Women who do not exercise are three times more likely to die prematurely of a heart attack than women in a fitness program, and more than 80 percent of American women go without regular exercise, a study says.

"Using statistical techniques, we took into consideration other risk factors like blood pressure, smoking habits, cholesterol values and still found a strong protective effect for exercise," said Dr. Lars Ekelund, research associate professor of medicine at the University of North Carolina.The findings were presented Monday at the 61st Scientific Sessions of the American Heart Association.

Cardiovascular disease is the leading cause of death among American women. Each year about 250,000 women die from coronary heart disease while another 200,000 die from heart failure and stroke.

"This work clearly indicates women need to become more active," Ekelund said. "Even if a woman doesn't want to jog, swim or ride a bicycle, she can increase her fitness level significantly by walking three or more times a week."