(Originated from http://saveyourself.ca)

Quite a Stretch

Stretching research clearly shows that a stretching habit isn’t good for much of anything that people think it is

by Paul Ingraham, Vancouver, Canada BIO

In a nutshell: Stretching just doesn’t have the effects that most runners hope it does, and probably cannot physically change muscles. In particular, plentiful recent stretching research has shown that it doesn’t (1) warm you up, (2) prevent soreness or injury, or (3) enhance peformance. No other measurable and significant benefit to stretching has ever been proven. Regardless of efficacy, stretching is inefficient, “proper” technique is controversial at best, and many key muscles are actually biomechanically impossible to stretch — like most of the quadriceps group (which runners never believe without diagrams). If there’s any hope for stretching, it might be a therapeutic effect on muscle “knots” (myofascial trigger points), but even that theory is full of problems.

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. Can all these people be barking up the wrong tree? Sure they can! And they are.

I stretch regularly. My personal favorites: hamstrings, hip flexors, neck, chest, lumbar muscles, and the deep gluteal muscles. But I don’t believe it’s doing much for me. For instance, I am as stiff and inflexible as I have always 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)

There is no “truth” about stretching

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 doesn or does not work. What kind of stretching, and for what? For every answer about stretching there are ten more questions, and for every safe assumption there’s an 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 practice 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 -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.

‘What Made Him Go So Wonderfully Mad?’ So Inquired a friend of David Moorcroft after the Briton broke the world 5,000 record in an amazing performance, Moore (sportsillustrated.cnn.com)

So why are people stretching?

Why people stretch

When challenged, many casual stretching enthusiasts actually have a hard time explaining why they are stretching. The value of stretching has been elevated to dogma without justification. Everyone just “knows” that it’s a good thing, and they haven’t really thought about why. 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

1. warming up
2. prevention of injury
3. prevention of muscle soreness
4. flexibility7

And sometimes you also hear:

5. “performance enhancement” (faster sprinting, for instance)

All of these overlapping stretching goals have serious problems. Either they have have 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,” more technically known as 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) self-stretching is almost certainly an imprecise, inefficient, and unreliable way of relieving trigger points,10 and (3) trying to stretch painful muscle 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

Kinds of stretching (not just static)

This article is emphatically not just about the inadequacies of “static” stretching.

Many stretching advocates in 2011 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.”

Things that sound too good to be true … still aren’t.

There’s also a serious problem with definitions here. Many of these advanced methods 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 it doesn’t involve elongating your own muscles for at least several seconds, it might be something interesting, but it’s not stretching. Ironically, this actually eliminates a number of advanced stretching methods from consideration.

Stretching research clearly shows that stretching is not an effective warmup

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.12

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.1314

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.

Warmup works

A large study of girls’ soccer teams showed warming up can cut injury rates by about a third. Notably, the warmup that was studied, FIFA’s “11+” warmup, did not include stretching!

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 osberve runners in their natural habitat, doing what runners do, and a great many of them participating in structued training programs and runing 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 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.

Stretching research shows that stretching does not prevent delayed-onset muscle soreness (DOMS)

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.15 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 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 emotional continuity than the truth.

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 DOMS161718 — and certainly not stretching.19

Think of DOMS as a tax on exercise. As one clever commentator put it, “Only soreness can prevent soreness.”

Stretching research shows that stretching does not prevent injury

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, 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.”20 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 American Journal of Sports Medicine showed “no significant differences in incidence of injury” in soldiers doing preventative exercises.21 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.”22 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.23 But for “general” injury prevention, I can think of Five Ways To Prevent Sports Injuries that are probably more effective than stretching.

Yes, stretching will make you more flexible … but so what?

“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 flexible? What is it you want to do with that power?

Hardly anyone 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 regimes that would definitely intimidate the rest of us, and with good reason: they often injure themselves along the way. Indeed, it’s 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.

Stretching probably doesn’t enhance performance (and it definitely doesn’t make you sprint faster)

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.24 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.25 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.26 However, the complexities only emphasize the absurdity of the legions of people who have an oversimplified faith that “stretching works.”

Stretching and irony in Runner’s World

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.27

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.

So … is stretching good for anything?

Probably not for the reasons or in the manner most people are stretching, no — not much good, anyway, and certainly not in a way 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 mobilization.

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.

So if all that’s true, if nothing I ever thought I knew about stretching turns out to be true, then why is it that I feel like I have to stretch or I’m going to seize up like an old piece of leather? Why do I have this compulsion to stretch, and why does it feel so good, if it’s not actually doing anything?

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, plus placebo. 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.

“But I find that stretching helps muscle soreness …”

I hear this one a lot, and I experience it myself as well. There is one plausible and partially understood mechanism by which stretching might actually reduce muscle pain and stiffness: by “releasing” myofascial trigger points, commonly known as muscle knots. I do take this idea seriously and explore it in (excruciating) detail in this article:

However, to boil that article down to a single brief paragraph: although stretching probably does help trigger points, I suspect it’s only one piece of a complex puzzle. There are simply too many problems with the theory, too many little niggling doubts, not the least of which is that it’s pretty clear that stretching routinely fails to treat serious trigger points, and can even aggravate them. It’s just too complicated and mysterious a relationship to say anything firm about it. Trigger point release is almost certainly a partial explanation for why stretching sometimes feels good, but it is just as certain that it isn’t the whole story.

“But don’t people just need to be taught how to stretch properly?”

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 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 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.

The unstretchables: the many muscles that are biomechanically impossible to stretch

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:

The Unstretchables: Eleven major muscles you can’t stretch, no matter how hard you try

“But isn’t yoga all about stretching? And Yoga has lots of benefits, doesn’t it?”

Yes, it is, and yes, it does — but probably not the benefits that people normally attribute to stretching. Even flexibility is suspect.28 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 risks. Too often people perceive yoga as a wholesome and harmless activity, when over-stretching injuries and muscle strains are actually common. As with dancing or martial arts, there are many ways to hurt yourself practicing yoga.

Back to the question of flexibility

There is really only one “benefit” to stretching that seems to be clear and 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.

The last theory standing

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.29 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.

Increased flexibility may simply be an increased tolerance for the discomfort of excessive muscle elongation.

Let’s get neurological

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.

The wisdom of the body

The evidence shows that there must be similar neurological limits on muscle elongation. 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 too 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.

So stretching is good for … stretching?

So that’s how increased flexibility works — a reasonably safe tentative conclusion. But it is not easy to achieve this — 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:

• bragging rights
• dominating Twister tournaments
• making full use of Indian love manuals

In short, stretching appears to be good for … more stretching. Oh, and:

• yes, stretching does feel pleasant

Further Reading

• SY A Stretching Experiment — What happens when you stretch your hamstrings intensely for several minutes a day in a steam room?
• SY The Unstretchables — Eleven major muscles you can’t stretch, no matter how hard you try
• SY How I Almost Ripped My Own Head Off — A cautionary tale about therapeutic stretching and the risks of self-treatment
• SY Five Ways To Prevent Sports Injuries — Get warm, co-ordinated, relaxed, smart and mobilized!
• SY Mobilize! — Dynamic joint mobility drills are an alternative to stretching that “massages you with movement”
• SY Basic Self-Massage Tips for Myofascial Trigger Points — Learn how to massage your own trigger points (muscle knots)
• Some other articles that critically examine popular ideas about health: Do Epsom Salts Work? and Water Fever and the Fear of Chronic Dehydration and Posture Exercises for Posture Correction.

Other interesting reading relevant to stretching:

• “Stretching ‘fails to stop muscle injury’,” a webpage on news.BBC.co.uk.
• “Reducing risk of injury due to exercise: Stretching before exercise does not help”. This is a superb British Medical Journal editorial, which adds about fifty pounds of credibility to this article.
• “Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review”. This is the much more technical article, to which the editorial mentioned above is referring.
• “Stretching before exercise: an evidence based approach”. Another more technical article, but also excellent and heavily referenced.
• Published since this, my article SY You Can’t Beat Muscle Soreness — The myth of prevention or treatment for muscle fever, nature’s little tax on exercise covers the subject of preventing DOMS more thoroughly.

Notes

1. Cooper, Bob. “The Rules Revisited.” Runner’s World. September, 2009. p. 59. Return to text.
2. Shrier. Stretching before exercise does not reduce the risk of local muscle injury: a critical review of the clinical and basic science literature. Clinical Journal of Sports Medicine. 1999. PubMed #10593217. Comments: 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. Return to text.
3. Herbert et al. Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review. British Medical Journal. 2002. Return to text.
4. Pope et al. A randomized trial of preexercise stretching for prevention of lower-limb injury. Medicine Science in Sports Exercise. 2000. PubMed #10694106. Comments: 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.” Return to text.
5. Tip of the hat to reader Jennifer M, who sent me this. Jennifer added that this passage reminded her of her father, “who remained competitive at the 800m until into his 60s, but could never come close to touching his toes.” Good example! Return to text.
6. I spent a decade in clinical practice as a massage therapist, routinely asking my patients about their stretching beliefs and habits, among many other things. These days I am a full-time writer on these topics with a global audience, so I heard vastly more about stretching from readers by email than I ever heard from my patients back in the day. I have a great bird’s eye view of popular opinions about stretch. Professionals send me a lot of mail as well, so I get a lot of exposure to their opinion’s. Are they more educated about stretch? You’d sure hope so, but that hasn’t really been my impression, to be honest — it really seems like everyone is just repeating things they heard other people say. Professionals just hear and repeat even more. Return to text.
7. Flexibility is routinely suggested both as a reason to stretch, and a reason why stretch works for other purposes. These are quite different things. Both will be considered in detail below. Return to text.
8. More evidence on this is coming, but meanwhile there’s an interesting general principle at work here that is worth pointing out: these goals are proven to be impossible either straightforwardly by an evidence of absence, or less obviously but almost as certainly by a preponderance of evidence of minor efficacy. Proof of the existence of a trivial benefit damns with faint praise, and proving that something barely works is literally almost the same as proving that it doesn’t work at all. This is chronic problem with many allegedly effective treatments and therapies: they may work a little, but they fail to impress. Stretching suffers from this problem in spades. Return to text.
9. A real phenomenon, certainly — but not necessarily a “thing” in the tissues. It’s likely that trigger points are not what they seem to be. It can be a controversial topic. Return to text.
10. Davies et al. The Trigger Point Therapy Workbook, p8. “Trying to get at … relatively small trigger points by stretching whole groups of recalcitrant muscles seemed unnecessarily indirected and inefficient.” Return to text.
11. Simons et al. Myofascial Pain and Dysfunction, pp127–135. Many therapists mistakenly believe that Travell and Simons’ well-documented “spray and stretch” method means that stretching is unequivocally good for trigger points. But the point of the vapocoolant spray is to “distract” the nervous system from the pain of stretching a dysfunctional muscle, which — as one theoretical model describes it — has both small patches of hypercontracted sarcomeres (trigger points) and long stretches of sarcomeres that are overextended. Without the spray, muscles in this predicament may contract defensively. Consequently, Travell and Simons do not recommend stretching trigger points without the spray, emphasizing that the concept is hardly risk free. Return to text.
12. Kay et al. Effect of Acute Static Stretch on Maximal Muscle Performance: A Systematic Review. Medicine & Science in Sports & Exercise. 2011. PubMed #21659901. Researchers looked at more than 4500 studies before choosing about 100 to look at more carefully. The found “overwhelming evidence” of “no significant effect,” and that is certainly no surprise for anyone who had been watching stretching science over the years. Return to text.
13. Soligard et al. Comprehensive warm-up programme to prevent injuries in young female footballers: cluster randomised controlled trial. British Medical Journal. 2008. PubMed #19066253. In 2008, Norwegian researchers compared injuries in over a thousand female footballers who participated in such a warmup for a season, to another several hundred who didn’t. The athletes with the warmup had fewer traumatic injuries, fewer overuse injuries, and the injuries they did have were less severe. Static stretching was not part of the warmup. “Active stretching” was … but “active stretching” is what I would call “mobilizations” — doing moving lunges, for instance — as opposed to the kind of static or passive stretching that most people think of when they think of stretching. Return to text.
14. Soligard et al. Compliance with a comprehensive warm-up programme to prevent injuries in youth football. British Journal of Sports Medicine. 2010. PubMed #20551159. Comments: 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! Return to text.
15. I am not certain, but I believe this is the paper in question: Tiidus. Manual massage and recovery of muscle function following exercise: a literature review. Journal of Orthopaedic & Sports Physical Therapy. 1997. PubMed #9007768. Return to text.
16. Lund et al. The effect of passive stretching on delayed onset muscle soreness, and other detrimental effects following eccentric exercise. Scandinavian Journal of Medicine & Science in Sports. 1998. PubMed #976444. Comments: 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.” Return to text.
17. Cheung et al. Delayed onset muscle soreness: treatment strategies and performance factors. Sports Medicine. 2003. PubMed #12617692. Comments: 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.” Return to text.
18. Weber et al. The Effects of Three Modalities on Delayed Onset Muscle Soreness. Journal of Orthopaedic & Sports Physical Therapy. 1994. PubMed #9512831. Comments: From the abstract: “… analysis indicated no statistically significant differences between massage, microcurrent electrical stimulation, upper body ergometry, and control groups.” Return to text.
19. Herbert et al. Stretching to prevent or reduce muscle soreness after exercise. Cochrane Database of Systematic Reviews. 2011. PubMed #21735398. Comments: 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.” Return to text.
20. Hart. Effect of stretching on sport injury risk: a review. Clinical Journal of Sports Medicine. 2005. PubMed #15782063. Abstract:
    

    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.

    Return to text.

21. Brushøj et al. Prevention of overuse injuries by a concurrent exercise program in subjects exposed to an increase in training load: a randomized controlled trial of 1020 army recruits. American Journal of Sports Medicine. 2008. PubMed #18337359. Return to text.
22. Pereles et al. A Large, Randomized, Prospective Study of the Impact of a Pre-Run Stretch on the Risk of Injury in Teenage and Older Runners. www.usatf.org. 2011. Return to text.
23. There is extensive experimental evidence showing that stretching is effective treatment for plantar fasciitis. See Wolgin, Giovanni, Batt, Barry and Powell. Return to text.
24. From Kay et al: “The detrimental effects of static stretch are mainly limited to longer durations (≥60 s) which may not be typically used during pre-exercise routines in clinical, healthy or athletic populations. Shorter durations of stretch (<60 s) can be performed in a pre-exercise routine without compromising maximal muscle performance.” Return to text.
25. Beckett et al. Effects of Static Stretching on Repeated Sprint and Change of Direction Performance. Medicine & Science in Sports & Exercise. 2009. Return to text.
26. The most obvious wrinkle is that the negative impact of static stretching on sprinting might be short term — were the runners slowed down for only ten minutes? Twenty minutes? As much as sixty? Another important consideration is that the potential therapeutic effects of stretching — still remarkably unproven at this late date in history, but still hypothetically possible — could conceivably outweigh the relatively small cost of being slowed down. For instance, if (big if) stretching significantly stretching reduced the risk of a muscle strain, would that risk reduction be worth the cost to sprinting speed? Probably! If. Return to text.
27. For more detail, see another article on SaveYourself.ca, Does Hip Strengthening Work for IT Band Syndrome? Despite its popularity, “weak hips” is a weak theory, and there is no compelling evidence that hip strengthening can treat or prevent running overuse injuries of leg. Return to text.
28. Many readers have pointed out that experienced yoga practitioners are flexible, especially the older ones. For instance, T.G. writes, “In my yoga class, the older people are way more flexible than the younger ones.” It may be that training has made them more flexible, but not necessarily. A perpetually neglected explanation for the flexible-yoga-oldster phenomenon is that people with natural gifts of flexibility like the activity and stick with it, because we humans enjoy almost anything we’re good at … and the less flexible tend to drop out, even if it takes yars and yars. I’m not saying this is how it is — I truly don’t know — just that it’s the kind of explanation that tends to get neglected. We need to consider such counter-intuitive, inside-out explanations that are, perhaps, less comforting to our biases. Even if there is a training effect, it’s extremely likely that it’s only part of the reason those folks are more flexible, and that’s something most “huge fans” of stretching have simply never considered. Return to text.
29. Weppler et al. Increasing muscle extensibility: a matter of increasing length or modifying sensation?. Physical Therapy. 2010. PubMed #20075147. Return to text.