Lean body mass and bone mineral density in physically exercising postmenopausal women

Objectives: To investigate whether the relative contribution of body composition (lean and fat mass component) to postmenopausal bone mineral density (BMD) differs between women participating in physical exercise and sedentary women. Methods: Subjects were 45 postmenopausal women participating in regular physical exercise and 89 sedentary controls aged 50-60 years. Baseline characteristics included age, height, weight, body mass index (BMI, Wt/Ht(2)), age at menopause, and years since menopause (YSM). Body fat mass, percentage of body fat, lean body mass, and lumbar spine BMD (L2-4) were measured by dual-energy X-ray absorptiometry. Results: Although age, height, weight, BMI, and YSM did not differ between the two groups, lean body mass and lumbar spine BMD were significantly higher (P < 0.05 and < 0.001, respectively), while body fat mass and percentage of body fat mass were significantly lower in exercising women than in sedentary controls (P < 0.05 and < 0.05, respectively). In exercising women, BMD was positively correlated with lean body mass (r = 0.415, P < 0.01) but not with body fat mass (r = 0.155, NS). Conversely, in sedentary controls, BMD was correlated with body fat mass (r = 0.25 1, P < 0.05) and lean body mass (r = 0.228, P < 0.05). Conclusions: Lean body mass is a more significant determinant of postmenopausal BMD in physically exercising women than in sedentary women. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.