Concentric versus eccentric strength of the quadriceps femoris in elderly and young women

Decreased isometric and concentric strength in the aging has been associated with muscle atrophy, deterioration of mechanical properties, and motor unit loss. However, recent evidence suggests a preservation of eccentric strength. The purpose of this study, therefore, was to examine isokinetic concentric and eccentric quadriceps strength between elderly and young women. Nine younger (24.1 +/- 1.64) and 7 older women (67.3 +/- 7.07) were tested at angular velocities of 60, 120, and 300 degrees .s(-1) for concentric and 60 and 120 degrees .s(-1) for eccentric peak torque (PT) on a Biodex II (Biodex Corporation, Shirley, NY) isokinetic dynamometer. Absolute PT was significantly greater in young women (p < 0.05). Relative strength, although not statistically different, revealed a trend as older women tended to generate more eccentric PT than did younger women. As a percentage of the young, the older group's average concentric decline was 33%, whereas eccentric loss was 25%. When normalized to 60<degrees>.s(-1), the older group's eccentric strength was an average of 9.5% more than that of the younger subjects, although not statistically significant.