Would like some opinions from folks knowledgeable on the subject. Is is a good or bad thing to pre tire a muscle group before you work out. What I mean, for example, on a day that I normally would work chest muscles by doing bench press etc. I will go into a side room in the gym and do multiple sets of varying types of push- ups. After 15-20 minutes of push-ups and some other core work I then go to complete chest work in the weight room. I sure can't lift as much on those days that I do this. Just don't know if this is a stupid thing to do or not. I just enjoy doing pushups and like to start workouts with them and other core exercises.