Leg skeletal muscle mass asymmetry is independently associated with gait speed in older adults requiring long-term care

Aim Decreased gait speed in older adults has been associated with incident disability, cognitive impairment, institutionalization, falls, deterioration in level of care, and mortality. Gait speed has been reported to be related to leg asymmetry. However, the relationship between gait speed and leg skeletal muscle mass asymmetry in older adults requiring long-term care has not been clarified. In this study, we examined the association between gait speed and leg skeletal muscle mass asymmetry and the cutoff values of leg skeletal muscle mass asymmetry that may affect gait speed. Methods The asymmetry index of leg skeletal muscle mass was measured in 230 older adults under the Japanese long-term care insurance system using bioelectrical impedance analysis. This cross-sectional study used multiple regression analysis and receiver operating characteristic (ROC) curve analysis to determine the relationship between gait speed and the asymmetry index of leg skeletal muscle mass. Results Multiple regression analysis revealed that the asymmetry index of leg skeletal muscle mass (beta = -0.19, P = 0.002, R-2 = 0.261) was independently and significantly associated with gait speed. Furthermore, ROC analysis showed that the cutoff value of the asymmetry index of leg skeletal muscle mass that identified reduced gait speed (<1.0 m/s) was 3.02% (Area under the curve = 0.62, sensitivity 47.3%, specificity 81.0%, P = 0.014). Conclusions The asymmetry index of leg skeletal muscle mass was associated with gait speed in older adults requiring long-term care. Future assessment and interventions directed towards symmetry of leg skeletal muscle mass may help to improve gait speed in older adults.