Correlations between Body Composition Components and Bone Mineral Content in Untrained Young Men and Women

PURPOSE: Low bone mineral content has been linked to the development of osteoporosis in humans. Research is divided as to whether fat or lean mass plays a more significant role in the development of bone mass. Physical activity has also been shown to increase bone mineral content in adolescents and combat the loss of bone density with aging. The purpose of this study was to examine correlations that exist between bone mineral content and anthropometric and performance measurements in untrained young men and women. METHODS: 78 untrained males (age 22.3±3.7) and 56 females (age 22.8±3.7) completed a battery of baseline testing measures. Anthropometric measurements such as height, weight, and waist circumference were recorded, as well as a Dual X-Ray Absorptiometry (DXA) scan to determine body composition, bone mineral content and density. In addition, subjects also completed maximal lower body strength and power tests. RESULTS: The primary finding of this investigation was that body mass shows the strongest correlation to bone mineral content in men, women, and the total group (r=0.740, p=0.00; 0.697, p=0.00; and r=0.797, p=0.00, respectively). When examining the components of body mass, lean mass is a stronger predictor of bone mineral content than fat mass in all groups. When examining the men and women grouped together, lean mass showed a correlation of r=0.795 (p=0.00) while fat mass did not correlate to BMC (r=0.263; p=0.00). Though the correlations for lean and fat mass in the separate male and female groups were not strong correlations, lean mass showed a stronger correlation to BMC than fat (r=0.647, p=0.00 and r=0.667, p=0.00 respectively, for lean mass; r=0.553, p=0.00 and r=0.550, p=0.00 respectively, for fat mass). We found that there were no significant correlations between maximal squat strength and bone mineral content in men or women. CONCLUSIONS: We found that body mass was the strongest predictor of bone mineral content in untrained men and women. As we expected, lean mass seems to play a greater role in this correlation than fat mass. Contrary to our hypothesis maximal lower body strength did not correlate with bone mineral content in men or women. We believe this to be the result of varied levels of physical activity between subjects, lending that physical activity levels may correlate better with BMC than sheer physical strength. PRACTICAL APPLICATIONS: Determining the relationships that exist with bone mineral content will allow us to see what might put individuals at risk for developing low BMC and osteoporosis. Despite that we cannot claim that lean mass causes bone mineral content to increase, we can show that there is a relationship between the two that should be explored through future research. In many settings the use of technology utilized in this study, such as the DXA scanner, is not possible. For these instances we used multiple regression analysis to show that using weight, height, and maximal squat strength can account for 77% of the variance in BMC measurements