I have no idea what ufc is but I would reckon that none of them are on the juice. Also, no professional athletes are on. Barry Bonds is not on. Oh, and wrestlers, they are natural too. As far as bodybuilders go, I think Arnold might have done a cycle of dbol/primo, but I seriously doubt any bodybuilders since him have done any anabolic steroids.
I think this is a testimony to nutrition and working out. And creatine. Oh, and Cell-tech.