Maximal power across the lifespan

Background. Previous investigators have reported that maximal power increas es during growth and decreases with aging. These age-related differences ha ve been reported to persist even when power is scaled to body mass or muscl e size. We hypothesized that age-related differences in maximal power were primarily related to differences in muscle size and fiber-type distribution rather than to age per se. Methods. Maximum cycling power (P-max) and optimal pedaling rate (V-opt, a surrogate measure for muscle fiber type) were determined for 195 boys and m en, 8-70 years of age, by using inertial load cycle ergometry. Anthropometr ic dimensions were used to estimate lean thigh volume (LTVest) of all subje cts, and magnetic resonance imagery was used to determine thigh and hip mus cle volume (MRIvol) for 24 subjects. Results. P-max was highly related to the product of LTVest and V-opt (LTVes t X V-opt; r(2) = .83). Multiple regression revealed that P-max was signifi cantly related to both LTVest X V-opt, and age (R-2 = .84). Power scaled by LTVest X V-opt was stable during growth and exhibited a small but signific ant decrease with aging. MRIvol was highly correlated with LTVest and the r atio of LTVest to MRIvol was independent of age. Conclusions. These results suggest that muscle volume and optimal pedaling rate are the main determinants of maximal power across the lifespan and tha t the contractile properties of muscle are developed early in childhood and remain nearly intact late into the lifespan.