Currently, over 10 million Americans already have osteoporosis and another 34 million have low bone mass (a condition called osteopenia), which places them at increased risk of developing osteoporosis. It is estimated that one out of every two women over 50 will have an osteoporotic-related bone fracture in her lifetime.

Women are more likely to develop osteoporosis than men because women generally have smaller bones and less calcium intake than men, and their estrogen levels plummet during menopause . Estrogen is a female hormone essential for building and maintaining bone mass. The drastic drop in estrogen levels during menopause is why postmenopausal women are at the highest risk of developing osteoporosis.

How can women help keep their bones strong after menopause? Research has shown that increasing calcium and vitamin D intake, quitting smoking, and limiting alcohol intake can help preserve bone mass. Exercise can help, too. There is a great deal of evidence that women who exercise throughout their reproductive lives lower their risk of osteoporosis later on. But what about women who don’t begin exercising until after menopause?

A new study in the May 24, 2004 issue of the Archives of Internal Medicine found that a 24-month exercise program helped preserve bone mass, improve strength and endurance, reduce lower back pain, and improve cholesterol and triglyceride levels in postmenopausal women.

About the Study

This study, which was part of the Erlangen (Germany) Fitness Osteoporosis Prevention Study, (EFOPS) included a total of 137 women who were 1-8 years postmenopausal and had osteopenia at the spine or hip, measured by duel x-ray absorptiometry (DXA). They had no prior osteoporotic fractures , diseases or medications known to affect bone metabolism, inflammatory diseases, history of cardiovascular disease , or major mobility problems. In addition, they had not participated in sports competitions within two decades before the start of the study.

The participants were given the option of joining the exercise group or the control group. Participants in the control group were instructed to continue their usual lifestyle, while those in the exercise group participated in a 24-month exercise program.

The exercise program consisted of four weekly training sessions (two 60-70-minute supervised group sessions and two 25-minute home training sessions). The group sessions consisted of warm-up, endurance, strength, and flexibility sequences. After six months of training, a jumping sequence was added. The home training session consisted of isometric and belt strength exercises, and a stretching sequence.

Before the study and 26 months after the exercise program began, the researchers measured the bone mineral density (BMD) of the participants at multiple sites using both DXA and quantitative computed tomography (QCT) measurements (two reliable measures of bone composition). The researchers measured blood markers for bone turnover in a subset of participants. In addition, the researchers measured the participants’ height, weight, body composition, waist-hip ratio, strength, endurance, and pain frequency and intensity before the study began and 26 months after.

The Findings

After excluding 17 women in the exercise group for poor compliance and two women from the control group for significantly increasing their physical activity, the final analysis consisted of 50 and 33 women in the exercise and control groups, respectively.

Bone density measurements generally remained stable in the exercise group, but decreased significantly in the control group. There was, however, a relatively large increase (+3.1%) in the BMD of the spine and a small decrease (-1%) in BMD of the femoral neck region of the upper hip in the exercise group. In the radius bone in the forearm, BMD decreased up to 4% in both groups. Blood markers for bone turnover did not change significantly in either group.

Neither of the groups experienced significant changes in height, weight, body composition, or waist-hip ratio. Compared with the control group, total cholesterol and triglycerides decreased significantly in the exercise group. Also, participants in the exercise group had significant decreases in pain intensity and frequency at the spine, but not the major joints.

These results are compelling, but the study is limited by the fact that participants were not randomly assigned to each group, but could choose which group they wanted to join. This type of bias in the selection process makes it harder to confidently link exercise with changes in bone density and other outcome measures of the study. Also, 24 months is a relatively short period of time in which to observe meaningful changes from an exercise program.

How Does This Affect You?

These findings suggest that postmenopausal women who participate in a regular exercise program that includes endurance, strength, and flexibility training can significantly improve bone density, not to mention other important benefits to their health. This is good news, considering hormone replacement therapy (HRT), which has been used to prevent bone loss in postmenopausal women for years, is now known to increase the risk of heart disease, breast cancer , blood clots, and stroke .

These findings should not be surprising, considering that evidence has been building for decades about the benefits of exercise. Exercise strengthens your bones, muscles, and heart, and can reduce the risk of falls (and subsequent fractures) in older people. It can help ward off other chronic diseases, including heart disease, stroke, diabetes , obesity , and certain cancers. It’s also good for your mental health; a regular exercise program can decrease feelings of depression and anxiety , improve your overall sense of well-being, and help you sleep better.

If scientists could package the benefits of exercise into a pill, it would make headlines and doctors would hand out prescriptions in mass quantities. But it’s not that easy. To reap the benefits of exercise, you must make the concerted effort to get up, get out, start moving, and keep moving. A regular exercise program should consist of 30-60 minutes of endurance, strength, and flexibility training on most days of the week. This may sound daunting now, but once you begin, you’ll be glad you did.