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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.
Surely there’s a fourth reason for stretching, which is to increase or maintain flexibility and range of movement. That’s important for some physical activities though not for all.
And based on personal experience of fairly intensive physiotherapy, I’d certainly agree that individually tailored stretching can be important in addressing specific imbalances.
@Hilary: Yes, absolutely. If you’re a hockey goaltender or a ballerina, range of motion is of course essential to success.
What about stretching already sore muscles? For example, my calves are killing me after Sunday. DOMS or overuse or tightness? I don’t know. I always have tight calves. When I stretch them (properly, as in, I stretch both calf muscles), the soreness goes away. Does that fall under the injury-reduction heading or the soreness-reduction heading?
You mean stretching already-sore calves makes the soreness go away instantly? Or it goes away the next day?
[P.S. Oh, and good race, by the way! I see from the splits that you used your wily veteran pacing to reel in Mihira!]
These studies are great, but all have one key flaw- they look at the impact of that particular bout of stretching in relation to the subsequent bout of exercise (or at least within a short time frame). So yes, if you stretch, for example, your soleus before and after your run, you will not have a positive impact on soleus soreness or performance relating that particular run.
However, following a routine soleus stretching regime to prevent hypomobility seems like it should decrease the likelihood in injury. There are references showing that Achilles tendonopathy is related decrease dorsiflexion, for instance (I’m too lazy to look that up right now though haha).
These studies just show that it does not matter if your stretching regime takes place before, after or nowhere near when your exercise (maybe just not to do it before, if anything).
I guess my point is, (and as you alluded to at the end) don’t let studies like this discourage you form maintaining flexibility by stretching regularly.
@Sean: I wouldn’t say that’s a “flaw” in the studies. The review I blogged about is looking specifically at the acute impact of stretching on next-day muscle soreness (i.e. the third of three reasons I listed for stretching). It’s a short time frame because that’s what the studies are looking at.
In terms of the ability of chronic stretching to reduce injuries (the first of the three reasons I listed), I agree that it remains an open question. That being said, a number of very large reviews have examined this question and failed to find any evidence that it’s true. For example, this 2004 review of 361 studies by the Centers for Disease Control and Prevention found that “stretching was not significantly associated with a reduction in total injuries.”
Of course, it makes sense that abnormally limited dorsiflexion would be associated with increased risk of Achilles tendinopathy. And as a result, it seems plausible that routine soleus stretching would reduce that risk. But just because there’s a correlation doesn’t mean the associated intervention will necessarily help. Maybe people with short calves are just more likely to have Achilles problems! To show that calf stretching prevents Achilles problems, we need a study showing that people who do calf stretching get fewer Achilles problems. And as far as I know, that type of evidence has proven to be far more elusive than we might have expected (e.g. see this review).
@alex
I guess “flaw” is the wrong word- the review drew conclusions on exactly what they set out to examine. However, I wanted to highlight the fact that this review does not address chronic stretching, especially with the title of your entry being “Stretching doesn’t prevent or reduce muscle soreness” (because, maybe it does in the long term).
@Sean: Sorry, maybe I misunderstood your previous comment. I thought you were arguing that chronic stretching might reduce injuries (like Achilles tendinopathy), which is a question addressed by the other review I linked to.
In this case, if you’re arguing that chronic stretching might reduce muscle soreness in the long term, that is indeed a different question. I’ve never actually heard anyone suggest that. Do you think it’s true?
I grew up with stretching, and in a sport like swimming where flexibility is considered far more important than in running, I always felt like I should be doing it. But with more information in the past few years I and my training partner have been stretching only small amounts and we are doing better. I am not saying that stretching is the reason why, but I will say it seems like I maintain more power over the long term by not stretching as often. (I know that is not worded very well, but that is the best way I can think to describe right now… almost like chronic stretching continually weakened me). I know Alex believes in proper studies (as do I), but this is my personal experience.
@Sean
Resistance training by itself has been shown to increase flexibility.
http://www.ncbi.nlm.nih.gov/pubmed/11834101
http://www.ncbi.nlm.nih.gov/pubmed/11842358
http://www.ncbi.nlm.nih.gov/pubmed/20940647
http://www.ncbi.nlm.nih.gov/pubmed/21969080
Static stretching is not always necessary.
@Hilary Curtis Im with Hilary on this one too.
I found a majority journal articles are not conclusive about stretching before exercise in regards to dynamic stretching. Its a very difficult subject matter, (considering protocol; participants; lab and field variations.) Whilst it is believed to hinder some 1RM exercises the jury is out about its effect on longer endurance activity. It is suggested that dynamic or static stretching after exercise, as Hiliary stated, is advantageous for range of movement, flexibility, and for reducing stiffness (for older participants)….. (me!)
Therefore, I wouldnt rule it out just yet 🙂
Perhaps there are people stretching to prevent DOMS, but fit athletes don’t even consider DOMS when incorporating post-run stretching into their routine. That’s because they don’t get DOMS anymore. Post-run stretching is all about lessening muscle tightness and tension at the beginning of the next day’s run. Just as trainers rush the field to stretch a football player’s calf when he tumbles to the ground with a calf muscle spasm, post-run stretching helps relieve tightness that results from the stress of workouts. Most top runners I know gave up pre-run static stretching long ago (before studies told them to do so), and they stretch post-run for the same reason: real-world experience.
@Pete
I am a post run stretcher, have been for years. My flexibility has not changed significantly over that time. Recently I began a weight training program in addition to my running. Almost immediately (within the first couple of weeks) I noticed greatly improved range of motion, hamstrings in particular, during post run stretching.
I was not aware of the studies @Christian lists, and I have only read their abstracts at this point, but my experience seems to be consistent with their findings. (I’m not as old as those study participants. I’ll just point that out.)
I’m happy to read the last line of this post: “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.”
In my case, I’ve dealt with some psoas and hip flexor issues. The main consequence of those issues (in my case) is that they cause a functional leg length difference. This difference leads to more pounding on one leg than the other which has, in the past, led to knee pain.
Doing a series of pre-running warm-up exercises and stretches has entirely eliminated this problem. It’s possible I suppose that the stretches are superfluous and it’s the warm-up exercises that are doing the work, but I’m not about to conclude that without experimenting and frankly in this one-person case, I’m not willing to risk the consequences.
Thanks for the great post.
Do you know if certified personal trainers are taught this information in the certification process? My trainer stresses the importance of stretching to me and I’m just wondering if this is a widely held notion.