OSTEOPOROSIS

One of the major health problems women face is osteoporosis: bone loss after menopause, when their bodies reduce production of estrogen, the female sex hormone. This reduction of bone mass, which affects more than half of American women over fifty, makes the bones break easily, leading to hip fractures, crushed vertebrae, and other painful problems.

Over the years, many studies have demonstrated that moderate exercise can slow or prevent the rate of bone loss, but until recently conventional wisdom had it that only weight-bearing exercises, such as running or aerobics, could produce this desirable effect. A 1994 study conducted by Esther Goldstein at Hebrew University-Hadassah School of Public Health and Community Medicine in Jerusalem suggests otherwise.

The study involved two groups of volunteer postmenopausal women over the age of fifty. Goldstein demonstrated that swimming and water aerobics add to bone mass in middle-aged women better than conventional, land-based exercise—thus providing an effective activity to mitigate the effects of osteoporosis.

A 1987 study by a Portland, Oregon, endocrinologist, Eric S. Orwoll, showed that swimming provides the same bone-saving protection in men. When their bone-mineral content was compared with that of seventy-eight nonexercising subjects the same age who were getting either mineral supplements or a placebo for another study, the swimmers clearly had a large edge. Diet could not account for the differences, since calcium and protein intake was the same for both groups. His findings, says Orwoll, “can be a boon for people who have difficulty with weight-bearing exercise—and for the large number of people who just enjoy swimming.”

Another study, conducted by Dr. Richard L. Prince and others from Sir Charles Gairdner Hospital in Nedlands, Australia, and published in The New England Journal of Medicine in 1992, found that combining exercise with low doses of estrogen was the most effective way of preventing bone loss among older, postmenopausal women. Women who took estrogen while engaging in light exercise increased their bone density by about 3 percent per year. In addition to strengthening bone, the supplements prevent heart disease and relieve hot flashes and other unpleasant symptoms of menopause. A combination of exercise and doses of calcium also slowed bone loss but was not as effective as the exercise-estrogen combination. The most effective combination of all is exercise plus calcium and estrogen supplements.

The good news about exercise and osteoporosis is not confined to older women. A 1992 study published in The Journal of the American Medical Association showed that even though they have stopped growing, women can build stronger bones throughout their twenties by engaging in exercise such as swimming and by taking in adequate amounts of calcium. This is the first time scientists have shown that bones can continue to gain mass and strength after they have stopped growing longer in late adolescence. The scientists at Creighton University School of Medicine in Omaha found that exercise and calcium increased the young women’s bone mass by 5 to 6 percent. These figures provide hope that a combination of exercise and a diet rich in calcium can actually prevent osteoporosis later in life.