May I know if there have been journal article reviews or studies that deal with how the body decides where to build or breakdown muscle first, and the metabolic/endocrinal/molecular mechanisms behind this? Hmmm this might be a trivial issue, like it might be quite obvious that if you train the deltoids, then the deltoids will grow, and not some other muscle. But I'd like to know if this issue has been investigated scientifically. I cannot seem to find any journal articles on this, mayb I am searching with the wrong terms.

The ultimate goal of course is to use this scientific knowledge to control where the body builds and breakdown muscles to achieve certain aesthetic/fitness aims.

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    Do you really need a study for something so blatantly obvious? The body builds muscle in response to a stimulus. Muscle will be lost most where there is the least stimulus. Additionally, the more “excessive” the quantity of muscle present, the more it is seen as expendable. Commented Nov 18, 2020 at 1:44
  • I mean, this isn't a journal article. You're talking about textbooks here.
    – C. Lange
    Commented Nov 18, 2020 at 23:08

1 Answer 1



If you want something to grow, work it hard. If you want it to not-shrink, work it at least a little.

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The only way I can interpret your question in a way that makes sense to me is "When I'm not exercising a variety of muscles, is there any way to control which of them degrades first/fastest?". Is that what you're asking? Because if so, AIUI, not really.

Muscle is expensive, and if it's not being used, the body gets rid of it. Assume every unused muscle will degrade by the same percentage over a time of disuse. Which means that it will be most visible on the largest muscles, as they're going to be larger relative to the (unchanging) skeleton than the small muscles. So if you're the stereotypical "mirror muscles" type with huge pecs and biceps, but no calf muscles at all, then if all your muscles atrophy by 10%, your overall calves will only shrink by say 2%, but your arms might by like 8%.

There is evidence that the more androgen sensitivity a muscle has, the faster it will grow, and there is some evidence that that also means the slower it will atrophy (so arms shrink faster than calves), but I haven't seen anything that investigated this directly. Nor do I imagine it's a huge effect. And you can't control it, so it doesn't seem to help what I think you're trying to do.

Good luck with whatever that turns out to be.

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