If you stretch before or after exercising because it feels good, go for it, health experts say.
But if you try to loosen up that way because you think you might prevent an injury, you should reconsider. Stretching can cause injuries and reduce muscle effectiveness, studies show.
"For the average person, stretching doesn't represent the panacea it's being billed as," says Jordan Metzl, a physician and avid runner who is preparing for his 27th marathon.
Metzl, 43, competes Sunday in the ING New York City Marathon and has raced in seven Ironman competitions. He specializes in non-operative sports medicine at the Hospital for Special Surgeries in New York.
Metzl does not rule out stretching, which has traditionally been drilled into athletes as a method to improve circulation and flexibility and prevent injuries. But he downplays its importance, saying a good warm-up can be sufficient for most people, unless they're dancers "who need to get their foot near their head."
"Stretching has received a fantastic publicity campaign," he says. "If I were given a choice and could go live on one island where they stretched all the time or one island where they do strength training, I'd go to the strength-training island."
For certain injuries, he agrees stretching can be beneficial. If he starts to cramp up in a race, he'll stop and gently stretch the muscle to prevent it from tearing.
Scott Sailor, athletic training education program director at California State University-Fresno, is a big believer in stretching for athletes, though he says there are limits.
"By stretching, they'll maintain a body that is in balance. Flexibility is one part of fitness, and it shouldn't be neglected," he says.
But, he says, "I like to get people to a functional range of motion. We don't have to be able to put our leg behind our head to be able to jog, to sprint and to swim. That's just excessive flexibility. There's no purpose for it."
Research by Robert Herbert and Marcos de Noronha at the University of Sydney showed stretching before exercise doesn't eliminate muscle soreness or prevent overuse or acute sports injuries. Bill Holcomb's research at the University of Nevada shows stretching can decrease strength, power and performance.
Static stretching in which you hold a pose too long or, even worse, bounce while trying to touch your toes, is the problem. Metzl says a good guideline is holding an easy stretch for 15 seconds and never extending until it's painful.
William Meller, an internist in Santa Barbara, Calif., goes a step further in Evolution R{-x}. He says do not stretch.
"In all the studies of modern-day hunter/gatherers, none have ever been seen to stretch forcefully before engaging in any activity, no matter how strenuous," Meller says. "Stretching does damage. Warm up instead."
"Dynamic warm-ups" include arm circles, jogging in place or a yoga exercise involving slow, controlled movements like sun salutations, a 12-step sequence traditionally done at sunrise that limbers up the spine, expands the chest and makes muscles supple.
Terry Noonan, director of athletic training services at the University of Northern Iowa in Cedar Falls, advises doing dynamic warm-ups for 10 minutes when possible.
"I'm always pushing it with my football coaches to get that much time before practice," he says. "When the players get out on the field, I have them jog a lap just to warm up and then do high knee jogs. I also have them move laterally because hip flexibility is important."
Metzl re-emphasizes that "strength training is so much more important than stretching" for protecting muscle.
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