Relationships between muscle strength and bone mineral density of three body regions in sedentary postmenopausal women

This cross-sectional study was designed to investigate correlations between muscle strength and regional bone mineral density (BMD) in sedentary postmenopausal women. Sixty-two women who ranged in age from 41 to 76 years were investigated. Hip and trunk muscle strength was measured by isokinetic dynamometry. Grip strength of the nondominant hand was measured using a hand-held dynamometer. Bone mineral density of the lumbar spine, femur, and distal radius was measured by dual-energy X-ray absorptiometry. Only the correlation between hip abductor strength and femoral BMD was significant (P=0.009, r=0.327). There was no correlation between trunk muscle strength and lumbar vertebral BMD or between grip strength and distal radius BMD. Subjects with osteoporosis (T score < -2.5) or osteopenia T (-2.5 to -1) and normal subjects (T > -1) exhibited similar isokinetic hip and trunk muscle strength. Women with osteoporotic distal radii had significantly lower grip strength than subjects who were osteopenic or normal at this site, but the osteoporotic group was also significantly older. In conclusion, our results indicate that the isokinetic strength of hip abductors weakly correlates with femoral BMD in postmenopausal women with and without osteoporosis. Trunk muscle strength did not correlate with lumbar vertebral BMD in either of these groups. The weaker handgrip we observed in the women with osteoporotic radii may be attributed to older age.