Stretching is bad for power… and endurance running


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[UPDATE – March 24, 2010: for further info on this study, including an interview with the author, see this post.]

Among the latest batch of papers accepted for future publication in the Journal of Strength and Conditioning Research is one on the effect static stretching during warm-up on jumping performance, by researchers from the University of Milan. It shows that stretching before exercise makes you jump lower, more slowly, and with less force. Ho-hum, right? Anyone who cares about this stuff has seen these studies before.

(For the record, what’s new in this latest study is that it looks at different joint angles. We already knew that power from full knee extension — e.g. in sprinting from starting blocks or playing football — was reduced. Now we know other angles, like you might encounter in swimming, basketball, soccer and so on, are also compromised.)

But for many people, these studies don’t carry much weight. The typical attitude is summed up by running guru Steve Boyd on his excellent blog:

Although I hedge my bets by not making a religion of stretching, I count myself among those millions who are convinced on the pure level of “feel” that flexibility work enables them to run further and faster, and cope with injuries better. And I think one day science will discover the secret of what many runners “know” deep in their fibers.

And to be fair, most of the existing studies look at explosive power rather than endurance. So I was definitely interested to see another study on the JSCR site that, for the first time, focuses on the effect of static stretching on endurance performance. (There was a study last year that found that less-flexible runners tend to have higher running economy, but it didn’t look explicitly at stretching.)

Lo and behold, stretching before a run makes you run more slowly and less efficiently.

The basic details of the study, which comes from Florida State University: 10 trained distance runners performed two one-hour runs, once with stretching before (four 30-second reps of five basic stretching exercises) and once without. The one-hour runs consisted of 30 minutes at a set pace (65% of VO2max) during which running economy was measured, then 30 minutes going as fast as they could to see how much distance they could cover. The non-stretchers burned ~5% fewer calories in the first part of the experiment, and ran 3.4% farther in the second part of the experiment.

I won’t get into the debate about what causes this. It may have to do with the energy storage abilities of floppy tendons, or the torque-producing capabilities of stretched muscles fibres; this study doesn’t address that. I’m also not making any pronouncements about the role of stretching in general — after all, it’s still very possible (though highly controversial) that a regular stretching program might reduce injury rates.

But I will say this. Static stretching may feel good (possibly in part because so many of us were brought up believing in it), but given the steady accumulation of evidence, you’d be a fool to keep it as part of your warm-up routine before a race. Or any type of athletic competition, for that matter, other that those where range of motion is a key factor, like gymnastics or hockey goaltending.

11 Replies to “Stretching is bad for power… and endurance running”

  1. I learned the hard way that ALL stretching is bad for me.
    This year I stopped stretching completely and I am running farther, faster, and more often than ever before. And my hamstring pain has disappeared. I hope my competition keeps stretching though 🙂

  2. Stretching isn’t bad, it just isn’t useful or effective as preparation for exertion. It remains a useful way to cool down and improve flexibility over time. For historical reasons it was adapted also as movement preparation – coaches affirming from gut wisdom that stretched muscles would be relaxed and more flexible and less prone to injury. Sometimes gut wisdom and tradition mislead us, and this is one of those cases. Research has been affirming from various perspectives that a stretched muscle is less well prepared for exertion, and that dynamic functional movement preparation does a much better job of adapting us for subsequent exertion and minimizing injuries. You still may need to stretch *if* the demands of your sport require more flexibility, but it is generally no longer considered a good idea to do it in the traditional passive way as a warmup. And there are other aspects of mobility besides flexibility and other ways to develop it besides or in addition to traditional stretching. That’s my understanding of this, fwiw.

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  4. @xtreme015 Answering 3 years later, LOL: in fact I see more and more runners in races not stretching. In fact there seems to be a certain trend among the “cabal of initiates” (those that read articles such as this one) that makes a sort of “sign of distinction” of it. And on the other side weekend warriors tend to be more flamboyant to the extend that some seem to be training for performing the Swans Lake instead of doing a short run 😉

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