The Associations of Handgrip Strength and Leg Extension Power Asymmetry on Incident Recurrent Falls and Fractures in Older Men

BACKGROUND: Evaluating asymmetries in muscle function could provide important insights for fall risk assessments. We sought to determine the associations of (i) handgrip strength (HGS) asymmetry and (ii) leg extension power (LEP) asymmetry on risk of incident recurrent falls and fractures in older men. METHOD: There were 5 730 men with HGS asymmetry data and 5 347 men with LEP asymmetry data from the Osteoporotic Fractures in Men (MrOS) study. A handgrip dynamometer measured HGS and a Nottingham Power Rig ascertained LEP. Percent difference in maximal HGS between hands was calculated, and asymmetric HGS was defined as men in the highest quartile of dissimilarity for HGS between hands. The same approach was used to determine asymmetric LEP. Participants self-reported falls every 4 months after the baseline exam, and persons with ≥2 falls in the first year were considered recurrent fallers. Fractures and their dates of occurrence were self-reported and confirmed with radiographic reports. RESULTS: Older men in the highest HGS asymmetry quartile had a 1.20 (95% confidence interval [CI]: 1.01-1.43) relative risk for incident recurrent falls. Likewise, men in the highest HGS asymmetry quartile had a higher risk for incident fractures: 1.41 (CI: 1.02-1.96) for hip, 1.28 (CI: 1.04-1.58) for major osteoporotic, and 1.24 (CI: 1.06-1.45) for nonspine. There were no significant associations between LEP asymmetry and recurrent falls or fractures. CONCLUSIONS: Asymmetric HGS could be a novel risk factor for falls and fractures that is more feasible to measure than LEP. Fall risk assessments should consider evaluating muscle function, including HGS asymmetry.