A 2-YEAR PROGRAM OF AEROBICS AND WEIGHT TRAINING ENHANCES BONE-MINERAL DENSITY OF YOUNG-WOMEN

Previous research suggests that physical activity may have a beneficia l effect on bone mineral density (BMD) in women. This relationship was explored in a 2-year, randomized, intervention trial investigating th e efficacy of exercise and calcium supplementation on increasing peak bone mass in young women. One hundred and twenty-seven subjects (ages of 20-35 years) were randomly assigned either to an exercise program t hat contained both aerobics and weight training components or to a str etching program. Calcium supplementation (up to 1500 mg/day including dietary intake) or placebo was given in a double-blinded design to all subjects. Spinal trabecular BMD was determined using quantitative com puted tomography (QCT). Spinal integral, femoral neck, and trochanteri c BMD were measured by dual X-ray absorptiometry (DXA) and calcaneal B MD by single photon absorptiometry (SPA). Fitness variables included m aximal aerobic capacity (VO2max), and isokinetic muscle performance of the trunk and thigh. Measurements were made at baseline, 1 year, and 2 years. Sixty-three subjects (32 exercise, 31 stretching) completed t he study, and all the measured bone parameters indicated a positive in fluence of the exercise intervention. There were significant positive differences in BMD between the exercise and stretching groups for spin al trabecular (2.5%), femoral neck (2.4%), femoral trochanteric (2.3%) , and calcaneal (6.4%) measurements. The exercise group demonstrated a significant gain in BMD for spinal integral (1.3 +/- 2.8%, p < 0.02), femoral trochanteric (2.6 +/- 6.1%, p < 0.05), and calcaneal (5.6 +/- 5.1, p < 0.01) measurements. In contrast to exercise, the calcium int ervention had no positive effect on any of the bone parameters. In reg ard to fitness parameters, the exercise group completed the study with significant gains in VO2max and isokinetic (peak torque) values for t he knee flexion and extension and trunk extension. This study indicate s that over a 2-year period, a combined regimen of aerobics and weight training has beneficial effects on BMD and fitness parameters in youn g women. However, the addition of daily calcium supplementation does n ot add significant benefit to the intervention.