Isokinetic strength and body composition of high school wrestlers across age.Med. Sci. Sports Exerc, Vol. 21, No. 1, pp. 105-109, 1989. The purpose of this study was to determine the changes in body composition as well as absolute and relative isokinetic forearm and leg strength of high school wrestlers across age. One hundred ninety-five wrestlers (X age ± SD=16.36 ± 1.12 yr) volunteered to be measured for strength using a Cybex II dynamometer at 30, 180, and 300° ·s-1. In addition, underwater weighing was used to determine body composition characteristics. The subjects were divided into four age groups: group 1 (Gl)=14.17-15.00 yr(N=20); group 2 (G2)=15.01-16.00 yr (N=60); group 3 (G3)=16.01-17.00 yr (N=52); and group 4 (G4)=17.01-18.50 yr (N=63). One-way ANOVA or ANCOVA with Tukey post hoc comparisons indicated significant (P<0.05) changes across age for height, body weight, and fat-free weight, as well as absolute and relative forearm and leg strength. The results of this study indicated that, while a large portion of the improvements in strength across age were associated with increases in lean tissue, there was an additional “age effect” which could not be accounted for by changes in fat-free weight. Although the mechanism responsible for the “age effect” is unclear, it is possible that neural development contributed to the strength increases across age.