So why in the world do so many of us still warm up by stretching?

"Of course, many of us might accept a temporary reduction in strength and even in speed if stretching protected us against injuries, as many of us have long believed that it must. But in multiple large-scale studies of military recruits during basic training, stretching before long marches and runs did not lessen the incidence of overuse injuries. In the largest of these studies, results showed that an almost equal number of soldiers developed lower-limb injuries (shin splints, stress fractures, etc. ), regardless of whether they had performed static stretches before training sessions. Similarly , in the largest study to date of everyday athletes who stretched, almost 1,400 recreational runners aged thirteen to 60-plus were assigned randomly to two groups. The first group did not stretch before their runs, while otherwise maintaining their normal workout and warm-up regimens. The second group did stretch.

Both groups followed their routines for three months. At the end of that time, quite a few of the runners had missed training days due to injury , a predictable result, since running is one of the most injury-plagued sports on the planet. But there was no difference in the final pain tally between the two groups. The same percentage of those who stretched injured themselves as those who didn’t. Static stretching had been a wash in terms of protecting against injury, raising the obvious question: So why in the world do so many of us still warm up by stretching?"

To stretch or not to?

"More surprising, when researchers compared the runners’ flexibility scores to their best times in a 10K road race, those with the tightest, least flexible hamstrings tended to be the fastest. They also had the best running economy , meaning that they used the least energy to go the same distance as other runners. Probably , the researchers concluded, tighter leg muscles allow “for greater elastic energy storage and use” during each stride. Think of a rubber band. If it’s overstretched and limp, it doesn’t snap back when pulled and released. So, too, with your hamstrings: If they’re loose, they don’t efficiently lengthen, shorten, and snap back into place with each stride. To some degree, as an endurance athlete you can be as flexible as Morph, or you can be good."

Stretching: Myth busted

"Most of us learned how to warm up in grade school , by touching our toes and slowly stretching our muscles, and haven’t changed our routines much since. Science, however , has moved on. In the past decade, a growing number of studies have shown that static stretching not only does not prepare muscles for activity; it almost certainly does the reverse. In a representative experiment conducted a few years ago at the University of Nevada, Las Vegas, athletes generated less force from their leg muscles after static stretching than they did without stretching. Other studies have found that stretching before exercise decreases strength in the stretched muscle by as much as 30 percent.Weirdly , stretching the muscles in one leg can even reduce strength in the other leg, an effect that can last for up to 30 minutes. In a few key real -world studies, basketball players who stretched before a game were unable to jump as high during play as when they hadn’t stretched."

Stretching the Truth

"For a study published in late 2010, scientists at the Florida State University , in Tallahassee, recruited ten competitive male collegiate athletes and asked them not to stretch during their warm-ups. Many athletes would, of course, balk at that request. A separate, large-scale study of recreational runners, conducted under the auspices of the USA Track and Field Association and also published in 2010, required years to complete, because the researchers couldn’t find a sufficiently large body of runners willing to give up their stretching routines, even in the interest of science. Thankfully , college-age men are, in general , not averse to avoiding physical exertion, even stretching, when they can, and so the ten men signed on.

The researchers brought the volunteers into the university’s exercise physiology laboratory for a series of fitness tests, including measurements of their flexibility , then had them return for two additional sessions. During both, the men ran on a treadmill for an hour . In one session, they prepared for the run by simply sitting quietly for sixteen minutes. In the other , they stretched first, following a scripted sixteen-minute static-stretching routine. Static stretching (which is what most of us mean when we talk about stretching) involves stretching a muscle to its maximum length and holding it for 20 or 30 seconds. After stretching, the men felt more flexible.

But their performance declined, significantly . During the hour-long run, they covered less distance than when they had just sat quietly .They also consumed more calories and oxygen during the run, suggesting that their strides had become less economical , that the running was physiologically harder . The implication, the scientists concluded, was obvious. “Static stretching should be avoided before endurance events, ”they wrote.To which many athletes would respond, if their on going behavior is any indication, with an eye roll and a brush-off."