Read more about it on Time: http://healthland.time.com/2012/10/10/for-better-heart-health-exercise-harder-not-longer/#ixzz29m2fugdP
"The general advice for most Americans is: Get more exercise. But the question is what kind of exercise, how intensely and for how long?
A new study suggests that for improvements in cardiovascular health, you should pick up the pace. More intense exercise (brisk walking) was better than longer bouts of lower-intensity activity (leisurely walking) at reducing people’s chances of developing risk factors for heart disease and diabetes, researchers found."