Ronaldo, 33, left Real Madrid for the Serie A champions this summer in a £88million.
And during formalities to wrap up the transfer, it was found the Portugal captain had the physical capacities of a 20-year-old.
Ronaldo has just 7% body fat, around 3% less than the average professional footballer.
He also has 50% muscular mass, 4% than the average professional.
At the just concluded World Cup in Russia, Ronaldo was named the fastest player, clocking an incredible top speed of 34 km/h according to FIFA.