Sex Differences in Muscle-Bone Interactions in Chinese Men and Women

Abstract

Muscle-bone interactions are important for bone health as mechanical forces from muscular contraction place large stresses on bone. Little is known about sex differences in bone and muscle characteristics in Asians. PURPOSE: To examine sex differences in bone characteristics, grip strength, and lower body strength and power in Chinese adults (n=53). METHODS: Chinese males (n=28) and females (n=25) had body composition and aBMD (total body, lumbar spine, dual femur) assessed by DXA, and bone geometry (4%, 38%, 66%) of the non-dominant tibia measured by pQCT. Leg strength (two-leg press) and power (jump mat) and maximal grip strength (handgrip dynamometer) were measured. RESULTS: There were no sex differences in physical activity or calcium intake. After adjusting for height and weight, males had significantly greater leg press 1RM, grip strength, jump height, jump time, lumbar spine aBMD, 4% total BMC, 4% total area, and 4% bone strength index (BSI) (p<0.05) than females. In males, leg 1RM was positively correlated with total body aBMD (r= 0.427), and left femoral neck aBMD (r=0.445), and jump power was positively correlated with total body aBMD (r=0.580) and all hip aBMD variables (r=.487 to 0.646) (all p< 0.05). Females generally had stronger correlations between muscle and bone variables: leg 1RM (all p<0.05) and jump power (all p<0.003) were positively related to all aBMD variables (r=0.432 to 0.819). Jump power and BSI were positively correlated (r=0.378, p=0.048) in males, whereas jump power and leg 1RM showed moderate to strong correlations with 4% total BMC, total area, and total BSI (r=0.460 to 0.836, p<0.05) in females. CONCLUSION: Based on our findings, Chinese males had greater bone size, bone strength, and muscle strength than females; however, females exhibited more and stronger relationships between muscle and bone variables than males.Table 1: Sex Differences in Muscle and Bone variables (unadjusted Means ± SD)