I got a little excited at the gym yesterday doing barbell squats and now my legs are really sore. Not just fatigue -- sharp pain in my quads. I've done it before and I know it will take a few days to get over enough to run or cycle again.
I don't want to spend the next few days without any exercise -- I'd like to do some upper body resistance stuff, but I don't want to do it without doing some cardio for warm up.
How can I warm up without using my legs?