They did it without supplements or barbells and dumbbells yet they sculpted their people with perfect symmetry. Now i'm going to assume that a good amount of people had to have looked like that for them to sculpt them like that. These people invented wrestling and the olympics so i'm going to assume they invented training their bodies as well
If you sculpted people the way Americans look today there would be some sad statues indeed. What do you think their athletic training regimen and diet was like?