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

1 Department of Kinesiology, College of Health and Human Performance University of Maryland, College Park; 2 Division of Gerontology and GRECC, School of Medicine, University of Maryland, Baltimore; 3 United States Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet and Human Performance Laboratory, Beltsville; and 4 Department of Aerospace Engineering, Space Systems Laboratory, University of Maryland, College Park, Maryland Submitted 25 October 2004 ; accepted in final form 29 June 2005 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. resistance training; aging Address for reprint requests and other correspondence: B. Hurley, Dept. of Kinesiology, Univ. of Maryland, College Park, MD 20742 (e-mail: benhur{at}umd.edu )