Effects of moderate-velocity strength training on peak muscle power and movement velocity: do women respond differently than men?

The effects of a 10-wk unilateral knee extension strength training (ST) program on peak power (PP) and peak movement velocity (PV), at given absolute ( force load) and relative ( same % of 1 repetition maximum) resistances ( loads), were examined in 30 older men [ 64 yr ( 7 SD)] and 32 older women [ 62 yr ( 6 SD)]. PP increased significantly in both men and women at the same absolute ( P < 0.001) and relative loads ( P < 0.01) with ST. Men had a significantly greater increase in relative PP than women with ST at 60% ( P < 0.01) and 70% ( P < 0.001) of 1 repetition maximum when covarying for baseline differences and age. However, when each subject was tested at the same absolute load and when PP was normalized for the muscle volume of the trained knee extensors (i.e., absolute muscle power quality), women increased by 9% ( P < 0.05), whereas men did not change. Both men and women increased their absolute PV ( P < 0.001) but decreased their relative PV significantly with ST ( P < 0.05). However, when baseline values and age were covaried, women had significantly less of a decrease in relative PV quality with ST than men ( P < 0.01), although the difference was small. These normalized data suggest that ST-induced increases in PP depend on muscular hypertrophy in men, but not in women, providing further support for the hypothesis developed from our previous report (Ivey FM, Tracy BL, Lemmer JT, NessAiver M, Metter EJ, Fozard JL and Hurley BF. J Gerontol A Biol Sci Med Sci 55: B152 - B157, 2000) that improvements in muscle function with ST result from nonmuscle mass adaptations to a greater extent in women than men.