For generations, gym students were taught to stretch before working out or playing games. Then the practice fell out of favor: Studies seemed to show that such ‘‘static’’ stretching (holding a pose for anywhere from a few seconds to several minutes) temporarily reduces muscular power, weakens athletic performance and increases the risk of injury. So most fitness experts currently advise against static stretches before exercise. But now a comprehensive new review of decades’ worth of research indicates that they might not be such a bad idea after all.
This month, the journal Applied Physiology, Nutrition and Metabolism published a study by four distinguished exercise scientists who analyzed more than 200 studies of how stretching affects subsequent exercise. (The authors had conducted some of these studies themselves.) In broad terms, they found that static stretching can briefly inhibit the ability to generate power. So if you reach for your toes and hold that position, tautening your hamstrings, you might not then be able to leap as high or start a sprint as forcefully as if you hadn’t stretched.
Those undesirable effects were generally found, however, only if each stretch was held for more than 60 seconds and the subject then immediately became fully active, with no further warm-up. Those are hardly real-world conditions, says Malachy McHugh, the director of research at the Nicholas Institute of Sports Medicine and Athletic Trauma at Lenox Hill Hospital in New York, who is the study’s co-author. Outside the lab, he says, most people are unlikely to hold a warm-up stretch for longer than about 30 seconds. The review found few lingering negative impacts from these short stretches, especially if the volunteers followed that stretching with several minutes of jogging or other basic warm-up movements. In fact, these short static stretches turned out to have a positive correlation. People who stretched in this way for at least five minutes during a warm-up were significantly less likely to strain or tear a muscle subsequently. 纽约时报中英文网 http://www.qqenglish.com
Do these findings mean that those who happily dropped pre-exercise stretching from their warm-ups should reinstate the practice and overturn, once again, accepted fitness wisdom?
Not necessarily, Dr. McHugh says: ‘‘Runners and cyclists don’t have much risk for acute muscle strains.’’ Stretching before these activities is therefore unlikely to protect against injury. (Stretching after workouts, or the occasional yoga class, is advisable for everyone, he adds. Such postexercise stretching was not a part of the review, though.) Runners and cyclists can adequately warm up, Dr. McHugh says, by jogging or pedaling lightly. But he suggests that people who play basketball, soccer, tennis and ultimate Frisbee — or other sports that involve leaping, sprinting and forceful, potentially muscle-ripping movements — should stretch in advance. Those who haven’t stretched since childhood gym class might want to consider consulting an athletic trainer about the best upper- and lower-body stretches, particularly for the shoulders, hamstrings and thighs.