走路有个量和质，量是走多少？质是走多快？两者不可缺一，否则没什么用！

The Mayo Clinic recently published an illuminating report showing that participating in excessive endurance exercises--like marathons, triathlons and long-distance bike races-- may actually change the structure of your heart and major arteries. The activity causes volume overload, and may result in stiff arteries, coronary artery calcification and other dangerous conditions that may ultimately lead to heart disease.

Another recent study followed runners and walkers who had already survived heart attacks. Although patients who continued to run or walk at moderate levels had a lower risk of repeat attacks, those who ran more than 7.1 kilometers or walked more than10.7 kilometers per day did not gain any cardiac benefits.