Today we have a guest post from author Alex Hutchinson. Alex writes a monthly column in Runner’s World (they also host his excellent Sweat Science blog) and is a Senior Editor at Canadian Running magazine. You can find more on Alex at the bottom of this post.
As Alex mentions below, he recently published a fantastic book which has a rather large section on the health benefits of stretching (or lack thereof). As a longtime skeptic of stretching myself, I was very excited when he agreed to summarize the research evidence in a guest post. Enjoy the post!
I guess I should start by stating my bias: I don’t like stretching. For over a decade, I stretched every day, usually twice a day – but I never enjoyed it. I still try to be as impartial as possible in analyzing the evidence for and against stretching, but I figure you have the right to know that I’m a stretching skeptic!
So what is this evidence I refer to? Over the past decade or so, there has been a complete change in how coaches and exercise scientists view stretching. It’s the biggest change in elite training that I’m aware of during that time, and these days it’s the biggest gap between elite athletes and the average person at the gym. I devote an entire chapter to the topic in my recent science-of-exercise book, Which Comes First, Cardio or Weights?, and I’m going to draw on that to present a few highlights of the recent research.
1. Does stretching help you avoid injury during exercise?
This is very difficult to “prove” one way or the other, because every person and every injury is unique. Still, a 2004 systematic review that analyzed 361 studies concluded that “stretching was not significantly associated with a reduction in total injuries.” Other reviews have reached similar conclusions. The early studies that suggested stretching would help always included stretching as part of a warm-up; it now appears that a warm-up (e.g. five minutes of gentle jogging) is important but stretching isn’t.
2. Does stretching help you avoid soreness after exercise?
No. A 2011 Cochrane review of 12 randomized studies with more than 2,000 subjects in total concluded that “muscle stretching, whether conducted before, after, or before and after exercise, does not produce clinically important reductions in delayed-onset muscle soreness.” This is not a surprise: post-exercise soreness is thought to result from microscopic damage to muscle fibres; you can’t “undamage” the muscles by stretching them.
3. Does stretching make you faster, stronger, or more powerful?
Quite the opposite, actually. A number of studies have found that stretching your muscles leaves them weaker and less powerful for somewhere between 30 minutes and two hours. You can’t jump as high and you can’t sprint as fast, possibly because you’ve disrupted the nerve signals from the brain to the muscle (after being stretched against their will, the muscle fibres basically put the brain on “mute”). And if you go for a longer run or bicycle ride, you’ll run slower at the same effort.
This doesn’t just apply to stretching immediately before a run, incidentally. Several studies have looked at correlations between “sit-and-reach” flexibility and running economy (which is like a car’s fuel economy, a measure of how much energy it takes to travel at a given speed). The consistent finding is that the more flexible you are, the less efficient you are as a runner. One theory is that, since your legs act like coiled springs while running, returning 40-50% of the energy you need for each stride, stretching gives you “floppy” springs that can’t store energy as well.
4. But what if I like stretching?
Then stretch away! None of this evidence really offers a compelling reason not to stretch, unless you’re an elite athlete worried about the milliseconds that could make the difference between glory and disgrace. Stretching will make you more flexible (which is pretty nice if, say, you every have to sit cross-legged on the floor), and it will also offer a little bit of strengthening. And for many people, it just makes them feel good.
And there are certain situations where stretching really is important. If you’re a ballerina or a hockey goaltender, extending your maximal range of motion is part of your job – stretching is not optional. But if you’re a runner, the injuries you should be worried about aren’t going to result from trying to do the splits.
5. So how should I prevent injuries?
The first and most important thing is a gradual warm-up. Whether it’s jogging, biking, skipping, skating, or whatever, take at least five minutes to get your heart pumping and your muscles warm. This will do precisely what we used to assume stretching would do: make your muscles softer, looser, and more flexible, simply because of the temperature increase.
That may be enough. But for vigorous activities, you may then want to do some “dynamic stretching.” Unlike traditional static stretching (which is what I’ve been talking about above), dynamic stretching involves movement, and focuses on taking the muscles you plan to use through their usual range of motion and a bit beyond (but not to their maximum range of motion). This article has three simple examples that I use before running a hard workout.
Ultimately, as I said above, the current body of evidence doesn’t make a convincing case that nobody should stretch. So if you enjoy stretching, by all means carry on. But as far as I can see, there’s no compelling reason than anyone should stretch if they don’t want to. And even better, for those of you who could never be bothered to stretch in the first place, you can stop feeling guilty about it.
About the author: A former quantum physics researcher and national-team distance runner, Alex Hutchinson blogs about the science of training and fitness, and writes the monthly Fast Lane training column in Runner’s World. His latest book is Which Comes First, Cardio or Weights? You can follow him on Twitter and Facebook.