It is unclear whether strength training (ST) or power training (PT) is the more effective intervention at improving muscle strength and power and physical function in older adults. The authors compared the effects of lower extremity PT with those of ST on muscle strength and power in 45 older adults (74.8 ± 5.7 yr) with self-reported difficulty in common daily activities. Participants were randomized to 1 of 3 treatment groups: PT, ST, or wait-list control. PT and ST trained 3 times/wk for 12 wk using knee-extension (KE) and leg-press (LP) machines at ~70% of 1-repetition maximum (1RM). For PT, the concentric phase of the KE and LP was completed “as fast as possible,” whereas for ST the concentric phase was 2–3 s. Both PT and ST paused briefly at the midpoint of the movement and completed the eccentric phase of the movement in 2–3 s. PT and ST groups showed significant improvements in KE and LP 1RM compared with the control group. Maximum KE and LP power increased approximately twofold in PT compared with ST. At 12 wk, compared with control, maximum KE and LP power were significantly increased for the PT group but not for the ST group. In older adults with compromised function, PT leads to similar increases in strength and larger increases in power than ST.
Anthony P. Marsh, Michael E. Miller, W. Jack Rejeski, Stacy L. Hutton, and Stephen B. Kritchevsky
Anthony P. Marsh, W. Jack Rejeski, Stacy L. Hutton, Cristal L. Brown, Edward Ip, and Jack M. Guralnik
Lateral mobility is integral to many activities of daily living involving transfer from one position to another. The objective of this study was to develop and evaluate the validity and test–retest reliability of a lateral-mobility (LATMOB) task for older adults. Measurements of lateral mobility, balance, and strength and self-reported and performance-based physical functioning were obtained in 63 women and 77 men ≥50 years of age. The LATMOB task was significantly correlated with age, knee-extensor strength, grip strength, functional reach, and one-leg-stance time. Test–retest reliability of the task was excellent. The LATMOB task was highly correlated with the car task. Balance was significantly correlated with time to get into and out of a car and performance on the LATMOB task. The LATMOB task was significantly correlated with the Short Physical Performance Battery score. The LATMOB task is valid and reliable, but additional work is needed to assess its sensitivity to change and predictive validity.