Eccentric knee strength of elderly females

This study compared the strength of the knee extension and flexion muscles in groups of young and elderly women under two conditions: eccentric exercise in which the muscles were lengthened while subjects tried to resist an external force, versus concentric contractions in which the muscles shortened. Twenty-six females, aged 20 to 29 (Mean 25 +/- 3 SD), and 26 elderly women, aged 66 to 89 (Mean 73 +/- 6 SD), were tested at two angular velocities of movement, 45 degrees and 90 degrees/s, on a KinCom isokinetic dynamometer. Elderly women had significantly lower peak and average torque values in all comparisons with the young female group (25 to 54% lower, p less than .01). However, differences between the age groups were consistently smaller for the eccentric type of muscle action than the concentric, in both knee extensors and flexors.