A catch-all diagnosis gym rats use to describe their injuries. Liftitis includes anything from tendonitis, to torn muscles, to broken bones.
Joe: Hey, I'm hitting up the gym tonight around seven, you coming?
Brian: I would, man, but I got liftitis bad in my shoulder. Gonna have to chill for a couple weeks.
Joe: Why don't you go to a doctor, man?
Brian: Why waste the money? All he's gonna tell me to do is ice it and stop lifting. Everyone knows that's how you treat liftitis.