Regular stretching over a few days or weeks before sports or exercise appears to improve performance, while performing stretches only just before these activities may actually decrease performance, according to a review of studies on the topic.

“Therefore, if one stretches, one should stretch after exercise, or at a time not related to exercise,” writes study author Dr. Ian Shrier of Sir Mortimer B. Davis-Jewish General Hospital in Montreal, Quebec.

Many clinicians and fitness instructors advise people to stretch before exercising to prevent injury, but recent reviews of studies examining the benefits of such stretching suggest it may not reduce one’s injury risk. Some experts also believe that stretching may improve performance.

To investigate this claim, Shrier analyzed the results of studies on stretching and sport performance. His findings are published in the current issue of the Clinical Journal of Sport Medicine.

The results of 22 of the 23 articles that looked at the benefits of stretching immediately before exercise showed that stretching did not improve the study participants’ outcome in various measures, including a test of their jumping height - a skill that can definitely affect a basketball player’s performance, Shrier found.

Of the four articles that examined whether pre-exercise stretching helps improve running speeds, one showed it to have a positive effect, while another showed it to be detrimental. The remaining two had ambiguous results.

Overall, Shrier writes, “an acute bout of stretching does not improve force or jump height, and the results for running speed are contradictory.”

In contrast, seven of the nine studies involving regular stretching showed it to have a beneficial effect on performance, the report indicates. Repeated stretching was found to improve study participants’ jump height, speed and force. None of the studies suggested that regular stretching hampered performance.

These findings are similar to those previously reported by researchers who found that regular stretching, rather than pre-exercise stretching, may reduce one’s risk of injury, the author notes.

Commenting on the study, Dr. Mike Bracko, Calgary, Alberta- based spokesperson for the American College of Sports Medicine, noted that the value of stretching is a “huge” topic among researchers these days.

“There isn’t as much benefit…as we once thought,” he told Reuters Health. Previous research about the benefits of stretching was “based on the perceived notion that flexibility improves performance and reduces injury risk,” he said.

“Flexibility is sport-dependent,” he added, noting it has greater benefit for athletes such as gymnasts and figure skaters. But in ice hockey, for example, and some other sports, players “don’t need a high level of flexibility,” he said.

SOURCE: Clinical Journal of Sport Medicine, September/October 2004.