Hold Back the Newbie

From The New York Times

The theory is that the three sports work different muscles, ideally minimizing the strain on any single muscle set. For runners in particular, adding biking and swimming to their repertory means less pounding against pavement.

But in practice, people who take up triathlons tend to train harder, adding rigors to their workouts without necessarily subtracting anything. Thus, the idea that people can reduce their chance of injury by competing in triathlons may be a fallacy.