Prevention of Postmenopausal Osteoporosis. A Comparative Study of Exercise, Calcium Supplementation, and Hormone-replacement Therapy

Background: Osteoporosis among older women is a major public health problem. We studied the effects of three approaches to the prevention of osteoporosis in women with low bone density.

Methods: One hundred twenty postmenopausal women (mean [+/- SD] age, 56 +/- 4) who were selected because they had low forearm bone density were enrolled in a double-blind, placebo-controlled, randomized study comparing the effects of an exercise regimen (exercise group, n = 41), exercise plus dietary calcium supplementation (exercise-calcium group, n = 39), and exercise plus continuous replacement of estrogen and progesterone (exercise-estrogen group, n = 40). Periodically during the two-year study period, we measured the women's bone density at three forearm sites, measured indexes of calcium metabolism, and recorded symptom scores. A comparison group of 42 women (mean age, 55.5 +/- 3.1) with normal bone density was also followed for two years.

Results: Significant bone loss in the distal forearm occurred in the group with normal bone density (control group) and the exercise group (change, -2.7 percent and -2.6 percent of the base-line value per year, respectively). Bone loss at the distal forearm site was significantly lower in the exercise-calcium group (-0.5 percent of the base-line value per year), and bone density increased at this site in the exercise-estrogen group (+2.7 percent of the base-line value per year). Bone loss at the median forearm site was significantly lower in the exercise-calcium group (-1.3 percent of the base-line value per year) than in the exercise group (-2.4 percent), and bone density at this site increased significantly in the exercise-estrogen group (+0.8 percent of the base-line value per year). Breast tenderness occurred in 47 percent of the women in the exercise-estrogen group but in only 20 percent in the other two treatment groups. Vaginal bleeding occurred at some time in 52 percent of the women who had not had a hysterectomy in the exercise-estrogen group, as compared with 11 percent and 12.5 percent, respectively, in the exercise and exercise-calcium groups.

Conclusions: In postmenopausal women with low bone density, bone loss can be slowed or prevented by exercise plus calcium supplementation or estrogen-progesterone replacement. Although the exercise-estrogen regimen was more effective than exercise and calcium supplementation in increasing bone mass, it also caused more side effects.