The archeologists study of the bones has revealed some fascinating details, but no more shocking in the light of many 300 gladiator based diet and training plans that it was veg rich diet high in carbohydrates, supplemented with calcium that kept them fighting fit, and not a high protein diet as would be assumed by many.
Iisotopic analysis to measures trace chemical elements (calcium, strontium, zinc, etc) showed that the gladiators ate more plants and very little animal protein. It seems that unlike the recent film, gladiators weren't afraid to pack on a few pounds. Maybe they did consume to many simple carbohydrates, (mainly barely and legumes) but apparently a little fat provided greater protection from cut wounds.
It seems that they supplemented with somewhat disgusting concoctions of charred wood and bone ash which are rich in calcium. Grossschmidt's research showed some pretty impressive calcium levels in the gladiator bones in comparison to the rest of the population. So despite a seemingly calcium deficient diet their supplementation kept them strong and ready to withstand the battle.
For those of you that take my recommended calcium supplement I should have a delivery arriving from the USA this week. Orders can be taken direct by me or you can buy online from my new client only site (sorry its not open to non clients as you would be just guessing which supplements you need).
Source: http://www.archaeology.org/0811/abstracts/gladiator.html