t, such as moving toxins and
nutrients through your body and out -- the more you sweat, the more you excrete, etc. It builds heart endurance by working the heart harder than less cardio based exercise. Etc. But you can do that with an elliptical machine or swimming or bicycling or playing a fast-moving sport. You can do that climbing mountains. You can do that rowing. So running itself isn't a necessary endeavor unless, of course, someone or something dangerous is chasing you!