Very few of the Christians recanted, although an altar with a fire burning on it was generally kept in the arena for their convenience. All a prisoner had to do was scatter a pinch of incense on the flame and he was given a Certificate of Sacrifice and turned free.
It was also carefully explained to him that he was not worshiping the emperor; merely acknowledging the divine character of the emperor as head of the Roman state. Still, almost no Christians availed themselves of the chance to escape.

About early Christians in the Arena. Those about to Die (1958), Chapter 14