It's more important in climbing to have a good strength:weight ratio than to have a massive amount of muscle mass. Consider that every pound of muscle you pack

It's more important in climbing to have a good strength:weight ratio than to have a massive amount of muscle mass. Consider that every pound of muscle you pack on has to be taken up the pitch, has to be borne by your fingertips during the hardest moves. Also, the act of climbing itself is not really the right volume to promote muscular growth. Bodybuilders like Kai Greene laid out their routines, where they do around 10-20 reps for high volume work, then obviously keeping up strength with 1-5 rep sets. Pile on a very large, protein rich diet, performance enhancing drugs, and you can gain incredible amounts of muscle mass. Contrast that to Alex Honnold, who does climbs for hours on end, which is more of an endurance sport than strength training. He also has a modest vegetarian diet, I don't believe he is slamming multiple chicken breasts per day like a body builder. I can't say if professional rock climbers use PED's, but they certainly are not interested in packing on extra muscle anywhere except the grip strength/forearms, which is crucial to surviving the hardest routes.