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We do not have the muscle balance science

 •  • 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.

“Muscle balance” might be important… but we do not have the science! More specifically: we have the science, but it’s too much of a mess to be informative.

Guan et al is a conclusively inconclusive new review of 28 trials of inter-limb asymmetries (e.g. hamstrings:quadriceps ratio, their relative strength, power, etc). There’s plenty of decent data here … but, as the research folks say, it is “heterogenous.” Soooo heterogenous. All measuring different stuff in different ways.

“Inconclusive” is never anyone’s favourite result. 😕 But it is good for confirming that most ideas about inter-limb asymmetries are guesses… not evidence-based.

I’ve just cited Guan et al. in my muscle strain book, a minor update to the muscle balance chapter. I delve into “muscle balance”: how much it might matter, and whether we can do anything about it.