Effects of aging on maximal and rapid velocity capacities of the leg extensors

• Velocity capacities of the leg extensors are reduced in old men.
• Rate of velocity production may be impaired more than maximal velocity in old age.
• Rapid velocity measures may be useful to identify age-related declines in function.

Declines in muscle strength and power are commonly reported as a consequence of aging; however, few studies have investigated the influence of aging on maximal and rapid velocity characteristics. The objective of this study was to examine the effects of aging on maximal and rapid velocity characteristics of the leg extensor muscles. Twenty-three young (age = 25 ± 3 yrs) and twenty-one old (72 ± 4 yrs) men performed three leg extension maximal voluntary contractions (MVCs) at 240°·s− 1 and at maximum unloaded velocity (Vmax). Vmax was calculated as the highest velocity attained during the unloaded MVC and RVD was the linear slope of the velocity–time curve for the 240 deg·s− 1 (RVD240) and maximum unloaded velocity (RVD–Vmax) contractions. The old men exhibited lower (P < 0.01) Vmax (10.1%), RVD240 (37.2%), and RVD–Vmax (26.7%) compared to the young men. These lower velocity characteristics for the old men may contribute to the increased functional limitations often observed in older adults. Interestingly, the greater age-related declines observed for RVD240 and RVD–Vmax compared to Vmax perhaps suggest an enhanced age-related impairment in the ability of the older adults' muscle to generate velocity rapidly versus the ability to generate maximal velocity. Such findings highlight the importance of time-dependent velocity measures when assessing the effects of aging on rapid velocity capacities.