Site-specific response of bone to exercise in premenopausal women

We studied the response of bone at specific skeletal sites to either lower body exercise alone or complemented with upper body exercise in premenopausal women. Thirty-five exercisers and 24 age-matched controls completed the 12-month study. Exercising women (N = 35) were randomly assigned to either lower body resistance plus jump exercise (LOWER) (N = 19) or to lower and upper body resistance plus jump exercise (UPPER + LOWER) (N = 16). Exercisers trained three times per week completing 100 jumps and 100 repetitions of lower body resistance with or without 100 repetitions of upper body resistance exercise at each session. Intensity for lower body exercise was increased using weighted vests for jump and resistance exercises, respectively. Intensity for upper body exercise was increased using greater levels of tautness in elastic bands. Bone mineral density (BMD) at the total hip, greater trochanter, femoral neck, lumbar spine and whole body were measured by dual energy X-ray absorptiometry (Hologic QDR-1000/W) at baseline, 6 and 12 months. Data were analyzed first including all enrolled participants who completed follow-up testing and secondly including only those women whose average attendance was ≥ 60% of prescribed sessions. Group differences in 12-month %change scores for BMD variables were analyzed by univariate ANCOVA adjusted for baseline differences in age. Post hoc tests were performed to determine which groups differed from one another. Initial analysis showed significant differences in greater trochanter BMD between each exercise group and controls, but not between exercise groups (2.7% ± 2.5% and 2.2% ± 2.8% vs. 0.7% ± 1.7%, for LOWER and UPPER + LOWER vs. controls, respectively; p < 0.02) and near significant group differences at the spine (p = 0.06). Excluding exercisers with low compliance, group differences at the greater trochanter remained, while spine BMD in UPPER + LOWER was significantly different from LOWER and controls, who were not significantly different from one another (1.4% ± 3.9% vs. - 0.9% ± 1.7% and - 0.6% ± 1.8%, for UPPER + LOWER vs. LOWER and controls, respectively; p < 0.05). No significant differences among groups were found for femoral neck, total hip or whole body BMD. Our data support the site-specific response of spine and hip bone density to upper and lower body exercise training, respectively. These data could contribute to a site-specific exercise prescription for bone health.