So, to be honest, I think it's definitely big - like a hefty 8 or 9 inches.
I think that ridiculous bulge is a combination of his thick thighs pushing his balls forward all the time, since they can't hang between his legs. This pushes EVERYTHING forward, which makes him look gigantic. He probably is big, but I don't think it's supernatural or anything; just good placement. Now, someone mentioned a cock ring, which is always possible, but I imagine it would be extremely uncomfortable when working out; but I guess that just depends on the quality and how long he wears it.
Gorgeous guy though! Hopefully he works off his mass properly when he no longer wants to compete.