Question: why do your muscles dissolve in space

Jenn Wadsworth answered on 4 Mar 2016:

Even though we don’t notice, we’re constantly ‘working out’ our muscles against gravity when we’re on earth. Just like when you stop going to the gym and your muscles shrink, astronauts’ muscles start to shrink when they’re not used as much due to the lack of gravity. To try and counteract this muscle loss, astronauts have to work out up to 3h a day, and even then they still lose muscle!