Feb. 16, 2000 (Atlanta) -- Even when the bathroom scales don't show weight loss, people who exercise at least three times a week are gaining health benefits. A study at Duke University Medical Center shows that regular exercisers make significant improvements in heart health. The study is published in the February issue of the journal Exercise Physiologist.
"A lot of people get discouraged with exercise programs when they don't lose weight. But that shouldn't discourage them. They're accruing health benefits despite the fact that they're not losing weight," study author William E. Krauss, MD, professor of cardiology at Duke University Medical Center, tells WebMD. "What we're really trying to study here is how much exercise someone needs to get health benefits -- not to get fit, but to get health benefits." Krauss says that, in their study, they found significant improvements in cholesterol and blood sugar levels.
While the study had only seven volunteers, Krauss says that the changes were so uniform that they are considered important. "We feel very confident about the conclusions of this study," he says. The study looks at the effects of a four-times-a-week exercise program in mildly obese patients. Says Krauss, "It's not like Olympic training, but it's hefty. We call it moderate exercise." The volunteers (all between 40 to 55 years old and nonsmokers) had mildly elevated cholesterol levels and no history of heart disease. Each reported to the Duke Center for Living fitness center for hour-long workouts on treadmills, stairclimbers, crosstrainers, and exercise bicycles.
All volunteers were weighed regularly, and caloric intake was adjusted to maintain the weights they had at the beginning of the study. "When there's not a true nutritional component to a weight-loss program, it's hard to lose weight," Krauss says.
All showed reductions in body fat and increases in aerobic fitness levels. And although triglyceride levels, a risk factor for heart disease, did not change significantly, there was a strong indication that decreases were occurring. LDL ('bad') cholesterol decreased in six of the volunteers and HDL ('good') cholesterol increased significantly in all. While obesity is a risk factor for diabetes, the study showed across-the-board improvements in all volunteers' sugar metabolism function -- therefore reducing risk of diabetes.
This pilot study paves the way for a larger, NIH-funded Study of Targeted Risk Reduction Interventions With Defined Exercise (STRRIDE), which will help define just how much physical activity -- in terms of intensity and frequency -- is necessary to improve a mildly overweight person's heart disease risk factors, says Krauss.
The larger study will measure effects of various exercise programs, including a two- or three-day-a-week regimen. Krauss tells WebMD, "There's a lot of confusion in the lay press about how much exercise we should be doing. As a community of health professionals, we say that doing something is better than nothing, that you can divide exercise into three parts, at 10 minutes each, and do it on your breaks or at lunch time. But we don't know whether that translates into health benefits; we really don't. It's not been proven."
Krauss compares his work with the famous Nurses Health Study, which showed that women who walked for exercise reduced incidence of cardiovascular events like heart attacks. The study also showed that more vigorous exercise gave the volunteers more small, incremental health benefits. However, the study was inconclusive, says Krauss. "It didn't show whether vigorous exercise was better for optimal benefit. In our study, we'll be measuring that."
Calling the study's results very promising, Virendra Mathur, MD, a cardiologist with the Texas Heart Institute at St. Luke's Episcopal Hospital in Houston, tells WebMD, "We've known for a very long time that moderate aerobic exercise is very helpful in not only preventing cardiovascular risk factors but also in reducing weight, improving control of hypertension and type 2 diabetes, reducing osteoporosis and fractures. I'm very happy to read that sometimes you can have the benefit of these exercise programs even without weight loss."
The study is preliminary and has limitations, says Mathur. "How long will health benefits last after people quit exercise programs? Will there be additional decreases in 'bad' cholesterol levels if they keep with the exercise program? Also, we don't know much about their diet -- did they start eating a lower-fat diet? Did they start making other smaller changes in their lifestyles? Were they walking faster in the parking lot, for instance? There are a lot of intangibles that aren't addressed here."
Exercise physiologist Amy Poole, MEd, of the cardiac rehabilitation program at St. Luke's, tells WebMD, "The aerobic benefits they saw were very significant. A lot of times you don't see that kind of gain. They did very well for just a three-month study."
- Exercising -- even if you don't lose weight -- can provide benefits to your health.
- A small study shows that moderate exercise four times per week with no weight loss improved risk factors for heart disease and diabetes, and reduced body fat.
- A larger, upcoming study will look at exactly how much exercise and at what intensity is necessary for health benefits.