Age differences in upper extremity joint moments and strength during a laboratory-based tether-release forward fall arrest in older women.

Abstract

Age-related declines in upper extremity muscle strength may affect an older adult's ability to land and control a simulated forward fall impact. The role of individual upper extremity joints during a forward fall impact has not been examined. The purpose was to evaluate the age differences in upper extremity joint moment contributions during a simulated forward fall and upper extremity muscle strength in older women. A convenience sample of 68 older women (70 (8) yrs) performed three trials of a simulated forward fall. Percentage joint moments of the upper extremity were recorded. Upper extremity muscle strength was collected via handgrip, hand-held dynamometry of the shoulder and elbow and a custom multi-joint concentric and eccentric strength isokinetic dynamometer protocol. Percentage joint moment contributions differed between women in their sixties and seventies with significantly greater relative shoulder joint involvement (P =.008), coupled with lower elbow joint contributions (P =.004) in comparison to 80 year olds. An increase in each year of age was associated with a 4% increase in elbow contribution (Beta = -0.421, r² = 17.9, P = 0.0001) and a 3.7% decrease in shoulder contribution (Beta = 0.373, r² = 14.6, P = 0.002). Older women exhibit different landing strategies as they age. Fall injury prevention research should consider interventions focused on these differences taking into account the contributions of upper extremity strength.