Play almost any sport at any level and chances are you will be called to stretch beforehand. The typical routine is well-known and widespread: Reach for your toes, hold the stretch for 10 or 15 or 30 seconds, release and move on to another muscle. It warms you up, limbers you up and gets you ready for tough competition, right? Not at all, according to the results of a recent study by kinesiology researchers — a study which does not appear to have taken the Yale athletic community by surprise. Staff reporter Monica Mark investigates.

Static stretches — stretching exercises that elongate the muscles, performed while the body is at rest — are likely not beneficial to a warm-up routine at all and could actually be dangerous, according to the research headed by scientists at the University of Nevada, Las Vegas. The study, which the New York Times featured in a recent article entitled “Stretching: The Truth”, instructed participants to perform static hamstring and quadriceps stretches and then measured their muscles’ power output. The results showed static stretching produces less-than-desirable results: In fact, less force was generated from leg muscles after a static stretching regime than from muscles that were not stretched at all.

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Dr. Peter Jokl, director of Yale’s Sports Medicine Center, said that it is true that static stretching may weaken muscles in the short-run. But he does not necessarily agree that it is “dangerous,” as the article claimed.

“They were talking about weakening the muscles — meaning how much power they can produce,” he said of the study’s authors. “Say you wanted to produce maximum force out of your muscles. If you disconnect links by overstretching, you can weaken the muscle in terms of how much horsepower, so to speak, you can produce.”

The primary function of a warm-up should be to increase body temperature, according to Jokl. Warm muscles use oxygen and stored energy more efficiently and can withstand more force.

“Connective tissue is like Tupperware,” he said. “If you put one in the fridge it gets stiff. When you run it under hot water, it’s more pliable.”

Increasing blood flow — another effect of warming up — also makes muscles more flexible, he added.

Experts recommend light jogging or comparable aerobic activity as a way to start a solid warm-up routine. The warm-up should last from five to 10 minutes, which will raise the body temperature between two to three degrees Fahrenheit, according to Jokl. However, the athlete should be careful to avoid too intense of a warm-up, which can itself lead to muscle strain or other injuries, he explained. Even if you do avoid injury, a burnout of a warm-upcan have a second unpleasant side effect: It could simply wear you out.

But, Jokl added, “The study overdramatized the idea that traditional stretching may not be good for you.”

Overdramatized or not, within Yale athletics, static stretching as a stand-alone warm-up went the way of leg warmers as fashionable workout gear a long time ago.

“This info is not new,” Richard Kaplan, assistant athletic trainer at Yale, said of the pitfalls of static stretching. “We have already instituted a ‘dynamic workout’ … with most of our teams and reserve the static stretching for right before our cool-down period.”

Indeed, dynamic stretching has taken the place of static stretching in many collegiate environments, though the latter still reigns supreme in amateur athletics. (Dynamic stretching is a process in which the muscles are stretched while moving — including squats, lunges, or the “Spider-Man,” which requires the athlete to get down on all fours and crawl as though he or she were climbing a wall.)

“We do a full dynamic warm-up,” Yale track and field head coach David Shoehalter said of the team’s pre-practice routine, “I’ve been coaching now for 20 years and have been doing dynamic warm-ups the entire time.”

In response to the claim that static stretching is dangerous, he added, “I wouldn’t say it’s dangerous, but it’s not helpful, and it can lead to injury.”

Alina Liao ’09, a member of the gymnastics team, said she was also skeptical of the idea that static stretches are dangerous if they are performed properly and at the right time.

“I’ve never seen anyone injured directly from static stretching,” she said in an e-mail message. “I don’t think it’s particularly harmful unless you do an extreme amount of static stretching immediately before active exercise.”

Still, according to Shoehalter, static stretching is problematic for reasons beyond muscle weakening.

While he says dynamic warm-ups wake up your nervous system, “static stretching sends the message to your brain that your muscles are done.”

“So the message the brain is getting is ‘All right, I’m finished,” he said, “and then all of the sudden, there you are redlining it, which can lead to muscle strains or pulls.”

But that’s is not to say static stretching should be nixed altogether.

Within the Yale track and field program, Shoehalter said, athletes perform an extensive static stretching routine following workouts, as opposed to preceding them.

Liao, whose warm-up routine includes both dynamic movements such as leg swings and static stretches like splits, also emphasized static stretching still has a place in a safe and healthy workout.

“Static stretching still might be important for preventing muscle tears or strains,” she said. “Especially as a gymnast, if my muscles are not already fully stretched and thus ready for the flexibility my sport demands, I certainly risk tearing a muscle.”

In the end, it may be more a question of power than of peril.

“More so than static stretching leading to injuries,” Shoehalter emphasized, “dynamic stretching enhances the ability to perform at high levels.”

In other words, static stretches won’t necessarily hurt you, but they won’t provide the performance boost of their dynamic counterparts — and could leave you sore and your muscles strained if used in lieu of an aerobic warm-up.

So if this research isn’t really new at all, then why are so many people outside the world of collegiate athletics hearing of it for the first time? Why is dynamic stretching such a well-kept secret?

“It’s hard to say,” Shoehalter said. “It’s kind of an ‘old-habits-die-hard’ situation. I think static stretching is the old school way of doing things, but if you look at any kind of major collegiate track program, they’re doing full dynamic warm-ups.”

Having come from amateur athletic environments, Shoehalter continued, many athletes have never been exposed to dynamic stretching, so when the warm-up is over, they ask why they haven’t yet had the chance to stretch.

“You just kind of have to change what they think is stretching,” he said. “You have to change their perception of what actually works.”