Moderate Velocity Strength Training Increases Peak Muscle Power Quality in Older Women

Abstract

Previous reports on the effects of strength training (ST) on muscle power did not report how the training affected power per unit of the muscle involvement (muscle power quality, MPQ), or peak movement velocity (PV). The expression of peak power normalized for muscle volume allows better understanding of potential mechanisms for training-induced adaptations. PURPOSE To evaluate the effects of ST on peak muscle power (PP) and PV per unit of muscle at given absolute and relative (same % of 1 RM) resistances in older adults. PURPOSE To evaluate the effects of ST on peak muscle power (PP) and PV per unit of muscle at given absolute and relative (same % of 1 RM) resistances in older adults. METHODS Sixty-two relatively healthy, previously sedentary older adults (23 older men, 65 ± 1 yr and 39 older women, 66 ± 1 yr) were studied before and after a 10 wk unilateral knee extension ST program. To quantify quadriceps muscle volume (MV), computed tomography (CT) imaging of the trained and untrained thighs was performed. Determination of peak knee extensor power was performed on a customized pneumatic resistance knee extension machine. Velocity and power data were filtered using a 10 Hz, low-pass Butterworth filter to remove sensor noise and obtain peak estimates. RESULTS As a result of the ST program, peak power increased significantly in both men and women at the same absolute (APP; P < 0.001) and relative loads (RPP; P < 0.05). Men had significantly greater increases in APP and RPP than women with ST when covarying for baseline differences (both P < 0.001). However, when each subject was tested at the same absolute load and when peak power was normalized for the muscle volume of the trained knee extensors (i.e., absolute MPQ), women increased their MPQ (P < 0.05), but men did not. Both men and women increased their absolute PV (P < 0.001), but decreased their relative PV significantly with ST (P < 0.01). CONCLUSIONS These data indicate that a moderate-velocity ST program increases muscle power quality in women, but not in men, suggesting that in contrast to men, women increase peak power with ST through adaptations other than muscular hypertrophy. Supported by NIH Grants R01 AG-4-2148 and AG-1620501 and NIH training grant T32AG00219.