Stretching Science Part 2: Muscle Soreness

Stretching may not be able to prevent acute injury, but what about ordinary muscle soreness that sometimes occurs as a result of physical activity, otherwise known as Delayed Onset Muscle Soreness, or DOMS? Just about everyone has had at least some experience with DOMS. After finishing a workout session without any noticeable discomfort, you develop increasing soreness and stiffness which peaks anywhere between 24-72 hours and then gradually subsides over the next couple of days. In the early 1960′s, researchers believed that exercise-induced muscle soreness was the result of restricted blood flow due to muscle spasm, and that normal blood flow could be restored to the muscle by stretching.

By the mid 1980′s, the muscle spasm theory was discredited but stretching continues to be recommended for the prevention and treatment of DOMS.Regardless of the actual mechanisms involved in producing DOMS, can stretching prevent or at least reduce exercise-induced muscle soreness? Again, rather than relying on anecdotal evidence, we’re going to take a brief look at a couple of research reviews which have examined the effects of stretching on the DOMS phenomenon…

Stretching for the prevention of DOMS is not supported by research

The Cochrane Collaboration published an updated 2011 review of 12 stretching studies, including one large study with 2377 participants (Herbert et al.) Their conclusion was that stretching either before, after, or both before and after exercise has an insignificant effect on muscle soreness. How insignificant? The pooled results averaged a 1-point reduction in soreness on a scale of 100, with little variation within or between individual trials. This lack of any noticeable effect of either static stretching or PNF stretching (involving an isometric contraction followed by a passive stretch) on DOMS is truly uninspiring. The authors comment that “the best available evidence indicates that stretching does not reduce muscle soreness.”

Another paper which reviewed many of the same stretching studies came to a similar conclusion: “Studies which have investigated the effect of stretching prior to, after, or before and after… exercise have shown no preventative effect of stretching on DOMS” (Cheung et al.) The researchers also reviewed an additional study which showed that soreness can actually be induced by lengthy sessions of intense static and ballistic stretching, with static stretching producing greater soreness than ballistic stretching. So much for the common belief that the more you stretch, the less soreness you will experience.

What if you already have DOMS? Well, stretching won’t “cure” any pre-existing muscle soreness, but it may provide some temporary relief. There’s certainly nothing wrong with seeking that relief, but this effect isn’t necessarily unique to stretching and you will likely find that any gentle movement through a gradually increasing range of motion will provide the same temporary tolerance to that movement. Unfortunately, the soreness will return and continue to run its full course.

Intense stretching can actually CAUSE muscle soreness

Instead of stretching the muscle, let’s try squeezing it

Compressive garments have been gaining attention as a potential recovery tool as highlighted by Cheung et al., but more research needs to be conducted in order to validate this approach. It would be interesting if compression clothing can be shown to provide a reliable reduction in muscle soreness, but not all studies have shown this effect (Trenell et al.) I’d also encourage a healthy skepticism of the typical explanations for how this might work, which focus on mechanical support or the elimination of metabolic toxins. As with the application of kinesiotape, any positive effect probably has more to do with the novel sensory input that compressive garments can provide rather than any supposed “healing” effect on the underlying soft tissues.

Even if compressive garments can reduce exercise-induced swelling, there’s still a potential downside to any method which inhibits the type of inflammation that is part of the normal response to training: perhaps you can recover faster in terms of perceived soreness, but you might hinder your overall progress because you’ve compromised the adaptation process. The longer-term consequences of interrupting that training effect would be an unwelcome trade-off for any short-term convenience.

Interestingly, other more common treatments like NSAIDs and icing which aim to reduce inflammation have little or no effect on DOMS, so wearing compressive garments for that purpose seems misguided. By the way, as great as a muscle-squeezing massage might feel, that hasn’t been shown to have any appreciable effect on exercise-induced muscle soreness either. Bummer. Does anything prevent muscle soreness?

Muscle soreness is a normal response to a newly imposed stress

It’s known that DOMS is precipitated by unfamiliar, high-force or long-duration physical activity with an eccentric muscular component. Therefore, sudden, drastic changes in your training program are much more likely to produce muscle soreness than smooth transitions. With that in mind, you should be able to ease your suffering by gradually adjusting the intensity and duration of your workload and cautiously introducing new movements or training methods into your routine. While complete avoidance of muscle soreness is an unrealistic goal for anyone who is seeking to improve their current physical condition, applying a little patience and good sense should help to reduce the occurrence and severity of DOMS without wasting too much valuable time on stretching.

Neither passive nor active stretching can prevent or reduce exercise-induced muscle soreness

Even though stretching has not been validated by research as an effective strategy for preventing or treating DOMS, it’s part of our human nature to swear by certain methods that we just know work for us. Often times, the seemingly positive effects of a particular intervention may be ascribed to placebo or confirmation bias. To illustrate: we might be convinced that chicken soup has particular healing properties that help us recover from a cold. After all, we always eat chicken soup when we’re sick, and we always get better! The mistake is in assigning cause when there is merely correlation. The simple fact is that every cold runs its course, unaffected by whether we eat chicken soup or not. Likewise, as long as you don’t needlessly challenge a sore muscle, DOMS will run its course and then subside on its own, regardless of whether you stretch or not. No amount of stretching will make the soreness dissipate any faster, and too much stretching might even make it worse.

Of course, stretching is still useful for increasing flexibility, but is more flexibility always better? The next post in this series will look at the effects of stretching on performance.

Sources

1. R. D. Herbert, M. de Noronha, S. J. Kamper. Stretching to prevent or reduce muscle soreness after exercise. Cochrane Database of Systematic Reviews 2011, Issue 7. Art. No.: CD004577. DOI: 10.1002/14651858.CD004577.pub3
2. K. Cheung, P. A. Hume, L. Maxwell. Delayed Onset Muscle Soreness: Treatment Strategies and Performance Factors. Sports Med 2003; 33 (2): 145-164.
3. M. I. Trenell, K. B. Rooney, C. M. Sue, C. H. Thompson. Compression Garments and Recovery From Eccentric Exercise. Journal of Sports Science and Medicine 2006; 5, 106-114.

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