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[UPDATE: Welcome Reddit Running and Running Times folks! In answer to the question on the Running Times homepage, 11 of the 12 studies in this review used static stretching, while one used PNF stretching.]

The British Journal of Sports Medicine just published an analysis of the most recent Cochrane Review on stretching to prevent or reduce muscle soreness. The title says is all: “Stretching before or after exercise does not reduce delayed-onset muscle soreness.” This isn’t a surprise — while the exact mechanism that leads to DOMS is still up for debate, it’s pretty clear that it involves microscopic damage to muscle fibres and the subsequent repair process. Once those muscle fibres are damaged, no amount of post-exercise stretching can magically undamage them!

The analysis incorporated 12 studies, including one very large randomized trial with 2,377 participants. There was no difference between pre-exercise and post-exercise stretching in the effect on soreness. Of the 12 studies, 11 used static stretching and one used PNF stretching. Here’s a forest plot of some of the results, from the BJSM summary:

As the Cochrane Review notes, people generally stretch for one of three reasons:

reduce the risk of injury; enhance athletic performance; reduce soreness after exercise.

There’s plenty of evidence that the second point is misguided: stretching actually seems to harm athletic performance in many contexts. Now this Cochrane Review reaffirms that the third point is misguided too — and the BJSM reviewers make it clear that, in their opinion, this isn’t one of those tentative findings that might be modified by future research:

The best available evidence indicates that stretching does not reduce muscle soreness. These findings were consistent across settings (laboratory vs field studies), types and intensity of stretching, populations (athletic or untrained adults of both genders) and study quality. As such, they are unlikely to be changed by further studies.

That leaves the first point — reducing injury. There’s still a little wiggle room here. Numerous studies have failed to find any reduction in injuries following stretching, but it’s certainly a complicated topic. In particular, I’m open to the possibility that individually tailored stretching targeted at specific areas of weakness, inflexibility or imbalance could help people avoid or treat certain injuries.