Effects of unilateral activity on bone mineral density and content in adolescent males

The effects of an unilateral sport, badminton, on radial bone mineral density (BMD) and content (BMC) in adolescent males were examined by dual energy X-ray absorptiometry (DXA) . Subjects were all junior high school students, and composed of nine badminton players (Group B; mean age 14.2 years) , who had practiced regularly for 2.5 years on the average, and ten control subjects (Group C; mean age 13.9 years) without regular physical activity. All subject had the dominance in the right arm. DXA measurements were done at distal radius and radial shaft for both arms. In group B, the BMC* and the BMD~ were significantly higher in the playing extremity in both radial sites measured (BMC.; p<0.01. BMD.; p<0.05) . On the other hand, side-to-side differences were not significant in the group C at any measured site. Also there were no significant differences between the groups for non-dominant arms. Thus, physical exercise may not have a generalized effect on the skeleton, but may increase the BMC and BMD Iocally in the exercised limb. It has been concluded that physical exercise increase bone mass in use-dependent manner, so the style of exercise must be carefully considered for mobilizing the bone needed to increase its mass in adolescence. Footnotes * The bone tissue area in the DXA measurements was an area which was surrounded by a 10.4 mm longitudinal length of bone and a transverse bone width, so bone tissue area was determined by bone width.