Stretching Before or After a Workout Doesn't Banish Soreness Later

SYDNEY, Australia, Oct. 17 -- Stretching before or after exercise won't spare either elite athletes or weekend warriors from muscle soreness one to three days later, investigators here have found.

A review of mostly lab-based studies showed that stretching before exercise reduced soreness on the day after by just half a point on a 100-point scale, and stretching after a workout reduced soreness by one point, and neither measure was statistically significant, reported Robert Herbert, Ph.D., and Marcos de Noronha, Ph.D., of the University of Sydney.

The effects of stretching on soreness were similar -- that is, negligible -- up to three days later, the authors noted in the fourth issue for 2007 of the Cochrane Library.

"Arguably the findings of this review are clear enough that further research into the effects of stretching on muscle soreness is not necessary. We see some merit in this view," the authors wrote. "However, in our opinion it would be useful to conduct further trials of the effects of longer-term stretching programs, in community-based populations and for people with reduced flexibility."

The authors based their confident assertions on a systematic review and meta-analysis of 10 published studies of stretching either before or after athletic activity.

They combed through orthopedic, sports medicine, and general medicine databases, using criteria that included randomized or quasi-randomized studies of any pre- or post-exercise stretching technique designed to prevent or treat delayed-onset muscle soreness, with the provision that the stretching was conducted soon before or soon after exercise. The studies had to include an assessment of muscle soreness or tenderness to be considered.

The authors assessed the methodological quality of the studies using the Cochrane Bone, Joint and Muscle Trauma Group's methodological quality assessment tool, with estimates of effects of stretching converted to a common 100-point scale. They also pooled study outcomes for a fixed-effect meta-analysis.

Nine of the 10 studies were performed in lab settings with standardized exercise protocols; the last one looked at post-exercise stretching ("active warmdown") in Australian-rules football players.

All studies involved healthy adults. Three looked at stretching before exercise, and seven looked at stretching after exercise. In two studies, both looking at the effects of stretching after exercise, participants underwent repeated stretching sessions at intervals of greater than two hours. The duration of stretching applied in a single session ranged from 40 to 600 seconds.

"All studies were small (between 10 and 30 participants received the stretch condition) and of questionable quality," the authors wrote.

When they pooled the estimates, they found that pre-exercise stretching was associated with a reduction in soreness on the day after exercise by an average 0.5 points on the 100-point scale (95% confidence interval -11.3 to 10.3; three studies).

In four studies, stretching after exercise was associated with a reduction in soreness the next day by an average of one point (95% CI -6.9 to 4.8), and there were similar effects (or lack thereof) of stretching pre- or post-exercise from one half to three days after the event, the authors said.

"The best available evidence indicates stretching does not reduce muscle soreness. However there are other justifications for stretching," they wrote. "Some evidence suggests that once muscle soreness has developed stretching may provide a transient relief of soreness: some people stretch to reduce risk of injury, others stretch to enhance athletic or sporting performance, and yet others stretch because it gives them a sense of well-being. The current review does not provide any evidence of an effect or otherwise of stretching on risk of injury, performance, or well-being."

The authors noted that, although the quality of the studies they looked at was generally poor by the standards of evidence-based medicine, there was a high degree of consistency across the studies regarding the effects of stretching.

Additionally, they wrote, the studies were unblinded and did not have an intention-to-treat analysis, which would tend to create an exaggerated treatment effect, yet the treatment effects detected were actually quite small.