A good example from the Roman period: Gladiators were very valuable athletes and had the specialized diet and training to match. They are referred to often in contemporary texts as hordearii (meaning "barley men") which is due to their diet, because gladiators ate very little animal protein and seemed to be mostly vegetarian, which is also backed up by analyses of their bone chemistry. They also had to accommodate for the low calcium levels provided by this diet and would mix wood or bone ash into their food or into brews to drink, much in the manner of modern athletes taking vitamin supplements. They also had access to trained masseuses and doctors, much like today's athletes. [1] [2]