BONE-MINERAL DENSITY IN ELITE 7 TO 9-YR-OLD FEMALE GYMNASTS AND SWIMMERS

It is has been suggested that physical activity may increase bone mine ral density (BMD) in children, thereby preventing development of osteo porosis later in life. We studied 14 gymnasts, 14 swimmers, and 17 con trols to investigate whether participation in different types of sport s among girls 7-9 yr of age is associated with higher total body BMD. Gymnasts were lighter than both swimmers and controls (P = 0.001), and a larger percent of gymnasts compared with swimmers and controls were below the 25th percentile for height and weight. Fat mass, percent bo dy fat, and lean mass were less in gymnasts compared with swimmers and controls (all P less than or equal to 0.05). The relationship between total body BMD and body weight differed among the three groups (inter action term of weight and sport, P < 0.001); the increase in BMD per u nit increase in body weight was more among gymnasts than among swimmer s and controls. These results indicate that high impact bone loading a ctivities may lead to increased bone density among young girls.