What could a gladiator do prevent his death?

Gladiator were athletes from Rome, and they were very well trained in fighting and fought against each other and normally led to the death of one of the gladiators.

But if one of them surrendered his weapon or showed that he wanted to give up, he could prevent himself from being killed. Even putting up a finger in the air was also a signal that he wanted to give up fighting and prevent from being killed.