Stretching is a comfortable and reassuring ritual for many people — it’s simple, it feels good, and it seems to promise easy benefits. For countless more, athletes and couch potatoes alike, stretching weighs on their conscience — one more thing they are supposed to find the time to do, like cooking more meals, or reading Anna Karenina. Can all these people be barking up the wrong tree? Sure they can! And they are.
I stretch regularly. My personal favourites: hamstrings, hip flexors, neck, chest, lumbar muscles, and the deep gluteal muscles. But I don’t believe it’s doing much for me. I am as stiff and inflexible as I have ever been!
Why is it that many Kenyans don’t stretch? Why was legendary coach Arthur Lydiard not a fan of stretching? Why does Galloway say, “In my experience runners who stretch are injured more often, and when they stop stretching, the injuries often go away”?
— Bob Cooper, Runner’s World Magazine1
What a sensible article, and about time somebody exploded the stretching myth! I remember as a schoolboy in South Africa forty years ago always being told to run slowly to warm up for our various rugby, cricket, and soccer games — nobody ever told us to stretch, and over the past ten or so years I’ve been puzzled to see this come in as dogma. As a runner of marathons for years and a GP with injured patients, I’ve never been able to figure out how on earth stretching the heck out of muscles, ligaments, and nerves could (a) warm them up or (b) do the slightest bit of good, and have sometimes been given “the jaundiced eye” when I’ve suggested such to my patients.
— Peter Houghton, MD, Vancouver (reader feedback)
I am a soccer referee, and mostly by happy accident began substituting what you call “mobilizing” for various stretches prior to my matches, and I find this does an excellent job of stimulating the muscles, whereas after only stretching I still seem to be tight for the first several minutes. Then I read this article, which corroborates what I have found in practice!
— Carlos Di Stefano, soccer referee (reader feedback)
The truth about stretching is that there is no truth about stretching to be had: it’s just too complicated a subject. There are too many mysteries and variables in muscle and connective tissue physiology, too many different stretching methods, and too many and vague goals for it to ever be possible to categorically say that stretching does or does not “work.” What kind of stretching, and for what? For every answer about stretching there are ten more questions — kind of like Lost — and for every safe assumption there’s a selection of exceptions.
However, plentiful recent research now shows that stretching as we know it — the kind of typical stretching that the average person does at the gym, or even the kind of stretching that most athletes do — is mostly a waste of time for most commonly identified goals. For instance, articles published in recent years, reviewing hundreds of studies, have concluded that there isn’t much evidence that any widely practiced form of stretching prevents injury or muscle soreness23 — arguably the single most common goal of stretching. Adding significantly to the credibility of those reviews, a major year 2000 clinical study of many hundreds of soldiers showed no sign of benefit from and even some risks to stretching.4 Some of this evidence, and similar evidence, is nicely summarized in a recent segment of a CBC Radio One science show (see Exorcizing Myths about Exercise).
Trainers, coaches and health care professionals are starting to insist on making recommendations based on evidence, or at least on a really convincing physiological rationale … and stretching just has not held up well under that pressure. Nor is it even a new idea that stretching might not be all that helpful. Consider this 30-year-old passage from an excellent 1983 Sports Illustrated article about David Moorcroft, a British middle and long distance runner and 5,000 metres world record holder:5
Stacked in a corner of Anderson’s [Moorcroft’s coach] office are bundles of scientific papers. “I’ve tried to interpret the findings of the best physiologists and translate them into sound practices,” says Anderson. “That’s made me a radical. We’ve turned some coaching sacred cows on their ear.”
For one, Anderson dismisses the stretching that most runners do. “It’s rubbish,” he says. “The received idea that by touching your toes you lengthen the fibers in your hamstrings is wrong. Soft tissue stretching like that is a learned skill and doesn’t carry over into running. Dave requires a flexibility, a joint mobility, but running fast is the right kind of stretching for him.”
The world-record holder mutely demonstrates his suppleness by reaching toward his toes. His fingertips get down to about midshin.
So why are people stretching?
When challenged, many casual stretching enthusiasts — and even many not-so causual ones — actually have a hard time explaining why they are stretching. Everyone just “knows” that it’s a good thing, and they haven’t really thought about why. It’s dogma, practically a religion. “Beliefs about flexibility and the optimal means of stretching have often proceeded from assumptions that have never been tested and from an almost religious zeal regarding the perceived benefits of stretching by a few.” (Sands) When pressed for reasons, most people will cough up a few predictable stretching goals. Here are the four hopeful reasons for stretching that I hear every day:6
And sometimes I also hear:
All of these overlapping stretching goals have serious problems. Either they have have long ago been proven to be impossible,8 or they lack a sensible and persuasive rationale, or both … or worse. Stretching for these reasons is probably a waste of your time. Other reasons are another issue, but their importance is reduced by their rarity — it doesn’t much affect my point if stretching solves some other problem that almost no one is even trying to solve.
A good example of another stretching goal is to treat muscle pain, and it is almost — but not quite — common enough to make the list above. Some therapists (and unusually well-informed laypeople) suggest that stretching is good for relieving the stiffness and discomfort cause by “muscle knots” (trigger points). I’ve even suggested that myself at times, and there are some reasons to believe it probably has some beneficial effects. But there are important caveats: (1) despite some interesting science, it remains unclear if trigger points are a “real” thing,9, (2) even if they are, there are still major theoretical and practical problems, and self-stretching is almost certainly an imprecise, inefficient, and unreliable way of relieving trigger points,10 and (3) trying to stretch painful tissue can definitely backfire.11 This topic is addressed in much greater detail in an important sister article to this one, Stretching for Trigger Points. This article concerns itself only with examining the usual motives people have for stretching — not more precise therapeutic usages.
Stretching does feel good, of course, and I will return to that important point later on. But this is almost never the reason that people give for stretching.
I stretch because it feels good. Just a couple seconds stretching this-a-way, then a couple more that-a-way, and I’m good to hop. Don’t overdo it! Holding stretches is over-rated.
— Murmel the bunny, master stretcher
This article is emphatically not just about the inadequacies of “static” stretching.
Many stretching advocates in 2013 are happy to pile on and criticize simple, old-school stretching — that is, elongating a muscle and then holding still for a while. They are happy to do so because they have decided that some other method of “stretching” actually does work, and therefore transcends the problems with stretching detailed here. As a result, I’m hearing a lot of this kind of reaction these days:
Oh sure, static stretching is useless, whatever, old news, yada yada yada. But Advanced Stretching Method X is so awesome that it will not only do everything you ever hoped static stretching would do, it will also achieve all your athletic goals, cure all your aches and pains, and find your lost socks.
I stay current with stretching research. Unfortunately, I have yet to see clear evidence that any stretching method is a clear winner at anything of much importance — no matter how “advanced.” Here’s a perfect example:
Alternately stretching and contracting a muscle is a staple of “advanced” stretching. This is called the contract-relax (CR) method, which is part of a general strategy with the very advanced sounding name of “proprioceptive neuromuscular facilitation” (PNF). However, it’s really nothing fancy: CR just adds contraction. Some readers will sniff at this and say that CR is still not “advanced” stretching, but it is certainly still widely used, taught and touted as being better than humble static stretching. I see trainers using it at the gym all the time. Patients can go for physical therapy pretty much anywhere in the world, and there’s a pretty good chance the therapist will do a whole bunch of CR stretching with them, while charging about a buck a minute.
Guess what? It doesn’t increase flexibility any more than static stretching. Science says so! A well-planned experiment tested whether or not the contraction component of a CR stretch actually makes a difference, and clearly found that it does not.12 Researchers compared a normal CR stretch of the hamstring to a modified one without any hamstring contraction (instead, some other “uninvolved, distant” muscle was contracted). The effect of both stretches was the same — “a significant moderate increase in range of motion.” In other words, it didn’t matter if the hamstring was contracted or not — with or without a contraction, the result was the same. This strongly undermines the central claim of CR-PNF stretching, and that’s being charitable. Actually, it kind of eviscerates it.
Things that sound too good to be true … still aren’t.
There’s also a serious problem with definitions here. Many of supposedly advanced methods of stretching are really not “stretching” at all. There are only so many things that you can change about stretching before it really becomes something else. The classic example is dynamic joint mobility drills — repeatedly moving through a range of motion (i.e. swinging your arms in a circle). Should we call that “stretching”? Perhaps. But I say no: although the kinship is clear, it’s a bit of a reach (har har), and it already has its own name. I would never look at someone doing that and think, “Behold! Stretching!”
So I follow a simple rule: if an exercise doesn’t involve elongating muscles for at least several seconds, it’s not stretching. It might be interesting, but it’s not stretching. This definition eliminates a few advanced “stretching” methods from consideration.
Nothing about static stretching is more clear. Your basic quick (static) stretch warmup is one of the most studied topics in all of musculoskeletal health care and exercise science. For instance, a huge 2011 review of all the research found “overwhelming evidence that stretch durations of 30-45 seconds … imparted no significant effect” and even some evidence of harm.13
Warming up is an unclear goal with many possible meanings. The most obvious and literal — an actual increase in tissue temperature — is a reasonable goal. It’s literally true that warm muscles function better than cold ones.
However, body heat is generated by metabolic activity, particularly muscle contractions. And it’s impossible to raise your metabolic activity without working up a sweat, which can't be achieved by stretching alone. You simply cannot “warm up” your muscles by stretching them: that’s like trying to cook a steak by pulling on it. Instead, the best way to warm up is probably to start by doing a kinder/gentler version of the activity you have in mind: e.g., walking before you run.
Metaphorically, “warming up” also refers to readiness for activity or body awareness. You are “warm” in this sense when you are neurologically responsive and coordinated: when your reflexes are sensitive and some adrenalin is pumping. Warmup for its own sake (i.e., without following it up with more intense exercise) is fairly pointless — the goal is to prevent injury and enhance performance. And those goals may be realistic. For instance, research has shown that a warmup routine focussed on these goals actually does provide decent insurance against the number and severity of both accidents and over-use injuries.1415
So, warmups in this second sense is probably helpful … but does stretching warm you up in this sense? No, probably not much — certainly no more than a bunch of other exercises you could do — and quite possibly not at all. One of the most-studied warmup regimens (including one of the studies just cited), FIFA’s “The 11+” programme, notably does not include stretching. The most compelling evidence that stretching doesn’t warm you up is the evidence that shows that it doesn’t prevent injury or enhance performance (discussed below). Static stretch is somewhat stimulating to tissue, but in ways that are quite different from most actual activities.
Because of all this, stretching to warm up does not even qualify as “official” exercise dogma anymore — most professionals actually gave up on it many years ago, and it is passé even in the opinion of a great many more informed joggers and weekend warriors. It simply doesn’t work, and it’s hard to imagine a common fitness practice more thoroughly contradicted by the evidence and by many professionals. And yet …
And yet I still see it all the time in the wild. I live and play on Vancouver’s famous “sea wall” — one of the best and most popular running routes in the world. I am able to constantly observe runners in their natural habitat, doing what runners do, and a great many of them participating in structured training programs and running groups, clearly being instructed by experts and coaches.
And they stretch to warm up. In droves. So despite the evolution of professional opinion, this practice clearly still needs to be debunked. There are still far too many people out there stretching before they run and play sports, trying to “warm up” almost exclusively by standing still and elongating muscles!
Once again, the best way to prepare for an activity is probably just to start it slowly.
Another popular idea about stretching is that it prevents that insidious deep tenderness that follows a hard workout. That soreness is called “delayed onset muscle soreness,” or DOMS for short. People believe that stretching can help DOMS like it’s religion.
I saw a similar example of this when I was in school: a science-minded instructor shared a research paper with us (something no other instructor ever did, which is shocking in itself). The paper suggested that massage therapy has no effect on the phenomenon of delayed-onset muscle soreness, and the evidence was compelling.16 But this was heretical! It was a crushing blow to one of the sacred cows of my profession, most of the class reacted angrily, and the hapless instructor was practically shouted out of the classroom.
I think the really amazing part of that story is that the students’ popular belief was less than two years old and the only basis for it was what they’d heard from instructors in their first year massage of therapy classes. Before that, most of them couldn’t have even defined “DOMS”! Yet already it was dogma, essential to their self-image as budding health professionals, a “fact” that they planned to use to promote their services, and so most of them were actually offended by the contradiction. It was a neat demonstration that most people are more interested in being consistent than correct.
People believe that stretching reduces DOMS with the same force. This does not make it true. Unfortunately, the evidence strongly suggests that stretching is completely useless for preventing DOMS. In fact, many studies have shown that nothing short of amputation can prevent DOMS171819 — and certainly not stretching.20
Think of DOMS as a tax on exercise. As one clever commentator put it, “Only soreness can prevent soreness.”
The commonly accepted idea that increased ROM and stretching prior to activity prevents injuries has been challenged and found to be on the shakiest of scientific foundations, or to come from such a paucity of data that no reasonable conclusions can be drawn.
Flexibility, by William Sands, p389
According to the evidence, stretching probably does not prevent injury. As I mentioned above, this has been suggested by a combination of recent literature reviews and large clinical studies, some of which I have already cited. Here’s some more.
In 2005, the Clinical Journal of Sports Medicine published a review of the scientific evidence to date, and found that the (admittedly limited) evidence “showed stretching had no effect in reducing injuries.”21 Neither poor quality nor higher quality studies reported any injury prevention effect. Regardless of whether stretching was of individual muscles or entire groups, there was no reduction in injury rates.
More experimental research has been done since. For instance, a 2008 study published in the American Journal of Sports Medicine showed “no significant differences in incidence of injury” in soldiers doing preventative exercises.22 Half of them participated in an exercise program including 5 exercises for strength, flexibility, and coordination of the lower limbs, and 50 of those soldiers sustained overuse injuries in the lower leg, either knee pain or shin splints. The other 500 soldiers were doing nothing at all to prevent injury in the lower limbs — no specific stretching, strengthening or coordination exercises — and only 48 of them had similar injuries. There were “no significant differences in incidence of injury between the prevention group and the placebo group,” and the authors concluded that the exercises “did not influence the risk of developing overuse knee injuries or medial tibial stress syndrome in subjects undergoing an increase in physical activity.”
However, what is clear is that the exercise regimen certainly included static stretching, and it certainly did not work any prevention miracles for some of the most common athletic injuries from the knees down. If stretching performs that poorly in such an experiment, how good can it possibly be at preventing other injuries? Probably not very.
Here in Vancouver — a running Mecca — researchers at Simon Fraser University have done an unusually large new study of pre-run stretching, with more than 2700 participants. They found “no statistically significant difference in injury risk between the pre-run stretching and non-stretching groups.”23 Injury rates for all kinds of injuries were the same, with or without stretching. It’s almost as though stretching made no difference at all. But make up your own mind!Injury rates for all kinds of injuries were the same, with or without stretching. It’s almost as though stretching made no difference at all.
I’m never surprised by such findings, because I’ve never heard a sensible explanation for how stretching can generally prevent injury. Usually, advocates have a vague notion that “longer” muscles are less likely to get strained: even if garden-variety stretching made muscles longer (which is doubtful in itself), and even if we knew exactly what kind of stretching to do (we don’t), and even if we had the time to stretch every significant muscle group, the benefits would still be relevant to only a small fraction of common sports injuries. An ankle sprain, for instance, or a blown knee — two of the most common of all injuries — probably have nothing to do with muscle length.
In truth, there may prove to be some modest injury prevention benefits to stretching — but I imagine that they are quite specific and missed by most stretching regimens. For instance, it is likely that diligent and specific calf and arch stretching can prevent plantar fasciitis.24 But for “general” injury prevention, I can think of Five Ways To Prevent Sports Injuries that are probably more effective than stretching.
“I want to be more flexible,” people say. Even when they have normal range of motion in every joint. What’s this about? Why are people so determined to be more bendy? What is it you want to do with that super power?
The fact that there are actually several elastic superheroes speaks to our genuine desire for greater range of motion. But the reality is that hardly anyone actually needs to be more flexible. Most people have a normal range of motion — that’s why it’s normal! Unless you are specifically frustrated because you lack sufficient range of motion in a joint to perform a specific task, you probably don’t need to be more flexible.
Stretching can increase flexibility. It’s not easy, and it’s not good bang for buck, and it may depend on your genes — I can’t do it, which I firmly established in 2011 with a really thorough personal experiment — but a diligent effort over a period of weeks might actually increase your range of motion. And more extreme efforts produce more extreme results. Acrobats, gymnasts, yogis, contortionists, and martial artists have clearly been pushing the limits for centuries, sometimes achieving uncanny mobility. But these are highly motivated athletes with specific and exotic performance goals and stretching regimens that would definitely intimidate the rest of us, and with good reason: they often injure themselves along the way. Indeed, it may even be necessary to injure joints — to traumatize their capsules and ligaments — in order to get them to move that far.
Fitness and health are not equivalent. You can be fit for a particular athletic pursuit, but that doesn’t mean you are a healthier person: high performance in a narrow category often comes at great costs (such as joint stability). Flexibility is “good for” a few things … and really not much else. It’s useful for gymnasts, for instance …
Is this child gymnast going to be more flexible? Oh, yes, I think she will be! Is she going to be “healthier” for it? Blatantly not. And she has a middle-aged guy sitting on her back … and that’s just gotta suck.
Flexibility is such a desired goal, however, that I will return to this topic later in the article. You will probably be surprised to learn how flexibility actually works. There are still some other myths to bust first, though.
The most flexible athletes are not necessarily the most successful.
Flexibility, by William Sands, p389
You don’t hear this argument for stretching as often as your hear the others. And yet it comes up, especially with athletes who play team sports. It’s a common practice to stretch when you’re off the field. The habit is probably usually rationalized as an injury prevention method, but many of those athletes will also insist that it enhances their performance — that the muscles “spring back” from the stretch and make them run faster. There’s actually an entire stretching book that is largely based on this idea — but that book is conspicuously full of armchair science, and no actual evidence that the ideas are true.
I’ve already mentioned a huge 2011 scientific review by Kay et al that found “overwhelming evidence” that pre-exercise stretching has “no significant effect.” That was not a surprise. What is a little surprising is that the same review showed the opposite of a benefit — that pre-exercise stretching might reduce muscle strength.25 I wouldn’t take the danger too seriously, but it certainly emphasizes the lack of benefit: if anything, it swings the other way. Yikes!
Similarly, research has shown that stretching does not improve sprinting … but it gets worse. What really happens to your sprint if you stretch first? It turns out that, all other things being equal, the athlete who didn’t stretch is actually going to leave you behind! All other things being equal, the athlete who didn’t stretch is going to leave you behind! An Australian research group in Perth did this experiment in early 2009. They rounded up a few athletes and tested their sprinting with and without a stretching regimen between sprints.26 And of course they didn’t just ask the atheletes, “So, how did you feel? Faster? Slower?” No, they cleverly measured the results: “Mean, total (sum of six sprints), first, and best sprint times were recorded for each set” … instead of relying on the athletes impression of how they did. The results of the tests were clear: “There was a consistent tendency for repeated sprint … times to be slower after the static stretching.” In other words, if you want to perform in a sprinty sport, you might not want to stretch right before getting your cleats dirty.
(Isn’t testing things just a marvelous idea? If you’re not sure what effect stretching has on sprinting, why not just try it? With measurements and stuff! It’s amazing what you can learn.)
There are many possible mitigating factors here.27 However, the complexities only emphasize the absurdity of the legions of people who have an oversimplified faith that stretching is important. In the face of so much discouraging evidence, it makes sense to assume that sport itself provides all the “stretching” one needs. The late Mel Siff:
It is almost heretical to question this stretching doctrine, yet it is important to disclose that there is no research which proves categorically that there is any need for separate stretching sessions, phases or exercises to be conducted to improve performance and safety. To appreciate this fact, it is useful to return to one of the clinical definitions of flexibility, namely that flexibility refers to the range of movement of a specific joint or group of anatomical tissues. Moreover, flexibility cannot be considered separate from other fitness factors such as strength and stamina. There is no real need to prescribe separate stretching exercises or sessions, since logically structured training should take every joint progressively through its full range of static and dynamic movement. In other words every movement should be performed to enhance flexibility, strength, speed, local muscular endurance and skill, so that separate stretching sessions then become largely redundant.
Facts and Fallacies of Fitness, by Mel Siff, p123
Siff’s sensible minimalism — from 1988 — stands in stark contrast to a much more common and marketable “flexibility first” approach, an approach that just happens (coincidence, I’m sure!) to give coaches, trainers and therapists something to be expert about: the idea that athletes must make a point of increasing flexibility first (by whatever stretching method), and then train for the strength and coordination to exploit this marvelous new range of motion. That picture is quite likely to be exactly backwards.
One of the most interesting chapters in my history of criticizing stretching was being quoted in the September, 2009, issue of Runner’s World, in an article called “The Rules Revisited.” Contributing editor, Bob Cooper, asked for my assistance: “Can you tell me everything you know about stretching in 4 or 5 sentences?” An interesting challenge!
The result was a rare and overdue example of critical thinking on the subject of stretching in a major magazine. Cooper does an admirable job of summarizing and challenging several chestnuts of conventional wisdom, including stretching.
But, in a truly dazzling display of irony, Runner’s World published another article in the same issue — “All in the Hips,” p. 46 — that very un-critically promoted another idea that I’ve been busily debunking on this website: that hip strengthening can treat and/or prevent lower leg injuries. It’s based on a pet theory championed since about 2005 almost exclusively by Calgary researcher Reed Ferber. Ferber’s confidence in his theory is way out of proportion to the evidence he presents, and there are many problems with it.28
But he’s in Runner’s World promoting a new myth to a new generation of runners! Even as I am quoted trying to debunk the (still prevalent!) myths of the last generation.
There is basically no hope that the average reader will know that Ferber’s advice is really weak, just as there was no hope for the last thirty years that the average person would understand how weak stretching science has been. Most will simply believe the article. About a million Runner’s World readers are going to conclude that hip strengthening “probably” works!
“Falsehood flies, and the truth comes limping after.” Falsehood was a sprinter long before Swift first wrote that in 1710, and little has changed in the 300 years since. So it has always been with stretching: an idea promoted with much greater confidence than has ever been justified by the evidence, and it’s only several decades later that — very slowly — the truth is catching up.
How about this? It’s good for your heart!29 “Enhanced vagal modulation.” That’s fairly straightforward good-news science about stretching. (And yet I’ve never heard anyone say they were stretching for their heart.)
It’s actually not too surprising an idea that any kind of movement exercise would have some systemic regulatory effects, but it’s nice to see some corroboration of that common sensical notion, and it’s also nice to know that perhaps just stretching did this (to the extent we can learn anything from a single study). If true, it makes for a nice point in favour of a general stretching habit and yoga, “massaging with movement,” and probably even massage itself. It may have a lot to do with why massage feels good.
But stretching is probably not good for the reasons or in the manner most people are stretching, no — not much good, anyway, and certainly not much in any ways anyone has figured out how to measure.
Undoubtedly, some specific stretching techniques are good for specific purposes … but quite different from the stretching goals that most people actually have in mind, if they have any clear goals at all. My concern is not that stretching itself is useless, but that people are stretching aimlessly and ineffectively, to the exclusion of evidence-based alternatives, such as a proper warm-up or mobilizations.For most people, most of the time, stretching has a lousy effort-to-reward ratio.
I don’t believe that stretching is any more generally useful for people than it is for cats — you do it when you get up in the morning for a few seconds and then you’re off to the sandbox. That feels good — it’s stimulating and enhances your body awareness, it scratches some simple physiological itch, and that’s fine and dandy. But for most people, most of the time? As a time-consuming therapeutic exercise ritual? Stretching simply has a lousy effort-to-reward ratio.
In the next few sections, I will respond to some of the common objections and questions that readers often have.
Because it is probably actually doing something! It’s just probably not doing what you thought it was doing. And we don’t really know for sure what it is doing. If we are intellectually honest, we simply have to admit that.
People routinely report that stretching feels good, that it reduces muscle soreness, or that they feel a strong urge to stretch. And I’m one of them. I have a stretching habit because it feels good, and because it feels like I’m going to “seize up” if I don’t. In particular, I stretch my hamstrings regularly and strongly, and it feels as pleasantly essential to my well-being as slipping into a hot bath — but the exact nature of the benefits are completely unclear to me.
It’s probably a complex stew of genuine but mysterious and subtle physiological benefits — like the heart rate regulatory effect noted in the last section — plus almost certainly some good placebo, too. I was raised on stretching. Despite my doubt about the conventional wisdom, I tend to emotionally “believe” in stretching just like everyone else — it’s deep in our culture, and, since stretching feels good, it’s easy for my mind to jump to the conclusion that it must be good. But of course that’s not really helpful at all — lots of things feel good without having any clear physiological benefits. Stretching might be like scratching: an undeniably strong impulse, but with almost no relevance to athletic performance or overall health. Or it might be like getting a massage for muscles that are sore with DOMS: undeniably pleasant, but with a proven lack of actual efficacy.
I just don’t know. And based on the research to date, no one else does either.
If feeling good was the only thing that stretching was good for, most people — especially the athletes — would drop it from their exercise routine immediately. Most of us have better things to do. However, if someone firmly declared, “I stretch just to feel good,” I would applaud and say, “Hallelujah! That is an excellent reason to stretch! And one of the few that I can defend!”
And, then again, there may actually be real physiological benefits to stretching — just not the usual ones that get tossed around.
I hear this one a lot, and I experience it myself as well. The anecdotal evidence that stretching “works” for stiff and aching muscles is substantial. (Ominously, so is the anecdotal evidence that it can backfire.) It doesn’t seem to come close to “curing,” but darned if it doesn’t also “take the edge off” enough to make it worth trying. So people in pain stretch, and sometimes they feel a little better for a while.
Stretching trigger points has some expert endorsement. In the weighty text Muscle Pain, researchers Dr. David Simons and Dr. Siegfried Mense wrote that stretching “by almost any means is beneficial.”30 They have a theory about why.31 If it’s correct, then it works about the same way that stretching out a calf cramp works: you win the tug-of-war with spasming muscle, just on a smaller scale. It sounds good on paper, but there are several major problems in both theory and practice. There are many circumstances in which you can not realistically hope to win a tug-of-war with a trigger point, because it would be too anatomically awkward & painful.Simons and Mense also emphasize that it has “not been firmly established” that stretching trigger points is helpful, and that stretch works primarily for “newly activated, single-muscle” trigger points (leaving out a lot of trigger points that are serious problems). There are many circumstances in which you can not realistically hope to win a tug-of-war with a trigger point, because it would be too anatomically awkward or painful.32 In fact, if it works at all, it probably mostly only works on the milder cases that don’t matter very much in the first place.
Nevertheless, it is a somewhat plausible way by which stretching might reduce muscle pain and stiffness, and it may be a partial explanation for why stretching sometimes feels good, but it is just as certain that it isn’t the whole story. I take this idea seriously and explore it in (excruciating) detail in my book about trigger points. I also have an abdridged summary of that topic here:
The nice thing about standards is that there are so many of them to choose from.
Andrew S. Tanenbaum
No, they don’t — because it’s impossible. There is just no way, so far, to confirm what a “proper” stretch is. Trying to teach proper stretching is like trying to teach proper finger painting. There are no accepted standards in stretching technique (not even close), no method that is clearly superior, no way to know what’s right, no definition of success and no accepted method of achieving it.
This is another protest I frequently hear from people who are clinging to the stretching dogma. The choice of words ranges widely, but the pretentious sentiment is always the same: stretching is only valuable if you “know what you’re doing.” And so a number of experts stay in business by advocating a stretching method or rationale that seems to trump all the others. Unfortunately, none of them can agree with each other.
My own former colleagues in massage therapy are sometimes the worst perpetrators of this idea, that clients just need to be “educated” and their stretching will magically become much more effective and valuable than it used to be. Valuable for what, I am not sure — as we discussed above, we’ve pretty much eliminated all the popular reasons. But even if we generously allow that there may be some other benefit to stretching, who are we to say how it should be achieved? Show me an authoritative source of information about stretching! Show me a “correct stretch”!
Here is a vivid example of the problem. This is an excerpt from one of my text books, a weighty and authoritative tome, a bible of therapeutic exercise:
Several authors have suggested that a period of 20 minutes or longer is necessary for a stretch to be effective and increase range of motion when a low-intensity prolonged mechanical stretch is used.
three citations listed, Therapeutic Exercise, 3rd Ed., Kisner/Colby, p157
Twenty minutes? I don’t know anyone who is stretching a muscle for twenty minutes! I don’t know a single therapist or trainer who is recommending it either! And yet “several authors” have found that it is “necessary”! It would seem to be a “correct” method of stretching, yet it is absent from professional wisdom on the subject … because, of course, it is contradicted in other text books, by other experts, not to mention the fact that it’s completely impractical. Imagine trying to stretch for injury prevention: 20 minutes for each of 20 important muscles!
You can see the problem. Even if you had clear and defensible goals for stretching, it is effectively impossible to form an evidence-based opinion on what stretching properly looks like.
Another significant practical difficulty with stretching that never gets discussed: there are several important muscles and muscle groups that are mechanically impossible to stretch, including ones (like the quadriceps) that people think they are stretching. Even if stretching actually had the benefits that people want to attribute to it — which it clearly does not — those benefits would still not actually be available in large sections of the body. See:
Yes, it is, and yes, it does — but probably not the benefits that people normally attribute to stretching. Even flexibility is suspect.33 Same with qigong, and the martial arts are full of stretching techniques — some of them appropriated from the modern Western fitness tradition, and others inherited from traditional practices. I advocate this kind of stretching elsewhere in my writings. So what’s the difference?
The difference is in intention. The intention of stretching in the context of good qigong, yoga or martial arts is to focus the mind, to stimulate vitality through a combination of mental and physical exercise. The intention is everything — without the intention, you might as well not bother with these activities.
Most westerners stretch without the foggiest notion of this underlying complexity. Stretching is generally stimulating to body awareness, of course: but that awareness is unsophisticated and incidental, rarely involving any insight more complex than “ooh, that muscle sure is sore.” Without education about intent — without a rich philosophical context — the value of stretching in yoga is just as dubious as it is in any other situation.
And stretching in yoga also involves some risks. Too often people perceive yoga as an entirely wholesome and harmless activity, but in fact over-stretching injuries and muscle strains are actually common. As with dancing or martial arts, there are many ways to hurt yourself practicing yoga.
There is really only one “benefit” to stretching that seems to be clear and (almost) uncontroversial: it does increase flexibility. For whatever it’s worth, people do seem to be more flexible when they stretch regularly for a while. It’s not easy to achieve, but it can be done. The phenomenon is widely observed, and has been confirmed by experiments.
The trouble is, what is it worth? Is it actually a benefit? I’ve already argued that is not, but to make the case more effectively, it’s important to study the nature of flexibility. When someoneone increases their flexibility, what changes, exactly? How does it work?
Probably not the way you expect.
A number of explanations have been proposed, and none have panned out. A 2010 paper in Physical Therapy reviews them all in great detail, and the full text is free.34 It’s not light reading, but there are some fascinating highlights. For instance, the authors torpedo the popular theory that muscles actually change length (“plastic deformation”):
In 10 studies that suggested plastic, permanent, or lasting deformation of connective tissue as a factor for increased muscle extensibility, none of the cited evidence was found to support this classic model of plastic deformation.
After reviewing several more disproven popular theories, they get to the good part: the last theory standing.
Increases in muscle extensibility observed immediately after stretching and after short-term (3 to 8-week) stretching programs are due to an alteration of sensation only and not to an increase in muscle length. This theory is referred to as the sensory theory throughout this article because the change in subjects’ perception of sensation is the only current explanation for these results.
Note the very interesting and sensible phrasing, “the only current explanation.” That’s a very Sherlock Holmesian way of putting it: “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” It’s a strange, cool, and unexpected conclusion … but it’s also all we’ve got left, so we should probably take it seriously.
Muscle doesn’t change, but our willingness to elongate it does. Therefore, elongation must normally be limited by a strict neurological edict. The brain and spinal cord decree: you’re only going to lengthen your muscles so far, period, end of discussion. It’s not a negotiation … at least not in the short term. Don’t make the mistake of thinking you could just blast through that barrier with will power.
There is a strong analogy to strength: we always have much greater muscle power available than we can safely use. We have deep reserves that are literally impossible to tap into on short notice, without large squirts of adrenalin. Contractions are normally reined in by the brain. Even with a powerful grunt of effort, only a small fraction of your muscle fibres get a signal to contract at any one time. If you recruited all of them, you might rip the muscle off your bones, or at least completely exhaust yourself in seconds. Your central nervous system has excellent reasons for imposing a power limit. Full contraction is for dramatic, obvious, life and death situations only.
However, with training, we can learn to recruit more fibres. In fact, when people train their muscles, early strength gains may be mainly a matter of learning to “recruit” more muscle fibres at once.
Here’s an interesting example from science of how increasing flexibility may be more of a nervous system “hack” than a matter of changing tissue. It appears that if you just add some vibration, even already flexible gymnasts can get a surprising boost in flexibility.3536 As described by Sands, Issurin et al gymnasts “used a vibrating ring suspended by a cable, in which the foot of the subject was placed while they stretched forward over the raised leg, targeting the hamstrings. The resulting increase in ROM was astonishing. These researchers demonstrated that vibration could enhance flexibility.” These results were replicated by Sands in 2006. Clearly that is a neurological effect on flexibility … and a very cool one.
As with contraction, your body probably has excellent reasons for strictly limiting elongation. When a stretch becomes uncomfortable, that’s your nervous system saying, “No way, sister, we don’t go there — we’ve got some sensible rules about this.”
And you really just can’t overrule your spinal cord on this. Talk about wisdom of the body!
But apparently we can get used to stretching — we can learn to tolerate greater elongation to some extent. Fascinating! This goes a long way to explaining the flexibility feats of yogis and martial artists, whose hypermobility might well be dangerously dysfunctional if it were attributable to plastic deformation. Plastic deformation simply does not occur in the most athletes, and maybe none. It might occur at the extremes of flexibility performance, but only so much — if you actually deformed your muscles and tendons enough to really preztel yourself, they would probably also be too loose to be useful the rest of the time.
It’s a tidy, attractive theory that plastic deformation is minimal, and contortionism largely powered by extremes of stretch tolerance — they have trained themselves to allow their latent capacity for full muscular elongation, but their muscles retain the ability to return to a normal length.
That’s a reasonably safe theory about how flexibility works. But it is not easy to achieve significant stretch tolerance — it takes weeks of diligent effort, quite a bit more than most people ever actually push themselves to achieve. Many people probably believe that they have achieved this, but it’s mostly wishful thinking, and the huge majority have only scratched the surface of their potential flexibility during brief phases of their lives.
More to the point, what’s the point? We already know that stretching does not do all the basic stuff we used to hope it was doing, especially injury prevention. Is it good for anything else?
There is no known benefit to greater flexibility, except for:
In short, stretching appears to be good for … more stretching. Oh, and:
Other interesting reading relevant to stretching:
This paper and Herbert are literature reviews: that is, they are reviews of many other studies. They both show many contradictions in existing research, but they both conclude that there is no convincing evidence that stretching is useful.BACK TO TEXT
Several hundred army recruits stretched before every training workout for 12 weeks: “one 20-s static stretch under supervision for each of six major leg muscle groups during every warm-up.” Their injuries were compared to hundreds more who didn’t stretch. The authors of the study concluded that “typical stretching does not produce clinically meaningful reductions in risk of exercise-related injury in army recruits.”BACK TO TEXT
Researchers found that injury rates were significantly lower in soccer (football) teams that diligently performed warmup exercises (“The 11+”, a warmup program recommended by FIFA, which notably does not include stretching). On the one hand, there was not much difference between a little warming up (low participation) and a bit more warming up (average participation). But players and teams that did an especially good job of warming up (“twice as many injury prevention sessions”) got solid results: “the risk of overall and acute injuries was reduced by more than a third among players with high compliance compared with players with intermediate compliance.” That extra enthusiasm went a long way!BACK TO TEXT
From the abstract: “There was no difference in the reported variables between experiments one and two. It is concluded that passive stretching did not have any significant influence on increased plasma-CK, muscle pain, muscle strength and the PCr/P(i) ratio, indicating that passive stretching after eccentric exercise cannot prevent secondary pathological alterations.”BACK TO TEXT
From the abstract: “Cryotherapy, stretching, homeopathy, ultrasound and electrical current modalities have demonstrated no effect on the alleviation of muscle soreness or other DOMS symptoms.”BACK TO TEXT
From the abstract: “… analysis indicated no statistically significant differences between massage, microcurrent electrical stimulation, upper body ergometry, and control groups.”BACK TO TEXT
Does stretching help either before or after exercise to reduce soreness? Nope. This large review of many scientific studies concluded with a clear thumbs down: “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.”BACK TO TEXT
BACK TO TEXT
OBJECTIVE: Effect of Stretching on Sport Injury Risk: a Review To assess the evidence for the effectiveness of stretching for the prevention of injuries in sports.
DATA SOURCES: MEDLINE (1966 to September, 2002), Current Contents, Biomedical Collection, Dissertation Abstracts, the Cochrane Library, and SPORTDiscus were searched for articles in all languages using terms including stretching, flexibility, injury, epidemiology, and injury prevention. Reference lists were searched and experts contacted for further relevant studies.
STUDY SELECTION: Criteria for inclusion were randomized trials or cohort studies of interventions that included stretching compared with other interventions, with participants who were engaged in sporting or fitness activities. One author identified 361 articles reporting on flexibility, methods and effects of stretching, risk factors for injury, and injury prevention, of which 6 articles fulfilled the inclusion criteria for meta-analysis.
DATA EXTRACTION: Three independent reviewers blinded to the authors and institutions of the investigations assessed the methodologic quality of the studies (100-point scale) and reached consensus on disagreements. Details of study participants, interventions, and outcomes were extracted. Weighted pooled odds ratios were calculated for effects of interventions on an intention-to-treat basis.
MAIN RESULTS: Reduction in total injuries (shin splints, tibial stress reaction, sprains/strains, and lower-extremity and -limb injuries) with either stretching of specific leg-muscle groups or multiple muscle groups was not found in 5 controlled studies (odds ratio [OR] 0.93; 95% CI, 0.78 to 1.11). Reduction in injuries was not significantly greater for stretching of specific muscles (OR, 0.80; CI, 0.54-1.14) or multiple muscle groups (OR, 0.96; CI, 0.71-1.28). Combining the 3 ratings of methodologic quality, median scores were 29 to 60/100. After adjustment for confounders, low quality studies did not show a greater reduction in injuries with stretching (OR, 0.88; CI, 0.67-1.15) compared with high quality studies (OR, 0.97; CI, 0.77-1.22). Stretching to improve flexibility, adverse effects of stretching, and effects of warm up were not assessed by appropriate intervention studies.
CONCLUSION: Limited evidence showed stretching had no effect in reducing injuries.
BACK TO TEXT
… multiple-set flexibility training session enhanced the vagal modulation and sympathovagal balance in the acute postexercise recovery, at least in subjects with low flexibility levels. … The present results suggest that stretching routines may contribute to a favorable autonomic activity change in untrained subjects.