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

Your body is constantly trying to economize and manage what it considers to be limited resources. Muscle is expensive to maintain, so, if you don’t keep making sufficient demands on your body to build and use that muscle, your body will consider it an unneeded expense and allow it to degrade.

The fact that most of us have enough food available to maintain a lot of muscle is a very new concept to evolution, which is geared to prevent us from starving to death.