Ive alwase wondered why muscles grow, it really was just a mysery, until I saw this.

this video, its, truely amaseing! the way muscles grow I mean you hurt your muscles to make them grow?! thats to unexpected.

You have loads of muscles in your body, They pump blood through your body and help you lift heavy things. You control some of your muscles, but some of them, like your heart do things by themselves.