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In the following diagram from the Love and Bailey textbook I see that injury causes a decrease in hypertrophy due to a decrease in the expression of IGF-1. Here Love and Bailey consider a skeletal muscle model.

From Love and Bailey

But in Robbins and Cotran (diagram attached), mechanical stretch and growth factors like IGF-1 cause an increase in contractile protein synthesis. Here Robbins and Cotran consider a heart muscle as model.

From Robbins and Cotran

So the question is whether injury causes hypertrophy or atrophy? I feel that if injury is beyond repair then atrophy should occur, but is this what Love and Bailey wanted to say or is it different? Does it depend on whether the muscle is skeletal muscle or cardiac muscle?

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    it would most likely depend on the muscle model. cardiac muscles will still contract even in the presence of injury due to its automaticity while skeletal muscles can reduce signs of inflammation like pain by simply immobilizing that muscle. immobilizing that muscle will produce the effect of "atrophy of disuse"
    – kit
    Commented Mar 5, 2019 at 13:20
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    This should be migrated to biology [physiology]
    – Graham Chiu
    Commented Apr 10, 2020 at 23:28
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    @GrahamChiu I would have done so had you flagged it but I didn't see this until now. It's too old to migrate now.
    – Carey Gregory ♦
    Commented May 20, 2020 at 14:35
  • @CareyGregory I only saw it last month!
    – Graham Chiu
    Commented May 20, 2020 at 23:45
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    If the OP wants, they can still copy/paste this question to Biology and delete this one.
    – Carey Gregory ♦
    Commented May 20, 2020 at 23:50

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The answer is hypertrophy, but if the injury is disabling, then it will lead to muscle atrophy due to disuse. Note that body builders lift weight until causing minor injury.

https://www.unm.edu/~lkravitz/Article%20folder/musclesgrowLK.html

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