What excercises are good to build up legs?

My 13 year old son has a hypermobile kneecap and the hospital has said he needs to do nothing but excercise to build up the muscles in his thigh to stop the kneecap moving quite so much. A referral for Physiotherapy has been made but that could take ages. In the mean time i wanna buy him some leg weights and get... show more My 13 year old son has a hypermobile kneecap and the hospital has said he needs to do nothing but excercise to build up the muscles in his thigh to stop the kneecap moving quite so much. A referral for Physiotherapy has been made but that could take ages. In the mean time i wanna buy him some leg weights and get him excercising more. Any ideas?
8 answers 8