The researchers extrapolated those results to the entire U.S. population born in the same years as those in the study. They estimate that 3.52 million Americans in that age group lead sedentary lives, and that almost 228,000 of them would have died during the years of the study. Of those 228,000 deaths that might be attributed to a sedentary lifestyle, more than 146,000, or 64 percent, would be among those with high cardiovascular risk.
Although it's impossible to tell which came first, the heart risk or the lack of exercise, Richardson notes they go hand in hand -- especially among people with existing cardiovascular illnesses who cling to outdated beliefs that they shouldn't exercise because it might set off a heart attack. In fact, she says, the benefit of physical activity for most high cardiovascular disease-risk individuals probably outweighs the risks.
"For these people, the risk of having an acute problem brought on by exercise is small compared with the much higher risk of remaining sedentary," says Richardson. She is currently leading a VA-funded multicenter randomized controlled trial that will enroll veterans with cardiovascular risk factors and follow them for six months of walking using a pedometer, and diet and exercise counseling. She's also planning a study funded by the National Heart, Lung and Blood Institute that will use enhanced pedometers to encourage people with cardiovascular disease to walk.