Practical Science on Movement and Pain
Practical Science on Movement and Pain
Here is a guest post from Paul Ingraham, a former massage therapist and current health science journalist and copyeditor for ScienceBasedMedicine.org, and creator of the excellent website PainScience.com. His website has an extensive collection of well researched ebooks and articles on a wide variety of topics related to common therapies for chronic pain and athletic performance, especially muscle pain and some common overuse injuries like IT band syndrome and plantar fasciitis. His approach is very skeptical and evidence based, and as such he does a lot of debunking, which I like. Here is his take on the alleged benefits of stretching.*
QUITE A STRETCH
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 Magazine.1
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 you are supposed to find the time to do. Can all these people be barking up the wrong tree? Sure they can! And they are.
Plentiful recent research now shows that stretching as we know it — the kind of stretching that the average person does at the gym, or even the kind of stretching that athletes do — could very well be a waste of time. Articles published in recent years, reviewing hundreds of studies, have concluded that there isn’t much evidence that stretching prevents injury or muscle soreness.2, 3 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
So why are people stretching?
Why people stretch
Trainers, coaches and health care professionals are starting to insist on making recommendations based on evidence, or at least a really convincing physiological rationale … and stretching just doesn’t hold up very well under that scrutiny. When challenged, many stretching enthusiasts 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.
When pressed for reasons, people will come up with a few predictable stretching goals. Here are the four hopeful reasons for stretching that I hear every day:
And sometimes you also hear:
Not one of these can be supported with evidence, or even has a persuasive rationale. Stretching for these reasons is probably a waste of your time.
Stretching research shows that stretching is not an effective warm up
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. Warm up 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 warm up routine focused on these goals actually might provide significant insurance against the number and severity of both traumatic and overuse-caused injuries.7
So, warm ups in this second sense might be 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. 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 barely even qualifies as “official” exercise dogma anymore — most professionals actually gave up on it many years ago, and it is passé even in the opinion of many joggers, weekend warriors and other amateurs. Yet there are still far too many people out there stretching before they run, trying to “warm up” almost exclusively by standing still and elongating muscles! Once again, the best way to prepare for an activity is probably 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 its religion. 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 DOMS — and certainly not stretching.6, 7 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.”8 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 500 soldiers doing preventative exercises, including stretching.9
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.
Hardly anyone needs to be more flexible
“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 worried about being 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 task, you probably don’t need to be more flexible.
Obviously, stretching can be effective at increasing flexibility — acrobats, gymnasts, yogis and martial artists have been doing it for centuries, sometimes achieving uncanny mobility. But these are highly motivated athletes with specific and extreme goals and stretching regimes that would intimidate the rest of us, and with good reason: they often injure themselves along the way.
Stretching probably doesn’t enhance performance (and it definitely doesn’t make you spring 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 claim that it enhances 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 (The Stark Reality of Stretching: An informed approach for all activities and every sport) — but that book is conspicuously full of armchair science, and no actual evidence that the ideas are true.
Predictably, research has shown that stretching does not improve sprinting. More surprisingly, research has shown the opposite. What happens to your sprint if you stretch first? All other things being equal, the athlete who didn’t stretch is going to leave you behind!10
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.