Insulin resistance and muscle strength in older persons

Background. The functional consequences of an age-related insulin resistance (IR) state on muscle functioning are unknown. Because insulin is needed for adequate muscle function, an age-related insulin-resistant state may also be a determining factor. We evaluated the relationship between IR and handgrip muscle strength in men and women from a large population-based study (n = 968). Methods. The degree of IR was evaluated by the homeostasis model assessment (HOMA) and muscle strength was assessed using handgrip. Results. Simple sex-stratified correlations demonstrated that, in men. body mass index-adjusted handgrip strength correlated positively with physical activity (r = 0.321; p <.001), muscle area (r = 0.420; p <.001), muscle density (r = 0.263; p = .001), plasma albumin (r = 0.156; p = .001), insulin-like growth factor-1 (r = 0.258; p <.001), calcium (r = 0.140; p = .006), and testosterone (r = 0.325; p <.001) concentrations, whereas a negative association was found for age (r = -0.659; p <.001) and myoglobin plasma levels (r = -0.164; p = .001). In women, body mass index-adjusted handgrip strength correlated positively with physical activity (r = 0.280; p <.001), muscle area (r = 0.306; p <.001), muscle density (r = 0.341; p = .001), plasma albumin (r = 0.140; p = .001), and insulin-like growth factor-1 (r = 0.300; p <.001), whereas a negative association was found for age (r = -0.563; p <.001), myoglobin levels (r = -0.164; p = .001), and IR (r = -0.130; p = .04). Conclusions. Sex-stratified analyses adjusted for multiple confounders showed that the relationship between IR and handgrip strength was found significant in women, whereas it was negligible and not significant in men.