Influence of grip strength on metacarpal bone mineral density in postmenopausal Japanese women: A cross-sectional study

Most published studies on the role of muscle strength in the maintenance of bone mineral density (BMD) focused on the relationship between specific mu scle groups and adjacent bones, mostly in young and premenopausal women. Th is study examined the influence of grip strength on BMD of the metacarpal i ndex in postmenopausal Japanese women. Subjects included 1168 postmenopausa l women aged 40-70 years. BMD measurement was done with computed X-ray dens itometry (CXD) by analyzing Xray films of the right second metacarpal index . Grip strength was measured in both the dominant and nondominant hands usi ng a squeeze dynamometer. Grip strength (r = 0.2474; P = 0.0001) and age (r = -0.5443; P = 0.0001) significantly correlated positively and negatively, respectively, with BMD. Physical activity (r = 0.1318; P = 0.0001) also co rrelated positively with BMD. Breastfeeding (r = -0.1658; P = 0.0001), howe ver, correlated negatively with BMD. Subjects with a history of regular phy sical activity had higher grip strengths and BMD, than those with no physic al activity. Adjustment for age, physical activity, calcium intake, BMI, br eastfeeding, testing site, and menopausal type indicated a significant (P f or trend = 0.0013) positive association of grip strength with BMD. Subjects with stronger grip strengths had a decreased risk for low BMD.