... my third injections for my right knee. I know I am supposed to rest for 48 hours after the shots... and I do. Why is this? I was able to schedule all my previous shots for days when I could rest but because of the holidays my shot today was scheduled for a day that I work out. Is it okay to work out (strenuous) after an injection? Is the concern just pain, or, will it make the shot less effective. I can deal with the pain but I don't want to waste the shot? Thanks, kevin