Characterization of Isometric Limb Muscle Strength of Older Adults

Overall muscle strength of extremities is often characterized by measurements from one or more selected actions. This study evaluated the legitimacy of that procedure. Measurements obtained by handheld dynamometry from 13 muscle actions of 156 apparently healthy individuals (50–79 years) were subjected to correlational analysis, principal-components analysis, and cluster analysis. The isometric strengths of all muscle actions correlated significantly with one another (r = .506–.965). Principal-components analysis without rotation showed that all tested actions loaded highly on overall limb muscle strength. Principal-componcnis analysis with varimax rotation revealed high loadings that were grouped by extremity (upper vs. lower). Ankle dorsiflexion strengths were exceptions. These findings, in conjunction with the cluster analysis, support using one or more actions to characterize isometric limb muscle strength among the elderly but suggest that muscle strength in an upper or lower extremity is best charac...