Aerobic, weight-bearing and resistance exercise improves bone mineral density (BMD) in postmenopausal women whether or not they use hormone therapy, according to results from the Bone, Estrogen and Strength (BEST) study funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the Department of Health and Human Services' National Institutes of Health.
Scott Going, Ph.D., Timothy Lohman, Ph.D., Linda Houtkooper, Ph.D., and their colleagues at the University of Arizona conducted a randomized clinical trial in 320 postmenopausal women between the ages of 45 and 65 to test the effect of a specific exercise regimen on bone mineral density. The women who were randomized to the exercise regimen-a combination of weight-bearing and resistance exercises-showed significant improvement (1 to 2 percent) in BMD after one year at the hip and spine, two important sites of fractures that may result from the bone-wasting disease osteoporosis. Notably, this benefit was found in both women taking postmenopausal hormone therapy and those who did not, although the women taking hormones had a somewhat greater response to exercise.
The exercises involved 20-25 minutes of resistance training using back extensions, leg presses, squats, pulldowns, dumbbell presses, and rowing, and 7-10 minutes of cardiovascular weight-bearing activity, such as skipping, jogging, and jumping rope.
The study shows that specific strength training and resistance exercises can retard and even reverse bone loss in healthy postmenopausal women, and that estrogen replacement is not necessary to gain the benefit of the exercise. All women received calcium supplements, and adequate calcium may be a factor in optimizing the effect of exercise on bone in postmenopausal women. The finding may provide reassurance for women who no longer take hormone replacement therapy because of the recent Women's Health Initiative findings. Osteoporosis is a disease characterized by low bone mass, bone fragility and increased susceptibility to fractures of the hip, spine and wrist. Women can lose up to 20 percent of their bone mass in the five to seven years following menopause, making them more susceptible to osteoporosis. In the United States today, 10 million individuals already have osteoporosis, and 18 million more have low bone mass, placing them at increased risk for this disorder.
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Going S, et al. Effects of exercise on bone mineral density in calcium-replete postmenopausal women with and without hormone replacement therapy. Osteoporosis International 2003; 14:637-643.