New Exercise Guidelines Just for Women

A new study released today in the New England Journal of Medicine has established age-specific exercise guidelines just for women. Until this study was released, the only exercise guidelines that were available were based on studies on men. This new study increases the knowledge about gender differences in disease processes as well as physiology.

The new study, led by a cardiologist from Northwestern University in Chicago, showed that women's exercise capacity is slightly lower than men's and that it declines a bit faster than men's as they age. The study found that women lose about 1 percent of their exercise capacity per year. For example, a 50-year-old woman should be able to reach 8.2 METs while a 50-year-old man should be able to reach 9.2 METs.

The data was taken from 5,721 exercise stress tests performed on women over the age of 35 and were compared to known fitness levels for men. The women in were given a standard exercise stress test in which they walk on a treadmill while the speed and incline are increased every three minutes until they became tired or developed other problems. The exercise capacity is then measured in metabolic equivalents, or METs, based upon the speed and incline of the treadmill.

One MET is the amount of energy required to sit quietly for one minute. Walking at a moderate pace requires 3 to 6 METs per minute. Running requires 6 to 10 or more METs per minute, depending upon the speed and incline.

Perhaps the most important finding of this study is that women whose exercise capacity was less than 85 percent of what it should be were twice as likely to die within eight years. The study tested the fitness equation to see how well it predicted survival during eight years the volunteers were followed and also looked at another group of 4,471 women with heart disease symptoms who were followed for five years. Surprisingly, women in both groups who did under 85 percent of their expected MET level had twice the risk of death compared to those who did more than 85 percent.

The bottom line? This study emphasizes the point that exercise is critical to good cardiovascular health and that measurements of good exercise tolerance are different between the sexes. Perhaps most importantly, this study showed that your risk of death is higher if you are not able to reach your expected METs, regardless of whether you have symptoms of heart disease.

There is no need for fancy physiologic testing to measure your fitness level. Most treadmill and bicycle machines at health clubs will calculate METs for you. As always, consult with your personal physician prior to initiating any exercise regimen. If you are at risk for heart disease, your doctor may prescribe an exercise stress test for you in a doctor's office so that your fitness level may be tested in a safe environment.

The entire study report as well as the exercise guidelines are available online at www.nejm.org.