Why was chariot racing so dangerous?

Chariot racing was quite a popular sport, and ancient charioteers enjoyed huge public attention. A typical race had 12 chariots racing in the team, and the team of four was called faction. However, the chariots needed to work as fast as possible to win the race, and thus, to gather speed, they needed good horses and light chariots. These were quite dangerous as the driver could be thrown and trampled. As a result, the race declined in popularity during the seven centuries after war broke out between Romans and Arabs.