Association between hip abductor muscle strength and mobility limitation (locally defined as locomotive syndrome) in community-dwelling adults undergoing osteoporosis screening: a cross-sectional study

BACKGROUND: Mobility limitation is associated with an increased risk of disability in older adults. In Japan, mobility limitation is commonly assessed using the concept of locomotive syndrome. Hip abductor muscle strength plays a key role in gait stability; however, its independent association with mobility limitation remains unclear, partly because previous studies have focused primarily on general muscle strength or muscle mass rather than frontal-plane hip stability. This study aimed to investigate the association between hip abductor muscle strength and mobility limitation in community-dwelling adults undergoing osteoporosis screening. METHODS: This cross-sectional study included 325 community-dwelling adults undergoing osteoporosis screening. Hip abductor muscle strength was measured isometrically in a seated position using a standardized dynamometer and normalized to body weight. Mobility limitation was assessed using the locomotive syndrome risk test, and participants with a Locomotive score ≥ 1 were classified as having mobility limitation. Logistic regression analyses were performed to examine the association between hip abductor muscle strength and mobility limitation. Odds ratios (ORs) were calculated per 1 standard deviation decrease in muscle strength, with adjustment for age, sex, body mass index, skeletal muscle mass index, and bone density. RESULTS: Among 325 participants (mean age 74.1 ± 5.4 years; 70 men and 255 women), 250 (76.9%) were classified as having mobility limitations. Participants with mobility limitations showed significantly lower hip abductor muscle strength than those without. In logistic regression analysis, reduced hip abductor muscle strength was significantly associated with mobility limitation. This association remained significant after adjustment for age, sex, body mass index, skeletal muscle mass index, and bone density (odds ratio per 1 standard deviation decrease: 2.40, 95% confidence interval: 1.71-3.38, p < 0.001). CONCLUSIONS: Reduced hip abductor muscle strength was independently associated with mobility limitation, regardless of muscle mass and bone density. Assessment of hip abductor muscle strength may provide useful information for identifying individuals at risk of mobility limitation during community-based screenings.