Short durations of stretching prior to activity may not alter muscle strength, and appears to temporarily improve joint range of motion (ROM), suggests a study published in the August 2008 issue of Medicine & Science in Sports & Exercise ®, the official scientific journal of the American College of Sports Medicine (ACSM). The outcomes add to the debate on whether pre-exercise stretching contributes to a deficit in muscle strength and performance.

The study focused on practical durations of lower-leg and ankle stretching - in two, four and eight-minute segments - among moderately active, nonathlete individuals. Researchers tested the individuals in intervals before and immediately after, and also 10, 20, and 30 minutes after stretching. Compared to no stretching at all among participants, the results indicated no stretching-induced changes in muscle strength, although there were improvements in ROM of the ankle joint.

Stretching prior to exercise or activity has been associated with increased flexibility, and enhanced flexibility was traditionally thought to aid or improve performance and reduce the risk of injury. The authors noted that the majority of recent studies suggest stretching may compromise a muscle's ability to produce maximal force, thus stirring controversy about whether muscles should be limber prior to activity.

"In moderately active individuals, short durations of stretching seem to temporarily improve flexibility without the detrimental strength losses that have been previously reported," said Eric Ryan, lead author on the study. "Pre-competition stretching became controversial due to what has been reported as decreases in performance, however, future research still needs to determine how these stretching durations may impact athletes."

ACSM recommends that flexibility exercises should be a part of an overall fitness program, sufficient to develop and maintain ROM.These exercises should stretch the major muscle groups and be performed a minimum of two to three days a week.

"Durations of stretching at or less than eight minutes may not significantly alter lower-leg strength," said Joel T. Cramer, Ph.D., FACSM, an author on the study. "Our findings, in conjunction with previous studies, suggest that for these muscles, there may be a 'threshold' of stretching between 8 and 10 minutes that would be necessary to decrease muscle strength."

Medicine & Science in Sports & Exercise® is the official journal of the American College of Sports Medicine, and is available from Lippincott Williams & Wilkins at 1-800-638-6423. For a complete copy of the research paper (Vol. 40, No. 8, pages 1529-1537) or to speak with a leading sports medicine expert on the topic, contact the Department of Communications and Public Information at 317-637-9200 ext. 127 or 133. Visit ACSM online at

The conclusions outlined in this news release are those of the researchers only, and should not be construed as an official statement of the American College of Sports Medicine.

American College of Sports Medicine