Pumpnpose is injected into the area of muscle that you want to enhance. You can actually increase the muscle size with a few injections. I believe (not for sure) that it is some type of fatty liquid that you inject into the muscle and it is broken down by the muscle, but remains there - if that makes sense. It is basically enhancing the muscle to a bigger size cosmetically. Side effects are that it creates striations or ripples in the muscles and this can be seen when you shred or cut-up.
PS: FDA Laws (USA): Any injectible is illegal without a physician prescription, except Insulin.
PS: Karma is always welcome here!