Your waistline may weigh more heavily in your risk of coronary heart disease, but exercise habits make a big difference as well.

Research shows that regular physical activity helps prevent coronary heart disease. Regular exercise helps to control weight, lower blood pressure, and improve blood lipid levels. Yet, despite these beneficial effects, too many Americans are content with a sedentary lifestyle. According to the American Heart Association, only about 30% of adult Americans participate in any regular physical activity, and this level of participation tends to decline as people get older. Only 16% of people age 75 and older exercise on a regular basis.

Now research reported in the Journal of the American Medical Association (Volume 295, page 1412 ) underscores the importance of BOTH exercise and weight control in maintaining a healthy heart. Researchers found that among more than 27,000 middle-aged women, those who were overweight or sedentary were more likely to have various biomarkers of higher coronary heart disease risk -- including high LDL cholesterol, low HDL cholesterol, and elevated levels of blood proteins like C-reactive protein (CRP) and fibrinogen.

Weight was a more significant factor than exercise for predicting the presence of these biomarkers, but even overweight women improved their heart risks by getting regular exercise. Still, women who were both normal weight and regularly active had the best heart-health profile. Compared with them, normal weight, sedentary women were 26% more likely to have high CRP levels, while the odds were tripled among those who were both overweight and inactive. Obese women had still higher risks. Similar associations were observed for the other biomarkers.

Bottom line: The findings point to the importance of both exercise and maintaining a normal weight. Though a thin physique may be preferable to an apple shape when it comes to heart health, even slim women need regular exercise.

Johns Hopkins Health Alert of April 11, 2008