Ratio strength measurements are used in an attempt to equate maximal strength values among individuals of different size. Allometric scaling has been proposed as a more equitable way of comparing groups for muscular strength.
PURPOSE: To evaluate the use of allometric scaling techniques for assessing the differences in 1RM bench press among NCAA Division II and III football players.
METHODS: College football players from 3 Division II schools (n = 298, age = 20.4 ± 1.4 y, height = 182.2 ± 7.4 cm, weight = 103.7 ± 18.6 kg) and 4 Division III schools (n = 130, age = 19.9 ± 1.2 y, height = 182.4 ± 6.4 cm, weight = 102.4 ± 19.5 kg) were assessed for 1RM bench press during off-season conditioning. Bench press was evaluated using a ratio standard and allometrically scaled for body mass (BP/BMk). Players were divided into thirds based on body mass (BM; Light = ≤91.3 kg, Medium = 91.4-110.3 kg, Heavy = ≥110.3 kg).
RESULTS: There was no significant difference in age, height, weight, 1RM bench press (138.9 ± 18.7 vs 136.8 ± 20.2 kg, respectively) between divisions and hence the 2 samples were combined for analysis. Log-transformed linear regression indicated neither of the coefficients for school nor school x lnBM were significant (p>0.08), indicating that the common exponent principle was acceptable. The common exponent for scaling BP by BM was 0.346 (95% CI = 0.277 to 0.415). Since the CI for the common exponent for BM did not include the theoretical 0.67 value, BP was scaled also by that coefficient. With ratio scaling (BP/BM), light (1.56 ± 0.21), medium (1.35 ± 0.14), and heavy (1.19 ± 0.17) groups were all significantly different and scaled values were significantly correlated with body mass (r = -0.67). When allometrically scaled by the theoretical exponent, all 3 groups were significantly different (6.68 ± 0.89, 6.19 ± 0.65, and 5.84 ± 0.79, respectively) and again significantly correlated with body mass (r = -0.41). When allometrically scaled by the new exponent, none of the 3 groups was significantly different (28.1 ± 3.7, 27.6 ± 2.9, and 27.9 ± 3.7, respectively), and the correlation with BM (r = 0.00) indicated that the procedure adequately accounted for removing the effect of BM.
CONCLUSION: The allometric exponent for 1RM bench press in college football players may be significantly lower than the theoretical values for scaling by body size.