journal submaxmal estimation

7/30/2019 Journal Submaxmal Estimation

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Clinical Kinesiology67(1); Spring, 2013 1

Submaximal Estimation of Strength in High School Football

AthletesEric Guyotte, MS

1, Michael Horvat, Ed.D.

1, Christine Franklin, MS

2, Christopher Ray,

Ph.D3, and R. Christopher Mason, MA

1

1

University of Georgia, Movement Studies Laboratory, University of Georgia, Department ofStatistics, University of Texas-Arlington, Department of Kinesiology

ABSTRACTThe purpose of this study was to investigate the effectiveness of upperbody strength assessments as predictors of

one repetition maximum (1RM) strength among high school football athletes. Sixty-two male high school football

athletes (13-18 yrs.) participated in this research and completed a 1 repetition maximum bench press (1RMBP),

repetitions to fatigue bench press (RTFBP), and a kneeling medicine ball throw (KMBT). A Pearson productcorrelation was used to determine the relationships between the repetitions to fatigue bench press, kneeling medicine

ball throwand the one repetition maximum test on upper body strength. Based on the data analysis, a strong linear

correlation was apparent between 1RMBP and both RTFBP (r = 0.907) and KMBT (r = 0.795) indicating that these

tests were viable alternatives to maximal testing and could be used as a predicator of maximal strength in high

school athletes.

Key Words: One repetition maximum bench press, repetitions to fatigue, medicine ball throw

INTRODUCTIONStrength training is a common practice for

developing and improving the overall performance

capabilities of high school football players. In orderto implement a viable training program that is

specific to developing the adolescent athlete and

increasing performance, coaches and teachersshould

approximatethe capabilities of their performers prior

to the initiation of a trainingprogram.

Submaximal estimates can be used to minimizeinjury to athletes in the weight room by eliminating

frequent periodic assessments and to track program

effectiveness. This will allow for the refinement of

currently implemented strength training programs. As

periodized programs require close monitoring of both

volume and intensity, it is imperative that safe and

statistically sound alternatives to maximal testing are

explored to avoid injuries. Strength-training

programs are common in high school athletics,

however, a scarcity of information is available with

regard to evidence-based solutions to monitor the

athletic capabilities and accommodate physiological

differences or maturation in high school boys.

Most coaches use one repetition maximum

(1RM) testing especially in football as the standard

for measuring strength and power without

considering the concerns of requiring adolescent

athletes to lift heavy loads during a period of

biological immaturity. The major concerns regarding

adolescent strength training are injuries to growth

plates, stress on the joints and the musculoskeletal

system especially during onset of maturation and

peak height velocity [1,2,7,9]. This is particularly

alarming because the background and training of high

school coaches is minimal concerning proper lifting

techniques, safety, and knowledge of biologicaldevelopment.

An alternative to maximal testing may include

the utilization of a sub-maximal load or repetitions to

fatigue test which has been used as a predictor of

maximal strength in athletes and non-athletes of

various demographics and training levels [5,8,11,14].The basic principle of repetitions to fatigue testing

utilizes a percentage of an athletes 1RM that is

within a range of 8-15 repetitions [5].

In addition, the utilization of an explosive

maneuver using a medicine ball throw as aperformance variable to estimate upper body strength

has not been documented. A variety of medicine ball

throws have previously been used to assess upper

body strength with mixed results. However, the

kneeling medicine ball throw (KMBT), which was

used in our study, has not been studied with

adolescent male athletes despite its use in Nike

Speed, Power, Agility, Reaction & Quickness

(SPARQ) testing in football combines for high schoolathletes [6,15,17]. Due to our interest in the

physiological development of adolescent male

football players and the utilization of strengthassessments that were safe and informative on the

subject population, this study was undertaken.

Therefore, the purpose of this investigation was to

determine the effectiveness of submaximal estimates

of strength in comparison to 1RM methods in


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evaluating upper body strength in male high school

football athletes.

METHODSParticipants

Sixty-two male high school football athletes ages

13-18 participated in this study with signed

permission and appropriate consent from theirparents and coaches. All participants had been

exposed to weight training in either a physical

education setting or through basic training for a

specific sport. All lifts were supervised by the

schools coaching staff. Initial testing occurred prior

to the off-season weight-training program, when the

athletes were not actively participating in a sport.

The study was approved by the Institutional Review

Board at the University of Georgia and Oconee

County Board of Education. All results were

discussed with the participants and parents orguardians after the analysis was completed.

Testing ProceduresThe principal investigator supervised all of the

lifting and performance tests in conjunction with the

school coaches and staff. Participants were instructed

on proper warm-up and lifting techniques prior to

testing and spotters were trained to assist participants

with lifting the bar off the rack and on failed

attempts. Strength assessments were randomized over

4 days to allow for muscle recovery and to avoid

potential problems due to test order.

1-Repetition Maximum Bench PressPrior to the 1-repetition maximum bench press, a

warm-up set of 5-10 repetitions was performed with a

standard barbell (20.45 kg). After a one-minute rest

period, 3-5 repetitions were completed with 4-9.0 kg

added to the bar. After a 2-minute rest period, an

estimated near maximal load was added, allowing the

participants to complete 2-3 repetitions with the

resistance. The athletes were then given a 2-4 minute

rest period between each lift and the load increased 4-

9.0 kg depending on the difficulty of the prior 1RM

attempt. Increase in the load and the length of therest period was determined by the athletes, and their

perceived readiness within the guidelines provided.

A complete repetition was defined as lowering the

bar to touch the chest followed by full extension of

the arms with no pause. If a subject failed tocomplete a repetition, the load was decreased by 2-

4.0 kg and another attempt was made after 2-4

minutes of rest [3].

Repetitions to Fatigue TestFor the repetitions to fatigue bench press,

participants performed as many repetitions aspossible using a load of 61.2 kg. The average

individual is able to complete 12-15 repetitions at 60-

70% of their maximal load (3,5). Thus, the load of

61.2 kg equals approximately 64% of the mean

1RMBP; while using 75% of the mean 1RMBP

would have eliminated 12-15 subjects from the

sample. The test required participants to touch the

barbell to their chest and then raise it to full extension

of the arms for a repetition to be counted. The test

continued until participants failed to complete a

repetition, used improper form, or hesitated for

greater than 2 seconds. The last properly executed

repetitions were recorded for the data analysis.

Kneeling Medicine Ball ThrowThe SPARQ training protocol [16] was followed

for the kneeling medicine ball throw. Participants

were instructed to kneel with back erect, both hands

directly overhead, and grasping a 2.7 kg medicine

ball on its sides. The participants feet were plantar

flexed with the top of the foot flat on the ground. Thethrow was performed by lowering the medicine ball

to the chest while sitting back with the hips towardsthe heels, and then using a chest pass to extend the

arms at an angle 30-40 degrees above the ground to

throw the ball for maximal distance. The participants

were allowed to fall forward after release, but their

knees were required to stay on the ground on top of

the start line. Participants were required to make the

throw with both hands while using one hand in a shot

put like throw resulted in a disqualification.

Participants were given a warm-up throw and 2minutes rest between attempts. The better of two

attempts was recorded to the nearest 1.0 in for the

data analysis.

Statistical AnalysesPearson product correlation coefficients,

coefficients of determination, regression analysis, and

scatter-plots were used in this study to determine the

relationship between 1RMBP and each of the upper

body strength assessments. Results were considered

statistically significant using the criteria of the r-sq.

having a p- value 0.05. Correlation coefficients, r

and coefficients of determination, r-sq. were used todetermine the strength of the relationship between the

variables. Linear regression analysis using the least

squares regression line was also used to formulate

prediction equations using the RTFBP and KMBT as

predictors for the variable 1 RMBP. Scatter-plotswere used to visualize the relationship of the

predictor variables with 1RMBP.

RESULTSThe data analysis showed a strong linear

relationship between 1RMBP and both the repetitionsto fatigue bench press (RTFBP; r = 0.907, predicted

1RMBP = 53.42 + (2.664) RTFBP, r2

= 82.3%, se of

predicted 1RMBP = 1.52 kg) and the kneeling


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Figure 1. Fitted line scatter plot of one repetition maximum benchpress (1RMBP) vs. repetitions to fatigue bench press (RTFBP).

Figure 2. Fitted line scatterplot of one repetition maximum benchpress (1RMBP) vs. kneeling medicine ball throw (KMBT).

Figure 3. Box plot of one repetition maximum bench press(1RMBP) by Age Group.

medicine ball throw (KMBT; r = 0.796, predicted

1RMBP = -14.36 + (0.1213) KMBT, r2 = 63.3%, SE

of predicted 1RMBP = 2.25 kg). The prediction

equation provides the predicted mean score for all

high school football athletes with similar scores on

the RTFBP and KMBT. The linear relationships

between the measures are evident in Figure 1

Figure 4. Box plot of repetitions to fatigue bench press (RTFBP)by Age Group.

Figure 5. Boxplot of repetitions to medicine ball throw (KMBT)

by age group.

Figure 6. Scatter-plot of one repetition maximum bench press

(1RMBP) vs. repetitions to fatigue bench press (RTFBP) coded by

age, 13-15 (r = 0.954) and 16-18 (r = 0.795).

(1RMBP vs. RTFBP) and Figure 2 (1RMBP vs.

KMBT).

Because of our interest in developmental

changes in strength, a comparison between the

younger participants (13-15 years) and the older

participants (16-18 years) was conducted to examine

differences in performance assessments. As shown


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(in the box plot Figures 3 5) the older male athletes

out performed the younger male athletes on all of the

assessments. For 1RMBP, 50% of the 13-15 year old

athletes had lower 1RMBP scores than all of the 16-

18 year olds. The median score for 13-15 year old

athletes was 77 kg. The median score for the 16-18

year old group was 102 kg, 15 kg higher than the

median for 13-15 year old athletes. The top 25% of

the 16-18 years old group scores were higher than the

maximal score of 125 kg for 13-15 year old athletes.

Although it is not surprising that 16-18 year old

athletes would be stronger and more physically

developed, it accentuates the differences between the

age groups, a point that high school coaches should

clearly understand. For the RTFBP, the 16-18 year

olds still similarly out performed the 13-15 year olds

but to a slightly lesser degree for the upper 25% of

the 16-18 year olds there is more overlap of theupper 25% of scores for the 13-15 year olds with the

16-18 upper 25%. Although the 16-18 year olds are

out performing the 13-15 years with respect to1RMBP and RTFBP (Figure 6), the 13-15 age

groups 1RMBP demonstrates a stronger correlation

with RTFBP (r = 0.954) than the 16-18 age groups

1RMBP (r = 0.795). It appears that the RTFBP (r =

0.954) is a stronger predictor of 1RMBP with the

younger and less developed male athletes.

DISCUSSIONBecause strength training has become such an

integral component of high school athletics it is

important to effectively determine the baseline

measures of strength that are required to facilitate a

safe and efficient strength and conditioning program.

If strength and conditioning coaches are concerned

with the frequency of maximal testing or lack of

appropriate expertise for such testing, they can still

accurately estimate upper body strength with the

RTFBP (r = 0.907) and the KMBT (r = 0.796). This

provides the teacher/coach with viable alternative

methods of assessment that may be more specific to

their program goals and the maturity of the athletesunder their supervision, especially those with limited

weight training experience.

From an absolute strength point of view, it is

evident that the higher performance boys were in the

(16-18) age group. Performance in this context was

attributed to increased physical maturity andincreased experience with the strength-training

program. From our viewpoint, it was evident that the

stronger correlation present between 1RMBP and

RTFBP for the 13-15 age group (r = 0.954) compared

to that of the 16-18 age group (r = 0.795) was anoteworthy finding. This correlation indicates an

exceptionally strong relationship between the tests

that suggests an alternative way to predict 1RMBP at

a time when the body is maturing for younger

athletes. In this context, the RTFBP may be more

appropriate for assessing strength in a group who has

less physical maturity and weight training experience

as compared to the 16-18 age groups.

The current literature clearly describes the

effectiveness of using RTFBP to predict 1RM

strength in a variety of populations [5,8,11,14]. Our

findings expand the knowledge base by showing that

the accuracy of prediction of 1RMBP from RTFBP

varies by age group. Furthermore, we have

illuminated an additional and previously untested

predictor of 1RMBP, the KMBT. The KMBT is a

performance measure that emphasizes the explosive

component needed for football and is a component

that may prove useful for coaches. In addition, the

KMBT used in our investigation was the SPARQ

training protocol that is commonly used for testing inhigh school combines. Although this procedure has

not been fully investigated in comparison to other

procedures to evaluate maximal strength [4,6,15,17]it appears useful for coaches as an alternative

measure of upper body strength. Because it is also

used extensively in high school combines, it is

appropriate for coaches to include this procedure on

their program. In addition, it has some adaptability

for other sports and it is recommended that the

procedure be studied further and expanded for all

sports as a performance consideration.

The primary aim in this study was to investigate

alternative methods for determining the upper body

strength of high school football players, especially

for athletes at various biological stages. The results of

this study provide evidence for a safer and moreefficient means of assessing upper body strength in a

high school setting. The investigation of RTFBP and

KMBT provided strong correlations of upper body

strength. Additionally, the KMBT does not require

expensive equipment and there is no need for other

athletes to be used as spotters. Furthermore, the

technique used in the KMBT is a multiple jointmovement, which is more specific to the explosive

power movements used in football, in comparison to

the traditional bench press. In order to eliminate the

risk of injury it may be helpful to limit the use of

1RM testing and use alternative methods supported

by our study to evaluate the progress of athletes anddetermine program effectiveness. Assessment and

training should complement each other as athletes

begin participation at an early age and continue to

develop physically.

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AUTHOR CORRESPONDENCE:

Michael HorvatTelephone: (706) 542-4455

E-Mail: [email protected]

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