GYMNASTIC TRAINING AND BONE-DENSITY IN PRE ADOLESCENT FEMALES

Bone mineral density (BMD) was compared between 7-11-yr-old female gym nasts (GYM: N = 16) with a history of high volume impact loading (mini mun of 15 h.wk(-1) for past 2 yr) and healthy nonathletic controls (CO N: N = 16). Whole body (WE) and regional areal BMD measures were deter mined by dual energy x-ray absorptiometry (DXA) normalized for height and body mass and also converted to bone mineral apparent density (BMA D). Volumetric BMD and bone cross-sectional areas were also measured b y peripheral QCT (pQCT) at the left distal radius. GYM were significan tly (P < 0.01) shorter (129.3 +/- 5.7 vs 136.7 +/- 4.4 cm; means +/- S D) and leaner (15.1 +/- 1.9 vs 19.6 +/- 4.3% body fat from DXA), and h ad significantly (P < 0.05) greater femoral neck; (0.698 +/- 0.058 vs 0.618 +/- 0.064 g.cm(-2)) and trochanter (0.616 +/- 0.060 vs 0.530 +/- 0.084 g.cm(-2)) areal BMD than CON. GYM also had significantly higher whole body (0.101 +/- 0.009 vs 0.094 +/- 0.007 g.cm(-3)), femoral nec k (0.245 +/- 0.060 vs 0.205 +/- 0.049 g.cm(-3)) and lumbar spine (0.22 7 +/- 0.014 vs 0.210 +/- 0.026 g.cm(-3)) BMAD compared with CON. Heigh t normal ized areal BMD measures were also significantly higher at all sites in GYM. Radial total (367.7 +/- 51.6 vs 307.4 +/- 27.6 mg.cm(-3 )), trabecular (207.9 +/- 45.3 vs 163.8 +/- 31.4 mg.cm(-3)), and corti cal (496.9 +/- 67.5 vs 429.8 +/- 33.8 mg.cm(-3)) BMD were also signifi cantly greater in the GYM compared with the CON. In conclusion, high v olume impact loading was associated with greater (compared with contro ls) whole body and regional bone mineral density in pre-adolescent fe male gymnasts.