Boning up with exercise - research on osteoporosis

Vegetarian Times, April, 1995 by Eric Patterson

RESEARCHERS HAVE KNOWN for some time that regularly lifting weights can keep osteoporosis at bay. But recent research indicates not only that the benefits of pumping iron may be more dramatic than scientists thought, but also that simply taking regular brisk walks may slow the onset of the disease.

Two studies on osteoporosis were conducted at the U.S. Department of Agriculture's Human Nutrition Research Center on Aging at Tufts University, in Medford, Mass. In the first study, older women who lifted weights twice a week for 50 weeks actually gained an average of 1 percent in their spine and leg bone densities; women who did not lift weights lost 2.5 percent of bone density. The women who engaged in the 45-minute, high-intensity weight workouts also gained more muscle, improved their balance and had more energy to perform daily activities.

"This is the first time a single program has been shown to affect so many risk factors of osteoporosis fractures," says lead researcher Miriam Nelson, Ph.D. And though the study looked at women ages 50 to 70, not women ages 70 to 90, who fracture bones most often, Nelson says that the study shows that middle-aged women can lay a foundation of strength for their older years. "Falling is what causes the fractures," says Nelson. "We hope we can keep women strong and with good balance, and keep them from falling." According to Nelson, any woman can benefit by using home equipment such as leg weights and dumbbells with adjustable weights.

In a second study, post-menopausal women who walked more than seven and one-half miles a week for a year maintained bone density in their legs, while women who walked less than one mile per week lost 0.5 percent bone density, an average amount for their age.

Research into exercise's role in osteoporosis started in the 1980s, spawned by the finding that athletes have higher bone density than non-athletes. "These [new] studies suggest not only that the stress of exercise helps bones get stronger, but it also helps the body absorb calcium," says William Evans, Ph.D., director of the Noll Physiological Research Center at Pennsylvania State University and co-author of the strength-training study. The body normally absorbs just 20 percent of the calcium a person ingests and excretes the rest. Says Evans: "You'll find real growth in the number of [exercise] studies over the next four to five years."