The hypothesis of the present study was that low-repetition and high-impact training of 10 maximum vertical jumps/day, 3 times/wk would be effective for improving bone mineral density (BMD) in ordinary young women. Thirty-six female college students, with mean age, height, and weight of 20.7 +/- 0.7 yr, 158.9 +/- 4.6 cm, and 50.4 +/- 5.5 kg, respectively, were randomly divided into two groups: jump training and a control group. After the 6 mo of maximum vertical jumping exercise intervention, BMD in the femoral neck region significantly increased in the jump group from the baseline (0.984 +/- 0.081 versus 1.010 +/- 0.080 mg/cm2; p < 0.01), although there was no significant change in the control group (0.985 +/- 0.0143 versus 0.974 +/- 0.134 mg/cm2). And also lumbar spine (L2 to L4) BMD significantly increased in the jump training group from the baseline (0.991 +/- 0.115 versus 1.015 +/- 0.113 mg/cm2; p < 0.01), whereas no significant change was observed in the control group (1.007 +/- 0.113 versus 1.013 +/- 0.110 mg/cm2). No significant interactions were observed at other measurement sites, Ward's triangle, greater trochanter, and total hip BMD. Calcium intakes and accelometry-determined physical daily activity showed no significant difference between the two groups. From the results of the present study, low-repetition and high-impact jumps enhanced BMD at the specific bone sites in young women who had almost reached the age of peak bone mass.

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