Ancient Rome

Gladiators consisted either of captives, slaves and condemned malefactors or of free-born citizens who fought voluntarily. Of those condemned, some were said to be condemned ad gladium, in which case they were obliged to be killed within a year, and others ad ludum, who might obtain their discharge at the end of the three years. Freemen who became gladiators for hire were called auctorati. 

Yes, just like Russel Crowe, Roman gladiators were trained on a regular system in barracks or ‘schools’ (ludi), of which the earliest and (up to the close of the Republican period) the most important were at Capua.

During the Empire, training schools were maintained at public expense and under the direction of state officials. The purpose of all the schools, public and private, was the same: to make the men to be as effective fighting machines as possible.