The running literature emphasizes that we should end our runs with a cool-down of several minutes. I've never thought much about cooling down. I just did it because the literature said to do it. However, I recently read in a couple of websites that cooling down helps prevent pooling of blood in ones feet, and I began to realize there may be medical reasons for it. Cooling down after exercise is just as important in reducing the risk of injury as the warming up process before exercise. Cooling down means gradually slowing down the level of activity. There are very definite medical reasons for cooling down, and I would suggest that if you're not doing it, start now! Be sure you include all three elements of cooling down: gentle exercising, stretching, and refueling.