AGE AND GENDER COMPARISONS OF MUSCLE STRENGTH IN 654 WOMEN AND MEN AGED 20-93 YR

To assess age and gender differences in muscle strength, isometric, co ncentric (Con), and eccentric (Ecc) peak torque was measured in the kn ee extensors at a slow (0.52 rad/s) and fast (3.14 rad/s) velocity in 654 subjects (346 men and 308 women, aged 20-93 yr) from the Baltimore Longitudinal Study of Aging. Regression analysis revealed significant (P < 0.001) age-related reductions in Con and Ecc peak torque for men and women at both velocities, but no differences were observed betwee n the gender groups or velocities. Age explained losses in Con better than Ecc peak torque, accounting for 30% (Con) vs. 19% (Ecc) of the va riance in men and 28% (Con) vs. 11% (Ecc) in women. To assess age and gender differences in the ability to store and utilize elastic energy, the stretch-shortening cycle was determined in a subset of subjects ( it = 47). The older women (mean age = 70 yr) showed a significantly gr eater enhancement in the stretch-shortening cycle, compared with men o f similar age (P < 0.01) and compared with younger men and women (each P < 0.05). Both men and women showed significant declines in muscle q uality for Con peak torque (P < 0.01), but no gender differences were observed. Only the men showed a significant decline in muscle quality (P < 0.001) for Ecc peak: torque. Thus both men and women experience a ge-related losses in isometric, Con, and Ecc knee extensor peak torque ; however, age accounted for less of the variance in Ecc peak torque i n women, and women tend to better preserve muscle quality with age for Ecc peak torque. In addition, older women have an enhanced capacity t o store and utilize elastic energy compared with similarly aged men as well as with younger women and men.