However big your biceps may be- and if they are so integral to punching power, could somebody explain Arguello, Danny Lopez, Saddler, Ricardo Lopez, etc...- and no matter how well you master technique, it is physically impossible to punch hard with weak wrists and forearms. Your wrist must be straight on every punch or you will be slapping or cuffing- catlike- and not punching. Turn your wrist one time on a full leverage left hook and you'll see what I mean. And on every punch the first place the shock of impact goes is right up the forearm. You don't need huge muscles here; a good exercise, and very simple and inexpensive, is to tie a cord to a wight, say 5 lbs or so. Tie the other end to a pipe or something similar, in the middle, so you can grab either end and roll the cord in, slowly, which lifts the weight. Roll it up, then back down slowly, about 100 times very day.