The Relationship between Common Anthropometric Measurements and Isokinetic Strength in Men’s College Soccer Team 

Shawn D. Felton, Paul A. Burkett, Mitchell L. Cordova, FACSM Sports Medicine Research Laboratory, Department of Rehabilitation Sciences, Florida Gulf Coast University, Fort Myers, FL USA

Abstract

Introduction

Methods

Results

Summary

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This study examined the relationship between common anthropometric variables and average and peak torque production of the knee extensors measured by isokinetic testing at three angular velocities in members of a men’s collegiate soccer team. In a previous study involving male college students who were not competitive athletes, knee isokinetic strength was reported to be significantly negatively correlated with the percentage of body fat and positively correlated with fat free mass. 6 The subjects tested in the current study were members of a NCAA Division I men’s soccer team. This group went on to win the conference regular season championship, suggesting that the subjects were highly skilled athletes in their sport. A previous study found body mass and percentage of body fat were among variables that explained the variance in isokinetic strength for both knee extensors and flexors in young male competitive soccer players aged 10 to 17 years. 4 Fat free mass has been reported to be related to anaerobic power in elite young male wrestlers. 7 This study supported the percent body fat and lean body mass are predictors of knee isokinetic strength in male college aged students who are highly skilled athletes in their sport. In conclusion, the results suggest that lean body mass and body fat percentage may be predictors of isokinetic knee muscle strength at angular velocities of 180°/sec and 300°/sec in highly skilled men’s intercollegiate soccer athletes.

Previous research has demonstrated the efficacy and reliability of isokinetic testing in the evaluation of muscular performance including lower extremity strength.1,2 Research has also suggested that isokinetic force production is associated with sports related performance in young male athletes. For example, It has been suggested that isokinetic force production in the legs could be used to evaluate and predict on-ice skating speed and skating power in men’s intercollegiate ice hockey players. 3 Prior research has also investigated the relationship between strength output and anthropometric measurements such as BMI and body fat percentage. The conclusions concerning these relationships have been inconsistent. In young male competitive soccer players ages 10 to 17 years, certain anthropometric measures were related to isokinetic strength for both knee extensors and flexors, with 73-93% of the variance explained by using combinations of age, body mass, percentage of body fat, and hours training per week. 4 Body mass was the main independent variable that explained variance, which was in agreement with a previous study. 5 In college students who were not competitive athletes, knee isokinetic strength was reported to be significantly negatively correlated with the percentage of body fat and positively correlated with fat free mass. 6 Fat free mass, but not percent body fat, was reported to be related to anaerobic power in male elite young wrestlers. 7 Percent body fat was found to be related to on-ice skating speed and skating power in men’s intercollegiate ice hockey players. 3 In contrast, lean body mass, percentage of fat tissue, and percentage of muscle tissue were reported to be poor predictors of sprinting performance in well-conditioned males. 8,9 The inconsistent findings concerning the relationship between strength output and anthropometric measurements such as BMI and body fat percentage suggest that the strength of the relationship may vary depending on the population studied. The purpose of this study was to investigate the relationship between common anthropometric variables and average torque production of the knee extensors measured by isokinetic testing at three angular velocities in a men’s collegiate soccer team.

The use of Isokinetic testing has been widely utilized by clinicians to evaluate lower extremity strength. Prior research has demonstrated its efficacy and reliability in clinical evaluation of muscular performance. Prior research has also investigated the relationship of anthropometric measurements such as BMI and body fat percentage in determining strength output with the non-athletic populations. However, in a prior study conducted by the authors no correlation between anthropometric measurements and men’s basketball athletes’ isokinetic torque were found. PURPOSE: To investigate the relationship between the use of common anthropometric measurements and average torque production of the knee extensors measured by isokinetic testing at three angular velocities in a college men’s soccer team. METHODS: Fifteen healthy male college soccer athletes aged between 18-22 participated. Athletes were screened on standard anthropometric measurements that included: height, weight, and common skinfold measures. The measurements allowed for calculation of BMI, LBMI, lean mass, and body fat percentage. The athletes’ isokinetic strength of extension was measured through three angular velocities of 60, 180 and 300 degrees/sec. RESULTS: The relationship between LBMI, body fat, lean mass and average peak torques at three angular velocities were analyzed through hierarchal linear regression and produced significant relationship for 180°/sec (F (3, 11) =6.7, P =.008) and 300 °/sec (F (3, 11) = 11.349 P = .001). Further analysis utilizing Pearson’s bivariate correlation found significant inverse correlation between body fat and peak torque produced at 180 and 300 degrees/sec range from (-.547 to -.692 P < 0.05) and significant positive correlation between lean mass and average peak torque at 180° and 300 degrees/ sec range from (.646 - .790 p<0.05). CONCLUSION: The results supported prior research indicating specific anthropometric measurements and isokinetic torque production are related. In this investigation, significant relationships between the anthropometric measurements: % body fat and lean mass existed between and the muscle torque production at two angular velocities. The results suggested the uses of anthropometric measurements in male soccer athletes are significantly correlated and could be utilized for prediction of annular velocity.

Subjects: Fifteen healthy male collegiate soccer athletes (mean: age 19.80, height 178.16cm ± 8.23 cm, mass 74.50kg ± 6.67 kg) volunteered for this study. The anthropometric measurements of interest and isokinetic strength measures were collected during routine pre-season athlete evaluations. No informed consent was needed because all athletes sign a medical release document releasing medical professionals to examine and share information while protecting their specific anonymity. This study was approved by the University institutional review board. Methods: Anthropometric measures were obtained including height, mass, and skinfold thickness. Skinfold measures were taken at three sites: pectoral, abdominal, and thigh. The sum of the skinfolds was used to estimate percent body fat and lean body mass (LBM) using equations specific for gender and age (2). Body mass was measured to the nearest 0.1 kg with participants clothed in shorts and tee shirts using digital scales (Healthometer). Height was measured to the nearest 0.1 cm with participants barefoot using a wall-mounted stadiometer (Heightronics, QuickMedical, Issaquah, USA). Body mass index (BMI, kg/m2) and lean body mass index (LBMI, kg/m2) were calculated. The athletes participated in a lower extremity warm-up and then Isokinetic strength of knee flexion and extension was measured through three angular velocities of 60°, 180°, and 300°/sec. Figure 1. Statistical Analysis: •  Descriptive Statistics Table 1 were calculated for all anthropometric

measurements and average peak torques of the bi-lateral thigh musculature at 60°, 180°, & 300°/sec.

•  Hierarchical linear regression utilized for prediction due to the hierarchical nature of the data set.

Mean Std. Deviation N Height (cm)   178.16   8.23   15  Mass (kg)   74.50   6.67   15  Age   19.80   1.57   15  % Body Fat   8.04   2.52   15  BMI   23.55   1.77   15  Lean Mass   151.05   14.04   15  LBMI   21.63   1.46   15  Avg Peak Torque 60 -R   148.06   29.80   15  

60 Peak Torque - R   158.65   30.07   15  

Avg Peak Torque 180-R   93.88   14.82   15  

180 Peak Torque - R   107.50   15.23   15  

Avg Peak Torque -300 R   64.55   11.83   15  

300 Peak Torque - R   74.41   15.00   15  

Avg Peak Torque 60 -L   141.60   30.93   15  

60 Peak Torque - L   154.30   31.44   15  

Avg Peak Torque 180-L   95.43   14.32   15  

180 Peak Torque - L   107.27   16.28   15  

Avg Peak Torque -300 L   69.27   9.40   15  

300 Peak Torque - L   80.13   11.37   15  

Height Weight Age Body Fat

BMI Lean Mass

LBMI 60 Avg. Peak

Torque R

60 Peak Torque

R

180 Avg. Peak

Torque R

180 Peak

Torque R

300 Avg. Peak

Torque R

300 Peak

Torque R

60 Avg. Peak

Torque L

60 Peak Torque -

L

180 Avg. Peak

Torque - L

180 Peak

Torque - L

300 Avg. Peak

Torque - L

300 Peak

Torque - L

Height 1 Weight .666** 1

Age -.518* -.166 1 Body Fat -.379 -.002 .091 1

BMI -.454 .360 .464 .463 1 ** sig at 0.01 Lean Mass .744** .954** -.175 -.301 .210 1 * sig at 0.05

LBMI -.350 .403 .492 .089 .923** .364 1 60 Avg Peak Torque

R .448 .422 -.257 -.415 -.061 .526* .118 1

60 Peak Torque R .437 .420 -.269 -.349 -.047 .505 .104 .989** 1 180 Avg Peak Torque

R .541* .533* .103 -.599* -.036 .687** .224 .750** .728** 1

180 Peak Torque R .653** .607* -.006 -.579* -.083 .753** .161 .732** .719** .956** 1

300 Avg. Peak Torque R

.540* .652** .154 -.533* .101 .790** .357 .434 .392 .778** .810** 1

300 Peak Torque - R .613* .647** -.196 -.248 .001 .689** .108 .356 .351 .575* .651** .707** 1

60 Avg Peak Torque L

.474 .606* -.022 -.221 .099 .646** .220 .619* .585* .678** .661** .724** .617* 1

60 Peak Torque - L .553* .703** -.051 -.235 .121 .743** .250 .678** .646** .729** .707** .715** .604* .973** 1 180 Avg Peak Torque

L .563* .513 -.061 -.547* -.104 .650** .123 .499 .476 .837** .802** .806** .651** .746** .721** 1

180 Peak Torque L .653** .636* -.099 -.414 -.068 .729** .104 .497 .483 .804** .809** .801** .736** .819** .800** .962** 1 300 Avg Peak Torque

L .541* .442 -.030 -.692** -.154 .625* .125 .558* .507 .839** .786** .791** .544* .655** .646** .918** .859** 1

300 Peak Torque L .585* .442 .027 -.559* -.042 .721** .196 .561* .521* .871** .827** .838** .642** .746** .749** .937** .917** .972** 1

Table. 2 Pearson Correlations Between Anthropometric Measurements and Quadriceps Isokinetic Torque Production Table. 1 Means and SD of Observed Variables

Discussion

•  The results of this study demonstrated a significant relationship between body fat percentage and the torque production of the knee extensors at angular velocities of 180 °/sec and 300°/sec. Significant relationships were also found between lean mass and the torques produced at angular velocities of °/sec and 300°/sec.

•  The results further suggest lean body mass and body fat percentage may be predictors of isokinetic knee muscle strength at angular velocities of 180°/sec and 300 °/sec in highly skilled men’s intercollegiate soccer athletes.

Figure 1. Isokinetic Knee Testing

•  Pearson Bivariate Correlations presented in Table.2

•  Hierarchical linear regression analysis was used to test if anthropometric measurements predicted isokinetic average peak torque at 180°/sec. The results of the regression indicated the three predictors (Lean Mass, LBMI, & % Body Fat explained 64.5% of the variance (R2 = .65, F(3, 11) = 6.67, P = .008. Table 3. It was found that Lean Mass significantly predicted 180°/sec average peak torque (β=.55, P =.027), as did % Body Fat (β=-2.625, P =.041)

•  Hierarchical linear regression analysis was used to test if anthropometric measurements predicted isokinetic average peak torque at 300°/sec. The results of the regression indicated the three predictors (Lean Mass, LBMI, & % Body Fat explained 75.6 % of the variance (R2 = .75, F(3, 11) = 11.349, P = .001. Table 4. It was found that Lean Mass significantly predicted 360°/sec average peak torque (β=.52, P =.004), as did % Body Fat (β=-1.796, P =.036)

•  A significant inverse correlation between body fat and peak torque produced at 180° and 300 °/sec ranged from (-.547 to -.692 P < 0.05) and significant positive correlation between lean mass and average peak torque at 180° and 300°/sec ranged from (.646 - .790 P<0.05)

•  The level of significance was established at P <0.05.

Model Sum of Sqaures

df Mean Square

F Sig.

1 Regression 1222.78 1 122.78 21.552 .000 Residual 737.56 13 56.74

Total 1960.34 14 2 Regression 1233.52 2 616.76 10.18 .003

Residual 726.82 12 60.57 Total 1960.34 14

3 Regression 1481.64 3 43.52 .001 Residual 478.69 11

Total 1960.34

a.  Dependent Variable: Avg. Peak Torque 300

b.  Predictors: (Constant), Lean Mass

c.  Predictors: (Constant), Lean Mass, LBMI

d.  Predictors: (Constant): Lean Mass, LBMI, % Body Fat

Table. 4 ANOVA for Predictors of Avg. Peak Torque at 300°/sec

Table. 3 ANOVA for Predictors of Avg. Peak Torque at 180°/sec

Model Sum of Sqaures

df Mean Square

F Sig.

1 Regression 1450.07 1 1450.07 11.61 .005 Residual 1623.09 13 124.85

Total 3073.16 14 2 Regression 1452.58 2 726.29 5.38 .022

Residual 1620.59 12 135.05 Total 3073.16 14

3 Regression 1982.56 3 660.85 6.67 .008 Residual 1090 11 99.15

Total 3073.16 14

a.  Dependent Variable: Avg. Peak Torque 180

b.  Predictors: (Constant), Lean Mass

c.  Predictors: (Constant), Lean Mass, LBMI

d.  Predictors: (Constant): Lean Mass, LBMI, % Body Fat