Gabe Mirkin, M.D.

A study from Montreal shows that there is no evidence that stretching helps to prevent injuries, but it can help to make you a better athlete.

Lots of people think that stretching prevents injuries. Every time you exercise, your muscles are injured. When they heal, they shorten and are more likely to tear. Nobody has shown that stretching prevents injuries. Muscles and tendons tear when the force on them is greater than their inherent strength. Heavy resistance training, not stretching, strengthens muscles and makes them less likely to be torn.

If you're over 50, be careful because aging robs muscles of their springiness, making them more likely to tear. Competitive athletes need to stretch to makes muscles and tendons longer to generate a greater torque about a joint, so you can lift heavier, run faster, jump higher and throw further. Stretching should be done after warming up. Resting muscles are cold. Warming up raises muscle temperature to make them more pliable. Stretch no further than you can hold for a few seconds. Bouncing gives you a longer stretch, but can tear muscles. Only competitive athletes need to stretch further than they can hold for a few seconds.

I Shrier. Stretching before exercise does not reduce the risk of local muscle injury: A critical review of the clinical and basic science literature. Clinical Journal of Sport Medicine, 1999, Vol 9, Iss 4, pp 221-227.