Gladiators were never just randomly chosen, they were always slaves, criminals, prisoners, or they were volunteers. They never were aloud to stop fighting until they got too old. when they got to that age they had to teach younger Gladiators how to fight
Every Gladiator was locked up in a cell. They did this so they Gladiators didn't escape, but if they did try they'd be put in a worse cell that is smaller and has rats. If they tried again any time after the first they would be beat or killed
When a man or women got chosen they were never just picked and left there until battle they were always trained. there were over 100 schools for this. When they got to the school the trainer was the one who chose what type of gladiator they were. They all trained in a practice arena, but they used wooden swords before they could be trusted with real ones.