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Is running downhill healthier than running up?

 •  • by Paul Ingraham
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Weekly nuggets of pain science news and insight, usually 100-300 words, with the occasional longer post. The blog is the “director’s commentary” on the core content of a library of major articles and books about common painful problems and popular treatments. See the blog archives or updates for the whole site.

The April 27 episode of the BBC health podcast, “Just One Thing,” with Michael Mosley was about eccentric exercise (emphasizing “braking” contractions), and he said this:

“Weirdly enough, running downhill is likely to be better for me than running up. … Eccentric exercise is actually really important for all sorts of health benefits… one of the quickest ways to make yourself stronger.”

Nope. Overstatement foul! Do not pass go, do not collect $200, and please stop talking about fitness!

It is a pleasant show, and I like listening to Mosley. But those are not minor overstatements: they push the truth to the breaking point. And it’s this kind of constant, casual hyperbole that makes health and fitness information such an exhausting minefield of misinformation. (I can live with the oversimplification — that's an inescapable reality of targeting general audiences. But this was also gross hyperbole.)

“Eccentric” muscle contractions are “braking” contractions — muscles generating force while elongating. We do them constantly. They are the yin to the yang of concentric contractions. They do make muscles more sore, a fact that seems to have been transmogrified into no-pain-no-gain hype. People now seem to believe that eccentric contraction is a special stimulus, a stimulus that is better than others for healing and/or adaptation to training.

Eccentric contraction is not a “special” stimulus. It is just a slightly more efficient way to challenge a muscle — trivially better bang for buck. Or perhaps not even that, because of the higher cost in soreness!

But, but, but … what about heel drops for Achilles tendinitis?!

This is the canonical example of an allegedly evidence-based way to use the “special stimulus” of eccentric contraction, recommended by fine physios everywhere. I recently spent about an hour re-reviewing the research on heel drops for Achilles tendinitis in the hopes of using it as an solid example of something that really “works” for recovery. Despite all my cynicism, I foolishly thought surely there’s good evidence for this extremely popular idea. Surprise surprise, there is not. It definitely does not clearly work! Couppé et al:

“There is no convincing clinical evidence to demonstrate that isolated eccentric loading exercise improves clinical outcomes more than other loading therapies.”

And I agree: I couldn’t find any either. For more information about eccentric exercise, see: Eccentric Contraction: A weird bit of muscle physiology.