EFFECTS OF EXERCISE AND HORMONE REPLACEMENT THERAPY ON BONE MINERAL DENSITY IN POSTMENOPAUSAL WOMEN

Abstract

Combination therapies are receiving increasing attention in the search for effective osteoporosis prevention programs. The Bone, Estrogen and Strength Training (BEST) Study was designed to test the effects of hormone replacement therapy (HRT) and exercise on bone mineral density (BMD). Early postmenopausal women (age = 55.6 ± 4.7y) who used HRT (1–4 years; n = 159) or who did not use HRT (NHRT, ≥ 1 year, n = 161) were randomized to 12 months of exercise (Ex) or no exercise (NEX). BMD and soft tissue composition was measured twice (averaged for analyses) before and after intervention by dual energy x-ray absorptiometry. All subjects received 800 mg/day calcium supplements. Exercise entailed supervised high load, low rep weight lifting 70–80% 1 RM, 2 sets of 6–8 reps, 8 exercises, moderate-impact aerobic weight-bearing (25 min), and steps/stair climbing with weighted vests 3 days per week. Controls maintained usual activity. Calcium compliance and Ex attendance averaged ≥ 78%. Baseline height (163.2 ± 6.6 cm), weight (68.2 ± 11.5 kg), percent fat (38.6 ± 6.7%) and BMD's at femur neck (FN, 0.88 ± 0.12 g/cm2), trochanter (FT, 0.74 ± 0.11 g/cm2) and lumbar spine (LS, 1.13 ± 0.15 g/cm2) were similar (p > .05) among groups. BMD changes were examined using multiple regression analysis to test contrasts of Ex versus NEX within HRT and NHRT groups. BMD adjusted for baseline BMD and years past menopause increased in women who exercised or used HRT by ∼ 1–2% and decreased in women who did not Ex and did not use HRT. Synergistic effects occurred at FT. Individual responses varied widely with some women increasing BMD ≥ 4–5% and others losing bone despite HRT and Ex. We conclude that exercise maintains BMD in postmenopausal women, and that HRT plus exercise has added benefit. Supported by NIH AR39559 and Mission Pharmacal.