Heart disease is (still) the number-one killer of women in the United States, so it's important to keep your ticker in shape.
Brisk walking might have the edge over running. Any aerobic activity improves heart health. But in a recent study published in Arteriosclerosis, Thrombosis and Vascular Biology, walkers saw twice the reduction in heart disease as runners when both groups burned the same number of calories while exercising. That means that if you walk you should exercise about twice as long as runners to get those benefits.