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Effects of Open− and Closed−chainExercise of the Serratus Anterior Muscle on
Isometric Strength and Muscle ActivityRatios in Subjects With Scapular Winging
The Graduate School
Yonsei University
Department of Physical Therapy
Kiseok Nam
Effects of Open− and Closed−chainExercise of the Serratus Anterior Muscle on
Isometric Strength and Muscle ActivityRatios in Subjects With Scapular Winging
Kiseok Nam
A DissertationSubmitted to the Department of Physical Therapy
and the Graduate School of Yonsei Universityin partial fulfillment of the
requirements for the degree ofDoctor of Philosophy
June 2014
This certifies that the doctoral dissertation ofKiseok Nam is approved.
The Graduate SchoolYonsei University
June 2014
Thesis Supervisor: Ohyun Kwon
Chunghwi Yi: Thesis Committee Member #1
Hyeseon Jeon: Thesis Committee Member #2
Heonseock Cynn: Thesis Committee Member #3
Jonghyuck Weon: Thesis Committee Member #4
Acknowledgement
I sincerely thank Professor Ohyun Kwon for his excellent guidance and support to
finish my doctoral degree course. He always showed me the right way of scholarship
and facilitated my passion for learning and pride in physical therapy. I would also
deeply thank my committee, Professor Chunghwi Yi, Professor Hyeseon Jeon,
Professor Heonseock Cynn and Professor Jonghyuck Weon. Especially I also wish to
acknowledge Professor Hyukcheol Kwon who guided me in the scholar way and gave
constant encouragement.
I also express my appreciation to my friends; especially thank Jiwon Park, Yunwon
Chae and team FMT members. Also, I wish to thank sincerely my colleagues:
Professor Insul Cho, Professor Yonghyun Kwon, Professor Jongsung Chang.
Finally, I want to share this pleasure with my lovely family – Hyein Jang,
Hyeokjun Nam and Yeonu Nam. They have always gave me love and trust. Thank
you.
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Table of Contents
List of Figures ···································································· iii
List of Tables ····································································· iv
Abstract ············································································ v
Chapter
I. Introduction ····································································· 1
II. Isometric Strength of the Serratus Anterior Muscle and UT/SA
and UT/LT EMG Activity Ratio in Subjects With and Without
Scapular Winging (Phase–1 study)
Method ············································································· 6
1. Subjects ······································································ 6
2. Measurement of Isometric Strength of SA muscle ······················· 9
3. EMG Recording and Data Analysis ······································· 10
4. Statistical Analysis ·························································· 12
Results ············································································ 13
III. Comparison of the Effectiveness of Open−chain and Closed−chain
Exercise of the Serratus Anterior Muscle on Isometric Strength
and Muscle Activity Ratios in Subjects Exhibiting Scapular winging
(Phase–2 study)
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Method ············································································ 18
1. Subjects ······································································ 18
2. Isometric SA Strength Measurement, EMG Recording,
and Data Analysis ···························································· 21
3. Exercise intervention ························································· 22
4. Statistical Analysis ·························································· 25
Results ············································································ 26
IV. Discussion ······································································ 31
V. Summary and Conclusion ···················································· 40
References ········································································· 42
Abstract in Korean ································································ 50
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List of Figures
Figure 1. Comparison of the isometric strength of serratus anterior
at the three scapular positions ········································· 15
Figure 2. Comparison of the EMG activity ratio of UT/SA and UT/LT ···· 17
Figure 3. Progression of closed−chain exercise ································· 23
Figure 4. Progression of open−chain exercise ··································· 24
Figure 5. Comparison of the isometric strength of serratus anterior
between pre− and post−exercise ······································ 28
Figure 6. Comparison of the EMG activity ratio of UT/SA
between pre− and post−exercise ······································ 30
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List of Tables
Table 1. Descriptive data for subjects in phase–1 study ·························· 8
Table 2. Comparison of the isometric strength of serratus anterior
at the three scapular positions ········································· 14
Table 3. Comparison of the EMG activity ratio of UT/SA and UT/LT······ 16
Table 4. Descriptive data for participants in phase–2 study··················· 20
Table 5. Comparison of the isometric strength of serratus anterior
between pre− and post−exercise······································ 27
Table 6. Comparison of the EMG activity ratio of UT/SA
between pre− and post−exercise ······································ 29
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ABSTRACT
Effects of Open− and Closed−chain Exercise of the
Serratus Anterior Muscle on Isometric Strength and
Muscle Activity Ratios in Subjects
With Scapular Winging
Kiseok Nam
Dept. of Physical Therapy
The Graduate School
Yonsei University
Scapular winging (SW) is caused by weakness of the muscles that stabilize the
scapula. Dysfunction of the serratus anterior (SA) muscle triggers loss of scapular
stability during shoulder movement. Thus, strengthening of the SA is needed to
correct SW.
The general aim of the present dissertation is evaluation of the outcomes of
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strengthening exercises on SA electromyographic (EMG) activity in subjects with
and without SW. To this end, two studies were conducted.
The purpose of the phase–1 study was to compare SA isometric strength at three
different scapular positions (retracted, neutral, and protracted) and the ratios of EMG
activity between the upper trapezius and serratus anterior (UT/SA) and the upper
trapezius and lower trapezius (UT/LT) muscles in the course of isometric arm
elevation in subjects with and without SW. Thirty−three SW subjects and 33 controls
were recruited. Isometric SA strength was significantly lower in the SW group than
in controls (p < 0.05). In both groups, SA isometric strength differed significantly at
various scapular positions (p < 0.05) and was greatest in the retracted position (p
< .05). The UT/SA EMG activity ratio was significantly higher in SW subjects than
in controls (p < .005), whereas the UT/LT ratio did not differ significantly between
groups.
The phase–2 study compared the effects of open−chain exercise (OCE) and
closed−chain exercise (CCE) on SA isometric strength and on the UT/SA and UT/LT
EMG activity ratios during isometric arm elevation in SW subjects. Thirty SW
subjects were randomly placed into an OCE (three males, 12 females) or CCE group
(three males, 12 females). Mixed−model ANOVA was used to compare exercise
effects (pre−exercise vs. post−exercise) between groups (OCE vs. CCE). After
exercise, SA isometric strength increased significantly in both groups (p < 0.05) but
did not differ significantly between the groups. The UT/SA EMG activity ratio in the
post−exercise period was significantly lower than that in the pre−exercise periods in
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both the OCE and CCE groups (p < 0.05), whereas the UT/LT ratios exhibited no
significant difference.
We found that SA isometric strength was the greatest in the retracted scapular
position in both SW and non−SW subjects. The higher UT/SA EMG activity ratio in
SW subjects compared with non−SW subjects suggests that the UT muscle assumes
an important role as a scapular upward rotator during shoulder elevation in SW
subjects. The 6−week OCE and CCE interventions improved SA muscle strength
and reduced UT activity during arm elevation in SW subjects.
Key Words: Electromyography, Scapular winging, Serratus anterior, Strengthening
exercise.
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ChapterⅠ
Introduction
Scapular winging (SW) is classically defined as a visible prominence of the
scapular medial border, as reflected in normal contact with the thoracic wall (Martin
and Fish 2008). SW represents a variant in the anatomical positioning and motion of
the scapular muscle under both static and dynamic conditions (Kibler, Wilkes, and
Sciascia 2013). Static SW is caused by either articular or bony deformities, and
dynamic SW is attributable to neuromuscular impairment. Dynamic SW is apparent in
exercise of the upper extremities accompanied by resistance (Hamano et al. 2012;
Wilk, Meister, and Andrews 2002).
Serratus anterior (SA) strength may be measured using isokinetic instruments such
as the Biodex and Cybex platforms. Commonly, SA strength measures are used to
compare variations in torque with the extent of resistance, arm elevation angle, and
shoulder position. SA strength is most commonly evaluated with the shoulder at 90°
flexion and the elbow fully extended as the subject protracts the scapula (Kendall,
Provance, and McCreary 1993).
Normal SA muscle function is essential to maintaining appropriate scapulohumeral
rhythm during arm elevation (Decker et al. 1999; Mueller et al. 2013; Wiater and
Flatow 1999; Yano 2010). SA weakness triggers changes in scapular position and thus
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in superior elevation and medial translation; the inferior pole is also medially rotated.
Ultimately, functional scapular motion is affected. Such abnormal positioning and
movement changes the scapulohumeral rhythm of the glenohumeral joint and triggers
development of impingement syndrome (Cools et al. 2003; Ludewig and Cook 2000;
Ludewig and Reynolds 2009). SW patients present with pain, rapid fatigue, and upper
limb functional disabilities (Wiater and Flatow 1999; Kisner and Colby 2007).
Patients cannot generate muscle power, cannot elevate the arms beyond an angle of
120°, and exhibit generally unstable shoulders (Hamano et al. 2012; Ludewig et al.
2004).
Variations in muscle length and direction in the shoulder area affect intermuscular
relationships and recruitment patterns (Mottram 1997; Sahrmann 2002). Smith et al.
(2002) compared the isometric strength associated with arm elevation at three
scapular positions and found that isometric strength was reduced in the protracted
scapular position compared with the neutral position, and it was further reduced in the
retracted scapular position compared with the neutral scapular position. Garner and
Shim (2008) found that protraction force was the greatest when healthy subjects
assumed a retracted scapular position. Many studies have measured shoulder joint
strength without considering scapular positioning, and evaluations were performed at
the neutral position only (Myers et al. 2006; Wilk, Meister, and Andrews 2002). To
the best of our knowledge, no prior study has evaluated the relationship between SA
isometric strength and scapular position in those with and without SW.
In many SW studies, electromyography (EMG) has been used to measure SA
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muscle activity, which is relevant to SW (Hardwick et al. 2006; Park et al. 2013). The
UT, LT, and SA muscles are intimately involved in upward rotation of the scapula
(Ekstrom, Donatelli, and Soderberg 2003; Ha et al. 2012). SA muscle activity
increased linearly as the arm elevation angle rose. The maximum EMG activity level
in the SA muscle was attained when subjects performed upward rotation of the
scapula with the shoulder flexed to 91% of maximal voluntary isometric contraction
(MVIC) in the sagittal plane or abducted at 89% MVIC in the plane of the scapula
against resistance. The activity of the LT muscle fell at angles of <90° and increased
in a log−linear manner when shoulder elevation exceeded 90°. UT muscle activity
was less than 10% MVIC in the mid−range of shoulder elevation (from 70° to 120°),
and high−level muscle activity was apparent in the end−range of shoulder elevation
and upon shrugging movement (Moon, Kim, and Roh 2013).
Recently, workers in the field have sought to define not only EMG activity levels in
particular muscles but also interactions among the SA, UT, and LT during arm
elevation (Cools et al. 2004; Ludewig et al. 2004; Martin and Fish 2008). Sahrmann
(2002) found that abnormal movement was attributable more to among−muscle
imbalance than to muscle weakness. Ludewig and Cook (2000) proposed that a high
UT/SA activity ratio was associated with abnormal movement. Increased UT
activation with reduced activity of the LT and SA muscles during shoulder flexion
may trigger an abnormal scapulohumeral rhythm and, ultimately, SW (Cools et al.
2007; Cools et al. 2004). SW assessment features the use of EMG and isokinetic
equipment, physical examination, X−rays, MRI, and three−dimensional motion
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analysis (3DMA). Physical examination, X−ray analysis, and 3DMA have all been
used to evaluate changes in outward scapular motion (Wang et al. 1999). These
methods measure changes in scapular angle and displacement of specific scapular
regions. Several studies of scapular movement have been performed using
radiographic procedures, but the accuracy of the data is questionable, as is the
evaluation of dynamic movement. Although many investigators claim that 3DMA is
reliable, some clinical limitations are evident. For example, it is difficult to precisely
fix markers because the relative movement of scapular bone and suprascapular skin
vary. Furthermore, these methods are too time consuming for routine clinical
application. EMG and isokinetic evaluation effectively measure muscle activity and
strength. Recently, anatomical SW changes have been evaluated by simple physical
examination using scapulometer. Weon et al. (2011) diagnosed SW by measuring the
distance between the chest wall and the inferior scapular angle; scapulometer afforded
high−level inter− and intra−test reliability.
Exercise programs for SW patients seek to strengthen the SA muscle. Recently,
diverse strengthening exercises have sought to elicit SA muscle activity to treat
shoulder dysfunction. SA exercise programs often include arm elevation, push
movements (scapular protraction), or combinations of these motions (Lombardi et al.
2008). Several exercises have been recommended to strengthen the SA and trapezius
(T) muscles based on EMG amplitudes and muscle strength.
SA strengthening exercises are principally open−chain exercise (OCE) of the
shoulder (Ha et al. 2012; Hibberd et al. 2012; Lephart and Henry 1995). Recently,
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axial load exercises, also termed closed−chain exercise (CCE), have been developed
(Vaseghi et al. 2013). CCE is suggested to be safe and to facilitate proximal joint
stability in the early stages of rehabilitation, establishing stable upper extremity
function in both patients and healthy subjects (Lehman et al. 2006; Vaseghi et al.
2013).
The most common CCEs used to strengthen the SA muscle are push−up and
modified push−up, termed push−up plus. Choi and Lee (2013) applied push−up for 4
weeks, and reported that shoulder pain decreased and upper limb stability increased
significantly. Although the importance of pre/post evaluation of training is accepted,
few data on functional improvements after strengthening exercises have appeared. To
the best of our knowledge, no prior study has compared the effectiveness of CCE and
OCE in SW subjects.
We performed the present study in two phases. The purpose of the phase–1 study
was to compare SA isometric strength at three different scapular positions (retracted,
neutral, and protracted) between subjects with and without SW. We also compared the
UT/SA and UT/LT EMG activity ratios during isometric arm elevation in each group.
The purpose of the phase–2 study was to compare the effectiveness of OCE and CCE
in increasing isometric SA strength and to measure UT/SA and UT/LT EMG activity
ratios during isometric arm elevation in SW subjects
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Chapter Ⅱ
Isometric Strength of the Serratus Anterior Muscle and
UT/SA and UT/LT EMG Activity Ratio in Subjects
With and Without Scapular Winging
(Phase–1 study)
Methods
1. Subjects
Sixty−six participants (16 males, 50 females) were recruited for the phase–1 study
(Table 1). We used scapulometer to identify those with and without SW. To measure
SW, each subject was asked to stand, to flex the elbow joint to 90°, and to hold the
forearm in a neutral position. A cuff weighing 5% of body weight was attached to the
wrist (Weon et al. 2011). The examiner stood behind the subject and placed the four
pads of the scapulometer on the posterior thoracic wall in positions medial to the
vertebral border of the scapula, with the sliding board set at the level of the inferior
angle of the scapula. While holding the scapulometer in place, the examiner next
moved the sliding board anteriorly until the board touched the inferior angle of the
scapula. A ruler fixed to the board was used to measure the posterior displacement of
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the inferior scapular angle from the thoracic wall. SW was diagnosed when the
distance between the thoracic wall and the inferior angle of the scapula was Non−SW
subjects exhibited scapulometric distances <1 cm. Weon et al. (2011) confirmed the
test–retest reliability of scapulometer for measuring SW and reported an interclass
correlation coefficient of 0.97 (95% confidence interval: 0.87–0.99, standard error of
measurement 0.1 cm).
Participants were excluded if any of the following criteria was met: 1) limited
shoulder motion; 2) gross shoulder instability; 3) any sign or symptom of cervical
pain; 4) presence of adhesive capsulitis; 5) presence of thoracic outlet syndrome; 6)
any current complaint of numbness or tingling in an upper extremity; 7) a history of
shoulder injury or surgery; 8) participation in overhead sports at a competitive level;
and 9) upper−limb strength training for more than 5 h per week.
.
- 8 -
Table 1. Descriptive data for subjects in phase−1 study (N=66)
aMean±SD
M: male
F: female
SW: scapular winging
Parameter With SW
(n1=33, M=7, F=26)
Without SW
(n2=33, M=7, F=26)
Age (years) 26.6 ± 3.1 a
25.9 ± 2.7
Weight (㎏) 62.2 ± 4.1 64.6 ± 3.9
Height (㎝) 158.2 ± 2.8 161.2 ± 2.2
Amount of SW (㎜) 23.7 ± 1.9 7.1 ± 2.8
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2. Measurement of Isometric Strength of the SA Muscle
SA isometric strength during scapular protraction was assessed using a Biodex
Dynamometer System 4 Pro (Biodex Medical Systems, Inc., Shirley, NY) with a
closed kinetic chain attachment. Subjects were seated upright in adjustable chairs that
accommodated subjects varying in body dimensions and were restrained using thigh,
pelvic, and trunk straps to prevent compensatory movement. A horizontal arm bar was
placed in the forward direction, and its length was adjusted to accommodate the arm
length of each subject. Prior to measurement, the arm was positioned at 90° forward
flexion of the shoulder joint with full extension of elbow joint in a thumb−up position.
During the protraction trials, SA muscle strength was measured in the retracted,
neutral, and protracted positions. The neutral position was approximately halfway
between the retracted and protracted positions. The protracted position was just short
of full protraction of the scapula, and the retracted position was just short of full
retraction. The test order was randomly selected to minimize fatigue and learning.
Isometric strength was automatically calculated by the Biodex Advantage Software
program Version 4 (Biodex, Medical Systems, Inc., Shirley, NY). Calibration of the
dynamometer was performed as described in the service manual.
- 10 -
3. EMG Recording and Data Analysis
A Noraxon TeleMyo 2400T (Noraxon TeleMyo 2400T, Noraxon, Inc., Scottsdale,
AZ) was used to measure SA, UT, and LT muscle activity. EMG electrodes were
attached to the upper and lower fibers of the T and to the SA. The latter electrodes
were placed vertically along the mid−axillary line at rib levels 6−8 (Ekstrom,
Soderberg, and Donatelli 2005). Electrodes on UT fibers were placed between a point
2 ㎝ lateral to the seventh cervical spinous process and the lateral tip of the acromion
with the shoulder held at 90° abduction. Electrodes on LT fibers were placed at
oblique vertical angles at points 5 ㎝ inferomedial from the root of the scapular
spine (Cram, Kasman, and Holtz, 1998).
Electrode sites were prepared by shaving and cleaning the skin with rubbing
alcohol (Cram, Kasman, and Holtz, 1998). Disposable silver/silver chloride surface
electrodes were positioned at inter−electrode distances of 2 ㎝. The reference
electrode was attached to the seventh cervical vertebra. Each subject was asked to
perform MVIC in test positions specific for each muscle. To measure the MVIC,
maximum SA resistance was applied to the hand and elbow with the subject in the
supine position (Ekstrom, Soderberg, and Donatelli 2005). Measurement of LT MVIC
was performed in the prone position with the shoulder externally rotated and the arm
placed overhead and parallel to the fibers of the LT while resistance was applied distal
to the elbow (Ekstrom, Soderberg, and Donatelli 2005). The UT was evaluated with
the shoulder abducted to 90° and the head in a neutral position. Downward resistance
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was applied to the shoulder (Ekstrom, Soderberg, and Donatelli 2005).
After MVIC testing, subjects were instructed to sit on the Biodex Dynamometer
System Pro, and the arm bar was set at 120° of shoulder flexion to allow
measurement of SA, UT, and LT EMG activity during isometric upper extremity
elevation. To avoid compensatory movement, the trunk and lower extremities were
restrained with Velcro tags and belts. When the researcher gave the “Start” signal, the
subject then lifted the arm upward with maximum effort for 5 s. To prevent fatigue,
about 1 min of relaxation time was allowed between trials.
EMG signals were digitally analyzed using MyoResearch Master Edition 1.06 XP
software (Noraxon, Inc., Scottsdale, AZ). Raw analog 16−bit EMG signals were
collected at 1,000 Hz and digitized. The raw data were digitally filtered at 30~400 Hz
using a band−pass filter, and the 60 Hz signals were removed using a notch filter.
Raw data were transformed to root mean square (RMS) values to permit analysis. In
terms of normalization, each MVIC was collected over 5 s, and the mean values from
the middle 3−s epochs were averaged to obtain a final mean value. SA, UT, and LT
activity was measured during 5 s of isometric arm elevation, and the data of the
middle 3−s epochs were normalized using the 100% MVIC method; EMG activity
ratios (UT/SA) were also calculated.
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4. Statistical Analysis
Demographic data including gender, age, height, and weight were noted. Average
values from three trials were used in analysis. In the phase–1 study, a mixed−model
analysis of variance (ANOVA) (between: group; within: position) was used to
determine differences in SA isometric strength at 90° shoulder flexion at the three
scapular positions between those with and without SW. If a significant effect was
evident, the post−hoc Bonferroni correction was applied. Independent t−tests were
used to examine differences in UT/SA and UT/LT EMG activity ratios between the
groups. All analyses were performed using SPSS version 18.0 (SPSS, Inc., Chicago,
IL), and a p −value <0.05 was considered to reflect statistical significance.
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Results
The SA isometric strengths at various scapular positions of subjects with and
without SW are shown in Table 3 and Figure 1. The principal effects were significant
by group (F = 9.75, p < 0.05) and position (F = 61.46, p < 0.05). No significant group
by position interaction effect was evident (F = 0.06, p = 0.92).
SA isometric strength was significantly lower in SW subjects than in controls (p <
0.05). The differences were significant at all scapular positions [retracted–protracted
(p < 0.05), protracted−neutral (p < 0.05), and neutral−retracted (p < 0.05)]. SA
isometric strength was greatest in the retracted scapular position (Table 3, Figure 1).
The UT/SA and UT/LT EMG activity ratios of subjects with and without SW are
shown in Table 4 and Figure 2. The UT/SA activity ratio in subjects with SW was
significantly higher than that in controls (p < 0.05), but the UT/LT activity ratios did
not differ significantly between the two groups (p = 0.62).
- 14 -
aMean
±S
D
UT
: up
per trap
ezius
SA
: serratus an
terior
LT
: low
er trapeziu
s
* p
<0
.05
Gro
up
Tab
le 2.
C
om
pariso
n o
f the E
MG
activity
ratio o
f UT
/SA
and U
T/L
T(u
nit: N
·m)
With
ou
t SW
With
SW
37
.11
31
.64
Retracted
Po
sition o
f Scap
ula
±
± 1
5.9
6
9.0
7a
27
.39
23
.20
Neu
tral
±
± 1
3.0
1
7.8
0
15.9
2
11.1
9
Pro
tracted
±
± 8
.25
4.1
7
9.75(0.00
*)
Group
F(p
)
61.46(0.00*)
Position
0.0
6(0
.94)
Gro
up
*P
ositio
n
- 15 -
Figure 1. Comparison of the isometric strength of serratus anterior at the three
scapular positions(mean ± SD) (*p<0.05)
- 16 -
Table3. Comparison of the EMG activity ratio of UT/SA and UT/LT
aMean±SD
SW: scapular winging
UT: upper trapezius
SA: serratus anterior
LT: lower trapezius * p<0.05
Ratio
Group
p
With SW Without SW
UT/SA 1.05 ± 0.45a 0.83 ± 0.33 0.03
*
UT/LT 1.49 ± 0.42 1.42 ± 0.62 0.62
- 17 -
Figure 2. Comparison of the EMG activity ratio of UT/SA and UT/LT
(mean ± SD) (*p<0.05)
UT/SA: ratio of upper trapezius to serratus anterior
LT/SA: ratio of lower trapezius to serratus anterior
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Chapter Ⅲ
Comparison of the Effectiveness of Open−chain and
Closed−chain Exercise of the Serratus Anterior Muscle
on Isometric Strength and Muscle Activity Ratios in
Subjects Exhibiting Scapular Winging
(Phase–2 study)
Methods
1. Subjects
Thirty−four subjects with SW (eight males, 26 females) were initially recruited to
the phase–2 study (Table 2); these were the 26 SW subjects of the phase 1 study and
eight additional SW subjects. SW was confirmed using the procedure described above.
To reduce bias, subjects were randomly allocated to the CCE and OCE groups. Two
subjects in each group did not complete the 6−week exercise program or follow−up
testing. Fifteen subjects (three males, 12 females) in the CCE and 15 (three males, 12
females) in the OCE group completed the exercise program and all follow−up tests.
The procedure was explained in detail to all subjects, and all signed written informed
consent forms prior to the trial. The study was approved by the Yonsei University
- 19 -
Wonju Institutional Review Board in accordance with the ethical standards set by that
Board.
- 20 -
Table 4. Descriptive data for participants in phase−2 study (N=30)
aMean±SD
M: male
F: female
SW: scapular winging
Parameter Open−chain exercise
(n1=15, M=3, F=12)
Closed−chain exercise
(n2=15, M=3, F=12)
Age (years) 25.7 ± 2.7a 24.9 ± 2.1
Weight (㎏) 64.9 ± 5.2 66.7 ± 5.1
Height (㎝) 157.1 ± 3.7 160.9 ± 3.2
Amount of SW (㎜) 24.1 ± 1.4 23.3 ± 1.2
- 21 -
2. Isometric SA Strength Measurement, EMG Recording, and Data
Analysis
The instruments and experimental procedure used to measure SA strength
were the same as those of the phase–1 study. In this phase–2 study,
measurement of SA strength was performed only at the neutral scapular position.
The experimental details of EMG data recording and analysis are identical to
those of the phase–1 study.
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3. Exercise interventions
CCE and OCE were used to strengthen the SA. A push−up plus exercise was
performed by the CCE group. Each subject placed the hands directly in front of the
shoulders with the elbows fully extended, progressed to a prone push−up using the
knees as a fulcrum, and then to a push−up while lying prone, lifting the entire body
weight (Figure 3).
Supine push−up exercises were performed by the OCE group. Each subject lay on
the floor with the shoulders flexed at 90° and the knees bent and protracted the
shoulder by pushing up a dumbbell with both hands. Resistance to protraction was
afforded initially only by the weight of the upper limb and was then increased from 1
kg to 6 kg by adding 1kg weights to the dumbbell as subjects progressed. Prior to
each exercise, the maximum distance from the table to the acromion during
protraction was noted, and subjects were verbally encouraged to maintain the
maximum protraction length during interventional exercise (Figure 4).
Each exercise was performed for 10 s and repeated 10 times per set with 7–8 sets
per day, 3 days per week over a period of 6 weeks. Resistance was progressively
increased according to individual ability. All subjects were instructed to avoid
compensatory movements. If a subject exhibited SW or continuous compensatory
movements, s/he was instructed to stop exercising, re−instructed on how the exercise
should be performed, and then asked to resume the exercise. If fatigue, pain, and
dizziness were absent, the protraction load was maximally increased.
- 23 -
Figure 3. Progression of closed−chain exercise
- 24 -
Figure 4. Progression of open−chain exercise
- 25 -
4. Statistical Analysis
Demographic data including gender, age, height, and weight were analyzed using
descriptive statistics. The averages of data from three trials were used in analysis. A
mixed−model analysis of variance (ANOVA) (between: group, within: period) was
used to explore differences in isometric SA strength pre−and post−−exercise in the
two groups. Also, a mixed−model analysis of variance (ANOVA) (between: group,
within: period) was used to evaluate pre− and post−exercise differences in UT/SA and
UT/LT EMG activity ratios between groups. All analyses were performed using SPSS
version 18.0 (SPSS, Inc.), and a p−value <0.05 indicated statistical significance.
- 26 -
Results
The isometric SA strengths of the OCE and CCE groups−by−exercise period are
shown in Table 5 and Figure 3. A significant main effect of period (F = 13.43, p <
0.05) was evident, but not of group (F = 0.86, p = 0.36). No significant
group−by−period interaction effect was noted (F = 0.04, p = 0.84). Upon post−hoc
testing, isometric strength in the post−exercise period was significantly greater than
that in the pre−exercise period in both groups (p < 0.05).
UT/SA EMG activity ratios in the two groups by exercise period are shown in
Table 6 and Figure 4. A significant main effect of period was evident (F = 18.68 p <
0.05), but not of group (F = 0.21, p = 0.65). No significant group−by−period
interaction effect (F = 0.07, p = 0.79) was noted. Upon post−hoc testing, the activity
ratios in the post−exercise period were significantly lower than those in the
pre−exercise period in both groups (both p−values <0.05).
The UT/LT EMG activity ratios in the two groups by exercise period showed no
significant main effect of period (F = 3.31, p = 0.08) or group (F = 0.02, p = 0.89).
No significant group−by−period interaction effect was evident (F = 1.72, p = 0.20).
- 27 -
Table 5. Comparison of the isometric strength of serratus anterior between pre− and
post−exercise (unit: N·m)
aMean±SD
CCE: closed−chain exercise
OCE: open−chain exercise * p<0.05
Group Period F(p)
Pre−Exercise Post−Exercise Group Period Group*Period
CCE 9.47 ± 3.40a 23.79 ± 18.26 0.86(0.36) 13.43(0.00
*) 0.04(0.84)
OCE 12.91 ± 4.26 28.92 ± 28.15
- 28 -
Figure 5. Comparison of the isometric strength of serratus anterior between pre− and
post−exercise
- 29 -
Table 6. Comparison of the EMG activity ratio of UT/SA between pre− and
post−exercise
aMean±SD
CCE: closed−chain exercise
OCE: open−chain exercise * p<0.05
Group Period F(p)
Pre−Exercise Post−Exercise Group Period Group*Period
CCE 0.91 ± 0.22a 0.69 ± 0.26 0.21(0.65) 18.68(0.00
*) 0.07(0.79)
OCE 0.93 ± 0.10 0.74 ± 0.30
- 30 -
Figure 6. Comparison of the EMG activity ratio of UT/SA between pre− and
post−exercise
- 31 -
Chapter Ⅳ
Discussion
The purpose of the phase–1 study was to compare SA isometric strengths at three
different scapular positions (retracted, neutral, and protracted) between subjects with
and without SW. We also compared UT/SA and UT/LT EMG activity ratios during
isometric arm elevation in both groups.
Uniquely, we measured SA isometric strengths at different scapular positions in
subjects with and without SW. Previous studies measured the strengths of the SA and
shoulder girdle muscles employing various maneuvers, but scapular position was not
considered, and all subjects were healthy (Cools et al. 2002; Garner and Shim 2008;
Smith et al. 2002; Wang, Normile, and Lawshe 2006). Cools et al. (2002) measured
unilateral isokinetic protraction strength in healthy subjects. Scapular position was not
considered when measuring SA strength in the scapular plane. Although Garner and
Shim (2008) measured bilateral isometric protraction strength at three scapular
positions (retracted, neutral, and protracted), all subjects were healthy. The cited
authors found that protraction force was strongest in the retracted scapular position, as
did we. The peak protraction force in the protracted position (951 N) was 85% of
that in the retracted position (1,117 N). We found that the isometric strength of the SA
in the protracted position was 35% and 42% that of the retracted position in SW
- 32 -
subjects and controls, respectively. The difference between these values and those of
Garner and Shim (2008) may be explained by the fact that those authors measured
bilateral protraction strength in healthy subjects, whereas we measured unilateral
protraction strength in subjects with and without SW.
The ability of a muscle to generate force depends on the length to which the muscle
is extended when delivering the maximum force; this is usually close to the normal
resting length in the mid−range of motion. However, our findings and those of
previous studies (Garner and Shim 2008) found that SA strength was greatest in the
retracted scapular position, when the SA is maximally extended. The relationship
between muscle strength and length is termed the length−tension relationship.
Muscles that tend to be long, such as the SA, the gluteus medius, and the gluteus
maximus, can generate substantial tension at appropriate points, affording positional
strength (Carrie, and Lori 2005). The positional strength of the SA is maximal at the
retracted scapular position. This muscle generates maximal tension when it is fully
extended and the least tension when it is contracted. When a lengthened muscle is
shortened, myofilaments overlap excessively and cannot develop maximal tension
(Sahrmann 2002). Therefore, an SA strength test should be performed at multiple
points in the extension range to determine whether the SA is positionally weak at any
point in that range (Carrie and Lori 2005).
In the present study, we measured SA strength at 90° forward flexion of the
shoulder joint, full extension of the elbow joint, and in the thumb−up position. Wang
et al. (2006) and Garner and Shim (2008) employed the same posture. Methods for
- 33 -
measuring SA strength have been described in several studies and include protraction
in the scapular plane, protraction when the shoulder is flexed at 90° in the sagittal
plane, and protraction at 90° shoulder flexion and 105° horizontal adduction of the
shoulder joint (Cools et al. 2002; Garner and Shim 2008; Wang et al. 2006). Of these
positions, shoulder protraction at 90° is most commonly applied during measurement
of SA strength. We used this method. The other methods may be effective, but they
are not recommended because other muscles are activated as agonists during arm
elevation. Thus, it is difficult to focus solely on the SA muscle using such methods.
The EMG activity of the SA, UT, and LT was measured, and we calculated the
UT/SA and UT/LT activity ratios. Previous studies found that the UT, LT, and SA
muscles acted agonistically during scapular movement with arm elevation and were
the only muscles involved in upward rotation of the scapula (John and Paula 2001).
The SA muscle generates resistance during upward rotation of the scapula with the
shoulder flexed. LT muscle activity falls when shoulder flexion is below 90° and
progressively increases as that angle rises. UT muscle activity is less than 10% of
maximal in the mid−range of shoulder elevation, becoming higher in the end range
(Moon, Kim, and Roh 2013). Furthermore, abnormal movements were associated
with muscle imbalance to a greater extent than muscle weakness was (Sahrmann
2002). Ludwig and Cook (2000) showed that a high UT/SA ratio contributed to
abnormal movement during shoulder elevation. Thus, increased UT activation may
trigger an abnormal scapulohumeral rhythm and, ultimately, SW. Reduced activity of
- 34 -
the SA and LT muscles during shoulder flexion is also believed to trigger abnormal
scapular movement (Cools et al. 2004; Cools et al. 2007). If the SA muscle does not
adequately rotate the scapula upward, activation of the UT muscle may increase,
stressing the acromioclavicular joint (Johnson et al. 1994). Poor control of the scapula
by the SA muscle can create stress at the glenohumeral joint (Sahrmann 2002).
The UT/SA EMG activity ratios differed significantly between groups. Thus, UT
muscle activity in the SW group was significantly higher than that in controls. Our
results are similar to those of previous studies. Huang et al. (2013) compared UT/SA
activation ratios during forward flexion in subjects with and without impingement
syndrome by contraction type (concentric, eccentric, and isometric contraction) and
found that the UT/SA ratio during isometric shoulder−forward flexion was almost 0.6
in normal subjects but 0.7–0.8 in those with impingement syndrome. Other studies
have yielded slightly different results. Martin et al. (2008) and Ludewig et al. (2004)
calculated ratios of almost 0.3 when subjects maintained the push−up plus posture on
both stable and unstable surfaces. Pirauá et al. (2014) calculated UT/SA muscle
activation ratios of 0.5–1 using electrodes attached to the SA muscle; the results
varied with exercise surface (stable or unstable) when SW subjects performed
push−up exercises. Differences in UT/SA ratios may be explained by variation in
exercise methods, the type of contraction measured, and the sites of electrode
placement on the SA muscle. Thus, higher UT activation reflects abnormal scapular
motion caused by a weakened SA. Specifically, when movements are performed over
the same range of motion, decreased activity in one muscle may be associated with
- 35 -
increased activity in another to achieve the same range of motion (Oh et al. 2007).
Page et al. (2010) found that muscles act synergistically. It was also reported that
reduced SA activation in subjects with shoulder pain triggered increased
compensatory UT muscle activity (Martin and Fish 2008). Thus, the UT/SA activity
ratio was significantly higher in SW patients.
The phase–2 study uniquely revealed that both OCE and CCE improved isometric
SA strength and UT/SA and UT/LT EMG activity ratios. To the best of our knowledge,
this is the first study to identify the utility of SA strengthening exercises during arm
elevation in SW subjects. No prior study has compared the effectiveness of OCE and
CCE used to strengthen the SA and improve the UT/SA ratio in subjects with SW.
CCE was the push−up plus exercise, performed in the prone position with the knees
on the floor and the shoulder protracted. OCE was applied in the supine position with
the shoulder protracted vertically upward and using hand−held dumbbells. In
previous work, CCE−mediated SA strengthening usually entailed push−up plus
exercises and modifications thereof. The SA muscle exhibited relatively high−level
activity, and the UT/SA ratio was low in the plus phase of this exercise (Huang et al.
2013; Kim 2014; Ludewig 2004; Pirauá 2014). Especially, the kneeling push−up plus
exercise is considered optimal for SA training based on the low UT/SA ratio achieved
(Huang et al. 2013). The CCE method we used was a knee push−up plus exercise,
similar to that of previous studies.
In previous studies, various OCEs have been used to strengthen the SA, including
the dynamic hug exercise, shoulder protraction, scaption, and wall−slide exercise with
- 36 -
resistance provided by body weight, an elastic band, or dumbbells (Decker et al. 1999;
Hardwick 2006). Of these methods, shoulder protraction using dumbbells or elastic
bands has most commonly been used to strengthen the SA. Therefore, we used
protraction with dumbbells in the present study
The effects of CCE and OCE were compared in terms of improvements in SA
isometric strength and UT/SA and UT/LT EMG activity ratios in subjects with SW.
The SA isometric strength increased significantly after exercise in both groups, and
no between group difference was evident. Also, the UT/SA EMG activity ratio
decreased significantly after exercise in both groups; again, no between−group
difference was evident. These findings suggest that both OCE and CCE improve SA
isometric strength in individuals with SW. Our current study revealed that SA
isometric strength improved by 150.26% after CCE and 124.01% after OCE; the
between group difference was not significant. The utility of CCE and OCE as SA
strengthening exercises for SW subjects has not been previously evaluated. Earlier
work sought to strengthen shoulder muscles in subjects with subacromial
impingement syndrome and in college−level and adolescent swimmers (Başkurt et al.
2011; Hibberd et al. 2012; Van de Velde et al. 2011). Başkurt et al. (2011) found that
scapular stabilization exercises improved SA strength from 8.79 kg before treatment
to 10.19 kg and increased SA strength by 15.9% in patients with subacromial
impingement syndrome. Hibberd et al. (2012) found that a 6−week strengthening
program directed toward stabilization of the shoulder and scapula did not improve
- 37 -
muscle strength or kinematic scapular parameters in college−level swimmers. Van de
Velde et al. (2011) found that a 12−week scapula training program improved the peak
protraction force in the dominant (13.7%) and nondominant sides (12.5%) compared
with pre−training values.
Ellenbecker and Davies (2001) developed a CCE that was effective for stabilizing
scapular synergy and the SA. Additionally, the exercise stabilized the shoulder when
the distal region of the upper limb was fixed, and facilitated proprioception by
redistributing pressure in the joint capsule (Iwasaki and Matsuse 2006). Antagonist
muscles were eccentrically co−activated with agonist muscles, increasing the stability
of injured joints (Iwasaki and Matsuse 2006). However, our findings differed,
although the maneuver used to measure SA isometric strength was similar to OCE. It
is generally true that the effects of training are most evident when the same exercise
type is used for both training and testing (Carrie and Lori 2005), and the training
mode chosen (OCE or CCE) influences the effectiveness of training (Timothy, Bruce,
and John 2009). The posture we chose for isometric SA strength measurement was
similar to the OCE position. Thus, the reason that our findings differ from those of
previous studies may be that the strengthening and testing modes differed in for CCE
but for OCE.
The UT/SA EMG activity ratio decreased significantly after OCE and CCE in the
present study. Recent work with SW subjects has treated the shoulder dysfunction by
using selective strengthening exercises to facilitate SA muscle activity (Kiss, Illyes,
- 38 -
and Kiss 2010; Neumann 2002). Additionally, many previous studies found that
strengthening regimens including push−up and push−up plus exercises increased
EMG activity of the SA muscle and rehabilitated the upper limbs (Hardwick et al.
2006). Other studies yielded similar results (Huang et al. 2013; Pirauá et al. 2014).
The UT/SA EMG activity ratio of SW subjects during push−up plus exercise on
stable and unstable surfaces were 0.52 and 0.87, respectively. The UT/SA ratio was
0.61 in normal adults and 0.70 in an impingement group during isometric
shoulder−forward flexion (Huang et al. 2013), in line with our finding that the UT/SA
ratio was higher in the SW group than in controls, with values of 1.05 and 0.83,
respectively.
Excessive UT activation is associated with abnormal kinematics of the shoulder
girdle and develops to compensate for reduced SA activity (Ludewig and Cook 2000).
Thus, we believe that the lower UT/SA ratio may be associated with increased SA
strength and reduced UT activation.
Both OCE and CCE improved isometric SA strength and the UT/SA EMG activity
ratio. Thus, both exercises correct imbalances in synergistic muscle activities during
upward scapular rotation.
However, our study had some limitations. Muscles including the pectoralis major,
pectoralis minor, and rhomboid, which could affect scapular movement, were not
considered. Furthermore, follow−up testing to evaluate the lasting nature of the
intervention was not performed. Despite these limitations, we provide useful clinical
evidence on the effectiveness of strengthening exercises in SW subjects. Further
- 39 -
studies lacking the above limitations are needed to gather more detailed evidence.
- 40 -
Chapter Ⅴ
Summary and Conclusion
In our phase–1 study, we compared SA isometric strengths at three different
scapular positions (retracted, neutral, and protracted) and the UT/SA and UT/LT
EMG activity ratios during isometric arm elevation in subjects with and without SW.
SA isometric strength was significantly lower in SW subjects compared with
controls. SA isometric strengths differed significantly between groups in the
retracted, neutral, and protracted scapular positions. SA isometric strength was
greatest in the retracted scapular position. Also, the UT/SA EMG activity ratio was
significantly higher in SW subjects than in controls, whereas the UT/LT ratios did
not differ significantly between groups.
In our phase–2 study, we compared the effectiveness of 6−week OCE and CCE SA
muscle therapy on SA isometric strength and the EMG activity ratios (UT/SA and
UT/LT) during isometric arm elevation in SW subjects. After exercise, the isometric
SA strength increased significantly in both groups and did not differ significantly
between groups. The UT/SA EMG activity ratios in the post−exercise period were
significantly lower than those in the pre−exercise period in both the OCE and CCE
groups, but the pre− and post−exercise UT/LT ratios did not differ significantly
between groups.
SA isometric strength was greatest in the retracted scapular position in subjects
- 41 -
with and those without SW. The higher UT/SA EMG activity ratio in SW subjects
compared with non−SW subjects suggests that the UT assumed a dominant role
among the upward scapular rotators during shoulder elevation in SW subjects.
Following 6−week OCE and CCE intervention, the strength of the SA muscle during
arm elevation increased, and that of the UT fell in SW subjects.
- 42 -
References
Başkurt Z, Başkurt F, Gelecek N, Özkan MH. The effectiveness of scapular
stabilization exercise in the patients with subacromial impingement syndrome. J
Back Musculoskelet Rehabil. 2011;24(3):173-179.
Carrie MH, and Lori TB. Therapeutic Exercise: Moving toward function. Lippincott
Williams & Wilkins, 2005
Choi SH, and Lee BH. Clinical Usefulness of Shoulder Stability Exercises for
Middle-aged Women. J Phys Ther Sci. 2013;25(10):1243-1246.
Cools AM, Declercq GA, Cambier DC, Mahieu NN, and Witvrouw EE. Trapezius
activity and intramuscular balance during isokinetic exercise in overhead athletes
with impingement symptoms. Scand J Med Sci Sports. 2007;17(1):25-33.
Cools AM, Dewitte V, Lanszweert F, Notebaert D, Roets A, Soetens B, Cagnie B,
and Witvrouw EE. Rehabilitation of scapular muscle balance: which exercises to
prescribe? Am J Sports Med. 2007;35(10):1744-1751.
Cools AM, Witvrouw EE, Declerq GA, Daneels LA, and Camblier DC. Scapular
muscle recruitment patterns: trapezius muscle latency with and without
impingement symptoms. Am J Sports Med. 2003;31(4):542-549.
Cools J, Mentens N, Furet P, Fabbro D, Clark JJ, Griffin JD, Marynen P, and
Gilliland DG. Prediction of resistance to small molecule FLT3 inhibitors:
- 43 -
implications for molecularly targeted therapy of acute leukemia. Cancer Res.
2004;64(18):6385-6389.
Cram JR, Kasman GS, Holtz J. Introduction to Surface Electromyography.
Maryland: an Aspen Publication, 1998.
Decker MJ, Hintermeister RA, Faber KJ, and Hawkins RJ. Serratus anterior muscle
activity during selected rehabilitation exercises. Am J Sports Med. 1999;27(6):784-
791.
Ekstrom RA, Donatelli RA, and Soderberg GL. Surface electromyographic analysis
of exercises for the trapezius and serratus anterior muscles. J Orthop Sports Phys
Ther. 2003;33(5):247-258.
Ekstrom RA, Soderberg GL, and Donatelli RA. Normalization procedures using
maximum voluntary isometric contractions for the serratus anterior and trapezius
muscles during surface EMG analysis. J Electromyogr Kinesiol. 2005;15(4):418-
428.
Ellenbecker T, and Davies G. Closed Kinetic Chain Exercise: A Comprehensive
Guide to Multiple Joint Exercises. Champaign: Human kinetics, 2001.
Garner BA, and Shim J. Isometric shoulder girdle strength of healthy young adults.
Clin Biomech. 2008;23(1):30-37.
Ha SM, Kwon OY, Cynn HS, Lee WH, Park KN, Kim SH, and Jung DY.
Comparison of electromyographic activity of the lower trapezius and serratus
- 44 -
anterior muscle in different arm-lifting scapular posterior tilt exercises. Phys Ther
Sport. 2012;13(4):227-232.
Hamano T, Mutoh T, Hirayama M, Uematsu H, Higuchi I, Koga H, Umehara F,
Komai K, and Kuriyama M. Winged scapula in patients with myotonic dystrophy
type 1. Neuromuscul Disord. 2012;22(8):755-758.
Hardwick DH, Beebe JA, McDonnell MK, and Lang CE. A comparison of serratus
anterior muscle activation during a wall slide exercise and other traditional exercises.
J Orthop Sports Phys Ther. 2006;36(12):903-910.
Hibberd EE, Oyama S, Spang JT, Prentice W, and Myers JB. Effect of a 6-week
strengthening program on shoulder and scapular-stabilizer strength and scapular
kinematics in division I collegiate swimmers. J Sport Rehabil. 2012;21(3):253-265.
Huang HY, Lin JJ, Guo YL, Wang WT, and Chen YJ. EMG biofeedback
effectiveness to alter muscle activity pattern and scapular kinematics in subjects
with and without shoulder impingement. J Electromyogr Kinesiol. 2013;23(1):267–
274.
Iwasaki T SN, Shiba N, Matsuse H, Nago T, Umezu Y, Tagawa Y, Nagata K, and
Basford JR. Improvement in knee extension strength through training by means of
combined electrical stimulation and voluntary muscle contraction. Tohoku J Exp
Med. 2006;209(1):33-40.
John DB, Paula ML, Comparison of scapular kinematics between elevation and
lowering of the arm in the scapular plane. Clin Biomech.2002;17(9-10):650-659
- 45 -
Johnson G, Bogduk N, Nowitzke A, and House D. Anatomy and actions of the
trapezius muscle. Clin Biomech. 1994;9(1):44.
Kibler WB, Wilkes T, and Sciascia A. Mechanics and pathomechanics in the
overhead athlete. Clin Sports Med. 2013;32(4):637-651.
Kim SH, Kwon OY, Kim SJ, Park KN, Choung SD, and Weon JH. Serratus anterior
muscle activation during knee push-up plus exercise performed on static stable,
static unstable, and oscillating unstable surfaces in healthy subjects. Phys Ther Sport.
2014;15(1):20-25.
Kisner CC, Colby LA: Therapeutic exercise. Foundation and techniques. FA Davis
Company, 2007.
Kiss RM, Illyés A, and Kiss J. Physiotherapy vs. capsular shift and physiotherapy in
multidirectional shoulder joint instability. J Electromyogr Kinesiol. 2010;20(3):489-
501.
Lehman GJ, MacMillan B, MacIntyre I, Chivers M, and Fluter M. Shoulder muscle
EMG activity during push up variations on and off a Swiss ball. Dyn Med. 2006;5:7.
Lephart SM, and Henry TJ. Functional rehabilitation for the upper and lower
extremity. Orthop Clin North Am. 1995;26(3):579-592.
Lombardi I jr, Magri AG, Fleury AM, Da Silva AC, and Natour J. Progressive
resistance training in patients with shoulder impingement syndrome: a randomized
- 46 -
controlled trial. Arthritis Rheum. 2008; 59(5):615-622.
Ludewig PM, and Cook TM. Alterations in shoulder kinematics and associated
muscle activity in people with symptoms of shoulder impingement. Phys Ther.
2000;80(3):276-291.
Ludewig PM, and Reynolds JF. The association of scapular kinematics and
glenohumeral joint pathologies. J Orthop Sports Phys Ther. 2009;39(2):90-104.
Ludewig PM, Hoff MS, Osowski EE, Meschke SA, and Rundquist PJ. Relative
balance of serratus anterior and upper trapezius muscle activity during push-up
exercises. Am J Sports Med. 2004;32(2):484-493.
Martin RM, and Fish DE. Scapular winging: anatomical review, diagnosis, and
treatments. Curr Rev Musculoskelet Med. 2008;1(1):1-11.
Martins J, Tucci HT, Andrade R, Araujo RC, Bevilaqua-Grossi D, and Oliveira AS.
Electromyographic amplitude ratio of serratus anterior and upper trapezius muscles
during modified push-ups and bench press exercises. J Strength Cond Res.
2008;22(2):477-484.
Moon SJ, Kim TH, and Roh JS. A Comparison of the Serratus Anterior Muscle
Activity according to the Shoulder Flexion Angles in a Closed Kinetic Chain
Exercise and an Open Kinetic Chain Exercise. J Korean Soc Phys Med. 2013;8:369-
378.
Mottram SL. Dynamic stability of the scapula. Man Ther. 1997;2(3):123-131.
- 47 -
Mueller AM, Entezari V, Rosso C, McKenzie B, Hasebrock A, Cereatti A, Della
Croce U, Deangelis JP, Nazarian A, and Ramappa AJ. The effect of simulated
scapular winging on glenohumeral joint translations. J Shoulder Elbow Surg.
2013;22(7):986-992.
Kendall FP, Provance P, and McCreary EK. Muscles, Testing and Function: With
Posture and Pain. Lippincott Williams & Wilkins, 1993.
Myers JM, Laudner KG, Pasquale MR, Bradley JP, and Lephart SM. Glenohumeral
Range of Motion Deficits and Posterior Shoulder Tightness in Throwers With
Pathologic Internal Impingement. Am J Sports Med. 2006;34(3):385-391.
Neumann DA. Kinesiology of the musculoskeletal system: foundations for physical
rehabilitation. St. Louis: Mosby, 2002.
Oh JS, Cynn HS, Won JH, Kwon OY, and Yi CH. Effects of performing an
abdominal drawing-in maneuver during prone hip extension exercises on hip and
back extensor muscle activity and amount of anterior pelvic tilt. J Orthop Sports
Phys Ther. 2007; 37(6): 320-324.
Page P, Frank CC, and Lardner R. Assessment and Treatment of Muscle Imbalance:
The JandaApproach. Champaign: Human Kinetics, 2010.
Park KM, Cynn HS, Yi CH, and Kwon OY. Effect of isometric horizontal abduction
on pectoralis major and serratus anterior EMG activity during three exercises in
subjects with scapular winging. J Electromyogr Kinesiol. 2013;23(2):462-468.
- 48 -
Pirauá A, Pitangui A, Silva J, Passos M, Oliveira V, Batista L, and Araújo R.
Electromyographic analysis of the serratus anterior and trapezius muscles during
push-ups on stable and unstable bases in subjects with scapular dyskinesis. J
Electromyogr Kinesiol. In Press.
Sahrmann SA. Diagnosis and Treatment of Movement Impairment Syndromes. St.
Louis: Mosby, 2002.
Smith J, Kotajarvi BR, Padgett DJ, and Eischen JJ. Effect of scapular protraction
and retraction on isometric shoulder elevation strength. Arch Phys Med Rehabil.
2002;83(3):367-370.
Timothy RA, Bruce CE, and John B. Applied Anatomy and Biomechanics in Sport.
Human Kinetics, 2009.
Van de Velde A, De Mey K, Maenhout A, Calders P, and Cools AM. Scapular-
muscle performance: two training programs in adolescent swimmers. J Athl Train.
2011;46(2):160-167.
Vaseghi B, Jaberzadeh S, Kalantari KK, and Naimi SS. The impact of load and base
of support on electromyographic onset in the shoulder muscle during push-up
exercises. J Bodyw Mov Ther. 2013;17(2):192-199.
Wang CH, McClure P, Pratt NE, and Nobilini R. Stretching and strengthening
exercises: their effect on three-dimensional scapular kinematics. Arch Phys Med
Rehabil. 1999;80(8):923-929.
- 49 -
Wang SS, Normile SO, and Lawshe BT. Reliability and smallest detectable change
determination for serratus anterior muscle strength and endurance tests. Physiother
Theory Pract. 2006;22(1):33-42.
Weon JH, Kwon OY, Cynn HS, Lee WH, Kim TH, and Yi CH. Real-time visual
feedback can be used to activate scapular upward rotators in people with scapular
winging: an experimental study. J Physio ther. 2011;57(2):101-107.
Wiater JM, and Flatow EL. Long thoracic nerve injury. Clin Orthop Relat Res.
1999;368:17-27.
Wilk KE, MeisterK, Andrews JR. Current concepts in the rehabilitation of the
overhead throwing athlete. Am J Sports Med. 2002;30(1):136-151.
Yano Y, Hamada J, Tamai K, Yoshizaki K, Sahara R, Fujiwara T, and Nohara Y.
Different scapular kinematics in healthy subjects during arm elevation and lowering:
glenohumeral and scapulothoracic patterns. J Shoulder Elbow Surg.
2010;19(2):209-215.
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국문 요약
날개어깨뼈 대상자를 위한 앞톱니근 열린사슬운동과
닫힌사슬운동이 앞톱니근의 등척성 근력과
근활성도 비에 미치는 영향
연세대학교 대학원
물리치료학과
남기석
날개어깨뼈는 앞톱니근, 위등세모근, 아래등세모근과 같은 어깨뼈 안정
화 근육의 불균형으로 발생한다. 앞톱니근의 기능부전은 어깨의 움직임 동
안 어깨뼈의 안정화 소실을 초래한다. 그러므로 앞톱니근의 강화운동은 날
개어깨뼈의 치료를 위해 거론된다.
1단계 연구는 날개어깨뼈가 있는 대상자와 없는 대상자간에 어깨관절의
등척 굽힘 동안 앞톱니근의 등척성 근력을 세 개의 어깨뼈 위치(들임위치,
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중립위치, 내밈위치)에서 비교하고, 위등세모근에 대한 앞톱니근의 근전도
활성비율 및 위등세모근에 대한 아래등세모근의 근전도 활성비율을 비교하
기 위하여 날개어깨뼈가 있는 대상자 33명과 날개어깨뼈가 없는 33명을
대상으로 하였다. 두 그룹간에 세 가지의 어깨뼈 위치에 따른 앞톱니근의
등척성 근력을 비교하기 위하여 혼합모형 분산분석 (mixed-model
ANOVA)을 실시하였으며, 근전도 활성비율을 비교하기 위하여 독립표본
t-검증을 실시하였다. 앞톱니근의 등척성 근력은 날개어깨뼈가 있는 그룹
이 없는 그룹에 비해 근력이 유의하게 약한 것으로 나타났다 (p<.05). 세
가지의 어깨뼈 위치에 따른 앞톱니근의 등척성 근력의 비교에서 날개어깨
뼈가 있는 그룹과 없는 그룹 모두에서 유의한 차이가 있었다 (들임위치-
내밈위치(p<.05), 내밈위치-중립위치 (p<.05), 중립위치-들임위치
(p<.05)). 어깨뼈 들임위치에서의 앞톱니근의 등척성 근력이 내밈위치와
중립위치에 비해서 유의하게 강하였다 (p<.05). 위등세모근에 대한 앞톱니
근의 근전도 활성비율은 날개어깨뼈가 있는 그룹이 없는 그룹에 비해 유의
하게 높았으며, 위등세모근에 대한 아래등세모근의 근전도 활성비율은 두
그룹간에 차이가 없었다 (p<.05).
2단계 연구는 날개어깨뼈가 있는 대상자에게 6주간의 열린사슬운동과
닫힌사슬운동을 적용하여 어깨관절 등척성 굽힘 동안 앞톱니근의 등척성
근력과 위등세모근에 대한 앞톱니근의 근전도 활성비율 및 위등세모근에
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대한 아래등세모근의 근전도 활성비율에 미치는 영향을 비교하기 위하여
실시하였다. 날개어깨뼈가 있는 30명을 열린사슬운동 그룹 (남자 3명, 여
자 12명)과 닫힌사슬운동 그룹 (남자 3명, 여자 12명)에 무작위 배정하였
다. 열린사슬운동 그룹과 닫힌사슬운동 그룹간 운동전후의 앞톱니근 등척
성 근력과 근전도 활성비율을 비교하기 위하여 혼합모형 분산분석
(mixed-model ANOVA)을 실시하였다. 두 그룹 모두에서 운동 후에 앞
톱니근의 등척성 근력이 유의하게 증가하였으며 (p<.05), 두 그룹간에는
유의한 차이가 없었다. 위등세모근에 대한 앞톱니근의근전도 활성비율은
열린운동사슬 그룹 (p<.05)과 닫힌사슬운동 그룹 (p<.05) 모두에서 운동
전에 비해 운동 후에 유의하게 감소하였다. 그러나 위등세모근에 대한 아
래등세모근의 근전도 활성비율은 두 그룹 모두에서 운동 전과 운동 후에
유의한 차이가 없었다.
이 연구의 결과를 요약하면 날개어깨뼈가 있는 대상자와 없는 대상자 모
두에서 어깨뼈 들임 자세에서 앞톱니근의 등척성 근력이 내밈자세와 중립
위치에 비해 유의하게 강하였다. 날개어깨뼈가 있는 대상자는 없는 대상자
에 비해 위등세모근에 대한 앞톱니근의 근전도 활성비율이 높았는데 이 결
과는 날개어깨뼈가 있는 대상자가 팔을 들어올리는 동안 어깨뼈 위쪽 돌림
근 중에서 위등세모근이 우세하게 사용한다는 것을 의미한다. 그리고 날개
어깨뼈 대상자에게 적용한 6주간의 열린 사슬운동과 닫힌 사슬운동은 두
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운동방법 모두 앞톱니근의 등척성 근력을 향상시키고, 팔을 위로 들어올리
는 동작 동안 위등세모근의 활성도를 감소시키는데 효과적일 것으로 사료
된다.
핵심 되는 말: 강화운동, 근전도, 날개어깨뼈, 앞톱니근.