Acute stretching immediately before sport or exercise may actually hinder, rather than improve, sport performance, suggests a review of research data published in the September/October Clinical Journal of Sport Medicine.
In contrast, a program of regular stretching seems to improve many aspects of sport performance, probably by increasing muscle strength, reports Dr. Ian Shrier of SMBD-Jewish General Hospital in Montreal.
Dr. Shrier collected and analyzed previous studies of the effects of stretching on sport performance. Rather than assessing performance in actual athletic events, the studies focused on the effects of stretching in specific tests related to sport performance.
The analysis included 23 studies evaluating the effects of "acute" stretching—that is, stretching immediately before the test. Nearly all of the studies found that stretching reduced performance on various tests, including muscle force, torque, and jumping height.
The sole exception was a study showing that stretching improved "running economy." Studies of the effect of acute stretching on running speed yielded mixed results.
Dr. Shrier also identified nine studies of the effects of regular stretching programs, usually lasting several weeks. Of these, seven studies found better performance with regular stretching. This included improved performance in tests of muscle force production and contraction velocity, suggesting that the benefits resulted from muscle strengthening.
One study found that regular stretching improved running speed in the 50-yard dash, although two studies found no effect on "running economy" during longer runs. None of the studies found worse performance after regular stretching.
Stretching has been widely recommended to reduce the risk of exercise-related injury, although recent studies have questioned whether stretching has any real effect on injury rates. If there is a protective effect, it appears to result from regular stretching rather than acute stretching.
The new review suggests that stretching improves performance in a number of athletic tests, but only if it is done regularly. As in studies of injury risk, stretching appears most beneficial if done regularly.
In contrast, acute stretching does not seem to improve sport performance. Pre-exercise stretching may even reduce performance, probably because of muscle damage caused at the time of the stretch. Dr. Shrier concludes, "if one stretches, one should stretch after exercise, or at a time not related to exercise."
The full-text article is available free at http://www.cjsportmed.com.