August 6 (HealthDay News) -- Short-duration stretching before exercise temporarily improves range of joint motion and doesn't weaken muscles, says new research that fuels the debate about whether stretching before exercise reduces muscle strength and performance.

In this study, moderately active, non-athlete participants did two, four and eight-minute sessions of lower leg and ankle stretching. The participants' exercise performance was assessed before and immediately after, and also 10, 20 and 30 minutes after stretching.

The stretching didn't cause any changes in muscle strength, but did improve range of motion of the ankle joint. The findings were published in the August issue of Medicine & Science in Sports & Exercise.

"In moderately active individuals, short durations of stretching seem to temporarily improve flexibility without the detrimental strength losses that have been previously reported," study author Eric Ryan said in an American College of Sports Medicine news release.

"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," Ryan said.

"Durations of stretching at or less than eight minutes may not significantly alter lower-leg strength," study co-author Joel T. Cramer said in the news release. "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."

SOURCE: American College of Sports Medicine, news release, July 23, 2008