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Top 10 myths about physical therapy rehabilitation. Part 1.5: Stretching revisited

I was confronted right after I posted the first part of this blog series by a friend and colleague who wasn’t too pleased with my take on stretching. So, unlike Donald Trump, I will back off a little, try to explain my “extreme” view and put it into context. Such a large, sweeping topic deserves perhaps a little more nuance than I provided.

First of all, if someone really wants to stretch because it feels good and they like it, who am I to tell them to stop? I won’t, unless I believe it’s actually exacerbating a condition (i.e. hamstring stretching will possibly aggravate and perpetuate high hamstring tendinopathy).

My problem is when people assume they should be stretching because, hey, that’s what you’re supposed to do for good health. These same people admit, ashamedly, that they don’t stretch enough and they believe that’s why they have pain or that’s why they got injured. This “stretching prevents injury and pain” message is so prevalent, but it’s mostly misguided. It’s based on well-meaning logical jumps and expert advice that have prevailed over time without much research to confirm or deny the claims. And now stretching is sacrosanct and most clinicians are afraid to tell people it’s not that important because that would fly in the face of accepted practice.

The worst part about this misconception is that stretching may be supplanting more important activities for injury prevention, like engaging in a basic strengthening program, which is much more likely to help (here and here). And I suspect that there are many thousands of people out there begrudgingly wasting money and time with yoga only because they assume that they’re bullet-proofing themselves against injury. (Any yogis out there: I’m not saying there aren’t many other benefits to yoga. Just saying that if you’re promoting flexibility as a panacea, you’re wrong).

Luckily, we do have a mounting body of evidence that stretching doesn’t prevent injury, pain, or soreness in most cases.

Here’s a sample:

Pereles D, Roth A, Thompson DJ. A Large, Randomized, Prospective Study of the Impact of a Pre-Run Stretch on the Risk of Injury in Teenage and Older Runners. USATF.org. 2011 Jun 15:

“Over a three-month period there was no statistically significant difference in injury risk between the pre-run stretching and non-stretching groups. Stretching neither prevented nor induced injury when compared to not stretching”

Hart L. Effect of stretching on sport injury risk: a review. Clin J Sport Med. 2005 Mar;15(2):113–113:

“Limited evidence showed stretching had no effect in reducing injuries.”

Herbert RD, de Noronha M, Kamper SJ. Stretching to prevent or reduce muscle soreness after exercise. Cochrane Database Syst Rev. 2011;(7):CD004577:

“The evidence from randomised studies suggests that muscle stretching, whether conducted before, after, or before and after exercise, does not produce clinically important reductions in delayed-onset muscle soreness in healthy adults.”

Cheung K, Hume P, Maxwell L. Delayed onset muscle soreness: treatment strategies and performance factors. Sports Med. 2003;33(2):145–64:

“Cryotherapy, stretching, homeopathy, ultrasound and electrical current modalities have demonstrated no effect on the alleviation of muscle soreness or other DOMS symptoms.”

Pope RP, Herbert RD, Kirwan JD. A randomized trial of preexercise stretching for prevention of lower-limb injury. Medicine Science in Sports Exercise. 2000 Feb;32(2):271–7:

“A typical muscle stretching protocol performed during preexercise warm-ups does not produce clinically meaningful reductions in risk of exercise-related injury in army recruits”

Sandler RD, Sui X, Church TS, et al. Are flexibility and muscle-strengthening activities associated with a higher risk of developing low back pain? J Sci Med Sport. 2014 Jul;17(4):361-5:

“In this sample [of 4610 adults followed for ~5 years], stretching or use of weight training machines is associated with increased risk of developing low back pain compared to use of free weights, callisthenics or exercise classes.”

Stutchfield BM, Coleman S. The relationships between hamstring flexibility, lumbar flexion, and low back pain in rowers. Eur J Sport Sci. 2006;6(4):255-60:

“Results obtained using the adjusted straight leg raise technique suggested that low back pain was not associated with hamstring inflexibility, which suggests that increasing hamstring flexibility for rehabilitation or prevention of low back pain in rowers might not be necessary.”

It’s not all bad news

In some situations, stretching may actually may have a role. For instance, this study concluded:

“The 10-week supervised hip flexor stretching program was effective in increasing stride length and peak hip extension during walking in elderly adults who had limited preintervention hip extension during walking.”

But, it’s important to note that it only worked for people who had limited hip extension. Stretching isn’t a blanket intervention for everyone, just those who have limitations. Also, we can only conclude that stretching improved stride length and hip extension, but we don’t know what effect, if any, that had on gait, quality of life, function, etc. You know, things that matter.

Then there’s this paper:

“In conclusion, the parasympathetic activity rapidly increased after stretching, whereas the sympathetic activity increased during exercise and had a slower postexercise reduction. Stretching sessions including multiple exercises and sets acutely changed the sympathovagal balance in subjects with low flexibility.”

In other words, stretching increased the activity of the system that results in relaxation. Thus, stretching may help us wind down after exercise. You can’t conclude anything from this study other than stretching may give you a relaxing feeling, which probably isn’t a surprise to most people, and probably also isn’t exclusive to stretching. I could probably do something similar by just lying down and doing some diaphragmatic breathing.

Any good news for people who stretch for injury prevention? This paper probably states the current argument best:

“With respect to the effect of pre-participation stretching on injury risk, the epidemiological studies show that pre-participation stretching in addition to warm-up will have no impact on injury risk during activities where there is a preponderance of overuse injuries.”

These are activities like running and biking.

“…while the four studies showing some effect of stretching [studied activities that] had a high prevalence of muscle strains.”

These studies looked at the effect of pre-participation stretching and a warm-up on muscle injuries in high school football, military training, yachting, and soccer.

Very important caveat:

“Several studies have shown that flexibility is not a significant intrinsic risk factor for muscle strain in various sports…While flexibility is an intrinsic factor inherent to the individual, stretching is an extrinsic factor that is either practiced or not. The acute effects of a pre-participation stretching intervention on injury risk may be very different from the chronic effects of habitual regular stretching.”

Basically, flexibility in and of itself doesn’t incur any particular injury prevention benefit, but the act of stretching before an activity may.

In conclusion

  1. Should you participate in a frequent program of static stretching to increase flexibility with the intention of preventing injury? Currently there is no evidence to suggest that such a course would have a positive effect on injury prevention. Having flexibility has not been shown to reduce one’s chance of injury.
  2. Should you engage in stretching of the major muscle groups before participating in an activity where the risk of a muscle strain injury is high? Research suggests that may reduce your risk of a muscle strain, so it wouldn’t be a bad idea. Risky activities are those that involve sprinting or sudden, powerful changes in direction, whether in the arms or legs.
  3. Should you stretch before you run, bike, or hike? There is no evidence to suggest that that will have any benefit on injury risk.
  4. Should you stretch to increase your flexibility? Sure, if you need flexibility for your pursuits. Or, if your range of motion is actually limited by muscle tightness (not joint issues) and it is affecting your activity. Or, if you just want to be flexible.

There. I hope that is a more balanced opinion.