Exercise Increases Bone Density in Women Using HRT
A combination of weight training and aerobic exercise improves bone mineral density and might add to the beneficial effect of hormone replacement therapy (HRT) at specific sites, according to a new study published in Osteoporosis International (2003;14:637–43).
Osteoporosis is a condition characterized by low bone density and increased risk of bone fracture. Exercise and estrogen are two factors that stimulate the proper use of minerals and prevent bone loss. Adequate intake of vitamin D and minerals such as calcium, magnesium, zinc, copper, and manganese are required to maintain bone density. Approximately one third of postmenopausal women in the United States have osteoporosis. Current treatment recommendations include supplemental calcium and vitamin D, as well as HRT or non-hormonal medications that prevent bone loss. A number of studies have demonstrated the beneficial effects of exercise on bone health. The results of several studies have suggested that a combination of exercise and HRT might be more beneficial than either treatment alone.
The current study examined the effects of exercise and HRT, alone and in combination, on bone mineral density in postmenopausal women over a one-year period. The subjects of the study were 266 healthy women who were three to ten years past the onset of menopause, had a low activity level, and had either been using HRT for more than one year or had not used any HRT for at least one year. The women were randomly assigned to an exercise group or a no-exercise group, resulting in the formation of four groups: no exercise and no HRT, no exercise and HRT, exercise and HRT, and exercise and no HRT.
During the study, the women using HRT remained on the protocol prescribed by their primary care physicians. The women assigned to exercise followed a program that included stretching; aerobic weight-bearing activity such as walking, jogging, or skipping; weightlifting; and stair climbing or box stepping with weighted vests. This supervised program was performed three times per week and lasted at least 30 minutes. The women in all four groups were given 800 mg of supplemental calcium per day. Bone mineral density was measured at three sites (the neck of the femur, the trochanter of the hip, and the lumbar spine) and for the total body at the beginning of the study and after one year.
The women in the no-exercise/no-HRT group had significant bone loss during the study, but bone density in women in all three treatment groups improved significantly. Exercising women in the HRT and the no-HRT groups had significantly more improvement in bone density at the trochanter than women who did not exercise. In women using HRT, the bone density of the trochanter improved about two times more in those who exercised than in those who did not. Differences in bone density changes at other sites and for total body were not significantly different between the HRT/exercising group and HRT/no exercise group.
The results of this study add to a wealth of evidence that exercise improves bone density. Furthermore, the exercise program used in this study was found to increase the positive effect of HRT on the bone density of the trochanter within one year. Future studies should examine the effect of other exercise regimens on bone density in women using HRT.
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
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