Soviet athletes were picked from a large pool, the best of the best
He was super strong, also super juiced. Add super technique to that, and you get a super athlete.
Like all super heavy big guys in olympic lifts, he started out muscular, and with a weightlifter physique, the extra bulk came later
The whole system was geared towards success, they started ultra young, and don't for a split second doubt they weren't on every available drug, to the excess.