Bone Mineral Density and Regular Swimming: Observational and Interventional Studies

Abstract

Although exercise in general is beneficial for enhancing bone mineral density (BMD), people who participate in non‐weight bearing, low impact, activities are at a greater risk for bone loss. A recent study indicates that excessive dermal calcium loss through sweat will create bone demineralization and decrease bone mineral density in some athletes. Swimming exercise is characterized by low impact activity but sweat loss is much smaller than other endurance‐trained athletes. First, using the cross‐sectional study, BMD was measured using dual‐energy x‐ray absorptiometry in 44 sedentary controls (56±1 years), 48 runners (54±1 years), and 27 swimmers (57±1 years). Body mass and body fatness were significantly lower in runners than in swimmers and sedentary controls. Total (whole‐body) BMD was not different among the groups. Runners had significantly higher leg BMD than swimmers and sedentary controls (1.38±0.02 vs. 1.33±0.04 and 1.32±0.02 g/m2). There were no differences in other regional (head, arms, trunk, ribs, pelvis and spine) BMD between the three groups. We then determined changes in BMD after 3 months of swimming exercise intervention in 24 previously sedentary adults (58±2 years). Total and regional BMD did not change. Collectively, our observational and interventional findings indicate that swimming exercise is not associated with a greater bone mineral density.