November 16, 2011, 12:01 AM
The Right Reasons to Stretch Before Exercise
By GRETCHEN REYNOLDS
For an article being published in next month’s issue of The British Journal of Sports Medicine, researchers at the University of Sydney in Australia reviewed dozens of recent studies of stretching, hoping to determine whether the practice prevents people from getting sore after they exercise. The authors found 12 studies completed in the past 25 years that looked directly at that issue. Most were small and short-term. But each produced essentially the same result, the review authors write, showing that “stretching does not produce important reductions in muscle soreness in the days following exercise.”
That does not mean that you shouldn’t stretch, the study’s authors add, but it does indicate that stretching may not provide the benefits that many of us expect.
Write about fitness, and you soon learn that stretching is one of the more contentious and emotional issues among people who exercise. Those who regularly stretch tend to assume that the practice will prevent soreness and injury. Those who do not stretch frequently claim, with equal fervor, that stretching is a waste of time.
A slowly growing body of science suggests that each group has some evidence backing it up, although reliable information about stretching remains hard to come by, in part because stretching is difficult to study.
Most of us, when we talk about stretching, mean the practice of assuming a pose, like bending over to touch our toes or leaning against a wall to stretch our hamstring muscles, and holding that position until the stretching feels uncomfortable, usually 30 seconds or so. This routine is known as static stretching, and it’s widely practiced by people before or after many types of activities. In one of the studies included in the new review, about 54 percent of the 2,377 active adult participants said that they regularly performed static stretching, and most added that they stretched in large part to avoid muscle soreness.
But in that study, which was conducted by Robert D. Herbert, a professor at the George Institute for Global Health at the University of Sydney, who also wrote the comprehensive review, the rates of reported muscle soreness were similar regardless of whether the volunteers completed a standard 15-minute program of static stretching. About 32 percent of those who didn’t stretch reported sore muscles the day after a workout. About 25 percent of those who had stretched reported the same.
Other studies have produced comparable data, with one experiment cited by Dr. Herbert finding that static stretching before or after endurance exercise reduced volunteers’ self-reported muscle soreness the next day by a grand total of just half a point on a 100-point scale of discomfort.
“Our interpretation of the data is that, on average, stretching really does reduce soreness, but the reduction is tiny,” Dr. Herbert told me, probably too small to be meaningful in practical terms. Most of us wouldn’t notice much difference in our muscle soreness regardless of whether we stretched.
This finding jibes with other, related science suggesting that static stretching is not particularly good at reducing injury risk, either. In the same randomized study by Dr. Herbert, those who stretched experienced about the same number of sports-related injuries as those who didn’t.
But most experts caution that it’s difficult to interpret these results, because no studies of stretching meet the scientific gold standard of being both randomized and blinded. You can randomly assign people to groups that stretch or don’t stretch, of course, but you can hardly disguise from them whether they’re stretching or not. At the same time, volunteers’ subjective opinions about stretching seem to affect study outcomes, too. In Dr. Herbert’s experiment, those volunteers who “strongly agreed” at the start of the study that stretching is important rarely reported sore muscles if they were assigned to the stretching group. If, on the other hand, these stretching enthusiasts were assigned to not stretch, they were more likely than other volunteers to feel that their muscles were now growing sore.
So what does all of this intriguing but still muddled science about stretching mean for those of us who regularly exercise?
“It does not mean that you should not stretch,” said Dr. Michael Fredericson, a professor of sports medicine at Stanford University and the chief physician for that school’s cross-country and track-and-field teams, who recently completed an online report about stretching. So-called dynamic stretching regimens, during which you move while lengthening muscles and connective tissues, could be more effective than static stretching at reducing injuries and soreness, he says. Try substituting jumping jacks for toe touches before a run, he says. “And if you feel frequent tightness” in certain muscles or tissues, like in the iliotibial band that runs along the outside of your knee, a common occurrence in distance runners, “then stretch those particular muscles after exercise to lessen your chances of serious injury.”
If you’ve never stretched, though, don’t feel obligated to begin now, Dr. Herbert says. “There is little evidence that stretching does anything important,” he says, “but there is also little to be lost from doing it. If you like stretching, then do it. On the other hand, if you don’t like stretching, or are always in a rush to exercise, you won’t be missing out on much if you don’t stretch.”
http://well.blogs.nytimes.com/2011/11/16/the-right-reasons-to-stretch-before-exercise/?ref=health
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