That's really not how it works

Anabolic steroids don't give you more cardio, they are... anabolic. They make you bigger or offset the catabolic properties of intense cardio training and let you recover faster (not fast enough to revover between rounds, tough). 

There are PEDs that do allow for a better gas tank but those are different substances, for example EPO. but if francis were to use very little EPO etc or not at all, he could still be on a metric fuck ton of trenbolone (not saying he is) and still have a terrible gas tank.

Francis is just too damn big and shredded to be clean. Like there are limits to human body and francis is way past that. Oh and so is Gane too.