Cooling Down after a Workout

You should not stop suddenly after running very fast or doing any other very intense exercise, because it may cause you to pass out.

During running, your leg muscles serve as a second heart. When your leg muscles relax, the veins near them fill up with blood. When your leg muscles contract, they push against the veins near them and squeeze the blood toward your heart. If you exercise vigorously and stop suddenly, the leg muscles stop contracting and blood can pool in your legs, so not enough blood passes to your brain and you can pass out. This is the reason you should always cool down after vigorous exercise. If you slow down gradually, your leg muscles stop pumping gradually and you heart has time to pick up its share of the workload.

Many people believe that cooling down helps to prevent muscle soreness by clearing lactic acid from muscles, but there is no evidence to support this theory. Muscle soreness after exercise is caused by small tears in the muscle fibers, not by accumulated lactic acid. Plan to cool down just to prevent dizziness or fainting.

Checked 10/9/09

Get our newsletter