Short-duration stretching before exercise temporarily improves joint range of motion (ROM) and does not appear to alter muscle strength, according to research findings published in the American College of Sports Medicine's Medicine & Science in Sports & Exercise adding another voice to the debate on whether pre-exercise stretching contributes to a deficit in muscle strength and performance.
The study assessed 13 moderately active non-athlete volunteers, asking them to do practical durations of two, four and eight-minute sessions of lower leg and ankle stretching. The participants' exercise performance was measured before and immediately after, and also 10, 20 and 30 minutes after stretching. The stretching didn't cause any changes in muscle strength, compared to no stretching at all, but it did improve range of motion of the ankle joint.
It's traditionally thought that stretching improves joint range of motion, performance and reduce the risk of injury. The authors of the study noted that the majority of recent research findings suggest that stretching may compromise a muscle's ability to produce maximal force, thus stirring controversy about whether muscle stretching was an advantage 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," says Eric Ryan, lead author of the study.
Ryan continued, "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 exercises may impact athletes."
"Durations of stretching at or less than eight minutes may not significantly alter lower-leg strength," according to study co-author Joel T. Cramer, Ph.D., FACSM. "Our findings, in conjunction with previous studies, suggest that for these muscles, there may be a 'threshold' of stretching between eight and 10 minutes that would be necessary to decrease muscle strength."
ACSM recommends that flexibility exercises be a part of an overall fitness program, sufficient to develop and maintain ROM. The exercises chosen should stretch the major muscle groups and be performed a minimum of two to three days a week.