When performing skillful movement muscular and nonmuscular forces act in concert to produce a resultant force that complies with the goal of the task. Nonmuscular forces are directly dependent on the anthropometry of the performer. The purpose of this study was to determine the effect of age-related changes in relative anthropometric characteristics between 5 and 10 years of age on muscular power production during pedaling. A secondary purpose was to determine the dependence of this effect on movement speed. A torque-driven model of two-legged pedaling was used to track experimental kinematics and forces obtained from 6 experienced adult cyclists pedaling at 60 and 120 rpm. Relative anthropometric characteristics were modified to simulate pedaling for children of 5, 7.5, and 10 years of age. Analyses of variance revealed that age-related differences in anthropometry did not affect the muscular contribution to crank power (p > .05), while they had a significant effect on the muscular contribution to limb power (p < .05). Adjustments by the proximal muscle groups (muscles spanning the hip and knee joints) were necessary to account for anthropometry-driven changes in nonmuscular power. These effects were independent of movement speed. Our results provide researchers with useful information to interpret age-related differences in muscular power production more accurately.
Korff is with the Centre for Sports Medicine and Human Performance, Brunel University, Uxbridge UB8 3PH, UK. Jensen is with the Dept. of Kinesiology and Health Education, University of Texas, Austin, TX 78712.