Excercise is a stress on the body, you lose muscle after every work out than theres a recovery period after that period your body can overcompensate (growth) if you workout prior to this you've short circuit the process. Also you need to train with more intensity each time. "Pump" is only bloood volume if you measure your arm than get a pump and measure your arm again it will measure the same, true with all muscles (except the penise which is technically a gland)
I recommened this book
http://www.bodybyscience.net/home.html/?page_id=18