Here's more from Gabe Mirkin MD, an athlete in his own right (
www.drmirkin.com):
"An article in the British Medical Journal shows that stretching before and after exercising does not prevent next-day muscle soreness or injuries. Researchers in Australia reviewed five studies, involving 77 subjects, on the effect of stretching on muscle soreness. Data from two studies on army recruits in training show that muscle stretching prevents one injury every 23 years. Yet most coaches think that stretching prevents injuries because most coaching instructions are developed by observation, not controlled studies.
Muscles and tendons tear because the force on them is greater than their inherent strength, so the prevention of injuries should be aimed at strengthening muscles, rather than stretching them. Stretching can make you a better athlete. Longer tendons allow a greater torque on a joint to generate more force to help you run faster, lift heavier, throw further and jump higher. Stretch to become a better athlete, not to prevent injuries. .... Competitive athletes need to stretch to makes muscles and tendons longer and more flexible. A longer muscle can exert a greater torque on a joint to help you run faster, lift heavier, throw further and jump higher. Stretching should always be done after your muscles are warmed up. You are likely to injure yourself if you stretch before you have warmed up or when your muscles are tired. 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. If you're over 50, be extra careful because older muscles are less springy and more likely to tear. "