Stretching Cold
A flurry of new studies suggests that the age-old practice of static stretching (think the pregame ten-second toe touch) doesn't reduce injury risk or improve performance. In fact, when done cold, aggressive static stretches can strain ligaments and tendons. "Static stretching isn't sport-specific," says Mike Rob­ertson, president of Indianapolis-based Robertson Training Systems. "It increases passive range of motion, but athletes don't need that. They need mobility." Put it this way: If flexibility is the ability to touch your palms to the floor without bending your knees—a good party trick—mobility is the functional range of motion you need to take long freestyle strokes in the pool.

The Fix: Never stretch cold. Instead, warm up and then try some mobility exercises, such as simple walking lunges, which increase strength and efficiency when you're moving through a normal range of motion. If you have a tendon or a muscle group that needs lengthening for your sport—a tight shoulder, if you're a swimmer, say—be sure to get blood flowing through the muscles and tendons with a light warm-up before you stretch.