Female Age-Related Differences in Biomechanics and Muscle Activity During Descents on the Outstretched Arms.

The purposes of this study were to examine female age differences in: (1) upper extremity (UE) and trunk muscle activity, elbow joint moment, loading force, and UE energy absorption during a controlled forward body descent; and (2) UE muscle strength. Twenty young (mean 24.8 ± 3.4 years) and 20 older (68.4 ± 5.7 years) women were assessed via dynamometry for isometric, concentric, and eccentric UE strength and performed forward descents on force plates at three body lean angles (60°, 45°, and 30° from horizontal). Significant differences (p < .05) were found for muscle strength, biomechanics, and muscle activity. Concentric UE strength averaged 15% lower in older women. At 30° body lean, older women absorbed less energy. Older women had greater biceps brachii activation and less external oblique activation at all body lean angles. Age differences in muscle strength, activation, and energy absorption may contribute to fall-related injury risk.