eli5 Why/how do muscles shrink?

Question

You get sore muscles when you train, because you muscle strings rip and when they heal, your muscles grow. As far as I know. So why and how do they shrink?

In: 213

Answer 1

The body can break down muscles for energy, and if you aren’t using them, your muscles are probably consuming more resources than they are worth (biologically speaking in the context of our path of evolution). Muscles are expensive tissue to maintain, and before the modern world, food scarcity was pretty much guaranteed sometimes. The body has to pick what of that limited energy goes where.