He's on growth hormone.
Its the only logical answer. No 6'5" 200 pound man can handle sprint training unless they're getting boosted.
The strain on his muscles is more than is humanly possible without injury.
He's getting some kind of Growth Hormone boost. Is it illegal? Who knows but I can tell you it is a secret.
We already know Blake and Fraser dope and they were caught. Was VCB and Powell doped? Probably. VCB had a terrible Olympics. She's showing age beyond her years likely from all the dope she was putting in her.
Powell is no surprise and has always been an enigma at major comps, probably because he backs off the doping so he doesn't get caught.
This is Bolts last big Olympics, he'll be way too shot from dope in Rio to beat Blake and likely a new American.