Abstract
Aging is associated with greater declines in muscular power compared with strength. These age-related declines in strength can be partially explained by the loss of muscle mass. However, the effect of muscle mass on the declines in muscular power is not well understood. PURPOSE: To determine the effect of leg muscle mass on knee extension peak force and average power in old adults. METHODS: The muscle mass of 29 old adults (7 men and 22 women, age: 70.7 ± 6.5 years; height:166.2 ± 10.1 cm, body mass: 69.1 ± 13.6 kg, mean ± SD) was assessed with dual energy x-ray absorptiometry. Knee extension strength (peak force) and average power (total work/time) was assessed during five concentric and eccentric velocities (10, 60, 90, 120, 180 degrees/s) using an isokinetic dynamometer. The knee range of motion was 80 degrees and the highest value produced from three trials was used for analysis. RESULTS: Age did not influence peak force or power production. Women produced greater normalized (to leg muscle mass) peak force, whereas men produced greater normalized (to leg muscle mass) peak force, whereas men produced greater power (absolute and normalized). Greater peak force and power were associated with larger leg muscle mass. The association of muscle mass with peak force was greter during the slowest concentric velocity and three fastest eccentric velocities. The association of muscle mass with power, however, was significantly associated only with velocities faster than 90 degrees/s. These associations were stronger during eccentric contractions. CONCLUSION: The larger the leg muscle mass in old adults the greater the power production during eccentric and fast contractions. This specific effect of muscle mass on power production during fast and eccentric contractions may be due to better maintenance of large motor units.
Published Version
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