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- Alex Hutchinson (@sweatscience)
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What we know so far: static stretching seems to cause a decline in maximal power, strength and speed, as well as hurting running economy in endurance runners. What a new study in the Scandinavian Journal of Medicine & Science in Sports reveals: stretching is bad for cyclists too — possibly even worse than it is for runners.
The authors of the study, from the University of Milan, argue that the performance-damping effects of stretching may be more obvious in endurance cycling than in running. The reason is that type II muscle fibres (a.k.a. fast twitch) are affected more than type I muscle fibres (slow twitch) by stretching. When you’re running at below-threshold paces, your leg muscles are only applying about 20% of their maximal force, so they can rely mainly on type I fibres. Cycling, on the other hand, requires a greater proportion of maximal force: about 60% of max force at 85% VO2max, according to the paper. As a result, cyclists recruit a higher proportion of type II fibres, and are thus more vulnerable to stretching-induced weakness.
That’s all fine in theory — but what do the experiments say? The researchers did a series of tests of VO2max, mechanical efficiency, time to exhaustion (with the power set at 85% of power at VO2max, so that exhaustion took about 30 minutes), and so on. Here are the efficiency results, with open circles corresponding to no stretching and closed circles corresponding to 30-minute pre-exercise stretching routine:
On average, efficiency was about 4% lower after stretching. The time to exhaustion was decreased by 26% after stretching (22:57 vs. 31:12).
I’ve been explaining the reduction in running economy caused by stretching by talking about the legs as a set of springs that store energy (and do so less efficiently when they’ve been stretched). But these results suggest that the effects of stretching on the muscle fibres themselves (and perhaps on neuromuscular signalling pathways) are just as important, since cycling doesn’t rely on that springy-legs effect.
Anyway, this is, as always, just one study — but probably worth keeping in mind if you do a lot of static stretching before cycling.
It would be nice to see some studies on the effects, if any, of post-run/exercise static stretching. I don’t think I know anyone who still static-stretches before working out!
Hi Alex:
Just read this article about the same topic and suggests, stretching for athletes involved in ‘static flexibility’, such as hockey goalies, dancers and gymnasts etc. Since I’m no expert on the topic, the article quotes a few studies by different institution. Have you seen this article?
Here is the link to the article.
http://well.blogs.nytimes.com/2011/06/22/to-stretch-or-not-to-stretch/?smid=tw-nytimeshealth&seid=auto
Cheers,
Brie
@tadkistani: Yes, there’s not much research either way about post-workout stretching. I can’t see any reason NOT to do it. But on other hand, I personally can’t see any reason to do it — so I don’t!
@Brie: The NYT article is a good one — Gretchen Reynolds is a careful reporter with a good handle on the literature. I agree that stretching (and flexibility in general) is important for certain activities (e.g. ballerinas and hockey goalies). And I agree that the evidence that stretching HURTS performances is relatively limited and depends on the details of the stretching routine, especially for recreational athletes where, say, a 0.5% decrease in power is unlikely to be noticeable. And I also agree that there’s no evidence that pre-workout stretching helps with performance or injury prevention in most cases. What each person does with those various pieces of information, of course, is up to them!