20 WEEKS OF WEIGHT TRAINING INCREASES LEAN TISSUE MASS BUT NOT BONE-MINERAL MASS OR DENSITY IN HEALTHY, ACTIVE YOUNG-WOMEN

Twenty young women (20.3+/-1.0 years) participated in a weight trainin g program in which upper and lower body exercises were done twice per week for 20 weeks. Ten other women (20.2+/-0.4 years) served as a cont rol group. Training resulted in significant (p<0.05) increases in arm curl (73%), bench press (33%), and leg press (23%) lifting performance . Whole body (3.7%), trunk (3.0%), arm (9.7%), and leg (3.3%) lean tis sue mass also increased significantly, based on measurements made by d ual energy x-ray absorptiometry (DEXA). Changes in the control group w ere small and nonsignificant. In contrast, training did not increase D EXA-measured bone mineral content (BMC) and density (BMD) in a whole b ody measure nor in arm, leg, ribs, thoracic and lumbar spine, and pelv is segments. Similarly, hip BMC and BMD at femoral neck, trochanter, i ntertrochanter, and Ward's triangle sites, and total hip did not incre ase with training. The data indicate that a resistance training progra m that effectively increases strength and lean tissue mass in young wo men may fail to increase BMC or BMD over a 20-week training period.