The purpose of this investigation was to examine the covariate influence of estimated muscle mass on age-related increases in isokinetic peak torque for flexion and extension of the forearm and leg in high school wrestlers. One hundred thirteen high school wrestlers volunteered to be measured for strength at 30, 180, and 300°·s⁻¹. Underwater weighing was performed to determine body composition characteristics, and the anthropometric equation of Martin et al. (10) was used to estimate total skeletal muscle mass (MM). There were significant (p < .05) relationships (r = .19 to .37) for age versus peak torque covaried independently for fat-free weight (FFW) and MM for forearm flexion at 30, 180, and 300°·s⁻¹; forearm extension at 180 and 300°·s⁻¹; and leg extension at 30, 180 and 300°·s⁻¹. The results of this study indicated that there was no increase across age in MM per unit of FFW, and the age-related increases in peak torque in high school wrestlers could not be fully accounted for by changes in MM.