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Do spasms hurt?

 •  • 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.

What a silly question: of course spasms hurt! Everyone knows that.

Or do we?

I just read a dense scientific review of the physiology of muscle cramps, so that you don’t have to (Minetto et al.). Very tricky subject matter! It raised more questions than it answered (as good science usually does). Cramps and spasms are amazingly weird. The authors say that the role of spinal mechanisms in spasm has been “proved unambiguously,” but many mysteries remain, most notably why cramping is much more likely in some people and some muscles.

Stranger still, not all spasms hurt… and when they do hurt we don’t actually know why.

Obviously large, acute cramps are painful, even injurious — no mystery there. And even small ones can be agonizing, as anyone who suffers from foot cramps knows all too well. But most spasms aren’t powerful enough to actually tear tissue. And if they aren’t causing damage, why do they hurt? But not always?

Given the amount of pain casually attributed to cramps and spasms, this is one of the toughest puzzles in all of musculoskeletal medicine: can a non-obvious spasm hurt? That is, can we have a spasm that isn’t obviously a spasm … but it’s enough of one to be painful? Or the right kind?

Probably? But no one really has a good answer.

This is just a weird, interesting thing I wanted to highlight, after citing Minetto in a recent update to my muscle strain book, which tries to answer the question: Is that pain a muscle strain, or does it just feel like one? See also Cramps, Spasms, Tremors & Twitches.