Question: how do muscles know when to stop growing

Jenni Tilley answered on 20 Jun 2011:

Like bones, tendons, skin, ligaments, muscles grow in response to the mechanical stimulation they feel. Essentially they grow and develop until they are strong enough to resist the force and deformation we apply to them.

A brilliant example of this is the bunion (hope fully you don’t have these yet, but ask your mum/gran if they do…) When you wear horrid (but very pretty) pointy shoes, or any shoe that deforms your foot for that matter, the bones in your feet are put under pressure. Because bone response to pressure and extension, the bone grows to resist the force it feels from your shoe, resulting in horrid lumpy bone where the shoe was rubbing.

Muscles grow to accomodate the force they feel. If you lay in bed and did nothing for 6 months your muscles would start to dissolve away because your body would think you don’t need them. This is why people in comas have to have physiotherapy – so that they still have some muscle left when they wake up.

To understand a bit more about *how* muscles grow, take a look here:
/sportsj11-zone/2011/06/why-do-we-ache-the-morning-after-exercise