0.95 0.66
DY AG ST ANT 0.897 0.07 0.94 0.44
*Indicates significantly different from normal distribution at p < 0.05
1.20 Peak Torque Knee Extension and Flexion
There was a main effect of time for Peak Torque Extension by BW (%MVC) [F(7) =
3.554, p = 0.001, ηp2 (large) = 0.17 [95%CI = 0.03-0.24] within-subject but not between subjects
(p = 0.139) or within-between subjects (p = 0.052) (Figures 15-17). Pairwise comparison showed
a moderate difference between ST AG and DY AG ST ANT, ST AG and DY AG ANT, and ST
AG ANT and DY AG ST ANT. In addition, there was a small difference between ST AG and
DY AG, ST AG and ST ANT, ST AG ANT and DY AG ANT, DY ANT and DY AG ST ANT,
ST ANT and DY AG ST ANT, ST AG ANT and DY AG, and DY AG and DY ST ANT. This
further demonstrates that dynamic stretching of the agonist muscles improves peak torque
extension, and static stretching of the antagonist muscles can have a moderate effect in
60
comparison to static stretching of the agonist. For Peak Torque Flexion / BW, there was no
interaction within stretching conditions [F(7) = 1.724, p = 0.112), between subjects [F(1) =
2.261, p = 0.154), or within and between subjects [F(7) = 1.344, p = 0.237) (Figures 18-20ttt).
1.21 Average Power Extension and Flexion
There was an interaction within-subjects by stretching condition [F(7) = 2.099, p = 0.005,
ηp2 (large) = 0.18 [95%CI = 0.04-0.26], but not between subjects [F(1) = 0.105, p = 0.155), or
between-within subjects [F(7) = 0.438, p = 0.241) on Average Power Extension (%MVC)
(Figures 20-23). Pairwise comparisons indicated there was a moderate effect size between ST
AG ANT and DY AG ST ANT, and ST AG and DY AG ST ANT. Furthermore, there was a
small effect size between ST AG and DY AG ANT, ST AG DY ANT and DY AG ST ANT, ST
AG ANT and DY AG ANT, ST ANT and ST AG ANT, DY AG and DY AG ST ANT, DY ANT
and DY AG ST ANT, ST ANT and DY AG ST ANT. With most conditions favoring the
dynamic stretching over static stretching for Average Power (W) Extension (Figure 23 & Table
14). Additionally, there was an no interaction by stretching condition within subjects [F(7) =
2.099, p = 0.050), or between-subjects [F(1) = 1.459, p = 0.246), or between-within subjects
[F(7) = 0.702, p = 0.669) on Average Knee Power Flexion (%MVC) (Figures 24-26).
1.22 Average Peak Torque Extension and Flexion
There was an interaction within-subjects by stretching condition condition [F(7) = 2.308, p
= 0.031, ηp2 (large) = 0.15 [95%CI = 0.04-0.26], and between-within subjects [F(7) = 2.215, p =
0.031, ηp2 (moderate) = 0.12 [95%CI = 0.04-0.26], but not between subjects (F(1) = 1.464, p >
0.05) on Average Knee Extension Torque (%MVC) (Figures 27-29). Pairwise comparisons
indicates that there was a moderate effect size between ST AG and DY AG ST ANT, and ST AG
61
ANT and DY AG ST ANT. Furthermore, there was a small effect size between ST AG and DY
AG ANT, and DY AG and DY AG ST ANT, and DY ANT and DY AG ST ANT (Figure 29 &
Table 21). This indicates that dynamic stretching is mostly favored over static stretching in
average peak torque extension. There was an no effect of time within-subjects by stretching
condition (F(1) = 1.355, p = 0.232) or between subjects (F(1) = 3.044, p = 0.102), or between-
within subjects (F(1) = 0.800, p = 0.588) on Average Knee Extension Torque (%MVC) (Figure
30-32 & Table 24).
1.23 Electromyography
There was no effect of time for EMG % MVC in the VL (p =0.20) or between subjects (p
= 0.60) or between-within subjects (p = 0.86) (Figures 33-34 & Table 25). There was not an
effect of time within-subjects for EMG % MVC in the VMO (p = 0.11), or between subjects (p =
0.49) or between-within subjects (p = 0.39) (Figures 35-36 & Table 26). Similarly, there was no
effect of time for EMG %MVC for RF (p = 0.411), or between subjects (p = 0.154) or between-
within subjects (p = 0.095) (Figures 37-38 & Table 27). There was also no effect of time for
EMG %MVC for the BF (p = 0.54), or between subjects (p = 0.28) or between-within subjects (p
= 0.79) (Figures 39-40 & Table 28). Finally, there was no effect of time in EMG %MVC in ST
(p = 0.33), or between subjects (p = 0.40), or between-within subjects (p = 0.38) (Figures 41-42
& Table 29).
62
Figure 17. Interaction plot of Peak Torque Knee Extension by BW (%MVC).
Figure 18. Interaction plot of Peak Torque Knee Extension by BW (%MVC) by group.
63
Figure 19. Normalized Peak Torque Knee Extension by BW (%MVC) by stretching condition
for all subjects.
64
Table 7. Descriptives of non-normalized raw data of Peak Torque Extension by BW by stretching condition and by group.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 233.54 56.3 214.8 232.77 82.21 149.2 328.6 179.4 0.17 -1.44 14.08
ST AG 237.69 51.47 232.4 238.74 49 132.8 327.8 195 -0.07 -0.73 12.87
ST ANT 266.64 56.57 255.1 267.22 49.22 163 362.2 199.2 -0.08 -1.05 14.14
ST AG ANT 252.76 57.76 253.95 252.67 70.79 158.6 348.1 189.5 0.01 -1.29 14.44
DY AG 269.76 62.48 277.25 271.09 61.75 162.3 358.6 196.3 -0.36 -1.38 15.62
DY ANT 260.42 60.26 243.05 259.7 57.15 172.4 358.6 186.2 0.24 -1.44 15.07
DY AG ANT 281.22 57.08 296.75 283.94 53.45 181.7 342.8 161.1 -0.52 -1.34 14.27
ST AG DY ANT 249.76 88.09 225 249.52 87.92 82.1 420.8 338.7 0.15 -0.74 22.02
DY AG ST ANT 285.23 46.59 296.95 286.35 47.89 203.1 351.7 148.6 -0.27 -1.36 11.65
Trained (n=8) Baseline 252.54 62.36 271.5 252.54 77.1 160 328.6 168.6 -0.23 -1.75 22.05
ST AG 249.81 41.13 255.25 249.81 25.8 174.7 314.1 139.4 -0.3 -0.81 14.54
ST ANT 267.94 66.22 255.1 267.94 72.87 163 362.2 199.2 -0.02 -1.49 23.41
ST AG ANT 261.01 54.87 254.65 261.01 46.03 170.1 348.1 178 -0.01 -1.12 19.4
DY AG 283.34 58.91 287.4 283.34 58.64 181.7 358.6 176.9 -0.31 -1.41 20.83
DY ANT 264.26 68.69 233.85 264.26 56.49 172.4 358.6 186.2 0.24 -1.77 24.29
DY AG ANT 275.89 60.98 296.75 275.89 56.26 181.7 341.2 159.5 -0.36 -1.77 21.56
ST AG DY ANT 231.88 102.47 215 231.88 90.29 82.1 420.8 338.7 0.36 -0.89 36.23
DY AG ST ANT 287.5 51.65 298.2 287.5 38.84 203.1 348.2 145.1 -0.5 -1.45 18.26
Untrained (n=8) Baseline 214.54 45.6 210.4 214.54 36.92 149.2 281.7 132.5 0.28 -1.38 16.12
ST AG 225.56 60.42 213.8 225.56 26.24 132.8 327.8 195 0.29 -1.08 21.36
ST ANT 265.35 49.67 265.4 265.35 40.25 179 335.1 156.1 -0.23 -1.23 17.56
ST AG ANT 244.5 63.1 236.65 244.5 69.76 158.6 332.3 173.7 0.1 -1.77 22.31
DY AG 256.18 66.88 277.25 256.18 67.75 162.3 334.7 172.4 -0.25 -1.9 23.65
DY ANT 256.59 55.05 255.4 256.59 65.23 178.9 331.3 152.4 0.07 -1.67 19.46
DY AG ANT 286.56 56.55 299.4 286.56 49.37 183.3 342.8 159.5 -0.58 -1.26 19.99
ST AG DY ANT 267.65 73.46 262.9 267.65 85.47 180.2 374.9 194.7 0.15 -1.79 25.97
DY AG ST ANT 282.96 44.41 287.8 282.96 45.07 228.9 351.7 122.8 0.11 -1.72 15.7
65
Table 8. Descriptives of Normalized Peak Torque Extension by BW to Baseline values (% MVC) by condition and by group.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1.05 0.28 0.98 1.04 0.27 0.74 1.58 0.84 0.65 -1.07 0.07
ST ANT 1.17 0.24 1.13 1.16 0.30 0.87 1.57 0.70 0.34 -1.39 0.06
ST AG ANT 1.11 0.24 1.02 1.10 0.17 0.79 1.56 0.77 0.61 -1.05 0.06
DY AG 1.17 0.22 1.15 1.16 0.18 0.90 1.61 0.71 0.70 -0.70 0.06
DY ANT 1.13 0.20 1.13 1.13 0.20 0.84 1.52 0.67 0.34 -0.94 0.05
DY AG ANT 1.19 0.18 1.18 1.18 0.13 0.97 1.61 0.64 0.87 0.03 0.05
ST AG DY ANT 1.14 0.40 1.08 1.16 0.39 0.25 1.76 1.51 -0.27 -0.55 0.10
DY AG ST ANT 1.26 0.24 1.19 1.24 0.16 0.95 1.77 0.82 0.74 -0.8 0.06
Trained (n=8) ST AG 1.03 0.25 0.95 1.03 0.11 0.78 1.58 0.80 1.15 0.02 0.09
ST ANT 1.08 0.20 1.01 1.08 0.21 0.87 1.38 0.52 0.42 -1.63 0.07
ST AG ANT 1.06 0.24 1.00 1.06 0.15 0.79 1.53 0.74 0.74 -0.86 0.08
DY AG 1.15 0.22 1.15 1.15 0.14 0.90 1.61 0.71 0.93 -0.14 0.08
DY ANT 1.06 0.20 1.05 1.06 0.25 0.84 1.37 0.52 0.26 -1.67 0.07
DY AG ANT 1.10 0.12 1.11 1.10 0.16 0.97 1.30 0.34 0.23 -1.60 0.04
ST AG DY ANT 0.96 0.39 0.93 0.96 0.26 0.25 1.55 1.30 -0.24 -0.94 0.14
DY AG ST ANT 1.17 0.26 1.10 1.17 0.13 0.95 1.77 0.82 1.46 0.82 0.09
Trained (n=8) ST AG 1.08 0.32 1.01 1.08 0.4 0.74 1.54 0.8 0.22 -1.86 0.11
ST ANT 1.26 0.25 1.25 1.26 0.28 0.93 1.57 0.64 0.03 -1.83 0.09
ST AG ANT 1.15 0.24 1.07 1.15 0.25 0.89 1.56 0.67 0.41 -1.58 0.09
DY AG 1.20 0.23 1.17 1.20 0.23 0.91 1.57 0.66 0.37 -1.52 0.08
DY ANT 1.21 0.19 1.17 1.21 0.15 1.00 1.52 0.52 0.55 -1.41 0.07
DY AG ANT 1.28 0.19 1.22 1.28 0.07 1.05 1.61 0.56 0.64 -1.26 0.07
ST AG DY ANT 1.33 0.33 1.29 1.33 0.37 0.94 1.76 0.82 0.09 -2.00 0.11
DY AG ST ANT 1.34 0.21 1.32 1.34 0.28 1.10 1.65 0.55 0.15 -1.82 0.07
66
Table 9. Effect size for pairwise comparisons of Peak Torque Extension / BW (% MVC).
Group 1 Group 2 z- statistic p-value Sig. ES (r) Magnitude
ST AG DY AG ST ANT 3 0.000 *** 0.423 moderate
ST AG DY AG ANT 20 0.011 * 0.360 moderate
ST AG ANT DY AG ST ANT 8 0.001 *** 0.336 moderate
ST AG DY AG 9 0.001 ** 0.293 small
ST AG ST ANT 29 0.044 * 0.260 small
ST AG ANT DY AG ANT 26 0.029 * 0.260 small
DY ANT DY AG ST ANT 21 0.013 * 0.220 small
ST ANT DY AG ST ANT 24 0.021 * 0.193 small
ST AG ANT DY AG 25 0.025 * 0.173 small
DY AG DY AG ST ANT 25 0.025 * 0.167 small
Significance (Sig.) was denoted with * as < 0.05, ** as < 0.01, and *** as <0.001; z-statistic, r
effect size (ES), and it’s interpretation (Magnitude) are listed from highest to lowest.
67
Figure 20. Interaction plot of normalized peak torque flexion (%MVC) by stretching condition.
Figure 21. Interaction plot of normalized peak torque flexion (%MVC) by condition and group.
68
Figure 22. Peak torque flexion / BW normalized by baseline values (% MVC) by stretching
condition.
69
Table 10. Descriptives of non-normalized Peak Torque Flexion by BW (%) by group and stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 107.67 30.74 104 106.96 35.51 59.8 165.4 105.6 0.21 -1.2 7.68
ST AG 118.61 46.11 112.05 113.42 21.79 45.3 264.6 219.3 1.72 3.75 11.53
ST ANT 137.66 40.81 138.55 136.13 35.29 70.7 226.1 155.4 0.3 -0.54 10.2
ST AG ANT 114.27 33.43 117.05 114.71 33.21 52.8 169.6 116.8 -0.08 -0.93 8.36
DY AG 125.13 56.69 126.9 122.01 46.85 27.3 266.6 239.3 0.47 0.34 14.17
DY ANT 123.21 33.42 123.8 125.21 39.96 50.6 167.8 117.2 -0.45 -0.81 8.36
DY AG ANT 134.91 36.03 142.8 136.16 43.59 70 182.4 112.4 -0.36 -1.3 9.01
ST AG DY ANT 118.19 44.91 108.5 118.48 47 48.2 184.2 136 0.15 -1.43 11.23
DY AG ST ANT 133.31 29.38 139.6 133.39 30.47 83.6 181.8 98.2 -0.22 -1.28 7.35
Trained (n=8) Baseline 120.04 29.82 116.8 120.04 33.95 80.5 165.4 84.9 0.16 -1.67 10.54
ST AG 126.49 71.44 110.3 126.49 58.19 27.3 266.6 239.3 0.58 -0.64 25.26
ST ANT 128.05 27.66 129.55 128.05 35.21 83.6 157.4 73.8 -0.23 -1.66 9.78
ST AG ANT 122.81 30.2 123.8 122.81 36.99 76.9 162.1 85.2 -0.08 -1.62 10.68
DY AG 117.3 19.52 112.6 117.3 17.12 98 158.2 60.2 0.94 -0.38 6.9
DY ANT 104.66 25.8 110.6 104.66 32.77 67 138.8 71.8 -0.18 -1.73 9.12
DY AG ANT 108.9 48.31 89.45 108.9 27.06 48.2 184 135.8 0.53 -1.41 17.08
ST AG DY ANT 139.24 45.23 140.45 139.24 30.02 79.9 226.1 146.2 0.5 -0.82 15.99
DY AG ST ANT 120.04 29.82 116.8 120.04 33.95 80.5 165.4 84.9 0.16 -1.67 10.54
Untrained (n=8) Baseline 95.3 28.02 91.35 95.3 32.02 59.8 135.7 75.9 0.2 -1.74 9.91
ST AG 119.92 64.58 106.15 119.92 33.58 45.3 264.6 219.3 1.18 0.39 22.83
ST ANT 136.09 38.96 138.55 136.09 39.96 70.7 195.6 124.9 -0.14 -1.22 13.77
ST AG ANT 123.88 38.96 128.1 123.88 38.99 52.8 169.6 116.8 -0.42 -1.11 13.78
DY AG 123.77 42.18 137.35 123.77 22.39 45.5 172.7 127.2 -0.69 -1.07 14.91
DY ANT 123.61 38.48 124.6 123.61 39.96 50.6 167.8 117.2 -0.56 -1 13.61
DY AG ANT 131.56 43.56 131.9 131.56 61.38 70 182.4 112.4 -0.1 -1.9 15.4
ST AG DY ANT 127.49 42.33 126.7 127.49 44.77 55.4 184.2 128.8 -0.25 -1.4 14.97
DY AG ST ANT 138.56 31.96 146.8 138.56 36.47 85.4 181.8 96.4 -0.29 -1.44 11.3
70
Table 11. Normalized Peak Torque Flexion by BW (%) by group and stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1.21 0.58 1.02 1.19 0.47 0.26 2.42 2.16 0.53 -0.66 0.14
ST ANT 1.29 0.57 1.1 1.21 0.3 0.76 3.05 2.29 1.75 2.67 0.14
ST AG ANT 1.32 0.5 1.17 1.26 0.31 0.83 2.77 1.94 1.53 1.82 0.12
DY AG 1.23 0.51 1.06 1.17 0.36 0.54 2.67 2.13 1.29 1.41 0.13
DY ANT 1.16 0.54 1.01 1.07 0.25 0.62 2.96 2.34 2.27 5.18 0.13
DY AG ANT 1.16 0.58 0.91 1.07 0.3 0.66 2.82 2.16 1.48 1.58 0.14
ST AG DY ANT 1.24 0.58 1.37 1.2 0.69 0.29 2.64 2.35 0.62 0.05 0.14
DY AG ST ANT 1.36 0.6 1.22 1.27 0.38 0.79 3.27 2.48 1.94 3.74 0.15
Trained (n=8) ST AG 1 0.16 0.98 1 0.12 0.77 1.3 0.53 0.46 -0.62 0.05
ST ANT 1.17 0.28 1.13 1.17 0.22 0.79 1.64 0.85 0.37 -1.27 0.1
ST AG ANT 0.9 0.26 0.82 0.9 0.17 0.66 1.49 0.82 1.22 0.21 0.09
DY AG 1.06 0.55 0.96 1.06 0.28 0.26 2.1 1.85 0.5 -0.77 0.2
DY ANT 1.04 0.23 1 1.04 0.17 0.76 1.49 0.73 0.66 -0.87 0.08
DY AG ANT 1.19 0.29 1.14 1.19 0.28 0.88 1.73 0.85 0.62 -1.16 0.1
ST AG DY ANT 0.96 0.42 0.9 0.96 0.59 0.29 1.45 1.16 -0.18 -1.59 0.15
DY AG ST ANT 1.09 0.22 1.02 1.09 0.15 0.83 1.54 0.71 0.84 -0.42 0.08
Untrained (n=8) ST AG 1.31 0.73 1.2 1.31 0.33 0.62 2.96 2.34 1.25 0.38 0.26
ST ANT 1.56 0.77 1.46 1.56 0.66 0.88 3.27 2.39 1.18 0.17 0.27
ST AG ANT 1.42 0.7 1.34 1.42 0.74 0.73 2.82 2.1 0.75 -0.73 0.25
DY AG 1.36 0.59 1.22 1.36 0.49 0.62 2.42 1.79 0.48 -1.26 0.21
DY ANT 1.41 0.66 1.36 1.41 0.62 0.54 2.67 2.13 0.55 -0.83 0.23
DY AG ANT 1.4 0.77 1.05 1.4 0.34 0.76 3.05 2.29 1.1 -0.25 0.27
ST AG DY ANT 1.52 0.61 1.42 1.52 0.52 0.81 2.64 1.84 0.52 -0.99 0.21
DY AG ST ANT 1.56 0.6 1.46 1.56 0.47 0.91 2.77 1.86 0.83 -0.63 0.21
71
Figure 23. Interaction plot for average power knee extension (%MVC) by stretching conditio
Figure 24. Interaction plot for average power knee extension (%MVC) by period and group.
72
Figure 25. Average Knee Extension Power normalized by Baseline values (% MVC).
73
Table 12. Descriptives of non-normalized Average Power Extension (W) by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 120.5 31.25 120.8 121.3 38.1 61.2 168.6 107.4 -0.05 -1.15 7.81
ST AG 129.84 30.22 132.4 130.26 34.54 77.3 176.4 99.1 -0.27 -1.28 7.55
ST ANT 146.22 22.2 151.05 147.1 21.72 106.9 173.3 66.4 -0.49 -1.22 5.55
ST AG ANT 131.12 25.33 132.6 131.14 36.84 93.7 168.4 74.7 0.05 -1.62 6.33
DY AG 140.5 25.21 143.85 140.69 29.87 97.4 181 83.6 0.03 -1.29 6.3
DY ANT 141.47 32.13 151.75 143.75 23.94 74.3 176.7 102.4 -0.91 -0.52 8.03
DY AG ANT 157.62 32.03 155.8 157.06 28.39 106.2 216.9 110.7 0.36 -0.88 8.01
ST AG DY ANT 128.83 38.81 122.4 130.84 40.99 40 189.5 149.5 -0.37 -0.37 9.7
DY AG ST ANT 160.81 29.45 161.6 160.56 29.13 108.8 216.4 107.6 0.06 -0.82 7.36
Trained (n=8) Baseline 127.85 28.13 128.2 127.85 32.99 87.4 168.6 81.2 0.04 -1.53 9.94
ST AG 131.15 34.86 133.05 131.15 41.66 87 176.4 89.4 -0.08 -1.83 12.32
ST ANT 142.56 22.76 144.2 142.56 21.72 106.9 173.3 66.4 -0.19 -1.48 8.05
ST AG ANT 138.84 21.11 135.1 138.84 28.24 107.7 168.4 60.7 -0.01 -1.62 7.46
DY AG 142.16 23.08 138.3 142.16 23.35 118.1 181 62.9 0.4 -1.52 8.16
DY ANT 140.49 29.07 149.9 140.49 18.01 74.3 166.2 91.9 -1.33 0.48 10.28
DY AG ANT 150.74 29.28 140.45 150.74 14.75 118.1 215.2 97.1 1.13 0.15 10.35
ST AG DY ANT 110.16 37.11 117.55 110.16 40.92 40 152.3 112.3 -0.53 -0.95 13.12
DY AG ST ANT 158 30.75 157.4 158 29.36 117 216.4 99.4 0.49 -0.88 10.87
Untrained (n=8) Baseline 113.15 34.33 108 113.15 33.73 61.2 165.1 103.9 0.09 -1.47 12.14
ST AG 128.52 27.16 132.4 128.52 27.58 77.3 155.8 78.5 -0.67 -1.03 9.6
ST ANT 149.89 22.51 156.3 149.89 14.75 108.8 171.5 62.7 -0.74 -1.15 7.96
ST AG ANT 123.41 28.16 110.4 123.41 18.46 93.7 165.2 71.5 0.39 -1.82 9.96
DY AG 138.84 28.69 144.05 138.84 33.73 97.4 179.3 81.9 -0.12 -1.69 10.14
DY ANT 142.45 36.95 156.45 142.45 29.13 81.1 176.7 95.6 -0.58 -1.51 13.06
DY AG ANT 164.5 35.11 171.25 164.5 24.31 106.2 216.9 110.7 -0.27 -1.21 12.41
ST AG DY ANT 147.5 32.46 147.4 147.5 38.4 100.3 189.5 89.2 -0.02 -1.74 11.48
DY AG ST ANT 163.62 29.91 165.7 163.62 27.95 108.8 205 96.2 -0.4 -1.01 10.57
74
Table 13. Normalized Average Power Extension (%MVC) by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1.1 0.41 1 1.1 0.3 0.68 2.1 1.5 0.92 -0.16 0.1
ST ANT 1.3 0.35 1.2 1.2 0.27 0.94 2 1.1 0.9 -0.71 0.09
ST AG ANT 1.2 0.37 1 1.1 0.2 0.57 1.9 1.4 0.67 -0.61 0.09
DY AG 1.2 0.33 1.1 1.2 0.29 0.8 1.9 1.1 0.57 -0.97 0.08
DY ANT 1.2 0.26 1.2 1.2 0.28 0.82 1.7 0.9 0.16 -1.1 0.07
DY AG ANT 1.3 0.41 1.3 1.3 0.28 0.88 2.5 1.7 1.5 2.1 0.1
ST AG DY ANT 1.2 0.49 1.1 1.2 0.51 0.31 2 1.7 0.14 -1.1 0.12
DY AG ST ANT 1.4 0.41 1.2 1.4 0.38 0.91 2.3 1.4 0.64 -0.83 0.1
Trained (n=8) ST AG 1 0.26 1 1 0.27 0.68 1.5 0.8 0.16 -1.2 0.09
ST ANT 1.1 0.2 1.1 1.1 0.13 0.94 1.6 0.64 0.92 -0.29 0.07
ST AG ANT 1.1 0.28 1 1.1 0.18 0.82 1.6 0.77 0.63 -1.4 0.1
DY AG 1.1 0.26 1.1 1.1 0.33 0.8 1.5 0.72 0.07 -1.7 0.09
DY ANT 1.1 0.25 1.1 1.1 0.33 0.82 1.5 0.72 0.29 -1.5 0.09
DY AG ANT 1.2 0.28 1.2 1.2 0.38 0.88 1.6 0.7 0.12 -1.9 0.1
ST AG DY ANT 0.92 0.45 0.9 0.92 0.4 0.31 1.7 1.4 0.37 -1 0.16
DY AG ST ANT 1.3 0.33 1.2 1.3 0.35 0.91 1.8 0.91 0.36 -1.7 0.12
Untrained (n=8) ST AG 1.2 0.52 1 1.2 0.43 0.72 2.1 1.4 0.49 -1.5 0.19
ST ANT 1.4 0.43 1.3 1.4 0.45 1 2 1 0.27 -1.9 0.15
ST AG ANT 1.2 0.46 1.1 1.2 0.18 0.57 1.9 1.4 0.45 -1.3 0.16
DY AG 1.3 0.38 1.1 1.3 0.3 0.91 1.9 1 0.42 -1.7 0.13
DY ANT 1.3 0.26 1.3 1.3 0.24 0.88 1.7 0.83 -0.01 -1.2 0.09
DY AG ANT 1.5 0.49 1.3 1.5 0.13 1.1 2.5 1.4 1.3 -0.03 0.17
ST AG DY ANT 1.2 0.52 1 1.2 0.43 0.72 2.1 1.4 0.49 -1.5 0.19
DY AG ST ANT 1.5 0.46 1.4 1.5 0.35 1 2.3 1.3 0.43 -1.6 0.16
75
Table 14. Average Power (%MVC) Extension Effect Sizes and Pairwise comparisons.
Group 1 Group 2 z-statistic P-value Sig. ES (r) Magnitude
ST AG ANT DY AG ST ANT 6 0.000 *** 0.366 moderate
ST AG DY AG ST ANT 11 0.002 ** 0.363 moderate
ST AG DY AG ANT 25 0.025 * 0.300 small
ST AG DY ANT DY AG ST ANT 21 0.013 * 0.286 small
ST AG ANT DY AG ANT 16 0.005 ** 0.273 small
ST ANT ST AG ANT 116 0.011 * 0.260 small
DY AG DY AG ST ANT 18 0.008 ** 0.233 small
DY ANT DY AG ST ANT 23 0.018 * 0.220 small
ST ANT DY AG ST ANT 17 0.016 * 0.170 small
Significance (Sig.) was denoted with * as < 0.05, ** as < 0.01, and *** as <0.001; z-statistic, r
effect size (ES), and it’s interpretation (Magnitude) are listed from highest to lowest.
76
Figure 26. Interaction plot for average power knee flexion (%MVC) by stretching condition.
Figure 27. Interaction plot for average power knee flexion (%MVC) by period and group.
77
Figure 28. Average Knee Power Flexion (%MVC) by stretching condition.
78
Table 15. Descriptives of non-normalized Average Knee Power Flexion (W) by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 62.83 21.62 62.85 62.3 24.91 26.2 106.9 80.7 0.17 -0.85 5.4
ST AG 67.34 21.71 71.85 67.85 20.09 22.8 104.8 82 -0.28 -0.77 5.43
ST ANT 73.86 19.82 75.9 74.33 18.31 34.4 106.7 72.3 -0.11 -0.8 4.95
ST AG ANT 63.03 21.53 64.45 62.77 15.86 25.8 103.9 78.1 -0.04 -0.71 5.38
DY AG 61.46 30.66 70.55 62.48 24.24 4.7 103.9 99.2 -0.64 -0.93 7.66
DY ANT 78.24 27.65 77.9 77.84 18.9 19.1 143.1 124 0.18 0.49 6.91
DY AG ANT 76.07 22.3 74.5 75.52 21.42 36.6 123.2 86.6 0.16 -0.6 5.57
ST AG DY ANT 67.73 30.8 65.5 66.32 25.87 15.2 140 124.8 0.41 -0.06 7.7
DY AG ST ANT 78.46 20.22 78.45 77.64 20.61 45.2 123.2 78 0.31 -0.58 5.05
Trained (n=8) Baseline 65.92 10.67 66.45 65.92 8.75 49.6 84.6 35 0.17 -1.04 3.77
ST AG 67.88 15.09 72.35 67.88 16.38 39.3 84.8 45.5 -0.61 -1.03 5.33
ST ANT 70.3 14.48 72.5 70.3 15.34 49.4 87.6 38.2 -0.28 -1.71 5.12
ST AG ANT 57.16 18.58 60.65 57.16 15.49 27.6 85.3 57.7 -0.17 -1.34 6.57
DY AG 60.64 27.55 70.55 60.64 20.61 5.2 86.5 81.3 -0.88 -0.72 9.74
DY ANT 81.85 28.88 77.9 81.85 17.42 44 143.1 99.1 0.88 -0.08 10.21
DY AG ANT 75.54 14.11 75.95 75.54 18.09 53.8 92.3 38.5 -0.16 -1.73 4.99
ST AG DY ANT 54.94 24.27 59.35 54.94 25.87 15.2 84.8 69.6 -0.29 -1.41 8.58
DY AG ST ANT 72.39 16.39 72.1 72.39 13.79 45.2 93.2 48 -0.14 -1.41 5.79
Untrained (n=8) Baseline 59.74 29.43 49.65 59.74 27.8 26.2 106.9 80.7 0.36 -1.7 10.4
ST AG 66.81 27.96 66 66.81 33.58 22.8 104.8 82 -0.13 -1.55 9.88
ST ANT 77.41 24.55 77.65 77.41 24.54 34.4 106.7 72.3 -0.3 -1.3 8.68
ST AG ANT 68.9 23.85 68.05 68.9 15.86 25.8 103.9 78.1 -0.24 -0.94 8.43
DY AG 62.27 35.41 70.25 62.27 29.58 4.7 103.9 99.2 -0.43 -1.51 12.52
DY ANT 74.64 27.84 75.1 74.64 20.31 19.1 110 90.9 -0.66 -0.62 9.84
DY AG ANT 76.6 29.42 74.5 76.6 36.03 36.6 123.2 86.6 0.12 -1.5 10.4
ST AG DY ANT 80.53 32.7 75.55 80.53 21.35 31.1 140 108.9 0.35 -0.89 11.56
DY AG ST ANT 84.53 22.87 85.2 84.53 22.24 50.4 123.2 72.8 0.15 -1.25 8.09
79
Table 16. Normalized Average Knee Power Flexion (W) by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1.16 0.51 1 1.11 0.16 0.54 2.42 1.88 1.35 0.88 0.13
ST ANT 1.29 0.55 1.1 1.24 0.31 0.71 2.62 1.91 1.3 0.49 0.14
ST AG ANT 1.12 0.59 0.93 1.06 0.39 0.45 2.61 2.16 1.15 0.35 0.15
DY AG 1 0.6 0.98 0.95 0.31 0.09 2.62 2.53 0.93 1.19 0.15
DY ANT 1.33 0.58 1.13 1.29 0.34 0.63 2.56 1.93 0.98 -0.19 0.14
DY AG ANT 1.3 0.47 1.14 1.23 0.31 0.83 2.67 1.84 1.48 1.85 0.12
ST AG DY ANT 1.34 1.24 0.99 1.14 0.37 0.21 5.34 5.13 2.13 4.03 0.31
DY AG ST ANT 1.39 0.59 1.19 1.34 0.24 0.65 2.79 2.14 1.09 0.11 0.15
Trained (n=8) ST AG 1.05 0.27 1.04 1.05 0.08 0.54 1.51 0.97 -0.2 -0.24 0.09
ST ANT 1.08 0.24 1.09 1.08 0.3 0.71 1.35 0.65 -0.35 -1.57 0.08
ST AG ANT 0.9 0.41 0.82 0.9 0.31 0.45 1.72 1.27 0.79 -0.63 0.14
DY AG 0.94 0.49 0.98 0.94 0.33 0.09 1.74 1.66 -0.14 -0.84 0.17
DY ANT 1.3 0.61 1.09 1.3 0.34 0.63 2.53 1.9 0.87 -0.66 0.22
DY AG ANT 1.17 0.3 1.07 1.17 0.06 0.83 1.81 0.98 1.09 0.01 0.1
ST AG DY ANT 0.88 0.44 0.89 0.88 0.53 0.21 1.46 1.25 -0.26 -1.56 0.16
DY AG ST ANT 1.14 0.38 1.12 1.14 0.26 0.65 1.88 1.23 0.56 -0.69 0.13
Untrained (n=8) ST AG 1.26 0.68 0.97 1.26 0.22 0.6 2.42 1.82 0.81 -1.26 0.24
ST ANT 1.5 0.71 1.17 1.5 0.4 0.89 2.62 1.73 0.57 -1.62 0.25
ST AG ANT 1.33 0.69 1.09 1.33 0.48 0.67 2.61 1.94 0.75 -1.13 0.24
DY AG 1.06 0.72 0.98 1.06 0.24 0.18 2.62 2.44 1 0.14 0.25
DY ANT 1.35 0.58 1.16 1.35 0.47 0.73 2.56 1.83 0.92 -0.42 0.21
DY AG ANT 1.42 0.59 1.28 1.42 0.55 0.83 2.67 1.84 0.93 -0.3 0.21
ST AG DY ANT 1.81 1.62 1.03 1.81 0.43 0.67 5.34 4.67 1.24 -0.03 0.57
DY AG ST ANT 1.64 0.69 1.27 1.64 0.26 1.03 2.79 1.76 0.66 -1.48 0.24
80
Table 17. Average Power Knee Flexion (%MVC) Effect Sizes and Pairwise comparisons.
Group 1 Group 2 z-statistic P-value Sig. ES (r) Magnitude
ST AG ANT DY AG ST ANT 2 0.000 **** -1.24 large
ST ANT ST AG ANT 115 0.013 * 0.571 moderate
DY AG DY AG ANT 24 0.044 * -0.536 moderate
DY AG DY AG ST ANT 23 0.018 * -0.57 moderate
ST AG DY AG ST ANT 20 0.011 * -0.633 moderate
DY AG DY ANT 15 0.012 * -0.66 moderate
ST AG ANT DY ANT 19 0.009 ** -0.345 small
ST AG ANT DY AG ANT 28 0.039 * -0.458 small
Significance (Sig.) was denoted with * as < 0.05, ** as < 0.01, and *** as <0.001; z-statistic, r
effect size (ES), and it’s interpretation (Magnitude) are listed from highest to lowest.
81
Figure 29. Interaction Plot of Average Peak Torque Extension (%MVC) by stretching condition.
Figure 30. Interaction Plot of Average Peak Torque Extension (%MVC) by group and stretching
condition.
82
Figure 31. Boxplot of Average Peak Torque Extension (%MVC) by stretching condition.
83
Table 18. Average Peak Torque (N) values by Stretching Condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 167.52 44.2 168.9 167.42 41.22 78 258.5 180.5 0.21 -0.36 11.05
ST AG 180.72 39.66 173.55 181.33 49.74 105.9 247.1 141.2 -0.13 -1.14 9.92
ST ANT 196.36 32.98 200.9 196.2 29.13 138.6 256.4 117.8 -0.24 -0.84 8.25
ST AG ANT 188.21 33.32 195.35 188.65 39.81 135.7 234.5 98.8 -0.21 -1.57 8.33
DY AG 188.41 39.42 188.35 187.41 43.51 129.9 261 131.1 0.06 -1.15 9.86
DY ANT 191.07 44.5 203.05 192.59 28.1 106.1 254.9 148.8 -0.86 -0.53 11.12
DY AG ANT 210.49 42.55 209.5 208.76 37.06 141.9 303.2 161.3 0.52 -0.41 10.64
ST AG DY ANT 173.57 63.03 170.65 174.7 53.15 48.9 282.5 233.6 -0.34 -0.58 15.76
DY AG ST ANT 217.82 41.41 219.25 217.58 31.06 135.7 303.3 167.6 0.22 -0.22 10.35
Trained (n=8) Baseline 176.66 34.09 173.2 176.66 28.98 131.8 226 94.2 0.31 -1.44 12.05
ST AG 191.71 40.44 193.9 191.71 52.71 141.9 247.1 105.2 0.03 -1.96 14.3
ST ANT 189.89 30.26 199.2 189.89 11.05 138.6 227.3 88.7 -0.63 -1.24 10.7
ST AG ANT 195.31 28.55 200.15 195.31 26.91 152.4 226 73.6 -0.54 -1.49 10.09
DY AG 193.89 34.16 188.35 193.89 41.59 139.4 242.5 103.1 -0.06 -1.48 12.08
DY ANT 191.36 36.19 198.5 191.36 21.94 109.9 224.7 114.8 -1.26 0.36 12.8
DY AG ANT 199.02 43.44 200.15 199.02 39.07 141.9 283.7 141.8 0.56 -0.74 15.36
ST AG DY ANT 149.41 65.66 162.3 149.41 59.01 48.9 223.6 174.7 -0.43 -1.54 23.21
DY AG ST ANT 219.06 41.48 219.25 219.06 34.25 175.6 303.3 127.7 0.75 -0.55 14.66
Untrained (n=8) Baseline 158.39 53.23 146.15 158.39 32.39 78 258.5 180.5 0.42 -0.73 18.82
ST AG 169.74 38.2 173.55 169.74 44.85 105.9 211.3 105.4 -0.42 -1.45 13.51
ST ANT 202.84 36.33 209.85 202.84 44.11 143.6 256.4 112.8 -0.14 -1.36 12.84
ST AG ANT 181.1 38.05 168.5 181.1 47.59 135.7 234.5 98.8 0.16 -1.8 13.45
DY AG 182.94 45.78 187.8 182.94 51.45 129.9 261 131.1 0.24 -1.43 16.18
DY ANT 190.79 54.15 211.15 190.79 34.03 106.1 254.9 148.8 -0.57 -1.42 19.15
DY AG ANT 221.95 41.15 225.75 221.95 23.94 170.7 303.2 132.5 0.57 -0.64 14.55
ST AG DY ANT 197.74 53.54 187.5 197.74 63.6 141.4 282.5 141.1 0.3 -1.74 18.93
DY AG ST ANT 216.57 44.16 220.3 216.57 25.06 135.7 287.6 151.9 -0.26 -0.72 15.61
84
Table 19. Normalized Average Peak Torque Extension (%MVC) by Baseline condition by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1.140 0.4 1 1.1 0.35 0.73 2.24 1.51 1.22 0.93 0.1
ST ANT 1.240 0.35 1.11 1.19 0.16 0.87 2.24 1.37 1.4 1.38 0.09
ST AG ANT 1.19 0.37 1.04 1.14 0.2 0.86 2.15 1.29 1.24 0.52 0.09
DY AG 1.16 0.24 1.08 1.15 0.21 0.81 1.7 0.88 0.74 -0.44 0.06
DY ANT 1.18 0.27 1.21 1.18 0.29 0.66 1.61 0.95 -0.28 -1.03 0.07
DY AG ANT 1.29 0.42 1.19 1.22 0.28 0.92 2.59 1.67 1.84 3.1 0.1
ST AG DY ANT 1.15 0.49 1.09 1.16 0.46 0.22 1.91 1.69 -0.16 -0.84 0.12
DY AG ST ANT 1.37 0.41 1.27 1.33 0.39 1 2.39 1.4 0.94 -0.07 0.1
Trained (n=8) ST AG 1.11 0.3 1 1.11 0.28 0.76 1.63 0.87 0.49 -1.45 0.11
ST ANT 1.09 0.17 1.09 1.09 0.14 0.87 1.42 0.54 0.44 -0.99 0.06
ST AG ANT 1.14 0.28 1.07 1.14 0.3 0.86 1.65 0.79 0.5 -1.38 0.1
DY AG 1.11 0.18 1.1 1.11 0.21 0.81 1.36 0.55 -0.14 -1.47 0.06
DY ANT 1.11 0.29 1.17 1.11 0.3 0.66 1.49 0.83 -0.28 -1.54 0.1
DY AG ANT 1.15 0.27 1 1.15 0.08 0.92 1.65 0.72 0.85 -1.09 0.09
ST AG DY ANT 0.9 0.46 0.95 0.9 0.36 0.22 1.58 1.36 -0.16 -1.49 0.16
DY AG ST ANT 1.28 0.34 1.14 1.28 0.2 1 1.82 0.82 0.63 -1.52 0.12
Untrained (n=8) ST AG 1.18 0.5 0.99 1.18 0.36 0.73 2.24 1.51 1.05 -0.22 0.18
ST ANT 1.38 0.44 1.26 1.38 0.38 0.99 2.24 1.25 0.74 -0.89 0.15
ST AG ANT 1.24 0.45 1.04 1.24 0.16 0.91 2.15 1.24 1.06 -0.61 0.16
DY AG 1.21 0.3 1.07 1.21 0.17 0.89 1.7 0.81 0.58 -1.5 0.1
DY ANT 1.24 0.26 1.23 1.24 0.28 0.83 1.61 0.79 -0.11 -1.37 0.09
DY AG ANT 1.43 0.51 1.24 1.43 0.11 1.03 2.59 1.56 1.4 0.51 0.18
ST AG DY ANT 1.4 0.4 1.35 1.4 0.46 0.97 1.91 0.94 0.17 -1.99 0.14
DY AG ST ANT 1.47 0.47 1.37 1.47 0.43 1 2.39 1.4 0.75 -0.8 0.17
85
Table 20. Effect Sizes for Average Peak Torque Extension by Stretching condition.
Group 1 Group 2 z-statistic P-value Sig. ES (r) Magnitude
ST AG DY AG ST ANT 11 0.002 ** 0363 moderate
ST AG ANT DY AG ST ANT 11 0.006 ** 0.336 moderate
ST AG DY AG ANT 22 0.033 * 0.250 small
DY AG DY AG ST ANT 22 0.016 * 0.247 small
DY ANT DY AG ST ANT 22 0.016 * 0.207 small
Significance (Sig.) was denoted with * as < 0.05, ** as < 0.01, and *** as <0.001; z-statistic, r
effect size (ES), and it’s interpretation (Magnitude) are listed from highest to lowest.
86
Figure 32. Interaction Plot of Average Peak Torque Knee Flexion (%MVC) by stretching
condition.
Figure 33. Interaction Plot of Average Peak Torque Knee Flexion (%MVC) by stretching
condition and by group.
87
Figure 34. Average Peak Torque Knee Flexion (%MVC) by Stretching Condition.
88
Table 21. Non-normalized Average Peak Torque Knee Flexion by Stretching Condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 80.58 28.16 80.8 80.27 18.46 32.2 133.3 101.1 0.02 -0.83 7.04
ST AG 91.75 23.19 93.8 93.19 28.17 35.9 127.4 91.5 -0.58 -0.19 5.8
ST ANT 100.01 23.04 100.95 101.22 18.38 50.4 132.6 82.2 -0.41 -0.5 5.76
ST AG ANT 86.24 24.69 89 87.29 23.2 39.4 118.4 79 -0.57 -0.85 6.17
DY AG 83.43 31.53 90.15 85.14 22.98 12.2 130.7 118.5 -0.76 -0.32 7.88
DY ANT 93.35 25.99 100.9 95.34 19.05 29.7 129.2 99.5 -0.9 -0.08 6.5
DY AG ANT 100.68 25.19 104.15 100.58 26.17 55.2 147.6 92.4 -0.06 -0.96 6.3
ST AG DY ANT 84.03 29 80.85 84.79 29.43 22.7 134.6 111.9 -0.19 -0.57 7.25
DY AG ST ANT 102.35 20.79 99.7 101.35 20.09 71.1 147.6 76.5 0.37 -0.69 5.2
Trained (n=8) Baseline 89.6 13.01 90.45 89.6 6.67 72.8 115 42.2 0.5 -0.64 4.6
ST AG 92.6 16 93.8 92.6 17.42 71.6 116.1 44.5 -0.03 -1.64 5.66
ST ANT 97.31 19.77 95.4 97.31 13.42 62.5 132.5 70 0.03 -0.53 6.99
ST AG ANT 78.8 22.93 84.8 78.8 15.94 42.3 112 69.7 -0.29 -1.35 8.11
DY AG 77.6 32.94 90.15 77.6 17.57 12.2 108.1 95.9 -0.91 -0.78 11.65
DY ANT 90.85 20.82 97.15 90.85 21.57 58.5 113.5 55 -0.42 -1.57 7.36
DY AG ANT 100.31 19.33 103.8 100.31 17.94 72.8 130.5 57.7 -0.05 -1.43 6.83
ST AG DY ANT 77.58 32.47 74.4 77.58 16.23 22.7 134.6 111.9 0.11 -0.72 11.48
DY AG ST ANT 97.2 18.04 93.5 97.2 14.83 72.5 128.6 56.1 0.38 -1.22 6.38
Untrained (n=8) Baseline 71.56 36.65 64.35 71.56 30.1 32.2 133.3 101.1 0.56 -1.36 12.96
ST AG 90.9 29.91 94.05 90.9 31.28 35.9 127.4 91.5 -0.48 -1.14 10.57
ST ANT 102.7 27.02 109.85 102.7 29.5 50.4 132.6 82.2 -0.64 -0.89 9.55
ST AG ANT 93.67 25.57 96.75 93.67 21.5 39.4 118.4 79 -0.97 -0.26 9.04
DY AG 89.26 31.11 90.55 89.26 28.61 31.3 130.7 99.4 -0.45 -1 11
DY ANT 95.85 31.62 106.15 95.85 14.16 29.7 129.2 99.5 -0.99 -0.37 11.18
DY AG ANT 101.05 31.39 104.15 101.05 33.58 55.2 147.6 92.4 -0.07 -1.53 11.1
ST AG DY ANT 90.47 25.54 96.2 90.47 18.68 45.4 126.7 81.3 -0.38 -1.14 9.03
DY AG ST ANT 107.5 23.24 110.55 107.5 22.76 71.1 147.6 76.5 0.11 -1.05 8.22
89
Table 22. Normalized Peak Torque Knee Flexion (%MVC) by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1.31 0.75 1.03 1.2 0.32 0.62 3.57 2.96 1.8 2.56 0.19
ST ANT 1.45 0.86 1.19 1.31 0.35 0.69 4.12 3.43 1.92 3.07 0.22
ST AG ANT 1.26 0.75 0.95 1.18 0.46 0.47 3.2 2.74 1.18 0.42 0.19
DY AG 1.19 0.72 1.04 1.13 0.3 0.14 3.11 2.97 1.12 0.93 0.18
DY ANT 1.3 0.71 1.06 1.19 0.32 0.64 3.56 2.91 1.95 3.47 0.18
DY AG ANT 1.38 0.79 1.11 1.23 0.34 0.78 4 3.22 2.26 4.7 0.2
ST AG DY ANT 1.27 0.76 1.05 1.19 0.52 0.25 3.3 3.05 1.18 0.95 0.19
DY AG ST ANT 1.47 0.75 1.23 1.37 0.39 0.72 3.57 2.86 1.51 1.44 0.19
Trained (n=8) ST AG 1.04 0.16 1.03 1.04 0.16 0.79 1.27 0.49 0 -1.53 0.06
ST ANT 1.1 0.23 1.12 1.1 0.22 0.69 1.39 0.7 -0.42 -1.14 0.08
ST AG ANT 0.91 0.35 0.89 0.91 0.37 0.47 1.49 1.02 0.36 -1.37 0.12
DY AG 0.89 0.4 0.94 0.89 0.4 0.14 1.31 1.17 -0.64 -1.07 0.14
DY ANT 1.03 0.29 1.02 1.03 0.32 0.64 1.51 0.87 0.19 -1.47 0.1
DY AG ANT 1.13 0.22 1.06 1.13 0.16 0.89 1.53 0.64 0.65 -1.19 0.08
ST AG DY ANT 0.89 0.4 0.88 0.89 0.33 0.25 1.43 1.18 -0.05 -1.34 0.14
DY AG ST ANT 1.11 0.27 1.13 1.11 0.26 0.72 1.53 0.82 0 -1.44 0.1
Untrained (n=8) ST AG 1.58 1.01 1.16 1.58 0.69 0.62 3.57 2.96 0.81 -0.83 0.36
ST ANT 1.79 1.12 1.39 1.79 0.75 0.87 4.12 3.25 0.95 -0.53 0.4
ST AG ANT 1.61 0.9 1.4 1.61 1.01 0.68 3.2 2.53 0.49 -1.39 0.32
DY AG 1.49 0.85 1.11 1.49 0.57 0.54 3.11 2.57 0.68 -1.08 0.3
DY ANT 1.57 0.92 1.21 1.57 0.48 0.85 3.56 2.71 1.14 -0.12 0.32
DY AG ANT 1.62 1.07 1.29 1.62 0.59 0.78 4 3.22 1.23 0.12 0.38
ST AG DY ANT 1.64 0.86 1.4 1.64 0.74 0.71 3.3 2.6 0.71 -0.93 0.3
DY AG ST ANT 1.82 0.92 1.43 1.82 0.61 0.93 3.57 2.65 0.73 -1.07 0.32
90
Figure 35. Interaction plot for EMG (%MVC) of the Vastus Lateralis by period and group.
Figure 36. EMG (%MVC) of the Vastus Lateralis by period and group.
91
Table 23. Vastus Lateralis (%MVC) activation by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n=18) ST AG 1.03 0.55 0.92 0.95 0.42 0.42 2.84 2.42 1.98 4.19 0.14
ST ANT 1.33 0.83 1.14 1.23 0.61 0.52 3.58 3.06 1.26 0.76 0.21
ST AG ANT 1.2 0.64 1.06 1.1 0.46 0.5 3.24 2.75 1.85 3.68 0.16
DY AG 1.08 0.45 1.11 1.09 0.58 0.38 1.69 1.31 -0.05 -1.75 0.11
DY ANT 1.42 0.92 1.1 1.3 0.54 0.68 3.94 3.25 1.4 0.97 0.23
DY AG ANT 1.39 0.82 1.24 1.28 0.59 0.43 3.93 3.5 1.66 2.85 0.21
ST AG DY ANT 1.28 0.68 1.2 1.22 0.76 0.58 2.79 2.22 0.76 -0.58 0.17
DY AG ST ANT 1.35 0.85 0.93 1.26 0.61 0.49 3.36 2.87 0.91 -0.42 0.21
Trained (n=8) ST AG 1 0.27 1.06 1 0.31 0.55 1.28 0.73 -0.37 -1.64 0.1
ST ANT 1.23 0.54 1.19 1.23 0.18 0.56 2.39 1.82 0.9 -0.02 0.19
ST AG ANT 1.11 0.24 1.06 1.11 0.31 0.74 1.4 0.66 -0.03 -1.67 0.08
DY AG 1.11 0.47 1.34 1.11 0.27 0.38 1.6 1.22 -0.45 -1.75 0.17
DY ANT 1.28 0.65 1.1 1.28 0.4 0.68 2.73 2.05 1.24 0.28 0.23
DY AG ANT 1.27 0.45 1.24 1.27 0.48 0.67 2.06 1.39 0.31 -1.26 0.16
ST AG DY ANT 1.18 0.47 1.2 1.18 0.46 0.58 1.97 1.39 0.21 -1.29 0.17
DY AG ST ANT 1.24 0.71 1.02 1.24 0.74 0.5 2.27 1.77 0.41 -1.7 0.25
Untrained (n=8) ST AG 1.43 1.08 0.86 1.43 0.39 0.52 3.58 3.06 0.85 -0.87 0.38
ST ANT 1.28 0.9 1.1 1.28 0.71 0.5 3.24 2.75 1.11 -0.02 0.32
ST AG ANT 1.05 0.46 0.86 1.05 0.32 0.64 1.69 1.05 0.37 -1.9 0.16
DY AG 1.57 1.16 1.06 1.57 0.52 0.69 3.94 3.25 0.95 -0.66 0.41
DY ANT 1.51 1.1 1.24 1.51 0.76 0.43 3.93 3.5 1.12 0.03 0.39
DY AG ANT 1.38 0.87 1.06 1.38 0.64 0.6 2.79 2.2 0.49 -1.62 0.31
ST AG DY ANT 1.46 1.01 0.93 1.46 0.39 0.49 3.36 2.87 0.8 -1.08 0.36
DY AG ST ANT 1.43 1.08 0.86 1.43 0.39 0.52 3.58 3.06 0.85 -0.87 0.38
92
Figure 37. Interaction plot for EMG (%MVC) of the Vastus Medialis Oblique by period and group.
Figure 38. EMG (%MVC) of the Vastus Medialis Oblique by period and group.
93
Table 24. Vastus Medialis Oblique (%MVC) activation by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n=18)
ST AG 1.17 0.86 1 1.04 0.29 0.14 4.02 3.87 2.15 4.78 0.21
ST ANT 1.24 0.47 1.19 1.2 0.38 0.51 2.5 1.99 1.01 0.97 0.12
ST AG ANT 1.04 0.39 0.96 1 0.28 0.41 2.11 1.69 1.05 1.23 0.1
DY AG 1.09 0.49 1.16 1.07 0.38 0.14 2.29 2.15 0.31 0.53 0.12
DY ANT 1.24 0.42 1.2 1.23 0.27 0.39 2.24 1.85 0.53 0.56 0.1
DY AG ANT 1.26 0.45 1.2 1.23 0.57 0.65 2.28 1.63 0.51 -0.69 0.11
ST AG DY ANT 1.13 0.31 1.14 1.13 0.33 0.5 1.73 1.23 -0.03 -0.79 0.08
DY AG ST ANT 1.24 0.4 1.17 1.22 0.4 0.61 2.14 1.52 0.53 -0.63 0.1
Trained (n=8) ST AG 0.8 0.36 0.92 0.8 0.12 0.14 1.23 1.08 -0.73 -1.08 0.13
ST ANT 1.26 0.42 1.34 1.26 0.26 0.51 1.84 1.33 -0.5 -1.06 0.15
ST AG ANT 0.94 0.33 0.88 0.94 0.26 0.41 1.45 1.04 0.06 -1.31 0.12
DY AG 1.05 0.5 1.27 1.05 0.18 0.14 1.52 1.38 -0.85 -1.12 0.18
DY ANT 1.07 0.31 1.1 1.07 0.18 0.39 1.39 1 -1.13 0.16 0.11
DY AG ANT 0.99 0.28 0.92 0.99 0.31 0.65 1.49 0.84 0.46 -1.34 0.1
ST AG DY ANT 1.06 0.32 1.03 1.06 0.33 0.5 1.49 0.98 -0.23 -1.31 0.11
DY AG ST ANT 1.12 0.31 1.08 1.12 0.26 0.8 1.75 0.95 0.79 -0.57 0.11
Untrained (n=8) ST AG 1.54 1.07 1.2 1.54 0.33 0.71 4.02 3.31 1.46 0.71 0.38
ST ANT 1.21 0.54 1.05 1.21 0.2 0.82 2.5 1.68 1.59 1.08 0.19
ST AG ANT 1.13 0.44 1 1.13 0.18 0.64 2.11 1.47 1.17 0.25 0.16
DY AG 1.14 0.51 0.96 1.14 0.27 0.77 2.29 1.52 1.33 0.44 0.18
DY ANT 1.41 0.46 1.28 1.41 0.46 0.92 2.24 1.32 0.58 -1.26 0.16
DY AG ANT 1.52 0.44 1.61 1.52 0.38 0.81 2.28 1.47 0.04 -1 0.16
ST AG DY ANT 1.19 0.31 1.23 1.19 0.35 0.77 1.73 0.97 0.22 -1.3 0.11
DY AG ST ANT 1.35 0.48 1.37 1.35 0.45 0.61 2.14 1.52 0.08 -1.25 0.17
94
Figure 39. Interaction plot for EMG (%MVC) of the rectus femoris oblique by period and group.
Figure 40. EMG (%MVC) of the rectus femoris by period and group.
95
Table 25. Rectus Femoris (%MVC) activation by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n=18) ST AG 1.17 0.86 1 1.04 0.29 0.14 4.02 3.87 2.15 4.78 0.21
ST ANT 1.24 0.47 1.19 1.2 0.38 0.51 2.5 1.99 1.01 0.97 0.12
ST AG ANT 1.04 0.39 0.96 1 0.28 0.41 2.11 1.69 1.05 1.23 0.1
DY AG 1.09 0.49 1.16 1.07 0.38 0.14 2.29 2.15 0.31 0.53 0.12
DY ANT 1.24 0.42 1.2 1.23 0.27 0.39 2.24 1.85 0.53 0.56 0.1
DY AG ANT 1.26 0.45 1.2 1.23 0.57 0.65 2.28 1.63 0.51 -0.69 0.11
ST AG DY ANT 1.13 0.31 1.14 1.13 0.33 0.5 1.73 1.23 -0.03 -0.79 0.08
DY AG ST ANT 1.24 0.4 1.17 1.22 0.4 0.61 2.14 1.52 0.53 -0.63 0.1
Trained (n=8) ST AG 0.8 0.36 0.92 0.8 0.12 0.14 1.23 1.08 -0.73 -1.08 0.13
ST ANT 1.26 0.42 1.34 1.26 0.26 0.51 1.84 1.33 -0.5 -1.06 0.15
ST AG ANT 0.94 0.33 0.88 0.94 0.26 0.41 1.45 1.04 0.06 -1.31 0.12
DY AG 1.05 0.5 1.27 1.05 0.18 0.14 1.52 1.38 -0.85 -1.12 0.18
DY ANT 1.07 0.31 1.1 1.07 0.18 0.39 1.39 1 -1.13 0.16 0.11
DY AG ANT 0.99 0.28 0.92 0.99 0.31 0.65 1.49 0.84 0.46 -1.34 0.1
ST AG DY ANT 1.06 0.32 1.03 1.06 0.33 0.5 1.49 0.98 -0.23 -1.31 0.11
DY AG ST ANT 1.12 0.31 1.08 1.12 0.26 0.8 1.75 0.95 0.79 -0.57 0.11
Untrained (n=8) ST AG 1.54 1.07 1.2 1.54 0.33 0.71 4.02 3.31 1.46 0.71 0.38
ST ANT 1.21 0.54 1.05 1.21 0.2 0.82 2.5 1.68 1.59 1.08 0.19
ST AG ANT 1.13 0.44 1 1.13 0.18 0.64 2.11 1.47 1.17 0.25 0.16
DY AG 1.14 0.51 0.96 1.14 0.27 0.77 2.29 1.52 1.33 0.44 0.18
DY ANT 1.41 0.46 1.28 1.41 0.46 0.92 2.24 1.32 0.58 -1.26 0.16
DY AG ANT 1.52 0.44 1.61 1.52 0.38 0.81 2.28 1.47 0.04 -1 0.16
ST AG DY ANT 1.19 0.31 1.23 1.19 0.35 0.77 1.73 0.97 0.22 -1.3 0.11
DY AG ST ANT 1.35 0.48 1.37 1.35 0.45 0.61 2.14 1.52 0.08 -1.25 0.17
96
Figure 41. Interaction plot for EMG (%MVC) of the Bicepss femoris by period and group.
Figure 42. EMG (%MVC) of the Bicepss femoris by period and group.
97
Table 26. Bicepss Femoris (%MVC) activation by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n=18) ST AG 1.27 0.88 0.99 1.14 0.6 0.5 3.8 3.3 1.58 1.86 0.22
ST ANT 1.29 0.73 1.17 1.25 0.53 0.37 2.79 2.41 0.75 -0.58 0.18
ST AG ANT 1.33 0.91 1.12 1.17 0.29 0.4 4.38 3.98 2.27 5.01 0.23
DY AG 1.21 0.81 0.91 1.13 0.43 0.37 3.13 2.76 1.25 0.3 0.2
DY ANT 1.52 0.89 1.14 1.47 0.69 0.38 3.36 2.98 0.65 -0.96 0.22
DY AG ANT 1.41 0.85 1.1 1.28 0.37 0.53 4.03 3.51 1.88 3.08 0.21
ST AG DY ANT 1.25 0.77 1.12 1.19 0.4 0.08 3.28 3.2 1.1 0.94 0.19
DY AG ST ANT 1.28 0.77 1.23 1.19 0.52 0.25 3.43 3.18 1.2 1.41 0.19
Trained (n=8) ST AG 1 0.47 0.93 1 0.47 0.5 1.74 1.23 0.51 -1.47 0.16
ST ANT 1.21 0.55 1.11 1.21 0.43 0.54 2.18 1.64 0.46 -1.32 0.19
ST AG ANT 1.14 0.3 1.12 1.14 0.21 0.69 1.74 1.06 0.58 -0.36 0.11
DY AG 1.12 0.8 0.86 1.12 0.4 0.37 2.9 2.53 1.23 0.2 0.28
DY ANT 1.26 0.98 0.93 1.26 0.41 0.38 3.36 2.98 1.12 -0.18 0.35
DY AG ANT 1.19 0.59 0.96 1.19 0.09 0.86 2.6 1.74 1.63 1.08 0.21
ST AG DY ANT 0.96 0.56 0.99 0.96 0.66 0.08 1.7 1.62 -0.16 -1.61 0.2
DY AG ST ANT 1.04 0.61 1.07 1.04 0.72 0.25 1.97 1.72 0.09 -1.67 0.21
Untrained (n=8) ST AG 1.54 1.13 1.18 1.54 0.6 0.5 3.8 3.3 0.94 -0.68 0.4
ST ANT 1.37 0.9 1.17 1.37 0.64 0.37 2.79 2.41 0.53 -1.41 0.32
ST AG ANT 1.52 1.27 1.07 1.52 0.55 0.4 4.38 3.98 1.31 0.37 0.45
DY AG 1.3 0.87 0.92 1.3 0.48 0.5 3.13 2.63 1.05 -0.41 0.31
DY ANT 1.77 0.77 1.57 1.77 0.85 0.94 2.81 1.87 0.26 -1.89 0.27
DY AG ANT 1.62 1.04 1.48 1.62 0.4 0.53 4.03 3.51 1.36 0.72 0.37
ST AG DY ANT 1.54 0.87 1.17 1.54 0.25 0.88 3.28 2.4 1.02 -0.75 0.31
DY AG ST ANT 1.51 0.87 1.25 1.51 0.46 0.85 3.43 2.59 1.23 0.05 0.31
98
Figure 43. Interaction plot for EMG (%MVC) of the semitendinosus by period and group.
Figure 44. EMG (%MVC) of the semitendinosus by period and group.
99
Table 27. Semitendinosus (%MVC) activation by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n=18) ST AG 1.06 0.6 0.86 1.03 0.45 0.24 2.29 2.05 0.72 -0.73 0.15
ST ANT 1.14 0.63 1.04 1.06 0.41 0.46 2.95 2.49 1.45 1.82 0.16
ST AG ANT 1.15 0.47 1.03 1.14 0.42 0.44 2.01 1.57 0.42 -1.13 0.12
DY AG 1.11 0.39 1.02 1.08 0.28 0.61 2.03 1.43 0.8 -0.2 0.1
DY ANT 1.28 0.79 1.17 1.18 0.26 0.32 3.54 3.22 1.65 2.07 0.2
DY AG ANT 1.29 0.71 0.99 1.21 0.39 0.55 3.09 2.54 1.25 0.55 0.18
ST AG DY ANT 0.99 0.48 0.93 0.98 0.4 0.14 1.97 1.83 0.5 -0.2 0.12
DY AG ST ANT 1.07 0.49 1.01 1.06 0.37 0.27 2.05 1.78 0.67 -0.37 0.12
Trained (n=8) ST AG 0.85 0.63 0.79 0.85 0.3 0.24 2.29 2.05 1.34 0.61 0.22
ST ANT 0.97 0.49 0.94 0.97 0.34 0.46 2.02 1.56 0.94 -0.18 0.17
ST AG ANT 1.11 0.5 0.99 1.11 0.31 0.44 2.01 1.57 0.47 -1.16 0.18
DY AG 1.06 0.27 1.05 1.06 0.21 0.64 1.46 0.83 -0.01 -1.27 0.09
DY ANT 1.03 0.35 1.17 1.03 0.11 0.32 1.3 0.98 -1.05 -0.61 0.12
DY AG ANT 1.32 0.8 1.15 1.32 0.54 0.55 3.09 2.54 1.17 0.18 0.28
ST AG DY ANT 0.98 0.58 1.08 0.98 0.46 0.14 1.97 1.83 0.14 -1.18 0.2
DY AG ST ANT 0.97 0.53 0.91 0.97 0.41 0.27 2.05 1.78 0.7 -0.51 0.19
Untrained (n=8) ST AG 1.28 0.51 1.18 1.28 0.57 0.73 2.06 1.33 0.36 -1.65 0.18
ST ANT 1.3 0.74 1.21 1.3 0.36 0.52 2.95 2.43 1.19 0.35 0.26
ST AG ANT 1.2 0.45 1.13 1.2 0.54 0.74 1.95 1.22 0.33 -1.65 0.16
DY AG 1.16 0.49 0.96 1.16 0.36 0.61 2.03 1.43 0.6 -1.33 0.17
DY ANT 1.53 1.04 1.1 1.53 0.35 0.61 3.54 2.94 0.94 -0.9 0.37
DY AG ANT 1.26 0.65 0.92 1.26 0.26 0.74 2.58 1.84 0.93 -0.7 0.23
ST AG DY ANT 0.99 0.4 0.88 0.99 0.1 0.6 1.9 1.31 1.36 0.62 0.14
DY AG ST ANT 1.16 0.45 1.01 1.16 0.33 0.67 2.03 1.36 0.75 -0.93 0.16
100
1.24 Vertical Jump
There was no time interaction on CMJ height %(MCV) (F(7) = 1.360, p = 0.230), or
between subjects (F(1) = 1.590, p 0.227) or between-within subjects (F (1) = 1.5900, p = 0.866)
(Figures 43-45, Tables 30-31). There was no interaction in any of the phase temporal, kinetic, or
kinematic variables between or within, or between-within subjects (p > 0.05) (Figures 46-61,
Tables 30-47). There was in interaction (F(7) = 2.127, p = 0.047, ηp2 (moderate) = 0.13 [95%CI
= 0.00-0.19]), in Push-Off distance, but not between (F(1) = 0.025, p = 0.876), or within-between
subjects (F(7) = 0.239, p = 0.974). Pairwise comparisons indicate a large effect size between ST
AG ANT and DY AG ST ANT, and ST AG and DY AG ST ANT. A moderate effect size
between ST AG ANT and DY AG ST ANT, ST AG ANT and DY AG, ST AG and DY AG, and
ST AG ANT and DY ANT (Table 51). Finally, there was no difference in SQJ and DJ within,
between, or within-between subjects.
There was no time interaction on SQJ height %(MCV) (F(7) = 3.004, p = 0.051), or between
subjects (F(1) = 1.068, p = 0.318) or between-within subjects (F (1) = 0.397, p = 0.901) (Figures
69-71, Tables 50-51). There was no time interaction on DJ height %(MCV) (F(7) = 1.0254, p =
0.418), or between subjects (F(1) = 0.399, p = 0.375) or between-within subjects (F (1) = 1.053,
p = 0.399) (Figures 72-74, Tables 52-53). There was no time interaction on CMJ height
%(MCV) (F(7) = 1.360, p = 0.230), or between subjects (F(1) = 1.590, p 0.227) but there was
interaction between-within subjects (F (1) = 4.210, p = 0.000, ηp2 (moderate) = 0.17 [95%CI =
0.00-0.24]) (Figures 75-77, Tables 54-55).
The smallest worthwhile (SWC) change analysis indicated that, on average, all subjects as a
group did not cross the SWC threshold. Furthermore, when stratifying by training status (group),
the trained individuals did not cross the SWC on any of the conditions. In contrast, the untrained
101
subjects only crossed the SWC on the DY AG ANT condition, with an average of 14.74%
(3.83cm) compared to baseline. Additionally, within subjects SWC analysis indicated a trend
towards the dynamic stretching condition (DY AG ANT, and DY AG ST ANT). This analysis
showed that Subject Three (Trained) crossed SWC on the ST AG ANT, DY ANT, ST AG DY
ANT, and DY AG ST ANT, with the last two being the highest recorded. Similarly, Subject Five
(Untrained) crossed SWC threshold under the ST AG, DY AG, DY ANT, DY AG ANT, and DY
AG ST ANT, with the last two being the highest. Subject Six (Trained), crossed SWC in the ST
AG, and ST ANT protocol, with the latest being the highest. Subject Seven (Untrained), only
crossed SWC in the ST AG DY ANT. Subject Nine (Trained) only crossed SWC in the ST ANT
condition. Subject Ten (Trained) crossed SWC on ST ANT, ST AG ANT, DY AG, DY ANT,
DY AG ANT, ST AG DY ANT, and DY AG ST ANT. Subject Eleven (Untrained), crossed the
SWC on the ST AG ANT and DY AG ANT. Subject Thirteen (Untrained), crossed SWC on all
of the stretching conditions. Subject Fourteen (Untrained) crossed SWC on the DY AG ST ANT.
Finally, Subject Fifteen (Untrained) crossed SWC on the ST ANT and DY ANT conditions.
Subjects One (Untrained), Two (Trained), Four (Trained), Eight (Trained), Twelve (Trained),
and Sixteen (Untrained) did not cross SWC in any of the conditions.
Moreover, there was a significant interaction in Push-Off distance in the CMJ [X2(7) =
18.63, p = 0.009, Kendall W (small) = 0.166] but not between subjects (p > 0.05). Pairwise
analyzes indicated large effect sizes between ST AG ANT and DY AG ST ANT, and ST AG and
DY AG ST ANT. Similarly, moderate effect size were found between ST AG ANT and DY AG
ANT, ST AG ANT and DY AG, ST AG and DY AG, and ST AG ANT and DY ANT. With all
of the interactions favoring dynamic stretching over static stretching. There were no other
102
significant findings between any of the other kinetic or kinematic metrics during the CMJ
(p>0.05).
Figure 45. Interaction plot of normalized CMJ height (%MVC) by period and group.
103
Figure 46. Boxplot of normalized CMJ height (%MVC) for all subjects
Figure 47. Boxplot of non-normalized Countermovement Jump Height (cm) by stretching
condition.
104
Table 28. Countermovement Jump Height (m) by stretching conditions and groups.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 30.1 5.1 31.41 30.24 6.01 20.1 38.2 18.1 -0.17 -1.08 1.27
ST AG 30.41 4.86 31.05 30.4 5.23 22.74 38.28 15.54 -0.07 -1.32 1.21
ST ANT 32.02 5.89 31.78 31.69 6.05 23.07 45.62 22.55 0.49 -0.4 1.47
ST AG ANT 30.87 5.18 30.66 30.52 6.23 24.47 42.26 17.78 0.55 -0.83 1.29
DY AG 31.05 4.8 30.7 30.92 4.03 23.28 40.62 17.33 0.49 -0.58 1.2
DY ANT 31.11 5.86 30.92 30.78 5.3 22.38 44.55 22.17 0.35 -0.35 1.47
DY AG ANT 32.33 5.21 32.2 32.16 4.63 24.25 42.73 18.49 0.3 -0.79 1.3
ST AG DY ANT 30.91 5.61 29.47 30.24 4.2 23.5 47.63 24.13 1.49 2.3 1.4
DY AG ST ANT 32.66 5.63 31.53 32.1 4.67 25.41 47.63 22.22 1.04 0.65 1.41
Trained (n=8) Baseline 34.23 2.46 33.08 34.23 1.64 31.33 38.2 6.87 0.54 -1.48 0.87
ST AG 34.16 4.44 33.99 34.16 4.54 27.86 40.62 12.76 0.21 -1.51 1.57
ST ANT 34.85 4.94 34.69 34.85 6 29.07 42.73 13.67 0.34 -1.49 1.75
ST AG ANT 36.43 5.44 35.82 36.43 5.3 31.24 47.63 16.39 0.85 -0.5 1.92
DY AG 34.12 6.29 34.42 34.12 3.29 22.53 44.55 22.02 -0.21 -0.57 2.22
DY ANT 34.04 2.85 33.53 34.04 3.91 30.82 38.28 7.47 0.22 -1.78 1.01
DY AG ANT 33.95 4.51 32.6 33.95 3.7 27.45 42.26 14.81 0.43 -0.96 1.6
ST AG DY ANT 34.11 6.04 32.48 34.11 2.41 27.77 47.63 19.86 1.22 0.31 2.14
DY AG ST ANT 35.59 5.46 35.64 35.59 5.3 27.62 45.62 18 0.36 -0.92 1.93
Untrained (n=8) Baseline 25.98 3.27 25.55 25.98 1.65 20.1 31.48 11.38 -0.09 -0.65 1.16
ST AG 26.79 3.51 25.94 26.79 2.9 22.74 32.39 9.65 0.42 -1.58 1.24
ST ANT 28.45 3.92 28 28.45 4.69 23.07 34.19 11.12 0.09 -1.74 1.39
ST AG ANT 27.8 3.93 26.46 27.8 2.05 24.47 36.5 12.03 1.22 0.13 1.39
DY AG 27.94 2.76 28.13 27.94 3.56 23.28 30.89 7.61 -0.39 -1.47 0.97
DY ANT 28.1 3.66 28.9 28.1 4.03 22.38 32.55 10.17 -0.26 -1.71 1.3
DY AG ANT 29.81 4.37 29.91 29.81 5.6 24.25 36.47 12.23 0.1 -1.68 1.55
ST AG DY ANT 27.71 2.72 28.05 27.71 1.12 23.5 33.12 9.62 0.49 -0.29 0.96
DY AG ST ANT 28.88 2.4 28.74 28.88 2.89 25.41 32.5 7.09 0.02 -1.48 0.85
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Table 29. Normalized Countermovement Jump Height by stretching conditions and groups.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1 0.13 0.99 1 0.07 0.87 1.4 0.51 1.4 1.9 0.03
ST ANT 1.1 0.19 1 1.1 0.14 0.84 1.6 0.76 1.3 1.4 0.05
ST AG ANT 1 0.15 1 1 0.07 0.78 1.4 0.61 0.78 0.45 0.04
DY AG 1 0.16 1 1 0.09 0.89 1.5 0.63 1.7 2.6 0.04
DY ANT 1 0.2 1 1 0.11 0.68 1.6 0.94 1.1 2.4 0.05
DY AG ANT 1.1 0.17 1.1 1.1 0.16 0.84 1.5 0.67 0.82 0.11 0.04
ST AG DY ANT 1 0.15 1 1 0.11 0.79 1.4 0.6 0.55 0 0.04
DY AG ST ANT 1.1 0.13 1.1 1.1 0.11 0.91 1.4 0.49 0.66 -0.42 0.03
Trained (n=8) ST AG 1 0.08 0.99 1 0.1 0.89 1.1 0.23 0.13 -1.7 0.03
ST ANT 1 0.15 1 1 0.13 0.84 1.3 0.46 0.38 -1.4 0.05
ST AG ANT 0.99 0.1 1 0.99 0.05 0.78 1.1 0.32 -0.74 -0.35 0.04
DY AG 1 0.11 0.94 1 0.05 0.89 1.2 0.34 1 -0.33 0.04
DY ANT 0.99 0.15 1 0.99 0.11 0.68 1.2 0.48 -0.72 -0.52 0.05
DY AG ANT 1 0.14 1 1 0.11 0.84 1.3 0.45 0.54 -0.92 0.05
ST AG DY ANT 1 0.15 0.98 1 0.14 0.79 1.2 0.46 0.16 -1.2 0.05
DY AG ST ANT 1.1 0.11 1.1 1.1 0.11 0.91 1.2 0.34 0.19 -1.3 0.04
Untrained (n=8) ST AG 1.1 0.19 1 1.1 0.09 0.93 1.5 0.59 1.4 0.54 0.07
ST ANT 1.2 0.18 1.1 1.2 0.15 0.97 1.5 0.54 0.81 -0.69 0.06
ST AG ANT 1.1 0.15 1.1 1.1 0.14 0.96 1.4 0.44 0.58 -1.2 0.05
DY AG 1.1 0.23 1 1.1 0.12 0.89 1.6 0.72 1.3 0.48 0.08
DY ANT 1 0.16 0.98 1 0.06 0.87 1.4 0.51 1.1 -0.14 0.06
DY AG ANT 1.1 0.18 1 1.1 0.1 0.86 1.4 0.54 0.58 -1.2 0.06
ST AG DY ANT 1.1 0.15 1.1 1.1 0.13 0.94 1.4 0.45 0.89 -0.37 0.05
DY AG ST ANT 1.1 0.22 1.1 1.1 0.14 0.92 1.6 0.68 1.3 0.33 0.08
106
Table 30. Individual analysis of mean Vertical Jump Height (cm) via Smallest Worthwhile Change
Subject Group Baseline SWC
ST
AG
ST
ANT
ST
AG ANT
DY
AG
DY
ANT
DY
AG ANT
ST AG
DY ANT
DY AG
ST ANT
One Untrained 31.48 34.87 32.39 34.19 27.05 30.50 31.35 33.83 33.12 30.12
Two Trained 32.97 36.36 30.96 27.62 32.57 31.01 22.53 29.51 32.31 31.24
Three Trained 38.20 41.59 38.28 35.49 42.26 39.93 44.55 40.88 47.63 47.63
Four Trained 32.61 35.99 33.82 31.39 32.62 30.84 33.87 35.31 34.03 35.31
Five Untrained 26.97 30.37 31.14 29.41 29.87 30.89 30.47 32.61 25.99 32.50
Six Trained 33.17 36.56 36.98 36.70 31.45 35.02 34.48 31.78 32.65 36.32
Seven Untrained 24.76 28.14 24.69 25.73 25.86 27.00 24.34 26.28 28.16 25.41
Eight Trained 37.49 40.87 33.23 35.79 37.11 34.89 34.35 35.48 31.04 38.99
Nine Trained 35.08 38.48 31.89 45.62 27.45 33.09 34.72 29.07 27.77 31.84
Ten Trained 32.98 36.36 36.33 39.63 36.45 40.62 38.31 42.73 36.69 38.35
Eleven Untrained 28.38 31.76 27.18 26.60 36.50 28.10 27.33 36.47 26.64 28.70
Twelve Trained 31.33 34.72 30.82 32.48 31.68 27.86 30.15 34.08 30.78 31.76
Thirteen Untrained 20.10 23.48 27.87 32.16 28.05 30.56 32.55 30.41 27.96 28.05
Fourteen Untrained 25.06 28.45 24.34 23.07 25.29 23.28 25.92 25.17 23.50 31.30
Fifteen Untrained 26.05 29.43 22.74 31.39 25.29 28.16 30.50 29.42 28.14 28.77
Sixteen Untrained 25.01 28.40 23.95 25.06 24.47 25.05 22.38 24.25 28.14 26.22
Group Trained 34.23 37.62 34.04 35.59 33.95 34.16 34.12 34.86 34.11 36.43
Group Untrained 25.98 29.36 26.79 28.45 27.80 27.94 28.11 29.81 27.71 28.88
All 30.10 33.49 30.41 32.02 30.87 31.05 31.11 32.33 30.91 32.66
*Smallest Worthwhile Change; red color indicates athlete crossing the SWC threshold after the stretching condition.
107
Figure 48. boxplot of RSImod values for all stretching conditions.
108
Table 31. RSImod values for all subjects by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 2.04 0.62 1.83 2 0.56 1.18 3.44 2.26 0.7 -0.6 0.16
ST AG 1.97 0.64 1.97 1.93 0.61 1.01 3.45 2.44 0.44 -0.44 0.16
ST ANT 1.86 0.54 1.72 1.82 0.53 1.28 2.97 1.69 0.7 -0.87 0.14
ST AG ANT 1.94 0.64 1.86 1.91 0.87 1.15 3.15 2 0.38 -1.33 0.16
DY AG 1.96 0.56 1.96 1.95 0.58 1 3.07 2.08 0.03 -0.87 0.14
DY ANT 2.01 0.86 1.71 1.92 0.43 1.14 4.2 3.06 1.3 0.63 0.21
DY AG ANT 1.81 0.51 1.89 1.79 0.6 1.02 2.95 1.94 0.37 -0.64 0.13
ST AG DY ANT 2.08 0.61 2.05 2.06 0.59 1.09 3.37 2.27 0.31 -0.85 0.15
DY AG ST ANT 1.93 0.56 1.86 1.92 0.69 1.09 2.9 1.81 0.26 -1.24 0.14
Trained (n=8) Baseline 1.75 0.48 1.62 1.75 0.26 1.18 2.57 1.38 0.63 -1.27 0.17
ST AG 1.72 0.57 1.63 1.72 0.59 1.01 2.6 1.59 0.28 -1.62 0.2
ST ANT 1.72 0.46 1.59 1.72 0.43 1.28 2.59 1.31 0.66 -1.07 0.16
ST AG ANT 1.79 0.53 1.75 1.79 0.48 1.15 2.78 1.63 0.53 -0.95 0.19
DY AG 1.73 0.47 1.83 1.73 0.51 1 2.4 1.4 -0.2 -1.55 0.17
DY ANT 1.88 0.99 1.58 1.88 0.55 1.14 4.2 3.06 1.48 0.84 0.35
DY AG ANT 1.73 0.47 1.72 1.73 0.54 1.02 2.3 1.28 -0.13 -1.78 0.17
ST AG DY ANT 1.91 0.55 2.04 1.91 0.61 1.09 2.49 1.4 -0.28 -1.84 0.19
DY AG ST ANT 1.72 0.47 1.65 1.72 0.58 1.09 2.47 1.38 0.2 -1.59 0.17
Untrained (n=8) Baseline 2.32 0.64 2.12 2.32 0.61 1.62 3.44 1.82 0.5 -1.42 0.23
ST AG 2.19 0.57 2.29 2.19 0.56 1.25 3.07 1.83 -0.15 -1.19 0.2
ST ANT 1.9 0.57 1.89 1.9 0.55 1.24 2.95 1.71 0.47 -1.01 0.2
ST AG ANT 2.14 0.59 2.13 2.14 0.67 1.28 2.9 1.63 0 -1.72 0.21
DY AG 2.15 0.74 1.78 2.15 0.35 1.4 3.61 2.21 0.82 -0.86 0.26
DY ANT 2.23 0.63 2.26 2.23 0.43 1.34 3.45 2.11 0.49 -0.66 0.22
DY AG ANT 2.09 0.74 2.17 2.09 0.97 1.25 3.15 1.9 0.04 -1.87 0.26
ST AG DY ANT 2.25 0.66 2.07 2.25 0.64 1.57 3.37 1.8 0.43 -1.58 0.23
DY AG ST ANT 1.99 0.61 1.91 1.99 0.64 1.31 2.97 1.66 0.43 -1.56 0.22
109
Figure 49. RSImod normalized by baseline condition by stretching condition.
110
Table 32. Normalized RSI values by stretching codition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
ST AG 0.97 0.16 0.95 0.98 0.17 0.66 1.21 0.56 -0.13 -0.98 0.04
ST ANT 0.93 0.19 0.86 0.93 0.14 0.62 1.32 0.7 0.33 -1.11 0.05
ST AG ANT 0.96 0.17 0.97 0.96 0.16 0.63 1.19 0.56 -0.41 -1.14 0.04
DY AG 0.98 0.18 0.96 0.98 0.18 0.67 1.25 0.58 0.04 -1.29 0.04
DY ANT 1.02 0.28 0.95 1 0.2 0.5 1.77 1.26 0.78 0.87 0.07
DY AG ANT 0.91 0.2 0.93 0.91 0.18 0.58 1.29 0.71 0.18 -0.84 0.05
ST AG DY ANT 1.04 0.22 0.95 1.03 0.15 0.78 1.49 0.71 0.81 -0.79 0.05
DY AG ST ANT 0.95 0.13 0.95 0.95 0.16 0.78 1.2 0.41 0.2 -1.28 0.03
Trained (n=8)
ST AG 0.97 0.14 0.95 0.97 0.18 0.77 1.18 0.4 0.08 -1.67 0.05
ST ANT 1 0.16 1.08 1 0.1 0.78 1.15 0.37 -0.38 -1.97 0.06
ST AG ANT 1.02 0.11 1.02 1.02 0.13 0.9 1.19 0.29 0.19 -1.73 0.04
DY AG 1 0.17 0.96 1 0.18 0.79 1.25 0.46 0.3 -1.73 0.06
DY ANT 1.09 0.33 1.03 1.09 0.28 0.74 1.77 1.03 0.85 -0.47 0.12
DY AG ANT 1 0.19 0.97 1 0.14 0.76 1.29 0.53 0.5 -1.38 0.07
ST AG DY ANT 1.1 0.22 1.08 1.1 0.2 0.78 1.4 0.62 0.1 -1.56 0.08
DY AG ST ANT 0.99 0.14 1.01 0.99 0.15 0.78 1.2 0.41 -0.11 -1.63 0.05
Untrained (n=8) ST AG 0.97 0.18 0.95 0.97 0.17 0.66 1.21 0.56 -0.2 -1.26 0.07
ST ANT 0.87 0.2 0.82 0.87 0.09 0.62 1.32 0.7 1.03 0.11 0.07
ST AG ANT 0.89 0.2 0.88 0.89 0.25 0.63 1.18 0.55 0.08 -1.88 0.07
DY AG 0.96 0.19 0.97 0.96 0.2 0.67 1.22 0.56 -0.12 -1.54 0.07
DY ANT 0.94 0.23 0.91 0.94 0.12 0.5 1.24 0.74 -0.38 -0.8 0.08
DY AG ANT 0.83 0.19 0.81 0.83 0.28 0.58 1.06 0.48 0.02 -1.91 0.07
ST AG DY ANT 0.98 0.22 0.91 0.98 0.06 0.85 1.49 0.65 1.57 0.95 0.08
DY AG ST ANT 0.92 0.1 0.91 0.92 0.11 0.79 1.06 0.27 0.17 -1.72 0.04
111
Figure 50. Boxplot of CMJ Contact time (s) by stretching conditions.
112
Table 33. Contact Time (s) values during the CMJ by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 0.59 0.16 0.55 0.58 0.17 0.36 0.91 0.55 0.35 -0.98 0.04
ST AG 0.59 0.18 0.57 0.59 0.2 0.31 0.87 0.56 0.02 -1.34 0.04
ST ANT 0.58 0.16 0.58 0.57 0.17 0.33 0.85 0.52 0.05 -1.19 0.04
ST AG ANT 0.58 0.17 0.55 0.58 0.18 0.3 0.9 0.6 0.18 -1.24 0.04
DY AG 0.6 0.16 0.59 0.6 0.18 0.3 0.82 0.52 -0.23 -1.23 0.04
DY ANT 0.6 0.19 0.54 0.6 0.2 0.3 0.97 0.67 0.31 -1.06 0.05
DY AG ANT 0.58 0.15 0.57 0.59 0.18 0.29 0.79 0.5 -0.11 -1.27 0.04
ST AG DY ANT 0.61 0.15 0.61 0.61 0.19 0.38 0.83 0.45 0.01 -1.52 0.04
DY AG ST ANT 0.61 0.16 0.59 0.61 0.2 0.33 0.82 0.5 -0.11 -1.4 0.04
Trained (n=8)
Baseline 0.58 0.15 0.54 0.58 0.11 0.37 0.83 0.46 0.31 -1.27 0.05
ST AG 0.59 0.18 0.57 0.59 0.16 0.31 0.87 0.56 0.1 -1.37 0.06
ST ANT 0.6 0.15 0.58 0.6 0.15 0.39 0.85 0.47 0.26 -1.18 0.05
ST AG ANT 0.59 0.16 0.55 0.59 0.13 0.37 0.9 0.53 0.63 -0.63 0.06
DY AG 0.59 0.15 0.56 0.59 0.16 0.36 0.82 0.46 0.04 -1.38 0.05
DY ANT 0.61 0.19 0.54 0.61 0.16 0.35 0.97 0.61 0.5 -1.08 0.07
DY AG ANT 0.59 0.14 0.57 0.59 0.17 0.39 0.78 0.4 -0.02 -1.63 0.05
ST AG DY ANT 0.61 0.14 0.61 0.61 0.16 0.38 0.82 0.44 -0.07 -1.47 0.05
DY AG ST ANT 0.61 0.16 0.56 0.61 0.19 0.38 0.82 0.45 0.1 -1.7 0.06
Untrained (n=8) Baseline 0.59 0.18 0.59 0.59 0.19 0.36 0.91 0.55 0.3 -1.36 0.06
ST AG 0.59 0.18 0.57 0.59 0.26 0.33 0.83 0.5 -0.06 -1.73 0.06
ST ANT 0.55 0.18 0.55 0.55 0.2 0.33 0.82 0.49 0.03 -1.72 0.06
ST AG ANT 0.57 0.2 0.56 0.57 0.28 0.3 0.8 0.5 -0.04 -1.98 0.07
DY AG 0.6 0.18 0.63 0.6 0.21 0.3 0.8 0.5 -0.36 -1.54 0.06
DY ANT 0.59 0.19 0.54 0.59 0.24 0.3 0.86 0.56 0.07 -1.66 0.07
DY AG ANT 0.57 0.18 0.56 0.57 0.18 0.29 0.79 0.5 -0.06 -1.58 0.06
ST AG DY ANT 0.6 0.17 0.56 0.6 0.21 0.38 0.83 0.45 0.09 -1.87 0.06
DY AG ST ANT 0.6 0.17 0.62 0.6 0.2 0.33 0.81 0.48 -0.26 -1.56 0.06
113
Figure 51. Boxplot of Yielding time (s) during CMJ by stretching condition and baseline.
114
Table 34. Yielding time (s) values during CMJ by stretching condition and baseline.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 0.14 0.05 0.14 0.14 0.03 0.08 0.27 0.19 1.13 0.83 0.01
ST AG 0.15 0.05 0.13 0.15 0.05 0.07 0.25 0.17 0.6 -0.82 0.01
ST ANT 0.14 0.05 0.13 0.14 0.04 0.07 0.22 0.15 0.29 -1.04 0.01
ST AG ANT 0.14 0.05 0.12 0.14 0.03 0.08 0.27 0.19 0.99 -0.09 0.01
DY AG 0.14 0.05 0.14 0.14 0.03 0.07 0.24 0.16 0.4 -0.65 0.01
DY ANT 0.13 0.04 0.12 0.13 0.03 0.08 0.25 0.17 1.23 1.16 0.01
DY AG ANT 0.14 0.04 0.13 0.13 0.03 0.07 0.22 0.15 0.68 0.04 0.01
ST AG DY ANT 0.14 0.04 0.13 0.13 0.03 0.09 0.21 0.12 0.85 -0.52 0.01
DY AG ST ANT 0.14 0.04 0.13 0.14 0.03 0.08 0.22 0.14 0.57 -0.42 0.01
Trained (n=8)
Baseline 0.13 0.03 0.14 0.13 0.03 0.09 0.19 0.09 0.36 -1.05 0.01
ST AG 0.13 0.03 0.14 0.13 0.02 0.07 0.15 0.08 -0.99 -0.27 0.01
ST ANT 0.13 0.02 0.13 0.13 0.02 0.1 0.16 0.06 0.17 -1.53 0.01
ST AG ANT 0.14 0.03 0.13 0.14 0.03 0.1 0.19 0.08 0.38 -1.45 0.01
DY AG 0.13 0.02 0.13 0.13 0.02 0.09 0.17 0.08 -0.02 -0.95 0.01
DY ANT 0.13 0.03 0.13 0.13 0.02 0.07 0.18 0.1 -0.22 -0.97 0.01
DY AG ANT 0.13 0.03 0.12 0.13 0.02 0.1 0.18 0.08 0.58 -1.38 0.01
ST AG DY ANT 0.13 0.02 0.13 0.13 0.01 0.1 0.16 0.06 0.22 -0.98 0.01
DY AG ST ANT 0.14 0.03 0.13 0.14 0.04 0.09 0.18 0.09 0.2 -1.76 0.01
Untrained (n=8) Baseline 0.15 0.06 0.14 0.15 0.04 0.08 0.27 0.19 0.69 -0.9 0.02
ST AG 0.17 0.07 0.15 0.17 0.09 0.08 0.25 0.17 0.13 -1.89 0.02
ST ANT 0.14 0.06 0.14 0.14 0.07 0.07 0.22 0.15 0.26 -1.54 0.02
ST AG ANT 0.15 0.07 0.12 0.15 0.04 0.08 0.27 0.19 0.54 -1.51 0.02
DY AG 0.16 0.06 0.15 0.16 0.08 0.07 0.24 0.16 -0.03 -1.72 0.02
DY ANT 0.14 0.06 0.12 0.14 0.04 0.08 0.25 0.17 0.77 -0.89 0.02
DY AG ANT 0.14 0.05 0.13 0.14 0.04 0.07 0.22 0.15 0.41 -1.4 0.02
ST AG DY ANT 0.14 0.05 0.12 0.14 0.03 0.09 0.21 0.12 0.38 -1.82 0.02
DY AG ST ANT 0.15 0.04 0.13 0.15 0.03 0.08 0.22 0.14 0.38 -1.09 0.02
115
Figure 52.Boxplot of Braking time (s) during CMJ by stretching condition and baseline.
116
Table 35. Braking time (s) values by stretching condition and baseline.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 0.18 0.07 0.16 0.18 0.08 0.1 0.34 0.24 0.65 -0.64 0.02
ST AG 0.19 0.08 0.17 0.18 0.07 0.09 0.37 0.28 0.77 -0.29 0.02
ST ANT 0.18 0.07 0.18 0.17 0.07 0.1 0.34 0.24 0.75 -0.22 0.02
ST AG ANT 0.18 0.07 0.18 0.18 0.07 0.08 0.34 0.25 0.43 -0.67 0.02
DY AG 0.18 0.07 0.17 0.18 0.08 0.08 0.34 0.26 0.41 -0.75 0.02
DY ANT 0.19 0.08 0.16 0.19 0.07 0.08 0.33 0.25 0.37 -1.33 0.02
DY AG ANT 0.18 0.06 0.18 0.18 0.08 0.09 0.3 0.21 0.24 -1.3 0.02
ST AG DY ANT 0.2 0.07 0.19 0.19 0.08 0.1 0.34 0.24 0.5 -0.97 0.02
DY AG ST ANT 0.19 0.07 0.18 0.19 0.08 0.09 0.35 0.26 0.42 -0.78 0.02
Trained (n=8)
Baseline 0.19 0.08 0.16 0.19 0.06 0.1 0.34 0.24 0.75 -0.95 0.03
ST AG 0.2 0.1 0.17 0.2 0.08 0.09 0.37 0.28 0.57 -1.35 0.03
ST ANT 0.19 0.07 0.18 0.19 0.06 0.11 0.34 0.23 0.78 -0.59 0.03
ST AG ANT 0.19 0.07 0.18 0.19 0.06 0.1 0.34 0.24 0.79 -0.48 0.03
DY AG 0.19 0.08 0.16 0.19 0.08 0.08 0.34 0.26 0.49 -1.28 0.03
DY ANT 0.2 0.09 0.16 0.2 0.07 0.09 0.33 0.24 0.34 -1.7 0.03
DY AG ANT 0.19 0.07 0.18 0.19 0.08 0.09 0.3 0.21 0.2 -1.66 0.03
ST AG DY ANT 0.21 0.08 0.2 0.21 0.09 0.11 0.34 0.23 0.33 -1.36 0.03
DY AG ST ANT 0.19 0.08 0.17 0.19 0.08 0.1 0.35 0.25 0.56 -1.26 0.03
Untrained (n=8) Baseline 0.18 0.06 0.18 0.18 0.08 0.1 0.26 0.16 0.07 -1.9 0.02
ST AG 0.17 0.06 0.17 0.17 0.06 0.09 0.26 0.16 -0.06 -1.59 0.02
ST ANT 0.17 0.06 0.16 0.17 0.05 0.1 0.28 0.19 0.49 -1.13 0.02
ST AG ANT 0.17 0.07 0.18 0.17 0.09 0.08 0.25 0.17 -0.06 -2.04 0.02
DY AG 0.18 0.06 0.19 0.18 0.07 0.09 0.25 0.16 -0.27 -1.72 0.02
DY ANT 0.18 0.08 0.17 0.18 0.07 0.08 0.3 0.23 0.25 -1.5 0.03
DY AG ANT 0.17 0.06 0.17 0.17 0.06 0.09 0.25 0.16 0.04 -1.72 0.02
ST AG DY ANT 0.18 0.07 0.17 0.18 0.06 0.1 0.31 0.21 0.55 -1.1 0.02
DY AG ST ANT 0.18 0.06 0.19 0.18 0.07 0.09 0.26 0.17 -0.27 -1.65 0.02
117
Figure 53. Boxplot of Concentric (Propulsive phase) time (s) during each stretching condition.
118
Table 36. Concentric time (s) values during the CMJ propulsive phase for each stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 0.26 0.06 0.26 0.26 0.05 0.16 0.38 0.23 0.22 -0.47 0.01
ST AG 0.26 0.06 0.27 0.26 0.07 0.15 0.35 0.2 -0.35 -1.24 0.02
ST ANT 0.26 0.06 0.26 0.26 0.07 0.16 0.36 0.2 -0.2 -1.31 0.02
ST AG ANT 0.26 0.07 0.26 0.26 0.06 0.15 0.38 0.24 0.03 -0.97 0.02
DY AG 0.27 0.06 0.27 0.27 0.06 0.15 0.35 0.21 -0.4 -0.96 0.01
DY ANT 0.28 0.08 0.26 0.27 0.07 0.14 0.47 0.33 0.55 -0.11 0.02
DY AG ANT 0.26 0.06 0.27 0.27 0.08 0.14 0.35 0.21 -0.32 -1.07 0.02
ST AG DY ANT 0.27 0.06 0.28 0.27 0.06 0.17 0.35 0.18 -0.27 -1.25 0.01
DY AG ST ANT 0.27 0.06 0.27 0.28 0.07 0.16 0.36 0.2 -0.35 -1.22 0.02
Trained (n=8)
Baseline 0.26 0.07 0.26 0.26 0.07 0.16 0.38 0.23 0.31 -1.08 0.03
ST AG 0.25 0.07 0.26 0.25 0.09 0.15 0.35 0.19 -0.07 -1.74 0.02
ST ANT 0.25 0.07 0.26 0.25 0.08 0.16 0.32 0.17 -0.19 -1.86 0.02
ST AG ANT 0.25 0.07 0.25 0.25 0.09 0.15 0.35 0.21 -0.06 -1.73 0.03
DY AG 0.27 0.07 0.27 0.27 0.07 0.15 0.35 0.21 -0.35 -1.4 0.02
DY ANT 0.26 0.07 0.26 0.26 0.07 0.14 0.37 0.22 -0.14 -1.39 0.03
DY AG ANT 0.26 0.07 0.26 0.26 0.08 0.14 0.33 0.19 -0.35 -1.52 0.02
ST AG DY ANT 0.27 0.06 0.26 0.27 0.06 0.18 0.35 0.17 -0.03 -1.74 0.02
DY AG ST ANT 0.27 0.07 0.29 0.27 0.07 0.16 0.36 0.2 -0.37 -1.55 0.02
Untrained (n=8) Baseline 0.26 0.05 0.26 0.26 0.04 0.18 0.35 0.17 0 -0.74 0.02
ST AG 0.26 0.06 0.27 0.26 0.07 0.15 0.33 0.18 -0.62 -0.95 0.02
ST ANT 0.27 0.06 0.26 0.27 0.05 0.18 0.36 0.18 -0.04 -1.29 0.02
ST AG ANT 0.27 0.06 0.26 0.27 0.05 0.17 0.38 0.21 0.34 -0.68 0.02
DY AG 0.27 0.05 0.28 0.27 0.06 0.2 0.34 0.14 -0.1 -1.74 0.02
DY ANT 0.29 0.09 0.26 0.29 0.08 0.18 0.47 0.29 0.73 -0.68 0.03
DY AG ANT 0.27 0.06 0.27 0.27 0.06 0.19 0.35 0.16 0.01 -1.51 0.02
ST AG DY ANT 0.28 0.05 0.28 0.28 0.05 0.17 0.34 0.17 -0.48 -1.03 0.02
DY AG ST ANT 0.28 0.06 0.27 0.28 0.07 0.17 0.35 0.17 -0.21 -1.4 0.02
119
Figure 54. Boxplot of eccentric time (s) values by stretching condition.
120
Table 37. Eccentric times (s) values by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 0.33 0.1 0.3 0.32 0.13 0.19 0.52 0.33 0.37 -1.26 0.03
ST AG 0.33 0.12 0.32 0.33 0.13 0.16 0.55 0.38 0.28 -1.31 0.03
ST ANT 0.32 0.1 0.31 0.31 0.1 0.16 0.51 0.34 0.32 -0.98 0.03
ST AG ANT 0.32 0.11 0.29 0.32 0.12 0.16 0.52 0.36 0.32 -1.32 0.03
DY AG 0.33 0.11 0.33 0.33 0.1 0.16 0.49 0.33 -0.05 -1.31 0.03
DY ANT 0.32 0.11 0.28 0.32 0.11 0.16 0.52 0.36 0.35 -1.26 0.03
DY AG ANT 0.32 0.1 0.31 0.32 0.11 0.16 0.46 0.31 0.1 -1.36 0.02
ST AG DY ANT 0.33 0.1 0.32 0.33 0.12 0.2 0.53 0.33 0.35 -1.23 0.03
DY AG ST ANT 0.33 0.1 0.32 0.33 0.12 0.17 0.48 0.32 0.1 -1.43 0.02
Trained (n=8)
Baseline 0.32 0.1 0.29 0.32 0.08 0.19 0.48 0.29 0.42 -1.47 0.04
ST AG 0.33 0.13 0.3 0.33 0.09 0.16 0.55 0.38 0.44 -1.33 0.04
ST ANT 0.33 0.09 0.32 0.33 0.08 0.21 0.5 0.29 0.42 -1.21 0.03
ST AG ANT 0.32 0.1 0.29 0.32 0.07 0.2 0.52 0.32 0.74 -0.7 0.04
DY AG 0.32 0.11 0.29 0.32 0.1 0.16 0.49 0.33 0.15 -1.31 0.04
DY ANT 0.32 0.1 0.29 0.32 0.09 0.18 0.5 0.32 0.31 -1.37 0.04
DY AG ANT 0.32 0.09 0.32 0.32 0.11 0.2 0.43 0.24 -0.04 -1.85 0.03
ST AG DY ANT 0.34 0.09 0.33 0.34 0.1 0.21 0.48 0.27 0.13 -1.62 0.03
DY AG ST ANT 0.33 0.1 0.3 0.33 0.1 0.2 0.48 0.27 0.21 -1.84 0.04
Untrained (n=8) Baseline 0.33 0.11 0.33 0.33 0.12 0.2 0.52 0.32 0.24 -1.53 0.04
ST AG 0.34 0.12 0.32 0.34 0.16 0.17 0.5 0.33 0.04 -1.71 0.04
ST ANT 0.3 0.12 0.3 0.3 0.12 0.16 0.51 0.34 0.33 -1.34 0.04
ST AG ANT 0.32 0.13 0.31 0.32 0.15 0.16 0.49 0.33 0.07 -1.97 0.05
DY AG 0.34 0.11 0.36 0.34 0.15 0.16 0.47 0.31 -0.23 -1.61 0.04
DY ANT 0.32 0.13 0.28 0.32 0.12 0.16 0.52 0.36 0.31 -1.6 0.04
DY AG ANT 0.31 0.11 0.31 0.31 0.11 0.16 0.46 0.31 0.21 -1.53 0.04
ST AG DY ANT 0.33 0.11 0.29 0.33 0.11 0.2 0.53 0.33 0.45 -1.43 0.04
DY AG ST ANT 0.33 0.1 0.32 0.33 0.12 0.17 0.48 0.32 -0.03 -1.45 0.04
121
Figure 55. Rate of Force Development during the Yielding Phase by stretching condition.
122
Table 38. Rate of Force Development (N/Kg/s) during the Yielding Phase of the CMJ by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 4.94 2.77 4.8 4.64 2.34 1.6 12.47 10.86 1.07 0.9 0.69
ST AG 5.33 2.67 4.94 5.23 2.27 1.57 10.38 8.81 0.47 -0.87 0.67
ST ANT 5.7 2.37 5.85 5.65 2.81 1.91 10.11 8.2 0.08 -1.13 0.59
ST AG ANT 5.22 2.02 5.7 5.17 2.78 2.49 8.71 6.22 0.07 -1.48 0.51
DY AG 5.58 2.13 5.71 5.67 2.54 1.4 8.55 7.15 -0.29 -1.16 0.53
DY ANT 4.98 2.59 5.51 4.92 3.84 1.42 9.38 7.96 0.04 -1.53 0.65
DY AG ANT 5.29 2.45 5.53 5.31 2.96 1.15 9.1 7.95 -0.06 -1.34 0.61
ST AG DY ANT 5.03 1.88 5.01 5.01 2.18 1.99 8.31 6.32 -0.01 -1.13 0.47
DY AG ST ANT 5.69 2.83 6.01 5.51 2.94 1.92 12.05 10.14 0.44 -0.65 0.71
Trained (n=8)
Baseline 5.19 1.96 5.22 5.19 2.17 2.33 8.19 5.86 0.03 -1.47 0.69
ST AG 5.73 2.22 5.38 5.73 1.65 3.03 10.16 7.14 0.74 -0.64 0.78
ST ANT 5.62 1.63 5.89 5.62 1.6 2.95 7.61 4.66 -0.35 -1.49 0.58
ST AG ANT 5.55 1.89 5.86 5.55 2.44 2.95 7.77 4.82 -0.18 -1.82 0.67
DY AG 6.05 1.82 5.71 6.05 1.88 3.41 8.55 5.14 0.11 -1.54 0.64
DY ANT 5.56 2.27 5.97 5.56 2.17 2.76 9.38 6.62 0.15 -1.4 0.8
DY AG ANT 5.36 1.68 5.8 5.36 1.32 2.65 7.02 4.37 -0.55 -1.5 0.59
ST AG DY ANT 5.34 1.59 5.05 5.34 1.61 2.56 7.77 5.21 -0.16 -1.04 0.56
DY AG ST ANT 5.6 2.35 6.61 5.6 1.97 2.42 8.64 6.22 -0.29 -1.75 0.83
Untrained (n=8) Baseline 4.69 3.53 4.02 4.69 2.51 1.6 12.47 10.86 1.16 0.12 1.25
ST AG 4.4 2.9 3.78 4.4 3.13 1.42 8.13 6.71 0.19 -1.99 1.03
ST ANT 5.79 3.41 4.99 5.79 3.17 1.92 12.05 10.14 0.56 -1.14 1.21
ST AG ANT 5.22 3.17 4.86 5.22 4.19 1.15 9.1 7.95 0.07 -1.92 1.12
DY AG 4.92 3.16 4.36 4.92 3.19 1.57 10.38 8.81 0.48 -1.41 1.12
DY ANT 5.11 2.43 5.23 5.11 3.08 1.4 7.86 6.46 -0.21 -1.8 0.86
DY AG ANT 5.78 3.06 5.65 5.78 4.07 1.91 10.11 8.2 0.08 -1.79 1.08
ST AG DY ANT 4.72 2.19 4.58 4.72 2.63 1.99 8.31 6.32 0.23 -1.53 0.77
DY AG ST ANT 4.89 2.22 4.96 4.89 2.17 2.49 8.71 6.22 0.32 -1.48 0.78
123
Figure 56. Rate of Force Development (N/Kg/s) of the Braking Phase of the CMJ during the
stretching conditions.
124
Table 39. Rate of Force Development (N/Kg/s) during the Braking Phase of the CMJ by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 8.93 5.83 8.55 8.63 6.08 1.49 20.59 19.11 0.57 -0.95 1.46
ST AG 9.8 7.54 7.15 9.15 4.57 1.68 27.07 25.39 0.96 -0.3 1.89
ST ANT 9.35 6.2 6.83 9.03 4.4 1.63 21.56 19.93 0.74 -0.89 1.55
ST AG ANT 9.99 7.55 6.71 9.29 5.85 1.94 27.78 25.84 0.89 -0.4 1.89
DY AG 9.82 8.44 6.01 8.85 4.56 1.92 31.17 29.26 1.35 0.69 2.11
DY ANT 9.91 8.63 7.86 8.94 6.64 1.85 31.47 29.62 1.32 0.72 2.16
DY AG ANT 9.96 7.33 7.43 9.31 5.32 2.21 26.78 24.56 1.05 -0.04 1.83
ST AG DY ANT 8.14 5.64 6.54 7.74 5.04 1.81 20.07 18.26 0.83 -0.43 1.41
DY AG ST ANT 9.24 6.78 6.35 8.61 4.27 1.85 25.33 23.48 1.08 0.07 1.69
Trained (n=8)
Baseline 5.19 1.96 5.22 5.19 2.17 2.33 8.19 5.86 0.03 -1.47 0.69
ST AG 5.73 2.22 5.38 5.73 1.65 3.03 10.16 7.14 0.74 -0.64 0.78
ST ANT 5.62 1.63 5.89 5.62 1.6 2.95 7.61 4.66 -0.35 -1.49 0.58
ST AG ANT 5.55 1.89 5.86 5.55 2.44 2.95 7.77 4.82 -0.18 -1.82 0.67
DY AG 6.05 1.82 5.71 6.05 1.88 3.41 8.55 5.14 0.11 -1.54 0.64
DY ANT 5.56 2.27 5.97 5.56 2.17 2.76 9.38 6.62 0.15 -1.4 0.8
DY AG ANT 5.36 1.68 5.8 5.36 1.32 2.65 7.02 4.37 -0.55 -1.5 0.59
ST AG DY ANT 5.34 1.59 5.05 5.34 1.61 2.56 7.77 5.21 -0.16 -1.04 0.56
DY AG ST ANT 5.6 2.35 6.61 5.6 1.97 2.42 8.64 6.22 -0.29 -1.75 0.83
Untrained (n=8) Baseline 9.03 6.06 7.56 9.03 6 2.7 18.88 16.18 0.42 -1.62 2.14
ST AG 9.6 6.89 7.15 9.6 3.23 3.81 23.59 19.78 0.99 -0.64 2.44
ST ANT 10.56 6.93 8.86 10.56 5.42 3.21 21.56 18.35 0.53 -1.51 2.45
ST AG ANT 11.33 8.93 8.87 11.33 8.13 3.05 27.78 24.73 0.58 -1.26 3.16
DY AG 9.45 7.95 5.02 9.45 1.07 4 26.59 22.59 1.15 -0.19 2.81
DY ANT 10.28 9.4 7.33 10.28 5.97 2.84 31.47 28.63 1.29 0.34 3.32
DY AG ANT 10.51 7.64 7.43 10.51 4.73 3.85 26.78 22.93 1.05 -0.29 2.7
ST AG DY ANT 8.58 5.48 7.94 8.58 4.8 2.08 19.39 17.31 0.69 -0.77 1.94
DY AG ST ANT 8.99 7.28 6.17 8.99 3.38 3.76 25.33 21.58 1.3 0.26 2.58
125
Figure 57. Rate of Force Development (N/Kg/s) of the Eccentric Phase of the CMJ during the
stretching conditions.
126
Table 40. Rate of Force Development (N/Kg/s) during the Eccentric Phase of the CMJ by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 2.84 2.05 2.59 2.52 1.38 0.99 9.3 8.31 1.85 3.41 0.51
ST AG 2.93 1.99 2.22 2.72 0.3 1.25 7.52 6.27 1.46 0.53 0.5
ST ANT 2.88 1.85 2.35 2.66 0.81 1.35 7.48 6.13 1.73 1.6 0.46
ST AG ANT 2.31 0.92 2.25 2.26 0.86 0.82 4.47 3.65 0.55 -0.27 0.23
DY AG 2.86 1.46 2.66 2.8 1.38 0.71 5.83 5.12 0.38 -0.95 0.37
DY ANT 2.67 1.72 2.37 2.49 1.05 0.83 7.03 6.2 1.23 0.45 0.43
DY AG ANT 3.06 1.79 2.79 2.93 0.97 0.6 7.35 6.75 1.22 0.81 0.45
ST AG DY ANT 2.58 0.78 2.61 2.59 0.74 0.91 4.12 3.21 -0.28 -0.24 0.2
DY AG ST ANT 3.29 2.39 2.51 3.09 2.05 0.74 8.75 8.01 1.02 -0.03 0.6
Trained (n=8)
Baseline 2.47 0.84 2.72 2.47 0.63 1.08 3.24 2.16 -0.66 -1.4 0.3
ST AG 2.51 1.22 2.18 2.51 0.22 1.58 5.48 3.9 1.71 1.4 0.43
ST ANT 2.24 0.41 2.35 2.24 0.41 1.57 2.68 1.12 -0.43 -1.61 0.15
ST AG ANT 2.34 0.89 2.49 2.34 0.92 0.82 3.44 2.63 -0.37 -1.35 0.32
DY AG 2.6 1 2.33 2.6 0.98 1.52 4.37 2.86 0.53 -1.36 0.35
DY ANT 2.44 1.35 2.14 2.44 0.43 1.39 5.63 4.24 1.53 0.97 0.48
DY AG ANT 2.62 0.45 2.76 2.62 0.32 1.79 3.1 1.31 -0.7 -1.1 0.16
ST AG DY ANT 2.62 0.72 2.8 2.62 0.74 1.34 3.33 1.99 -0.48 -1.42 0.25
DY AG ST ANT 2.85 1.52 2.51 2.85 2 0.81 5.21 4.4 0.16 -1.58 0.54
Untrained (n=8) Baseline 3.22 2.82 2.15 3.22 1.72 0.99 9.3 8.31 1.12 -0.16 1
ST AG 2.9 2.1 2.65 2.9 2.14 0.83 7.03 6.2 0.79 -0.81 0.74
ST ANT 3.74 3.08 2.68 3.74 2.08 0.74 8.75 8.01 0.65 -1.42 1.09
ST AG ANT 3.5 2.49 3.34 3.5 2.74 0.6 7.35 6.75 0.45 -1.48 0.88
DY AG 3.35 2.56 2.28 3.35 0.99 1.25 7.52 6.27 0.84 -1.27 0.9
DY ANT 3.13 1.85 3.02 3.13 2.42 0.71 5.83 5.12 0.03 -1.64 0.65
DY AG ANT 3.53 2.49 2.68 3.53 1.41 1.35 7.48 6.13 0.76 -1.36 0.88
ST AG DY ANT 2.54 0.89 2.55 2.54 0.41 0.91 4.12 3.21 -0.08 -0.36 0.32
DY AG ST ANT 2.28 1.01 2.02 2.28 0.57 1.29 4.47 3.18 1.1 -0.08 0.36
127
Figure 58. Rate of Force Development (N/Kg/s) of the Concentric Phase of the CMJ during the
stretching conditions.
128
Table 41. Rate of Force Development (N/Kg/s) of the Concentric Phase of the CMJ during the stretching conditions.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 2.55 2.06 1.83 2.27 0.81 0.6 8.44 7.84 1.61 1.65 0.52
ST AG 2.83 1.68 2.39 2.72 1.56 0.55 6.65 6.1 0.72 -0.48 0.42
ST ANT 2.7 1.41 2.33 2.68 1.5 0.61 5.14 4.53 0.27 -1.44 0.35
ST AG ANT 2.75 1.83 2.19 2.52 1.45 1.04 7.69 6.64 1.27 0.89 0.46
DY AG 2.45 1.54 2.32 2.35 1.85 0.52 5.77 5.25 0.45 -0.92 0.38
DY ANT 2.29 1.51 1.94 2.17 1.09 0.5 5.79 5.3 0.92 -0.25 0.38
DY AG ANT 2.84 2.24 2.15 2.64 1.56 0.66 7.74 7.09 1.14 0.02 0.56
ST AG DY ANT 2.19 0.89 2.51 2.2 0.72 0.6 3.66 3.06 -0.38 -1.18 0.22
DY AG ST ANT 2.64 2.16 2.35 2.44 1.66 0.49 7.64 7.16 1.06 -0.01 0.54
Trained (n=8)
Baseline 2.26 1.46 1.95 2.26 0.73 0.6 5.45 4.85 1.08 0.11 0.52
ST AG 3.15 1.55 3.34 3.15 2.06 1.22 5.46 4.24 0.06 -1.74 0.55
ST ANT 2.71 1.1 2.72 2.71 1.64 1.22 3.94 2.72 -0.11 -1.87 0.39
ST AG ANT 2.61 1.51 2.53 2.61 1.21 1.06 5.67 4.61 0.77 -0.6 0.53
DY AG 2.87 1.23 3.04 2.87 1.33 0.66 4.39 3.73 -0.43 -1.2 0.43
DY ANT 2.43 1.65 1.94 2.43 0.8 0.5 5.79 5.3 0.85 -0.56 0.59
DY AG ANT 2.85 2.17 2.02 2.85 1.29 0.66 7.64 6.99 1.16 0.11 0.77
ST AG DY ANT 2.1 1.01 2.12 2.1 1 0.6 3.66 3.06 -0.01 -1.42 0.36
DY AG ST ANT 2.53 2.22 1.88 2.53 1.16 0.67 7.64 6.98 1.38 0.6 0.79
Untrained (n=8) Baseline 2.83 2.61 1.7 2.83 0.62 1.03 8.44 7.41 1.2 -0.2 0.92
ST AG 2.51 1.85 2.18 2.51 0.86 0.55 6.65 6.1 1.19 0.34 0.65
ST ANT 2.69 1.74 1.92 2.69 1.35 0.61 5.14 4.53 0.32 -1.84 0.62
ST AG ANT 2.9 2.21 2.16 2.9 1.47 1.04 7.69 6.64 1.12 -0.1 0.78
DY AG 2.03 1.78 1.2 2.03 0.73 0.52 5.77 5.25 1.05 -0.38 0.63
DY ANT 2.15 1.45 1.8 2.15 1.09 0.67 4.93 4.26 0.73 -0.99 0.51
DY AG ANT 2.83 2.46 2.15 2.83 1.68 0.66 7.74 7.09 0.92 -0.73 0.87
ST AG DY ANT 2.28 0.83 2.61 2.28 0.41 0.89 3.01 2.12 -0.8 -1.28 0.29
DY AG ST ANT 2.76 2.24 2.62 2.76 2.8 0.49 6.87 6.38 0.55 -1.19 0.79
129
Figure 59. Concentric Peak Force (N) of the CMJ by stretching condition.
130
Table 42. Concentric Peak Force (N) of the CMJ by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 2.53 0.36 2.4 2.51 0.25 2.09 3.28 1.18 0.77 -0.65 0.09
ST AG 2.56 0.45 2.41 2.52 0.3 2 3.57 1.58 0.87 -0.44 0.11
ST ANT 2.55 0.39 2.43 2.53 0.3 2.07 3.28 1.21 0.69 -1 0.1
ST AG ANT 2.58 0.43 2.38 2.56 0.37 2.06 3.46 1.4 0.72 -0.8 0.11
DY AG 2.54 0.47 2.38 2.5 0.31 1.99 3.69 1.7 1.19 0.45 0.12
DY ANT 2.53 0.51 2.45 2.49 0.39 1.93 3.77 1.84 1.11 0.42 0.13
DY AG ANT 2.58 0.46 2.51 2.54 0.33 2.01 3.74 1.73 1.06 0.39 0.11
ST AG DY ANT 2.47 0.33 2.35 2.45 0.18 2.06 3.24 1.18 1.04 0.06 0.08
DY AG ST ANT 2.52 0.4 2.36 2.5 0.41 2 3.39 1.39 0.85 -0.25 0.1
Trained (n=8)
Baseline 2.55 0.32 2.43 2.55 0.16 2.32 3.28 0.96 1.38 0.54 0.11
ST AG 2.61 0.47 2.41 2.61 0.28 2.2 3.57 1.37 0.93 -0.59 0.17
ST ANT 2.54 0.35 2.43 2.54 0.31 2.17 3.19 1.02 0.62 -1.16 0.12
ST AG ANT 2.55 0.37 2.37 2.55 0.14 2.24 3.36 1.13 1.18 -0.05 0.13
DY AG 2.6 0.48 2.41 2.6 0.25 2.17 3.69 1.52 1.31 0.39 0.17
DY ANT 2.54 0.48 2.49 2.54 0.33 1.93 3.52 1.6 0.77 -0.37 0.17
DY AG ANT 2.57 0.39 2.52 2.57 0.31 2.12 3.39 1.27 0.86 -0.38 0.14
ST AG DY ANT 2.5 0.35 2.34 2.5 0.15 2.22 3.24 1.02 1.06 -0.37 0.12
DY AG ST ANT 2.6 0.36 2.52 2.6 0.34 2.27 3.34 1.07 0.84 -0.64 0.13
Untrained (n=8) Baseline 2.52 0.41 2.39 2.52 0.43 2.09 3.18 1.08 0.38 -1.69 0.15
ST AG 2.5 0.46 2.36 2.5 0.36 2 3.35 1.35 0.66 -1.13 0.16
ST ANT 2.56 0.46 2.44 2.56 0.3 2.07 3.28 1.21 0.57 -1.47 0.16
ST AG ANT 2.62 0.51 2.54 2.62 0.58 2.06 3.46 1.4 0.34 -1.56 0.18
DY AG 2.48 0.48 2.37 2.48 0.35 1.99 3.46 1.48 0.89 -0.54 0.17
DY ANT 2.53 0.56 2.38 2.53 0.34 1.96 3.77 1.81 1.13 0.06 0.2
DY AG ANT 2.59 0.55 2.48 2.59 0.43 2.01 3.74 1.73 0.92 -0.34 0.19
ST AG DY ANT 2.44 0.34 2.41 2.44 0.24 2.06 3.14 1.08 0.82 -0.42 0.12
DY AG ST ANT 2.45 0.45 2.34 2.45 0.41 2 3.39 1.39 0.94 -0.39 0.16
131
Figure 60. Time to peak force (s) during the CMJ by stretching condition.
132
Table 43. Time to peak force (s) values during the CMJ by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 0.69 0.27 0.68 0.68 0.36 0.36 1.17 0.81 0.36 -1.36 0.07
ST AG 0.68 0.21 0.7 0.68 0.27 0.35 0.99 0.64 -0.23 -1.45 0.05
ST ANT 0.64 0.2 0.6 0.63 0.24 0.33 0.96 0.63 0.33 -1.34 0.05
ST AG ANT 0.7 0.26 0.69 0.67 0.18 0.37 1.47 1.1 1.38 1.9 0.07
DY AG 0.7 0.24 0.75 0.7 0.24 0.29 1.21 0.92 0.13 -0.75 0.06
DY ANT 0.77 0.32 0.79 0.74 0.25 0.36 1.65 1.3 0.95 0.91 0.08
DY AG ANT 0.64 0.16 0.66 0.64 0.22 0.4 0.89 0.49 -0.05 -1.41 0.04
ST AG DY ANT 0.7 0.21 0.68 0.7 0.25 0.37 1.03 0.66 0.08 -1.4 0.05
DY AG ST ANT 0.69 0.24 0.7 0.67 0.22 0.31 1.29 0.98 0.62 0.12 0.06
Trained (n=8)
Baseline 0.68 0.26 0.62 0.68 0.22 0.42 1.17 0.74 0.63 -1.21 0.09
ST AG 0.65 0.26 0.6 0.65 0.34 0.35 0.99 0.64 0.14 -1.93 0.09
ST ANT 0.67 0.21 0.6 0.67 0.26 0.42 0.95 0.52 0.17 -1.85 0.07
ST AG ANT 0.74 0.32 0.68 0.74 0.17 0.45 1.47 1.03 1.3 0.48 0.11
DY AG 0.73 0.28 0.7 0.73 0.31 0.41 1.21 0.79 0.35 -1.5 0.1
DY ANT 0.66 0.25 0.58 0.66 0.26 0.39 1.05 0.66 0.37 -1.7 0.09
DY AG ANT 0.66 0.2 0.69 0.66 0.27 0.4 0.89 0.49 -0.14 -1.89 0.07
ST AG DY ANT 0.76 0.24 0.82 0.76 0.3 0.42 1.03 0.6 -0.27 -1.76 0.08
DY AG ST ANT 0.72 0.3 0.68 0.72 0.31 0.4 1.29 0.89 0.62 -1 0.11
Untrained (n=8) Baseline 0.7 0.28 0.68 0.7 0.42 0.36 1.1 0.75 0.07 -1.77 0.1
ST AG 0.71 0.17 0.75 0.71 0.11 0.36 0.91 0.55 -0.81 -0.61 0.06
ST ANT 0.6 0.2 0.57 0.6 0.15 0.33 0.96 0.63 0.44 -1.16 0.07
ST AG ANT 0.67 0.21 0.69 0.67 0.22 0.37 1.02 0.65 0.17 -1.29 0.07
DY AG 0.67 0.21 0.75 0.67 0.15 0.29 0.87 0.59 -0.74 -1.14 0.07
DY ANT 0.88 0.37 0.89 0.88 0.17 0.36 1.65 1.3 0.74 -0.08 0.13
DY AG ANT 0.63 0.12 0.65 0.63 0.1 0.44 0.83 0.39 -0.06 -1.32 0.04
ST AG DY ANT 0.63 0.17 0.61 0.63 0.11 0.37 0.88 0.52 0.05 -1.34 0.06
DY AG ST ANT 0.66 0.18 0.7 0.66 0.14 0.31 0.9 0.59 -0.55 -0.92 0.07
133
Figure 61. Peak power (w/kg) during the CMJ by stretching condition.
134
Table 44. Peak power (w/kg) values during the CMJ by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 5.13 0.54 5.25 5.14 0.49 4.08 5.98 1.9 -0.3 -0.86 0.13
ST AG 5.16 0.53 5.08 5.16 0.44 4.14 6.24 2.1 0.28 -0.5 0.13
ST ANT 5.33 0.66 5.23 5.29 0.67 4.2 6.94 2.74 0.57 -0.05 0.17
ST AG ANT 5.23 0.54 5.23 5.24 0.54 4.23 6.17 1.94 -0.1 -0.92 0.14
DY AG 5.28 0.62 5.19 5.24 0.41 4.29 6.77 2.48 0.72 0.04 0.16
DY ANT 5.23 0.59 5.28 5.24 0.48 4.08 6.2 2.12 -0.17 -0.75 0.15
DY AG ANT 5.31 0.58 5.27 5.31 0.45 4.25 6.38 2.12 0.2 -0.75 0.14
ST AG DY ANT 5.21 0.57 5.13 5.15 0.49 4.4 6.84 2.44 1.22 1.66 0.14
DY AG ST ANT 5.34 0.59 5.39 5.32 0.56 4.23 6.84 2.61 0.49 0.54 0.15
Trained (n=8)
Baseline 5.53 0.29 5.41 5.53 0.23 5.24 5.98 0.74 0.4 -1.78 0.1
ST AG 5.55 0.41 5.44 5.55 0.44 5.04 6.24 1.2 0.37 -1.51 0.15
ST ANT 5.7 0.66 5.83 5.7 0.52 4.78 6.94 2.16 0.34 -0.92 0.23
ST AG ANT 5.51 0.44 5.47 5.51 0.36 4.86 6.17 1.32 0.12 -1.45 0.15
DY AG 5.68 0.59 5.47 5.68 0.52 5.09 6.77 1.68 0.65 -1.2 0.21
DY ANT 5.52 0.6 5.56 5.52 0.43 4.31 6.2 1.89 -0.67 -0.59 0.21
DY AG ANT 5.58 0.56 5.39 5.58 0.59 4.97 6.38 1.41 0.29 -1.85 0.2
ST AG DY ANT 5.5 0.61 5.41 5.5 0.46 4.85 6.84 1.99 1.06 0 0.22
DY AG ST ANT 5.65 0.58 5.6 5.65 0.4 4.98 6.84 1.86 0.8 -0.42 0.2
Untrained (n=8) Baseline 4.72 0.4 4.78 4.72 0.29 4.08 5.3 1.22 -0.26 -1.41 0.14
ST AG 4.78 0.3 4.81 4.78 0.21 4.14 5.12 0.98 -0.97 -0.12 0.11
ST ANT 4.95 0.43 4.98 4.95 0.37 4.2 5.59 1.39 -0.25 -1.08 0.15
ST AG ANT 4.96 0.51 5.05 4.96 0.65 4.23 5.76 1.53 0.05 -1.51 0.18
DY AG 4.88 0.35 4.91 4.88 0.41 4.29 5.29 1 -0.38 -1.46 0.12
DY ANT 4.94 0.44 4.98 4.94 0.42 4.08 5.4 1.32 -0.66 -0.85 0.15
DY AG ANT 5.05 0.49 5.05 5.05 0.54 4.25 5.76 1.5 -0.2 -1.38 0.17
ST AG DY ANT 4.92 0.34 4.87 4.92 0.38 4.4 5.47 1.07 0.09 -1.4 0.12
DY AG ST ANT 5.04 0.46 5.13 5.04 0.48 4.23 5.48 1.25 -0.47 -1.42 0.16
135
Figure 62. Peak velocity (m/s) of the CMJ by stretching condition.
136
Table 45. Peak Velocity (m/s) of the CMJ by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 2.59 0.2 2.67 2.59 0.25 2.2 2.87 0.67 -0.33 -1.13 0.05
ST AG 2.59 0.19 2.63 2.59 0.21 2.29 2.9 0.6 -0.16 -1.28 0.05
ST ANT 2.65 0.22 2.65 2.64 0.21 2.31 3.14 0.83 0.32 -0.44 0.05
ST AG ANT 2.61 0.19 2.61 2.61 0.22 2.3 3.01 0.71 0.3 -0.97 0.05
DY AG 2.65 0.18 2.67 2.65 0.17 2.33 2.95 0.63 -0.16 -0.84 0.05
DY ANT 2.64 0.19 2.66 2.64 0.13 2.26 3.01 0.75 -0.12 -0.52 0.05
DY AG ANT 2.67 0.19 2.67 2.67 0.19 2.31 3.01 0.71 -0.08 -0.84 0.05
ST AG DY ANT 2.63 0.19 2.61 2.61 0.14 2.33 3.18 0.85 1.09 1.43 0.05
DY AG ST ANT 2.69 0.19 2.65 2.67 0.16 2.42 3.18 0.76 0.81 0.32 0.05
Trained (n=8)
Baseline 2.74 0.08 2.71 2.74 0.04 2.67 2.87 0.2 0.73 -1.39 0.03
ST AG 2.73 0.1 2.72 2.73 0.1 2.57 2.9 0.33 0.08 -1.38 0.04
ST ANT 2.79 0.18 2.79 2.79 0.19 2.56 3.14 0.57 0.58 -0.8 0.06
ST AG ANT 2.73 0.16 2.71 2.73 0.12 2.47 3.01 0.54 0.17 -0.8 0.06
DY AG 2.79 0.11 2.77 2.79 0.1 2.65 2.95 0.3 0.43 -1.53 0.04
DY ANT 2.76 0.14 2.75 2.76 0.05 2.53 3.01 0.48 0.17 -0.65 0.05
DY AG ANT 2.77 0.16 2.78 2.77 0.21 2.53 3.01 0.48 0.07 -1.54 0.06
ST AG DY ANT 2.74 0.2 2.7 2.74 0.13 2.52 3.18 0.66 1.11 0.11 0.07
DY AG ST ANT 2.81 0.18 2.8 2.81 0.2 2.63 3.18 0.55 0.72 -0.73 0.07
Untrained (n=8) Baseline 2.43 0.14 2.44 2.43 0.1 2.2 2.67 0.47 0.06 -0.9 0.05
ST AG 2.45 0.14 2.44 2.45 0.15 2.29 2.65 0.36 0.24 -1.71 0.05
ST ANT 2.52 0.15 2.5 2.52 0.21 2.31 2.73 0.43 0.03 -1.78 0.05
ST AG ANT 2.49 0.15 2.47 2.49 0.09 2.3 2.81 0.51 0.86 -0.26 0.05
DY AG 2.52 0.13 2.53 2.52 0.15 2.33 2.69 0.36 -0.26 -1.63 0.05
DY ANT 2.52 0.15 2.55 2.52 0.17 2.26 2.66 0.4 -0.42 -1.51 0.05
DY AG ANT 2.57 0.17 2.6 2.57 0.19 2.31 2.81 0.51 -0.16 -1.58 0.06
ST AG DY ANT 2.53 0.12 2.52 2.53 0.11 2.33 2.7 0.37 0.05 -1.34 0.04
DY AG ST ANT 2.56 0.11 2.57 2.56 0.12 2.42 2.7 0.28 -0.25 -1.63 0.04
137
Figure 63. Vertical Displacement (Depth) of the Center of Mass (cm) during the CMJ by
stretching condition.
138
Table 46. Non-normalized Vertical Displacement Values during the CMJ by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 27.71 7.44 28.1 27.66 6.26 41.95 14.23 27.73 0.09 0.79 1.86
ST AG 28.68 8.28 31.83 29.07 7.62 39.86 12.03 27.83 0.54 1.02 2.07
ST ANT 28.42 8.27 29.78 28.65 7.4 39.67 13.98 25.69 0.42 1.25 2.07
ST AG ANT 28.4 8.79 29.69 28.56 7.82 42.07 12.52 29.56 0.31 0.94 2.2
DY AG 28.76 8.26 29.67 29.14 8.01 39.98 12.24 27.74 0.47 1.08 2.07
DY ANT 29.15 8.28 31.07 29.59 7.73 41.61 10.54 31.07 0.53 0.58 2.07
DY AG ANT 29.6 9.21 33.15 30.02 10.17 42.62 10.68 31.95 0.5 0.97 2.3
ST AG DY ANT 29.62 7.18 30.64 29.8 6.83 40.32 16.44 23.87 0.28 1.19 1.8
DY AG ST ANT 31.29 8.93 34.13 31.57 9.12 44.8 13.86 30.93 0.49 1.02 2.23
Trained (n=8)
Baseline 29.9 5.63 31.03 29.9 5.25 36.88 19.38 17.5 0.54 1.04 1.99
ST AG 30.34 7.31 31.83 30.34 5.63 39.86 15.95 23.91 0.65 0.7 2.58
ST ANT 31.07 6.78 31.25 31.07 4.6 39.67 17.98 21.69 0.52 0.8 2.4
ST AG ANT 30.98 7.36 32.27 30.98 8.02 40.56 18 22.56 0.38 1.29 2.6
DY AG 30.09 7.03 30.59 30.09 6.64 37.79 16.99 20.8 0.51 1.09 2.49
DY ANT 31.37 6.83 33.58 31.37 6.53 39.06 17.99 21.07 0.72 0.85 2.42
DY AG ANT 31.7 7.53 33.47 31.7 7.78 42.62 19.51 23.11 0.21 1.43 2.66
ST AG DY ANT 31.24 6.1 32.62 31.24 4.96 39.38 19.39 20 0.6 0.76 2.16
DY AG ST ANT 33.17 8.53 35.69 33.17 10.1 44.8 18.62 26.17 0.32 1.35 3.01
Untrained (n=8) Baseline 25.52 8.72 26.45 25.52 6.53 41.95 14.23 27.73 0.42 0.91 3.08
ST AG 27.02 9.34 28.92 27.02 10.74 38.59 12.03 26.56 0.26 1.65 3.3
ST ANT 25.77 9.19 26.92 25.77 11.57 38.18 13.98 24.2 0.05 1.87 3.25
ST AG ANT 25.82 9.82 27.87 25.82 6.73 42.07 12.52 29.56 0.01 1.27 3.47
DY AG 27.44 9.63 29.17 27.44 11.75 39.98 12.24 27.74 0.23 1.64 3.4
DY ANT 26.93 9.42 26.75 26.93 8.15 41.61 10.54 31.07 0.16 1.06 3.33
DY AG ANT 27.5 10.72 29.76 27.5 11.85 40.38 10.68 29.7 0.29 1.65 3.79
ST AG DY ANT 28 8.2 27.71 28 9.44 40.32 16.44 23.87 0.1 1.61 2.9
DY AG ST ANT 29.42 9.5 32.49 29.42 8.8 40.09 13.86 26.23 0.48 1.54 3.36
139
Figure 64. Interaction plot of Push-off Distance (%MVC) by stretching condition for all subjects.
Figure 65. Interaction plot of Push-off Distance (%MVC) by stretching condition by group.
140
Figure 66. Boxplot of Push-Off Distance (%MVC) by stretching condition.
141
Table 47. Push-off Distance (cm) values by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
Baseline 38 7.54 38.96 38.01 6.5 22.24 53.65 31.41 -0.13 -0.3 1.89
ST AG 38.38 8.24 41.39 38.77 6.11 22.46 48.7 26.24 -0.68 -1 2.06
ST ANT 39.38 8.12 41.12 39.73 7.28 23.47 50.44 26.97 -0.42 -0.92 2.03
ST AG ANT 38.22 7.83 39.62 38.81 8.51 21.28 46.94 25.66 -0.6 -0.88 1.96
DY AG 40.88 7.95 42.05 41.43 7.57 21.36 52.68 31.32 -0.69 -0.04 1.99
DY ANT 41.26 9.83 41.3 41.06 8.26 20.97 64.26 43.29 0.25 0.25 2.46
DY AG ANT 40.52 8.61 42.63 41.13 10.96 20.41 52.1 31.7 -0.5 -0.48 2.15
ST AG DY ANT 40.29 7.05 40.83 40.44 8.3 27.46 51.05 23.59 -0.32 -1.18 1.76
DY AG ST ANT 41.61 8.53 44.55 41.72 7.59 24.22 57.48 33.26 -0.33 -0.64 2.13
Trained (n=8)
Baseline 40.03 4.95 40.94 40.03 3.85 29.54 44.95 15.41 -0.97 -0.28 1.75
ST AG 40.38 7.36 42.49 40.38 4.64 23.83 46.5 22.68 -1.27 0.32 2.6
ST ANT 41.76 6.77 41.95 41.76 4.31 28.86 50.44 21.59 -0.42 -0.78 2.4
ST AG ANT 40.29 6.59 42.75 40.29 5.61 29.26 46.83 17.57 -0.47 -1.61 2.33
DY AG 43.02 5.16 43.3 43.02 7.41 36.94 49.92 12.97 0 -1.88 1.82
DY ANT 44.45 9.92 43.48 44.45 7.79 31.19 64.26 33.07 0.65 -0.56 3.51
DY AG ANT 42.39 7.33 43.13 42.39 12.14 33.98 52.1 18.13 0.13 -1.76 2.59
ST AG DY ANT 41.44 6.4 43.29 41.44 5.77 28.39 47.31 18.92 -0.87 -0.62 2.26
DY AG ST ANT 43.3 8.35 44.99 43.3 6.05 29.07 57.48 28.42 -0.05 -0.85 2.95
Untrained (n=8) Baseline 35.96 9.38 35.11 35.96 7.23 22.24 53.65 31.41 0.42 -0.78 3.32
ST AG 36.37 9.07 37.91 36.37 11.14 22.46 48.7 26.24 -0.15 -1.66 3.21
ST ANT 37.01 9.09 37.28 37.01 9.41 23.47 50.11 26.64 -0.13 -1.56 3.21
ST AG ANT 36.15 8.85 37.54 36.15 9.25 21.28 46.94 25.66 -0.37 -1.43 3.13
DY AG 38.73 9.92 38.62 38.73 11 21.36 52.68 31.32 -0.29 -1.2 3.51
DY ANT 38.07 9.23 37.89 38.07 7.82 20.97 51.62 30.65 -0.35 -0.88 3.26
DY AG ANT 38.64 9.86 39.8 38.64 10.39 20.41 49.81 29.4 -0.5 -1.16 3.49
ST AG DY ANT 39.15 7.9 36.72 39.15 8.24 27.46 51.05 23.59 0.14 -1.56 2.79
DY AG ST ANT 39.91 8.91 41.73 39.91 9.07 24.22 49.57 25.35 -0.47 -1.4 3.15
142
Table 48. Push-off Distance (%MVC) normalized by baseline values by stretching conditon.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16)
ST AG 1.01 0.1 1.01 1.01 0.08 0.81 1.19 0.39 -0.05 -0.37 0.02
ST ANT 1.04 0.11 1.05 1.04 0.13 0.85 1.21 0.36 -0.15 -1.27 0.03
ST AG ANT 1.01 0.08 1.02 1 0.08 0.87 1.16 0.3 -0.07 -1 0.02
DY AG 1.08 0.12 1.06 1.08 0.14 0.92 1.29 0.36 0.32 -1.51 0.03
DY ANT 1.08 0.14 1.07 1.07 0.1 0.9 1.47 0.57 1.03 0.95 0.04
DY AG ANT 1.07 0.13 1.06 1.06 0.15 0.9 1.35 0.45 0.36 -1.04 0.03
ST AG DY ANT 1.08 0.17 1.07 1.06 0.15 0.88 1.55 0.67 1.39 1.36 0.04
DY AG ST ANT 1.1 0.14 1.08 1.1 0.12 0.91 1.36 0.45 0.5 -1.03 0.04
Trained (n=8)
ST AG 1 0.09 1.02 1 0.03 0.81 1.08 0.27 -1.32 0.59 0.03
ST ANT 1.04 0.08 1.04 1.04 0.09 0.93 1.15 0.22 -0.01 -1.64 0.03
ST AG ANT 1 0.07 1.02 1 0.05 0.87 1.07 0.2 -0.76 -0.96 0.02
DY AG 1.08 0.11 1.07 1.08 0.11 0.95 1.26 0.31 0.34 -1.56 0.04
DY ANT 1.1 0.16 1.07 1.1 0.06 0.9 1.47 0.56 1.21 0.52 0.06
DY AG ANT 1.06 0.12 1.08 1.06 0.13 0.9 1.2 0.3 -0.14 -1.92 0.04
ST AG DY ANT 1.03 0.06 1.05 1.03 0.07 0.96 1.1 0.14 -0.11 -2.07 0.02
DY AG ST ANT 1.08 0.1 1.06 1.08 0.08 0.96 1.28 0.32 0.72 -0.66 0.04
Untrained (n=8) ST AG 1.02 0.11 0.99 1.02 0.11 0.89 1.19 0.31 0.4 -1.6 0.04
ST ANT 1.04 0.14 1.05 1.04 0.17 0.85 1.21 0.36 -0.13 -1.85 0.05
ST AG ANT 1.01 0.1 1 1.01 0.11 0.87 1.16 0.29 0.15 -1.6 0.03
DY AG 1.08 0.14 1.04 1.08 0.15 0.92 1.29 0.36 0.25 -1.85 0.05
DY ANT 1.06 0.13 1.06 1.06 0.16 0.9 1.24 0.34 0.08 -1.76 0.04
DY AG ANT 1.08 0.15 1.06 1.08 0.18 0.92 1.35 0.43 0.47 -1.35 0.05
ST AG DY ANT 1.12 0.23 1.07 1.12 0.21 0.88 1.55 0.67 0.63 -1.17 0.08
DY AG ST ANT 1.13 0.17 1.09 1.13 0.25 0.91 1.36 0.45 0.13 -1.76 0.06
143
Table 49. Effect size of Push-Off Distance (%MVC) by stretching condition.
Group 1 Group 2 Statistic P-value Sig. ES Magnitude
ST AG ANT DY AG ST ANT -3.963 0.001 ** -0.94 large
ST AG DY AG ST ANT -3.596 0.003 ** -0.853 large
ST AG ANT DY AG ANT -2.935 0.01 * -0.697 moderate
ST AG ANT DY AG -2.918 0.011 * -0.692 moderate
ST AG DY AG -2.252 0.04 * -0.534 moderate
ST AG ANT DY ANT -2.238 0.041 * -0.531 moderate
Significance (Sig.) was denoted with * as < 0.05, ** as < 0.01, and *** as <0.001; ES (Cohen’s
D effect size with Hedges (g) correction) and it’s interpretation (Magnitude) are listed from
highest to lowest.
144
Figure 67. Interaction plot of normalzied SQJ for all subjects by stretching condition.
Figure 68. Interaction Plot of SQJ by trained and untrained subjects by stretching condition.
145
Figure 69. Boxplot of SQJ normalized values (%MVC) for each stretching condition.
146
Table 50. Non-Normalized SQJ (cm) values by stretching condition for all subjects and by groups.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 31.02 5.3 32.57 31.24 4.33 18.83 40.06 21.23 -0.53 -0.36 1.33
ST AG 30.35 4.22 29.68 30.36 4.46 23.31 37.2 13.89 0.08 -1.26 1.05
ST ANT 31.41 3.52 31.86 31.42 3.72 25.46 37.2 11.74 -0.02 -1.22 0.88
ST AG ANT 30.62 4.99 29.75 30.31 5.05 25.06 40.52 15.46 0.77 -0.74 1.25
DY AG 31.12 4.13 30.41 31.03 4.84 24.7 38.84 14.13 0.25 -1.11 1.03
DY ANT 31.53 4.26 31.48 31.46 3.9 24.65 39.33 14.67 0.22 -0.87 1.06
DY AG ANT 32.25 4.61 31.28 32.22 3.76 24.38 40.51 16.14 0.25 -1.09 1.15
ST AG DY ANT 30.92 3.78 30.97 30.67 2.1 24.9 40.43 15.53 0.56 0.44 0.94
DY AG ST ANT 33.11 4.72 31.72 33.09 3.72 26.16 40.43 14.27 0.28 -1.46 1.18
Trained (n=8) Baseline 35.03 2.38 34.67 35.03 2.18 32.81 40.06 7.25 0.97 -0.33 0.84
ST AG 33.32 3.15 33.39 33.32 3.67 28.14 37.2 9.06 -0.24 -1.46 1.11
ST ANT 34.16 2.07 33.47 34.16 2.18 31.68 37.2 5.52 0.29 -1.81 0.73
ST AG ANT 33.48 5.46 32.66 33.48 6.77 25.74 40.52 14.78 0.03 -1.76 1.93
DY AG 34.22 3.11 34.17 34.22 3.69 29.45 38.84 9.38 -0.04 -1.5 1.1
DY ANT 34.52 3.33 34.04 34.52 2.23 29.45 39.33 9.87 0.17 -1.36 1.18
DY AG ANT 35.38 3.91 36.14 35.38 5.39 29.88 40.51 10.63 -0.13 -1.81 1.38
ST AG DY ANT 33.16 3.37 32.33 33.16 2.02 29.88 40.43 10.55 1.1 -0.12 1.19
DY AG ST ANT 35.34 4.2 35.73 35.34 4.54 29.25 40.43 11.18 -0.29 -1.69 1.48
Untrained (n=8) Baseline 27 4.21 27.24 27 3.24 18.83 32.32 13.5 -0.58 -0.83 1.49
ST AG 27.38 2.83 27.4 27.38 2.79 23.31 32.22 8.91 0.2 -1.27 1
ST ANT 28.66 2.25 28.05 28.66 2.58 25.46 32.04 6.58 0.16 -1.64 0.8
ST AG ANT 27.77 2.21 27.69 27.77 2.79 25.06 30.46 5.4 0.03 -1.99 0.78
DY AG 28.02 2.24 28.23 28.02 2.21 24.7 30.98 6.28 -0.17 -1.72 0.79
DY ANT 28.54 2.7 28.58 28.54 3.47 24.65 32.04 7.39 -0.13 -1.73 0.95
DY AG ANT 29.12 2.8 29.13 29.12 2.39 24.38 33.56 9.19 -0.16 -1.05 0.99
ST AG DY ANT 28.68 2.79 29.29 28.68 3.83 24.9 32.22 7.32 -0.15 -1.84 0.99
DY AG ST ANT 30.89 4.34 30.3 30.89 2.25 26.16 40.37 14.21 1.07 0.09 1.53
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Table 51. Normalized Values of SQJ by baseline values for all subjects and subsets by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1 0.17 0.99 0.97 0.08 0.8 1.55 0.74 2.04 4.55 0.04
ST ANT 1.03 0.18 0.99 1 0.07 0.9 1.63 0.73 2.29 4.87 0.04
ST AG ANT 1 0.18 0.99 0.98 0.1 0.78 1.54 0.76 1.6 2.59 0.04
DY AG 1.02 0.17 0.99 0.99 0.11 0.83 1.58 0.75 2.12 4.71 0.04
DY ANT 1.04 0.19 0.98 1.01 0.06 0.83 1.64 0.81 1.92 3.63 0.05
DY AG ANT 1.06 0.18 1.03 1.03 0.12 0.88 1.65 0.77 2.1 4.51 0.04
ST AG DY ANT 1.02 0.2 0.99 0.99 0.11 0.78 1.67 0.9 2.06 4.48 0.05
DY AG ST ANT 1.09 0.23 1.04 1.07 0.14 0.83 1.66 0.83 1.32 0.73 0.06
Trained (n=8) ST AG 0.96 0.11 1 0.96 0.11 0.8 1.12 0.31 -0.15 -1.71 0.04
ST ANT 0.98 0.07 0.97 0.98 0.05 0.9 1.12 0.22 0.68 -0.73 0.02
ST AG ANT 0.96 0.15 0.91 0.96 0.14 0.78 1.22 0.43 0.49 -1.4 0.05
DY AG 0.98 0.11 0.97 0.98 0.15 0.83 1.12 0.28 -0.02 -1.78 0.04
DY ANT 0.99 0.12 0.98 0.99 0.13 0.83 1.18 0.34 0.07 -1.37 0.04
DY AG ANT 1.01 0.11 0.98 1.01 0.14 0.88 1.17 0.29 0.21 -1.81 0.04
ST AG DY ANT 0.95 0.11 0.93 0.95 0.09 0.78 1.11 0.34 0.04 -1.25 0.04
DY AG ST ANT 1.01 0.14 1 1.01 0.15 0.83 1.22 0.39 0.2 -1.58 0.05
Untrained (n=8) ST AG 1.04 0.21 0.98 1.04 0.06 0.92 1.55 0.63 1.75 1.45 0.07
ST ANT 1.09 0.24 0.99 1.09 0.1 0.91 1.63 0.72 1.37 0.43 0.08
ST AG ANT 1.05 0.2 1 1.05 0.03 0.91 1.54 0.63 1.72 1.4 0.07
DY AG 1.06 0.22 1.01 1.06 0.07 0.92 1.58 0.67 1.67 1.26 0.08
DY ANT 1.08 0.24 0.99 1.08 0.05 0.94 1.64 0.71 1.46 0.57 0.09
DY AG ANT 1.1 0.23 1.04 1.1 0.07 0.95 1.65 0.7 1.62 1.15 0.08
ST AG DY ANT 1.09 0.25 1.01 1.09 0.09 0.89 1.67 0.79 1.48 0.81 0.09
DY AG ST ANT 1.17 0.28 1.04 1.17 0.09 0.95 1.66 0.71 0.85 -1.26 0.1
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Figure 70. Interaction plot of DJ for all subjects by stretching conditions.
Figure 71. Interaction plot of DJ for trained and untrained groups by stretching conditions.
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Figure 72. Boxplot of normalized Depth Jump (DJ) by baseline values by stretching condition.
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Table 52. Non-Normalized values for Depth Jump (DJ) by group and by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 30.75 6.39 30.86 31.11 6.67 16.64 39.83 23.19 -0.41 -0.7 1.6
ST AG 30.18 5.97 31.27 30.38 5.34 17.69 39.84 22.14 -0.33 -0.74 1.49
ST ANT 30.1 5.66 30.25 30.3 4.94 17.29 40.11 22.83 -0.37 -0.32 1.42
ST AG ANT 30.83 6.31 30.31 30.61 4.1 21.24 43.44 22.2 0.58 -0.45 1.58
DY AG 30.66 5.69 30 30.73 5.41 19.32 41.03 21.71 0.07 -0.46 1.42
DY ANT 30.92 6.37 31.46 30.48 5.77 22.94 45.02 22.07 0.48 -0.62 1.59
DY AG ANT 31.95 6.08 31.99 31.78 6.42 22.95 43.45 20.5 0.47 -0.86 1.52
ST AG DY ANT 33.35 6.68 32.16 33.1 5.27 23.85 46.33 22.48 0.58 -0.98 1.67
DY AG ST ANT 33.35 6.68 32.16 33.1 5.27 23.85 46.33 22.48 0.58 -0.98 1.67
Trained (n=8) Baseline 35.27 3.59 35.31 35.27 4.93 30.3 39.83 9.53 -0.06 -1.82 1.27
ST AG 34.39 3.58 34.19 34.39 3.54 29.1 39.84 10.74 0.11 -1.47 1.27
ST ANT 33.01 4.11 32.54 33.01 4.58 28.26 40.11 11.85 0.38 -1.43 1.45
ST AG ANT 34.6 6.1 32.41 34.6 5.16 26.74 43.44 16.7 0.38 -1.57 2.16
DY AG 34.56 4.32 34.02 34.56 3.99 29.51 41.03 11.52 0.43 -1.45 1.53
DY ANT 34.78 5.48 33.05 34.78 2.84 27.99 45.02 17.03 0.67 -0.99 1.94
DY AG ANT 35.2 6.1 34.62 35.2 6.88 27.51 43.45 15.94 0.13 -1.6 2.16
ST AG DY ANT 36.14 6.83 33.42 36.14 6.33 27.79 46.33 18.54 0.32 -1.77 2.41
DY AG ST ANT 36.14 6.83 33.42 36.14 6.33 27.79 46.33 18.54 0.32 -1.77 2.41
Untrained (n=8) Baseline 26.22 5.28 26.37 26.22 3.91 16.64 34.79 18.14 -0.21 -0.74 1.87
ST AG 25.96 4.79 26.25 25.96 4.5 17.69 32.23 14.54 -0.28 -1.28 1.69
ST ANT 27.19 5.7 27.51 27.19 5.76 17.29 35.57 18.28 -0.23 -1.17 2.01
ST AG ANT 27.06 3.96 27.72 27.06 4.03 21.24 32.91 11.67 -0.11 -1.53 1.4
DY AG 26.76 4.01 27.34 26.76 3.47 19.32 31.74 12.42 -0.54 -1.07 1.42
DY ANT 27.06 4.79 24.52 27.06 2.3 22.94 35.57 12.63 0.62 -1.45 1.69
DY AG ANT 28.71 4.22 27.8 28.71 4.55 22.95 35.57 12.62 0.24 -1.51 1.49
ST AG DY ANT 30.56 5.58 30.02 30.56 4.62 23.85 41.84 17.99 0.73 -0.56 1.97
DY AG ST ANT 30.56 5.58 30.02 30.56 4.62 23.85 41.84 17.99 0.73 -0.56 1.97
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Table 53. Normalized Depth Jump values by baselinev values by group and stretching conditions.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1.01 0.25 0.98 0.96 0.09 0.75 1.87 1.12 2.54 6.43 0.06
ST ANT 1.01 0.26 0.96 0.96 0.11 0.76 1.9 1.14 2.55 6.3 0.06
ST AG ANT 1.03 0.09 1.02 1.03 0.1 0.86 1.2 0.34 0.1 -0.78 0.02
DY AG 1.02 0.22 0.97 0.98 0.1 0.81 1.76 0.96 2.43 5.84 0.05
DY ANT 1.03 0.25 0.99 0.99 0.11 0.79 1.9 1.11 2.43 5.9 0.06
DY AG ANT 1.07 0.26 1.02 1.03 0.1 0.77 1.96 1.18 2.34 5.63 0.07
ST AG DY ANT 1.03 0.28 0.95 0.98 0.15 0.79 2 1.21 2.44 5.81 0.07
DY AG ST ANT 1.13 0.35 1.03 1.09 0.14 0.83 2.01 1.18 1.44 0.69 0.09
Trained (n=8) ST AG 0.98 0.06 1 0.98 0.05 0.88 1.06 0.18 -0.4 -1.41 0.02
ST ANT 0.94 0.06 0.95 0.94 0.06 0.86 1.03 0.17 0.15 -1.42 0.02
ST AG ANT 1 0.1 0.98 1 0.12 0.86 1.13 0.27 0.06 -1.81 0.03
DY AG 0.98 0.08 0.95 0.98 0.07 0.88 1.14 0.26 0.63 -1.09 0.03
DY ANT 0.98 0.08 0.97 0.98 0.08 0.89 1.13 0.24 0.53 -1.2 0.03
DY AG ANT 1 0.14 1.01 1 0.13 0.77 1.19 0.42 -0.27 -1.5 0.05
ST AG DY ANT 0.94 0.12 0.93 0.94 0.13 0.84 1.16 0.33 0.71 -0.98 0.04
DY AG ST ANT 1.03 0.22 0.95 1.03 0.15 0.85 1.53 0.68 1.3 0.4 0.08
Untrained (n=8) ST AG 1.03 0.35 0.94 1.03 0.15 0.75 1.87 1.12 1.53 0.98 0.13
ST ANT 1.08 0.36 0.99 1.08 0.17 0.76 1.9 1.14 1.4 0.7 0.13
ST AG ANT 1.05 0.07 1.03 1.05 0.04 0.97 1.2 0.23 0.91 -0.53 0.03
DY AG 1.06 0.3 1.01 1.06 0.11 0.81 1.76 0.96 1.5 0.93 0.11
DY ANT 1.08 0.35 1.01 1.08 0.15 0.79 1.9 1.11 1.42 0.76 0.13
DY AG ANT 1.14 0.34 1.02 1.14 0.06 0.92 1.96 1.04 1.71 1.33 0.12
ST AG DY ANT 1.11 0.38 1.04 1.11 0.15 0.79 2 1.21 1.51 0.96 0.13
DY AG ST ANT 1.23 0.44 1.07 1.23 0.16 0.83 2.01 1.18 0.86 -1.18 0.16
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Figure 73. Interaction plot of RSI for all subjects by stretching condition.
Figure 74. Interaction plot of RSI by training status by stretching condition.
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Figure 75. Boxplot of normalized RSI values (%MVC) by baseline values by stretching
condition.
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Table 54. Non-Normalized DJ values for all subjects and by groups by stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) Baseline 1.16 0.26 1.12 1.16 0.35 0.77 1.58 0.81 0.03 -1.44 0.06
ST AG 1.19 0.37 1.07 1.16 0.34 0.78 2.07 1.29 0.89 -0.26 0.09
ST ANT 1.23 0.42 1.18 1.21 0.51 0.76 1.99 1.23 0.31 -1.5 0.1
ST AG ANT 1.25 0.37 1.12 1.24 0.39 0.73 1.97 1.24 0.48 -1.12 0.09
DY AG 1.21 0.44 1.03 1.18 0.41 0.74 2.18 1.44 0.61 -0.95 0.11
DY ANT 1.25 0.41 1.14 1.23 0.54 0.76 1.97 1.21 0.3 -1.44 0.1
DY AG ANT 1.25 0.43 1.06 1.23 0.4 0.78 2.01 1.23 0.45 -1.46 0.11
ST AG DY ANT 1.19 0.37 1.08 1.18 0.46 0.74 1.83 1.1 0.27 -1.52 0.09
DY AG ST ANT 1.16 0.34 1.07 1.16 0.47 0.74 1.69 0.95 0.17 -1.65 0.09
Trained (n=8) Baseline 1.17 0.31 1.19 1.17 0.33 0.77 1.58 0.81 -0.1 -1.85 0.11
ST AG 1.31 0.42 1.25 1.31 0.39 0.81 2.07 1.26 0.5 -1.21 0.15
ST ANT 1.21 0.44 1.08 1.21 0.38 0.81 1.99 1.18 0.51 -1.4 0.15
ST AG ANT 1.26 0.39 1.25 1.26 0.34 0.73 1.97 1.24 0.38 -1.13 0.14
DY AG 1.27 0.47 1.21 1.27 0.41 0.81 2.18 1.37 0.63 -1 0.17
DY ANT 1.25 0.42 1.12 1.25 0.44 0.77 1.97 1.2 0.43 -1.46 0.15
DY AG ANT 1.29 0.44 1.19 1.29 0.52 0.81 2.01 1.2 0.32 -1.68 0.16
ST AG DY ANT 1.2 0.38 1.19 1.2 0.36 0.74 1.83 1.1 0.24 -1.53 0.13
DY AG ST ANT 1.2 0.31 1.25 1.2 0.35 0.74 1.53 0.79 -0.23 -1.84 0.11
Untrained (n=8) Baseline 1.15 0.22 1.12 1.15 0.25 0.87 1.5 0.63 0.25 -1.44 0.08
ST AG 1.07 0.28 1 1.07 0.19 0.78 1.64 0.86 0.87 -0.6 0.1
ST ANT 1.25 0.43 1.24 1.25 0.6 0.76 1.79 1.03 0.05 -1.94 0.15
ST AG ANT 1.25 0.38 1.12 1.25 0.32 0.88 1.86 0.98 0.49 -1.63 0.13
DY AG 1.16 0.44 1.03 1.16 0.41 0.74 1.81 1.07 0.41 -1.74 0.15
DY ANT 1.25 0.43 1.26 1.25 0.52 0.76 1.89 1.13 0.12 -1.82 0.15
DY AG ANT 1.21 0.45 1.05 1.21 0.38 0.78 1.94 1.16 0.51 -1.6 0.16
ST AG DY ANT 1.18 0.38 1.08 1.18 0.46 0.76 1.69 0.93 0.25 -1.88 0.14
DY AG ST ANT 1.12 0.39 0.99 1.12 0.35 0.74 1.69 0.95 0.43 -1.73 0.14
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Table 55. Normalized DJ values by baseline values by groups and stretching condition.
mean sd median trimmed mad min max range skew kurtosis se
All (n = 16) ST AG 1.03 0.17 1 1.01 0.13 0.81 1.49 0.69 1.15 1.14 0.04
ST ANT 1.05 0.22 1.05 1.04 0.18 0.74 1.54 0.79 0.54 -0.5 0.06
ST AG ANT 1.06 0.14 1.04 1.06 0.14 0.83 1.33 0.49 0.42 -0.78 0.04
DY AG 1.03 0.2 0.98 1.01 0.14 0.72 1.57 0.86 1.03 0.85 0.05
DY ANT 1.07 0.2 1.05 1.06 0.16 0.75 1.42 0.67 0.24 -0.84 0.05
DY AG ANT 1.07 0.22 1.03 1.06 0.21 0.75 1.56 0.8 0.71 -0.47 0.06
ST AG DY ANT 1.02 0.18 0.99 1.01 0.08 0.75 1.46 0.71 0.96 0.53 0.04
DY AG ST ANT 1.01 0.2 1.03 1.01 0.11 0.55 1.49 0.94 -0.02 1.39 0.05
Trained (n=8) ST AG 1.12 0.18 1.06 1.12 0.1 0.98 1.49 0.51 1.11 -0.26 0.06
ST ANT 1.03 0.22 1.05 1.03 0.24 0.8 1.44 0.63 0.49 -1.03 0.08
ST AG ANT 0.96 0.08 0.95 0.96 0.1 0.83 1.05 0.21 -0.24 -1.43 0.03
DY AG 1.07 0.21 1.02 1.07 0.1 0.91 1.57 0.67 1.53 0.95 0.07
DY ANT 1.06 0.18 1.04 1.06 0.11 0.79 1.42 0.64 0.48 -0.54 0.07
DY AG ANT 1.1 0.18 1.08 1.1 0.16 0.85 1.45 0.6 0.56 -0.73 0.06
ST AG DY ANT 1.02 0.13 0.98 1.02 0.05 0.93 1.32 0.39 1.49 0.81 0.05
DY AG ST ANT 1.03 0.06 1.03 1.03 0.05 0.95 1.13 0.18 0.16 -1.34 0.02
Untrained (n=8) ST AG 0.93 0.1 0.91 0.93 0.08 0.81 1.09 0.29 0.39 -1.6 0.04
ST ANT 1.07 0.24 1.07 1.07 0.15 0.74 1.54 0.79 0.43 -0.78 0.09
ST AG ANT 1.16 0.12 1.15 1.16 0.07 0.96 1.33 0.37 0.04 -1.19 0.04
DY AG 0.99 0.2 0.92 0.99 0.2 0.72 1.28 0.57 0.24 -1.63 0.07
DY ANT 1.07 0.22 1.07 1.07 0.24 0.75 1.41 0.66 0.05 -1.48 0.08
DY AG ANT 1.04 0.26 0.96 1.04 0.15 0.75 1.56 0.8 0.8 -0.85 0.09
ST AG DY ANT 1.02 0.22 1 1.02 0.2 0.75 1.46 0.71 0.68 -0.68 0.08
DY AG ST ANT 0.98 0.28 1.01 0.98 0.15 0.55 1.49 0.94 0.2 -0.81 0.1
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Chapter 5: Discussion
The purpose of this work was to study the effects of different configurations of the static
and dynamic stretching modalities on isokinetic strength, vertical jump performance, and
muscular activation of the lower leg as measured by electromyography. Study hypotheses
included: 1) the dynamic stretching of the agonist and antagonist condition would improve
isokinetic knee extension peak torque, average power, and average knee extension torque, 2)
improvements on peak torque would be modulated by increases in electromyography (peak
amplitude) of the knee extensors during the dynamic conditions, and 3) the dynamic stretching
conditions would result in greater vertical jump performance. Hypothesis 1 was fully supported
by the findings, while 2 was not supported, and 3 was partially supported.
1.25 Isokinetic Strength
The dynamic of agonist and antagonist conditions shown to induce a statistically significant
improvement of knee extension peak torque relative to bodyweight of 17.06% (233.54±56.3 to
281.22±57.08 PT/BW). In addition, we observed a statistical difference between the dynamic of
agonist and antagonist and static of the antagonist and agonist of 11.2% (252.76±57.76 and
281.22±57.08 PT/BW, respectively). This is consistent with previous literature on dynamic
stretching; for example, an earlier study by Sekir et al. (2010) reported similar findings to the
current study results, Under the static condition, a sample of 10 elite athletes performed two
unassisted stretches that were held four times for 30 seconds with 30 seconds between repetitions
a total of 6 minutes; the dynamic condition performed similar stretches but were only held for 2
seconds contraction, four times slowly, then 15 times as quickly and powerful as possible for a
total of 6 minutes. Rest interval between sets was 20-30sec. Subjects were tested at two different
157
speeds of 60 deg/sec and 180 deg/sec, with the Dynamic stretching improving from baseline (no-
stretching), from 226 ± 17 (Nm) to 245 ± 17 (N m) (Sekir et al., 2010).
Additionally, the experimental condition of Dynamic stretching of the agonist followed
by static stretching of the antagonist also showed an statistically increase of 18.93% from
233.54±56.3 to 285.23±46.59 PT/BW when compared to baseline, and when compared to the
static of agonist and antagonist condition 11.49% (252.76±57.76 PT/BW). This could have been
due to several factors: 1) static stretching has been known to reduce muscular stiffness
(Evetovich et al., 2003; Kubo et al., 2001), and 2) muscular activity and motor unit activation
(Beedle et al., 2008). This could have led to a decreased co-activation or stiffness of the
hamstring muscles and allowed for an increased isokinetic knee extension strength. However, we
were unable to measure muscular or tendon stiffness within this study. Future studies might
consider studying muscle-tendon stiffness to potentially clarify our results.
It was also observed that the static stretching also induced improvements in isokinetic
testing when compared to baseline of 7.6% (233.54±56.3 to 252.76±57.76 PT/BW), however this
was not statistically signfician, and this condition was lower than all of the dynamic stretching
conditions, as previously mentioned. There have been conflicting results within the literature
regarding static stretching and isokinetic knee testing. For example, a recent report showed that
static stretching did not affect isokinetic knee torque at 60 and 180 deg/sec; for two sessions,
subjects performed a 5-minute warm-up on a stationary cycle ergometer followed by 4
repetitions of 4 knee extensor stretches for 30 seconds followed by isokinetic testing at 60 and
180 deg/sec. No changes in isokinetic knee torque, EMG, and mechanography were reported in
knee eccentric actions (Cramer et al., 2006). Additionally, another study also observed no
changes with static stretching. In this study, subjects completed a 5-minute general warm-up on
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the cycle ergometer followed by either static, dynamic, or no stretching (baseline). The static
condition consisted of 5 exercises, each held for 30 seconds, whereas the dynamic consisted of
the same exercises but performed continuously for 15 repetitions. Following this, isokinetic
testing was performed at 60, 180, and 240 deg/sec. No changes were observed in any of the
conditions, however, slight increases were observed in the Dynamic stretching condition (Ayala,
De Ste Croix, Sainz de Baranda, & Santonja, 2015a). In contrast, earlier studies have shown that
static stretching decreases peak torque. For example, Cramer et al. (2005), also showed that 4
exercises performed for 4 repetitions at 30 seconds each were enough to reduce isokinetic
strength at 60 and 240 deg/sec (Cramer et al., 2005). Similarly, Nelson and colleagues (2001)
also reported decreased torque with 3 exercises performed for 4 repetitions at 30 seconds each.
Indicating that static stretching is impaired at 60 deg/sec (1.05 radians) (Nelson et al., 2001).
Furthermore, no other stretching condition induced statistical improvements when compared to
baseline. Moreover, the dynamic of agonist and antagonist, and the dynamic of agonist followed
by static of the antagonist showed superior values and statistical difference when compared to all
of the static stretching conditions.
1.26 Electromyography during Isokinetic Testing
No statistical differences among mean amplitude sEMG activity were observed for any of
the muscles and for any of the stretching conditions. However, Untrained subjects showed a
different trend than Trained subjects. For example, the Trained subjects displayed an increase in
sEMG amplitude for all muscles at all conditions (Table 7). On the contrary, Untrained subjects
showed that both the Static of Agonist, and the Static of Agonist and Antagonist, decreased in
sEMG mean amplitude of the Rectus femoris by -11.66% and -3.78%, respectively.
Additionally, the Static of Agonist condition also reported an -25.17% decrease in the Vastus
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Lateralis and a minimal increase of 1.86% in the Vastus Medialis. On the contrary, the Dynamic
of Agonist and Antagonist showed an increase in mean sEMG amplitude of 28.84, 18.76, and
40.96% for the Vastus Lateralis, Rectus Femoris, and Vastus Medialis, respectively. A similar
upwards trend was observed also for the Dynamic of Agonist and Static of Antagonist condition,
where there was increased activation of 17.25, 14.57, and 39.78% for Vastus Lateralis, Rectus
Femoris, and Vastus Medialis, respectively. It could be the case that untrained individuals were
more sensitive to the stretching of the muscle fibers and relaxation that is inherent in the static
stretching. Previous studies have also seen this decay in muscular activation with static
stretching; recently, a study by Palmer et al. (2019) studied the effects of 30s, 60s, and 120s
passive static stretching of the hamstring muscles on range of motion, isometric torque, rate of
torque development, peak EMG amplitude, and rate of EMG rise; results showed that range of
motion was increased on all the conditions; however, only the 120s condition showed significant
decreases in isometric torque and EMG activity, whereas the 30 and 60-second static conditions
did not show decrease nor increase (Palmer et al., 2019). Furthermore, the current findings are in
partial agreement with Palmer et al. (2019), as the current results also do not indicate any
decreases, but small non-significant increases in isokinetic extension/flexion and EMG activity.
The static stretching proposed in this study was of 60 seconds per muscle group, this could
perhaps have been insufficient to induce the negative effects often seen with static stretching.
Therefore, a future study could address this issue by studying different time durations (i.e. 60s,
120s, 180s, 240s, etc..) of the static stretching and comparing it to dynamic stretching on peak
torque and EMG activity to determine the appropriate volume of each stretching modality.
1.27 Vertical Jump Performance
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We observed that both Dynamic of Agonist and Antagonist, and Dynamic of Agonist and
Static of Antagonist conditions were superior to Baseline, as they induced 12.36% and 6.68%
increases in vertical jump performance, respectively. Similar trends – although not statistically
significant – were observed for these two conditions on squat jump in where these conditions
also induced increases by 10.15% and 6.17%, respectively. Similar trends were observed for the
depth jump with 11.51% and 4.98% increases, respectively. Finally, RSImod increased 7.24%
with the Dynamic of Agonist and Antagonist condition compared to the Dynamic of Agonist and
Static of Antagonist condition inducing only 0.63% increase. Difference between the Dynamic of
Agonist and Static of Antagonist conditions was also observed, where the Static of Antagonist
condition only induced 2.5% increase compared to baseline in RSImod. The increments observed
with the Dynamic of Agonist and Antagonist conditions are in line with the vast majority of
research in the strength and conditioning field (Dalrymple et al., 2010; Holt & Lambourne, 2008;
Montalvo & Dorgo, 2019; Opplert & Babault, 2018; Samson et al., 2012). Additionally, we
observed that trained subjects on average reduced vertical jump height on all conditions in the
countermovement jump, squat jump, and depth jump when compared to baseline values,
however, these were not statisticaly significant. This downward practical trend could have been
in part to the prior knee extensions performed on the isokinetic testing and could have led to
neuromuscular fatigue. In contrast, the increments seen with trained subjects can perhaps be
explained by the Post-Activation Potentiation concept, as it has been seen that near-maximal or
sub-maximal movements can potentiate subsequent explosive movements in trained athletes
(Chiu et al., 2003; Hamada et al., 2000; Rixon et al., 2007; Seitz & Haff, 2016). Furthermore, the
changes from baseline to dynamic stretching conditions appear to have been modulated by the
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Push-off Distance of the center of mass from the CMJ, indicating that perhaps the dynamic
stretching condition facilitated the overall range of motion during the vertical jump.
Although no differences were found between stretching conditions when data were
normalized by the baseline condition in jump performance, jump kinetics, or jump kinematics,
we observed that the Dynamic of Agonist and Antagonist condition crossed the smallest
worthwhile change when compared to Baseline, and was the only condition to have surpassed
this threshold. The smallest worthwhile change (SWC) has been used by sports scientists in order
to quantify a clinically meaningful change (Magnitude-based inferences) of the performance that
in some cases cannot be observed using frequentists statistics (Franceschi & Conte, 2018;
Hopkins et al., 1999). However, this method has been criticized by some statisticians due to the
potential type 1 error (Lohse et al., 2020). At the same time, Hopkins and Batterham (2016),
have defended the SWC and magnitude-based inference by using a simulation of 500,000 mean
effects and found a Type 1 rate lower than traditional null hypothesis testing (Hopkins &
Batterham, 2016). Therefore, and in line with prior studies on dynamic vs static stretching, the
concept that Dynamic stretching should be preferred when attempting to increase vertical jump
performance is supported.
An interesting observation was that the Static of the Agonist and Dynamic of Antagonist
condition also induced increases in isokinetic strength, muscular activation, and vertical jump.
This condition was performed with the static stretching first followed by the dynamic stretching.
A few studies have reported similar findings, specifying that when static stretching is followed
by dynamic stretching, sport-specific stretching, or sport-specific jumps, the overall negative
effects seen with static stretching are restored. For example, an earlier study with elite netball
players performed two stretching conditions: 1) 15 minutes of static stretching followed by
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netball sport-specific warm-up, and 2) 15 minutes of dynamic stretching followed by a sport-
specific warm-up. It was reported that static conditions followed sport-specific warm-ups
dissipated the negative effects seen with static stretching in vertical jump and sprint performance.
Moreover, it was also noticed that dynamic stretching followed by sport-specific condition was
superior to static or dynamic alone, and slightly – yet not statistically significant – to static +
sport-specific warm-up in vertical jump and sprinting (Taylor et al., 2009).
It is also worth mentioning that the difference between Static stretching vs Dynamic
stretching-induced performance was far greater in isokinetic strength than in Vertical Jump
Height (CMJ, SQJ, and DJ). This reduction in between differences could be attributed in part to
the 16 repetitions of knee extensions performed at 60deg/sec (4 repetitions for 2 sets for each
leg) before performing the vertical jumps. Perhaps, a Post-Activation Potentiation effect could
have appeared and confounded the negative effects seen in static stretching. Similar effects have
been previously seen with elite gymnasts. For example, a study using 15 seconds of static
stretching followed by 5 tuck jumps vs a 30 seconds static stretching followed by 3 sets of 5
repetitions of tuck jumps showed that the later condition improved range of motion and the
countermovement jump remained similar to no warm-up. Therefore, it was suggested that
perhaps the conditioning activity was the driving factor to the dissipation of the negative effects
seen with static stretching (Donti et al., 2014).
Finally, it was also observed that the Static of Antagonist condition was superior to either
Static of Agnoist, or Static of Agonist and Antagonist conditions, but no greater than any of the
Dynamic conditions in isokinetic strength, sEMG, and vertical jump height. These findings are in
concordance with previous findings on stretching of the antagonist muscles (Miranda et al.,
2015; Sandberg et al., 2012; Serefoglu et al., 2017). However, in each of these studies, a
163
dynamic condition or a comparative stretching condition was not present. Although the present
study results indicate that Statics of Antagonist does increase isokinetic strength, sEMG, and
vertical jump height, it can be concluded – within the premises of this study – that such
increments are not statistically significant, and when compared to Dynamic conditions, these are
not better than such.
Limitations
First and foremost, the findings within this study can only be extrapolated to a trained and
untrained male population similar to the one presented in this study. Previous research shows
that the effects of static stretching are dependent on the training history and status of the
individual. For example, previous research from our laboratory with college-age gymnasts
showed that vertical jump height does not decrease after a series of static stretches; on the
contrary, a slight increase was observed. However, this was not statistically significant, rather,
the only condition that was statistically significant in terms of improvements was the dynamic
condition (Montalvo & Dorgo, 2019). Also, the 60-second static stretching showed neither
significant decrease or increase in isokinetic strength, muscular activation, or vertical jump
height. However, a slight increase in knee extension strength was noted, which could have been
attributed to the prior general warm-up; the increased temperature and blood flow could have
confounded the inhibitory effects of static stretching (Simic et al., 2013). Furthermore, a
statistically non-significant increase in vertical jump height and muscular activation was also
observed.
Second, there were no repeated sessions for each of the conditions. Due to time-cost
constraints, each stretching condition was only performed once. However, the randomization that
is inherent in the study design does allow for statistical control of the time effect. That is, for
164
each subject individually we see a similar trend as expressed by the statistical analysis.
Moreover, future studies might want to increase the reliability of their study by including
replication of each stretching condition over several testing periods.
Third, only males were utilized in this study. This was done primarily due to
convenience. However, a group compromising of females is also needed to present more
heterogeneous data and extrapolate these results to female athletes.
Fourth, the post-hoc testing after the ANOVA or Friedman’s repeated measures (for
parametric and non-parametric data, respectively), was performed using the Fisher’s east
Significant Differences (Fisher’s LSD). This post-hoc testing does not adjust for the critical t-test
and does not adjust for the alpha level. Given the multiple pairwise comparisons carried out
when the ANOVA or Friedman’s test was significant, it is expected to have at least a 5% of these
comparisons a Type 1 Error (false positive). Traditionally, and in order to account for these
multiple comparisons, the Bonferroni correction is usually applied to the post-hoc testing. The
Bonferroni correction involves adjusting the alpha level (usually 0.05) by the number of pairwise
comparisons. Thus, in the case of the present study, a total of 8 stretching experimental
conditions yielded a total of 28 comparisons. Following the Bonferroni adjusting formula, this
would have given us an adjusted p-value of 0.0017 (adjust p-value = 8 stretching conditions / 28
pairwise comparisons). This adjustment method has been heavily criticized, as adjusting the p-
value allows for an increased rate of Type 2 error (false negative) (Moran, 2003; Nakagawa,
2004; Perneger, 1998). To date there appears to be no consensus on the appropriate post-hoc p-
value adjustment; however, in lies to avoid increases of Type 2 error the Fisher's LSD was
conducted, thus, a potential Type 1 error can be expected in some of the pairwise comparisons.
165
Finally, even though we presented sEMG that provides an insight into central
mechanisms through muscular activation, we were unable to measure peripheral mechanisms
such as muscular temperature, muscle-tendon stiffness, mechanoreceptors such as the muscle
spindles, and the stretch reflex (e Lima et al., 2015; Simic et al., 2013).
1.28 Future Research Directions
There was a limited amount of evidence on isokinetic strength and different stretching
protocols. Hence, a replication of this study with multiple sessions (reliability) at different
angular speeds to test different physical qualities (i.e. strength, power, velocity) is recommended.
Additionally, it was found a discrepancy among studies, in where studies indicated that dynamic
stretching does favor isokinetic strength (Ayala et al., 2012), and other evidence that does not
indicate improvement for either stretching modality (Costa et al., 2014). A meta-analysis with a
systematic review could allow us to resolve this disagreement among stretching modalities
before isokinetic testing.
Since there were two maximal tests performed in the same session (isokinetic strength
test and vertical jump performance), it is recommended that future studies replicate these
conditions with separate testing sessions to avoid the potential confounding factor that can be
present due to muscular fatigue.
1.29 Conclusion
It was concluded that when the Dynamic stretching modality is applied, enhanced
performance in isokinetic strength, muscular activation, and vertical jump performance is
observed. In contrast, when a Static Stretching condition is applied, it appears to not have a
statistical effect – but a minimal increase – in isokinetic strength, muscular activation, and
166
vertical jump performance. Additionally, the experimental condition of applying Dynamic
stretching on the agonist muscles followed by the Static Stretching of the antagonist's muscles
improves performance with a similar magnitude as the dynamic stretching modality.
Consequently, a combination of these two modalities (Dynamic at the Agonist and Static at the
Antagonist) appears to be appropriate when seeking to acutely improve isokinetic strength and
vertical jump performance.
1.30 Practical Applications
The Dynamic of Agonist and Static Stretching of Antagonist stretching condition
represents an alternative to a general Dynamic stretching condition of the agonist and antagonist
muscles. Furthermore, individuals, coaches, and researchers seeking to improve isokinetic
strength, muscular activation, and vertical jump performance might opt for the inclusion of either
of these two stretching conditions.
167
References:
Aggeloussis, N., Giannakou, E., Albracht, K., & Arampatzis, A. (2010). Reproducibility of
fascicle length and pennation angle of gastrocnemius medialis in human gait in vivo. Gait
& posture, 31(1), 73-77. https://doi.org/10.1016/j.gaitpost.2009.08.249 [doi]
Andersen, J. C. (2005). Stretching before and after exercise: effect on muscle soreness and injury
risk. Journal of athletic training, 40(3), 218-220.
Ayala, F., De Ste Croix, M., Sainz de Baranda, P., & Santonja, F. (2012). Absolute reliability of
hamstring to quadriceps strength imbalance ratios calculated using peak torque, joint
angle-specific torque and joint ROM-specific torque values. (1439-3964 (Electronic)).
Baker, D. (2003). Acute effect of alternating heavy and light resistances on power output during
upper-body complex power training. Journal of strength and conditioning research,
17(3), 493-497.
Barker, L. A., Harry, J. R., & Mercer, J. A. (2018). Relationships Between Countermovement
Jump Ground Reaction Forces and Jump Height, Reactive Strength Index, and Jump
Time. J Strength Cond Res, 32(1), 248-254.
https://doi.org/10.1519/jsc.0000000000002160
Beedle, B., Rytter, S. J., Healy, R. C., & Ward, T. R. (2008). Pretesting static and dynamic
stretching does not affect maximal strength. Journal of strength and conditioning
research, 22(6), 1838-1843. https://doi.org/10.1519/JSC.0b013e3181821bc9 [doi]
Bergh, U., & Ekblom, B. (1979). Influence of muscle temperature on maximal muscle strength
and power output in human skeletal muscles. Acta Physiologica Scandinavica, 107(1),
33-37. https://doi.org/10.1111/j.1748-1716.1979.tb06439.x [doi]
168
Blazevich, A. J., Gill, N. D., & Zhou, S. (2006). Intra- and intermuscular variation in human
quadriceps femoris architecture assessed in vivo. Journal of anatomy, 209(3), 289-310.
https://doi.org/JOA619 [pii]
Brumitt, J., & Cuddeford, T. (2015). Current Concepts of Muscle and Tendon Adaptation to
Strength and Conditioning. International journal of sports physical therapy, 10(6), 748-
759.
Buckthorpe, M., Morris, J., & Folland, J. P. (2012). Validity of vertical jump measurement
devices. Journal of sports sciences, 30(1), 63-69.
https://doi.org/10.1080/02640414.2011.624539 [doi]
Castagna, C., Ganzetti, M., Ditroilo, M., Giovannelli, M., Rocchetti, A., & Manzi, V. (2013).
Concurrent validity of vertical jump performance assessment systems. Journal of
strength and conditioning research, 27(3), 761-768.
https://doi.org/10.1519/JSC.0b013e31825dbcc5 [doi]
Chaabene, H., Behm, D. G., Negra, Y., & Granacher, U. (2019). Acute Effects of Static
Stretching on Muscle Strength and Power: An Attempt to Clarify Previous Caveats.
Front Physiol, 10, 1468. https://doi.org/10.3389/fphys.2019.01468
Chiu, L. Z., Fry, A. C., Weiss, L. W., Schilling, B. K., Brown, L. E., & Smith, S. L. (2003).
Postactivation potentiation response in athletic and recreationally trained individuals.
Journal of strength and conditioning research, 17(4), 671-677. https://doi.org/R-12062
[pii]
Chleboun, G. S., Busic, A. B., Graham, K. K., & Stuckey, H. A. (2007). Fascicle length change
of the human tibialis anterior and vastus lateralis during walking. The Journal of
169
orthopaedic and sports physical therapy, 37(7), 372-379.
https://doi.org/10.2519/jospt.2007.2440 [doi]
Chleboun, G. S., France, A. R., Crill, M. T., Braddock, H. K., & Howell, J. N. (2001). In vivo
measurement of fascicle length and pennation angle of the human biceps femoris muscle.
Cells, tissues, organs, 169(4), 401-409. https://doi.org/47908 [pii]
Condon, S. M., & Hutton, R. S. (1987). Soleus muscle electromyographic activity and ankle
dorsiflexion range of motion during four stretching procedures. Physical Therapy, 67(1),
24-30.
Costa, P. B., Herda, T. A., Herda, A. A., & Cramer, J. T. (2014). Effects of dynamic stretching
on strength, muscle imbalance, and muscle activation. (1530-0315 (Electronic)).
Cramer, J. T., Housh, T. J., Coburn, J. W., Beck, T. W., & Johnson, G. O. (2006). Acute effects
of static stretching on maximal eccentric torque production in women. J Strength Cond
Res, 20(2), 354-358. https://doi.org/10.1519/r-18105.1
Cramer, J. T., Housh, T. J., Weir, J. P., Johnson, G. O., Coburn, J. W., & Beck, T. W. (2005).
The acute effects of static stretching on peak torque, mean power output,
electromyography, and mechanomyography. Eur J Appl Physiol, 93(5-6), 530-539.
https://doi.org/10.1007/s00421-004-1199-x
Dallas, G., Smirniotou, A., Tsiganos, G., Tsopani, D., Di Cagno, A., & Tsolakis, C. (2014).
Acute effect of different stretching methods on flexibility and jumping performance in
competitive artistic gymnasts. The Journal of sports medicine and physical fitness, 54(6),
683-690. https://doi.org/R40Y2014N06A0683 [pii]
Dalrymple, K. J., Davis, S. E., Dwyer, G. B., & Moir, G. L. (2010). Effect of static and dynamic
stretching on vertical jump performance in collegiate women volleyball players. Journal
170
of strength and conditioning research, 24(1), 149-155.
https://doi.org/10.1519/JSC.0b013e3181b29614 [doi]
De La Torre, I. N. M., Samuel; Conde, Daniel; Mejia, Gabriel; and Dorgo, Sandor (2019).
Increasing Vertical Jump Height using Two Alternative Post-Activation Potentiation
Methods. International Journal of Exercise Science: Conference Proceedings, 2(11).
de Oliveira, F. C., & Rama, L. M. (2016). Static Stretching does Not Reduce Variability, Jump
and Speed Performance. International journal of sports physical therapy, 11(2), 237-246.
de Weijer, V. C., Gorniak, G. C., & Shamus, E. (2003). The effect of static stretch and warm-up
exercise on hamstring length over the course of 24 hours. The Journal of orthopaedic and
sports physical therapy, 33(12), 727-733. https://doi.org/10.2519/jospt.2003.33.12.727
[doi]
Di Cagno, A., Baldari, C., Battaglia, C., Monteiro, M. D., Pappalardo, A., Piazza, M., &
Guidetti, L. (2009). Factors influencing performance of competitive and amateur
rhythmic gymnastics--gender differences. Journal of science and medicine in sport,
12(3), 411-416. https://doi.org/10.1016/j.jsams.2008.01.006 [doi]
Dias, J. A., Dal Pupo, J., Reis, D. C., Borges, L., Santos, S. G., Moro, A. R., & Borges, N. G., Jr.
(2011). Validity of two methods for estimation of vertical jump height. Journal of
strength and conditioning research, 25(7), 2034-2039.
https://doi.org/10.1519/JSC.0b013e3181e73f6e [doi]
Donti, O., Tsolakis, C., & Bogdanis, G. C. (2014). Effects of baseline levels of flexibility and
vertical jump ability on performance following different volumes of static stretching and
potentiating exercises in elite gymnasts. (1303-2968 (Print)).
171
e Lima, K. M., Carneiro, S. P., Alves Dde, S., Peixinho, C. C., & de Oliveira, L. F. (2015).
Assessment of muscle architecture of the biceps femoris and vastus lateralis by
ultrasound after a chronic stretching program. Clinical journal of sport medicine : official
journal of the Canadian Academy of Sport Medicine, 25(1), 55-60.
https://doi.org/10.1097/JSM.0000000000000069 [doi]
Eagles, A. N. L. S. M. G. B. M., & Lovell, D. I. (2016). Motion Capture System versus Common
Force Platform Methodologies for Vertical Jump Analysis. International Journal of
Physical Medicine & Rehabilitation, 4(5).
Ebben, W. P., & Petushek, E. J. (2010). Using the reactive strength index modified to evaluate
plyometric performance. Journal of strength and conditioning research, 24(8), 1983-
1987. https://doi.org/10.1519/JSC.0b013e3181e72466 [doi]
Enoka, R. M. (2008). Neuromechanics of Human Movement Champaign. In (4th ed., pp. 305-
309-305-309). Human Kinetics.
Evetovich, T. K., Nauman, N. J., Conley, D. S., & Todd, J. B. (2003). Effect of static stretching
of the biceps brachii on torque, electromyography, and mechanomyography during
concentric isokinetic muscle actions. Journal of strength and conditioning research,
17(3), 484-488.
Fletcher, I. M., & Monte-Colombo, M. M. (2010). An investigation into the possible
physiological mechanisms associated with changes in performance related to acute
responses to different preactivity stretch modalities. Applied physiology, nutrition, and
metabolism = Physiologie appliquee, nutrition et metabolisme, 35(1), 27-34.
https://doi.org/10.1139/H09-125 [doi]
172
Franceschi, A., & Conte, D. (2018). Individual changes in CMJ performance in track and field
athletes during an indoor season Individual changes in countermovement jump
performance in national youth track and field athletes during an indoor season.
Frantz, T. L., & Ruiz, M. D. (2011). Effects of dynamic warm-up on lower body explosiveness
among collegiate baseball players. Journal of strength and conditioning research, 25(11),
2985-2990. https://doi.org/10.1519/JSC.0b013e31820f509b [doi]
Fukutani, A., & Kurihara, T. (2015). Comparison of the muscle fascicle length between
resistance-trained and untrained individuals: cross-sectional observation. SpringerPlus, 4,
341-015-1133-1131. eCollection 2015. https://doi.org/10.1186/s40064-015-1133-1 [doi]
Garcia-Ramos, A., Stirn, I., Padial, P., Arguelles-Cienfuegos, J., De la Fuente, B., Strojnik, V., &
Feriche, B. (2015). Predicting vertical jump height from bar velocity. Journal of sports
science & medicine, 14(2), 256-262.
Gerrit Jan van Ingen Schenau, M. F. B. A. d. H. (1997). Does Elastic Energy Enhance Work and
Efficiency in the Stretch-Shortening Cycle? Human Kinetics Journal, 13(4).
Glatthorn, J. F., Gouge, S., Nussbaumer, S., Stauffacher, S., Impellizzeri, F. M., & Maffiuletti,
N. A. (2011). Validity and reliability of Optojump photoelectric cells for estimating
vertical jump height. Journal of strength and conditioning research, 25(2), 556-560.
https://doi.org/10.1519/JSC.0b013e3181ccb18d [doi]
Gogte, K., Srivastav, P., & Miyaru, G. B. (2017). Effect of Passive, Active and Combined Warm
up on Lower Limb Muscle Performance and Dynamic Stability in Recreational Sports
Players. Journal of clinical and diagnostic research : JCDR, 11(3), YC05-YC08.
https://doi.org/10.7860/JCDR/2017/24766.9595 [doi]
Haff, G. G., & Triplett, N. T. (2015). Essentials of Strength Training and Conditioning. (4th).
173
Hamada, T., Sale, D. G., MacDougall, J. D., & Tarnopolsky, M. A. (2000). Postactivation
potentiation, fiber type, and twitch contraction time in human knee extensor muscles.
Journal of applied physiology (Bethesda, Md.: 1985), 88(6), 2131-2137.
Hamill, J. K. K. M., & Derrick, T. R. (2015). Biomechanical Basis of Human Movement (4th
ed.). Lippincott Williams & Wilkins.
Hatze, H. (1998). Validity and Reliability of Methods for Testing Vertical Jumping Performance.
Journal of Applied Biomechanics, 14(2), 127 -140.
Hodgson, M., Docherty, D., & Robbins, D. (2005). Post-activation potentiation: underlying
physiology and implications for motor performance. Sports medicine (Auckland, N.Z.),
35(7), 585-595. https://doi.org/3574 [pii]
Holt, B. W., & Lambourne, K. (2008). The impact of different warm-up protocols on vertical
jump performance in male collegiate athletes. Journal of strength and conditioning
research, 22(1), 226-229. https://doi.org/10.1519/JSC.0b013e31815f9d6a [doi]
Hopkins, W. G., & Batterham, A. M. (2016). Error Rates, Decisive Outcomes and Publication
Bias with Several Inferential Methods. Sports Med, 46(10), 1563-1573.
https://doi.org/10.1007/s40279-016-0517-x
Hopkins, W. G., Hawley, J. A., & Burke, L. M. (1999). Design and analysis of research on sport
performance enhancement. Med Sci Sports Exerc, 31(3), 472-485.
https://doi.org/10.1097/00005768-199903000-00018
Ishikawa, M., Dousset, E., Avela, J., Kyrolainen, H., Kallio, J., Linnamo, V., Kuitunen, S.,
Nicol, C., & Komi, P. V. (2006). Changes in the soleus muscle architecture after
exhausting stretch-shortening cycle exercise in humans. European journal of applied
physiology, 97(3), 298-306. https://doi.org/10.1007/s00421-006-0180-2 [doi]
174
Kipp, K., Kiely, M. T., & Geiser, C. F. (2016). Reactive Strength Index Modified Is a Valid
Measure of Explosiveness in Collegiate Female Volleyball Players. Journal of strength
and conditioning research, 30(5), 1341-1347.
https://doi.org/10.1519/JSC.0000000000001226 [doi]
Komi, P. V. (1984). Physiological and biomechanical correlates of muscle function: effects of
muscle structure and stretch-shortening cycle on force and speed. Exercise and sport
sciences reviews, 12, 81-121.
Komi, P. V. (1990). Relevance of in vivo force measurements to human biomechanics. Journal
of Biomechanics, 23 Suppl 1, 23-34. https://doi.org/0021-9290(90)90038-5 [pii]
Kubo, K., Kanehisa, H., Kawakami, Y., & Fukunaga, T. (2001). Influence of static stretching on
viscoelastic properties of human tendon structures in vivo. Journal of applied physiology
(Bethesda, Md.: 1985), 90(2), 520-527. https://doi.org/10.1152/jappl.2001.90.2.520 [doi]
Latash, M. L. (2018). Muscle coactivation: definitions, mechanisms, and functions. Journal of
neurophysiology, 120(1), 88-104. https://doi.org/10.1152/jn.00084.2018 [doi]
Leard, J. S., Cirillo, M. A., Katsnelson, E., Kimiatek, D. A., Miller, T. W., Trebincevic, K., &
Garbalosa, J. C. (2007). Validity of two alternative systems for measuring vertical jump
height. Journal of strength and conditioning research, 21(4), 1296-1299.
https://doi.org/R-21536 [pii]
Linthorne, N. P. (2001). Analysis of standing vertical jumps using a force platform. American
Association of Physics Teacher, 69(11).
Lohse, K. R., Sainani, K. L., Taylor, J. A., Butson, M. L., Knight, E. J., & Vickers, A. J. (2020).
Systematic review of the use of "magnitude-based inference" in sports science and
175
medicine. PloS one, 15(6), e0235318-e0235318.
https://doi.org/10.1371/journal.pone.0235318
Maia, M. F., Willardson, J. M., Paz, G. A., & Miranda, H. (2014). Effects of different rest
intervals between antagonist paired sets on repetition performance and muscle activation.
Journal of strength and conditioning research, 28(9), 2529-2535.
https://doi.org/10.1519/JSC.0000000000000451 [doi]
Malisoux, L., Francaux, M., Nielens, H., & Theisen, D. (2006). Stretch-shortening cycle
exercises: an effective training paradigm to enhance power output of human single
muscle fibers. Journal of applied physiology (Bethesda, Md.: 1985), 100(3), 771-779.
https://doi.org/01027.2005 [pii]
Massey, G. J., Balshaw, T. G., Maden-Wilkinson, T. M., Tillin, N. A., & Folland, J. P. (2017).
The influence of patellar tendon and muscle-tendon unit stiffness on quadriceps explosive
strength in man. Experimental physiology, 102(4), 448-461.
https://doi.org/10.1113/EP086190 [doi]
McBride, J. M., Deane, R., & Nimphius, S. (2007). Effect of stretching on agonist-antagonist
muscle activity and muscle force output during single and multiple joint isometric
contractions. Scandinavian Journal of Medicine & Science in Sports, 17(1), 54-60.
https://doi.org/SMS495 [pii]
McGowan, C. J., Pyne, D. B., Thompson, K. G., & Rattray, B. (2015). Warm-Up Strategies for
Sport and Exercise: Mechanisms and Applications. Sports medicine (Auckland, N.Z.),
45(11), 1523-1546. https://doi.org/10.1007/s40279-015-0376-x [doi]
McKinlay, B. J., Wallace, P., Dotan, R., Long, D., Tokuno, C., Gabriel, D., & Falk, B. (2018).
Effects of Plyometric and Resistance Training on Muscle Strength, Explosiveness and
176
Neuromuscular Function in Young Adolescent Soccer Players. Journal of strength and
conditioning research. https://doi.org/10.1519/JSC.0000000000002428 [doi]
McMahon, J., Suchomel, T., Lake, J. P., & Comfort, P. (2018). Understanding the key phases of
the countermovement jump force-time curve. Strength and Conditioning Journal, 1.
Miranda, H., Maia Mde, F., Paz, G. A., & Costa, P. B. (2015). Acute effects of antagonist static
stretching in the inter-set rest period on repetition performance and muscle activation.
Research in sports medicine (Print), 23(1), 37-50.
https://doi.org/10.1080/15438627.2014.975812 [doi]
Mohr, M., Krustrup, P., Nybo, L., Nielsen, J. J., & Bangsbo, J. (2004). Muscle temperature and
sprint performance during soccer matches--beneficial effect of re-warm-up at half-time.
Scandinavian Journal of Medicine & Science in Sports, 14(3), 156-162.
https://doi.org/10.1111/j.1600-0838.2004.00349.x [doi]
Moir, G. L. (2008). Three Different Methods of Calculating Vertical Jump Height from Force
Platform Data in Men and Women. Measurement in Physical Education and Exercise
Science, 12:4, 207-218.
Montalvo, S., & Dorgo, S. (2019). The effect of different stretching protocols on vertical jump
measures in college age gymnasts. J Sports Med Phys Fitness, 59(12), 1956-1962.
https://doi.org/10.23736/s0022-4707.19.09561-6
Montalvo, S., Gonzalez, M. P., Dietze-Hermosa, M. S., Eggleston, J. D., & Dorgo, S. (2021).
Common Vertical Jump and Reactive Strength Index Measuring Devices: A Validity and
Reliability Analysis. LID - 10.1519/JSC.0000000000003988 [doi]. (1533-4287
(Electronic)).
177
Moore, M. A., & Hutton, R. S. (1980). Electromyographic investigation of muscle stretching
techniques. Medicine and science in sports and exercise, 12(5), 322-329.
Moran, M. D. (2003). Arguments for Rejecting the Sequential Bonferroni in Ecological Studies.
Oikos, 100(2), 403-405. http://www.jstor.org/stable/3548200
Nakagawa, S. (2004). A farewell to Bonferroni: the problems of low statistical power and
publication bias. Behavioral Ecology, 15(6), 1044-1045.
https://doi.org/10.1093/beheco/arh107
Nelson, A. G., Guillory, l. K., Cornwell, C., & Kokkonen, J. (2001). Inhibition of maximal
voluntary isokinetic torque production following stretching is velocity-specific. (1064-
8011 (Print)).
Nicol, C., Avela, J., & Komi, P. V. (2006). The stretch-shortening cycle : a model to study
naturally occurring neuromuscular fatigue. Sports medicine (Auckland, N.Z.), 36(11),
977-999. https://doi.org/36114 [pii]
Opplert, J., & Babault, N. (2018). Acute Effects of Dynamic Stretching on Muscle Flexibility
and Performance: An Analysis of the Current Literature. Sports medicine (Auckland,
N.Z.), 48(2), 299-325. https://doi.org/10.1007/s40279-017-0797-9 [doi]
Owen, N. J., Watkins, J., Kilduff, L. P., Bevan, H. R., & Bennett, M. A. (2014). Development of
a criterion method to determine peak mechanical power output in a countermovement
jump. J Strength Cond Res, 28(6), 1552-1558.
https://doi.org/10.1519/jsc.0000000000000311
Page, P. (2012). Current concepts in muscle stretching for exercise and rehabilitation.
International journal of sports physical therapy, 7(1), 109-119.
178
Palmer, T. B., Pineda, J. G., & Agu-Udemba, C. C. (2019). Duration-Dependent Effects of
Passive Static Stretching on Musculotendinous Stiffness and Maximal and Rapid Torque
and Surface Electromyography Characteristics of the Hamstrings. (1533-4287
(Electronic)).
Papaiakovou, G. (2013). Kinematic and kinetic differences in the execution of vertical jumps
between people with good and poor ankle joint dorsiflexion. Journal of sports sciences,
31(16), 1789-1796. https://doi.org/10.1080/02640414.2013.803587 [doi]
Peck, E., Chomko, G., Gaz, D. V., & Farrell, A. M. (2014). The effects of stretching on
performance. Current sports medicine reports, 13(3), 179-185.
https://doi.org/10.1249/JSR.0000000000000052 [doi]
Perneger, T. V. (1998). What's wrong with Bonferroni adjustments. BMJ (Clinical research ed.),
316(7139), 1236-1238. https://doi.org/10.1136/bmj.316.7139.1236
Rixon, K. P., Lamont, H. S., & Bemben, M. G. (2007). Influence of type of muscle contraction,
gender, and lifting experience on postactivation potentiation performance. Journal of
strength and conditioning research, 21(2), 500-505. https://doi.org/R-18855 [pii]
Samson, M., Button, D. C., Chaouachi, A., & Behm, D. G. (2012). Effects of dynamic and static
stretching within general and activity specific warm-up protocols. Journal of sports
science & medicine, 11(2), 279-285.
Samukawa, M., Hattori, M., Sugama, N., & Takeda, N. (2011). The effects of dynamic stretching
on plantar flexor muscle-tendon tissue properties. Manual therapy, 16(6), 618-622.
https://doi.org/10.1016/j.math.2011.07.003 [doi]
Sandberg, J. B., Wagner, D. R., Willardson, J. M., & Smith, G. A. (2012). Acute effects of
antagonist stretching on jump height, torque, and electromyography of agonist
179
musculature. Journal of strength and conditioning research, 26(5), 1249-1256.
https://doi.org/10.1519/JSC.0b013e31824f2399 [doi]
Seiberl, W., Power, G. A., Herzog, W., & Hahn, D. (2015). The stretch-shortening cycle (SSC)
revisited: residual force enhancement contributes to increased performance during fast
SSCs of human m. adductor pollicis. Physiological reports, 3(5),
10.14814/phy14812.12401. https://doi.org/10.14814/phy2.12401 [doi]
Seitz, L. B., & Haff, G. G. (2016). Factors Modulating Post-Activation Potentiation of Jump,
Sprint, Throw, and Upper-Body Ballistic Performances: A Systematic Review with Meta-
Analysis. Sports medicine (Auckland, N.Z.), 46(2), 231-240.
https://doi.org/10.1007/s40279-015-0415-7 [doi]
Sekir, U., Arabaci, R., Akova, B., & Kadagan, S. M. (2010). Acute effects of static and dynamic
stretching on leg flexor and extensor isokinetic strength in elite women athletes. (1600-
0838 (Electronic)).
Serefoglu, A., Sekir, U., Gur, H., & Akova, B. (2017). Effects of Static and Dynamic Stretching
on the Isokinetic Peak Torques and Electromyographic Activities of the Antagonist
Muscles. Journal of sports science & medicine, 16(1), 6-13.
Simic, L., Sarabon, N., & Markovic, G. (2013). Does pre-exercise static stretching inhibit
maximal muscular performance? A meta-analytical review. Scandinavian Journal of
Medicine & Science in Sports, 23(2), 131-148. https://doi.org/10.1111/j.1600-
0838.2012.01444.x [doi]
Su, H., Chang, N. J., Wu, W. L., Guo, L. Y., & Chu, I. H. (2017). Acute Effects of Foam
Rolling, Static Stretching, and Dynamic Stretching During Warm-ups on Muscular
180
Flexibility and Strength in Young Adults. J Sport Rehabil, 26(6), 469-477.
https://doi.org/10.1123/jsr.2016-0102
Taylor, K. L., Sheppard, J. M., & Plummer, N. (2009). Negative effect of static stretching
restored when combined with a sport specific warm-up component. (1878-1861
(Electronic)).
Tillin, N. A., & Bishop, D. (2009). Factors modulating post-activation potentiation and its effect
on performance of subsequent explosive activities. Sports medicine (Auckland, N.Z.),
39(2), 147-166. https://doi.org/10.2165/00007256-200939020-00004 [doi]
Toumi, H., Best, T. M., Martin, A., F'Guyer, S., & Poumarat, G. (2004). Effects of eccentric
phase velocity of plyometric training on the vertical jump. International Journal of
Sports Medicine, 25(5), 391-398. https://doi.org/10.1055/s-2004-815843 [doi]
Turki-Belkhiria, L., Chaouachi, A., Turki, O., Chtourou, H., Chtara, M., Chamari, K., Amri, M.,
& Behm, D. G. (2014). Eight weeks of dynamic stretching during warm-ups improves
jump power but not repeated or single sprint performance. European journal of sport
science, 14(1), 19-27. https://doi.org/10.1080/17461391.2012.726651 [doi]
Van Hooren, B., & Zolotarjova, J. (2017). The Difference Between Countermovement and Squat
Jump Performances: A Review of Underlying Mechanisms With Practical Applications.
Journal of strength and conditioning research, 31(7), 2011-2020.
https://doi.org/10.1519/JSC.0000000000001913 [doi]
Wakefield, C. B., & Cottrell, G. T. (2015). Changes in hip flexor passive compliance do not
account for improvement in vertical jump performance after hip flexor static stretching.
Journal of strength and conditioning research, 29(6), 1601-1608.
https://doi.org/10.1519/JSC.0000000000000794 [doi]
181
Wobbrock, J., Findlater, L., Gergle, D., & Higgins, J. (2011). The aligned rank transform for
nonparametric factorial analyses using only anova procedures. Proceedings of the
SIGCHI Conference on Human Factors in Computing Systems.
182
Appendix
1.31 Approval IRB Document
Institutional Review Board
Office of the Vice President for Research and Sponsored Projects
The University of Texas at El Paso IRB
FWA No: 00001224
El Paso, Texas 79968-0587
P: 915-747-7693 E: [email protected]
Date: January 28, 2020
To: Samuel Montalvo, MS
From: University of Texas at El Paso IRB
Study Title: [1376857-3] The Effects of Different Stretching Modalities on the Antagonist
and Agonist Muscles on Isokinetic Strength, Muscular Power, and Reactive
Strength Index before and after a Complex Exercise Training Intervention
IRB Reference #: College of Health Sciences
Submission Type: Amendment/Modification
Action: APPROVED
Review Type: Expedited Review
Approval Date: January 28, 2020
Expiration Date: February 4, 2021
The University of Texas at El Paso IRB has approved your submission. This approval is based on the
appropriate risk/benefit ratio and a study design wherein the risks have been minimized. All research
must be conducted in accordance with this approved submission.
This study has received Expedited Review based on the applicable federal regulation.
183
Based on the risks, this project requires Continuing Review by this office on an annual basis. Please use
the appropriate renewal forms for this procedure. The renewal request application must be submitted,
reviewed and approved, before the expiration date.
This approval does not replace any departmental or other approvals that may be required. Other
institutional clearances and approvals may be required. Accordingly, the project should not begin until
all required approvals have been obtained.
Please note that you must conduct your study exactly as it was approved by the IRB. Any revision to
previously approved materials must be approved by this office prior to initiation, except when
necessary to eliminate apparent immediate hazards to the subject.
All serious and unexpected adverse events must be reported to this office. Please use the appropriate
adverse event forms for this procedure. All FDA and sponsor reporting requirements should also be
followed.
Please report all Non-Compliance issues or Complaints regarding this study to this office.
Remember that informed consent is a process beginning with a description of the study and insurance
of participant understanding followed by a signed consent form. Informed consent must continue
throughout the study via a dialogue between the researcher and research participant. Federal
regulations require each participant receive a copy of the signed consent document.
Upon completion of the research study, a Closure Report must be submitted the IRB office.
You should retain a copy of this letter and any associated approved study documents for your records.
All research records must be retained for a minimum of three years after termination of the project.
The IRB may review or audit your project at random or for cause. In accordance with federal regulation
(45CFR46.113), the board may suspend or terminate your project if your project has not been
conducted as approved or if other difficulties are detected.
If you have any questions, please contact the IRB Office at [email protected] or Christina Ramirez
at (915) 747-7693 or by email at [email protected]. Please include your study title and
reference number in all correspondence with this office.
Sincerely,
Dr. Lorraine Torres, Ed.D, MT(ASCP)
IRB Chair
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Institutional Review Board Office
The University of Texas at El Paso
Office of Research and Sponsored Projects
Research Protocol
Instructions: This form must be reviewed and completed in its entirety. All applications for review should contain the information presented in paragraphs. Indicate N/A when not applicable. A complete description of the planned research needs to be submitted in order to determine if all regulatory policy requirements have been met.
As such, the IRB will not consider any research that does not fulfill ethical principles reflected in the Belmont Report. These three basic ethical principles are:
Respect for Persons (autonomy ) - individuals should be treated as autonomous agents and persons with diminished autonomy are entitled to protection.
Beneficence- human participants should not be harmed and the research should maximize possible benefits and minimize possible harms.
Justice- the benefits and risks of research must be fairly distributed.
Please type and submit this form along with finalized copies of all project related materials via IRBNet. Attention to these elements will facilitate the IRB’s review of your project.
For further guidance or assistance, please contact the IRB office at (915) 747-7693 or by email at [email protected].
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Vita
Samuel Montalvo Hernandez was born and raised in Cd. Juarez, Mexico. In 2011 he
graduate from the University of Texas at El Paso with a Bachelor of Science in Kinesiology with
a concentration in Physical Education. After graduation, he worked as a Physical Educator for
Eastwood Knolls International elementary school in El Paso, Texas. During this time, Samuel
obtained his Masters in Kinesiology with a concentration in Exercise Physiology from the same
university. In 2015, he entered the Interdisciplinary Health Science Ph.D. program at the
University of Texas at El Paso. In 2016, he started working under the mentorship of Dr. Sandor
Dorgo and exploring research topics in the area of Strength and Conditioning. Since then,
Samuel has been actively publishing and presenting his academic work at National and
International conferences in the US and Mexico. In addition to his academic work, Samuel is an
active member of the National Martial Arts (Wushu Kung-Fu) team from Mexico and has
represented Mexico at multiple international and world competitions since 2009. In 2011,
Samuel was awarded Mexico’s National Sports Award “Luchador Olmeca” by the
Confederacion Deportiva Mexicana (CODEME) for his contribution to sports and science in
Mexico. In late 2020, Samuel was selected to form part of the Stanford PRISM (postdoctoral
research initiative in science and medicine) cohort, with hopes of obtaining a postdoctoral
position at Stanford. In the future, Samuel hopes to become a University Professor.
Contact information: [email protected]