i was playing in a summer league in my area and i was hit by some old un-athletic white guy that ended with me having a torn mcl. so i was wondering what i can do to stay in shape so that when i can play again (i play in college and i report back soon) its only my legs that i need to get back into shape, so pretty much how can i work on keeping my lungs and heart in condition but at the same time not hurting my knee more. I have a grade three tear so i cant ride a bike yet. so would swimming be a good alternative?