Favorable effects of skeletal muscle on bone are distinguished according to gender and skeletal sites

OBJECTIVES: The aim of this study was to investigate associations between skeletal muscle mass and bone mineral density according to gender and skeletal sites. METHODS: Using the data from Korean National Health and Nutrition Examination Survey (KNHANES IV) 2009, a total of 711 males and 847 females over 65 years of age were evaluated. Bone mineral density (BMD) and body composition were assessed using dual-energy X-ray absorptiometry. RESULTS: Relative appendicular skeletal muscle (RASM) was positively related with the femur BMD with a stronger relationship in males (r = 0.207, p < 0.001) than in females (r = 0.095, p < 0.05). However, lumbar spine BMDs in both males and females did not show any significant associations with the RASM value. In the logistic regression for osteoporosis expressed as a decrease of risk per increase of RASM by 1 standard deviation (SD) of the same sex healthy reference group, the age- and BMI-adjusted odds ratio (OR) for osteoporosis was 0.42 (95% CI 0.12–0.76) in the femur neck and 0.24 (95% CI 0.07–0.76) in the total hip for males. Among females, the age- and BMI-adjusted OR for osteoporosis was 0.65 (95% CI 0.33–1.00), which showed importance only in the total hip. CONCLUSIONS: Higher RASM was significantly associated with lower risk for osteoporosis and the areas at the femur neck and total hip appeared to more likely be affected positively by muscle. Moreover, because males showed faster muscle loss with aging than females, the bones of males may be more prone to favorable effects of muscle.