Margarito and Katsidis Strength and Conditioning regimen?

I understand margaritos history with loaded gloves but lets call it like it is. Dude has a BEASTLY stamina as well as michael katsidis. Now I do understand that the culture of strength and conditoning in the world of boxing isnt perfect and neither is dieting. That being said, these two folks have super human stamina and endurance. Now my question is: 1. Are these guys genetic freaks? 2.Or do they have some crazy conditioning coaches? P.S: I know people are going to bring up peds but lets be honest here, so many fighters are in it both in the mma and boxing but they dont produce these type of stamina and volume punching so lets not blame it on the peds here.