Like conditioning I'm saying.Let me know

go to a bookstore online or in person, get a book called "Nolan Ryans Pitchers' Bible". :) Read it religiously ;) a fantastic book written by the most unhittable pitcher in baseball history. he talks all about his training regimends.

former Braves pitching coach Leo Mazzone came out with a video to help pitchers in the mid to early 90s. I would recommend gettting it.

to answer your question pitch and pitch and pitch some more. the only way to strengthen the pitching muscle is reptiton

There is a college pitching book that is known in some baseball circles as the pitching bible. Probably produced by a major college baseball program like Stanford, Texas, or LSU etc. I have heard that it has helped many a pitchers get to the next level. I can't remember the title but I hope i started you in the right direction of where to look.