"2 stints per drive"가 무슨뜻인가요?

In total 307 laps were driven by the team in 8 stints (2 stints per driver). 

- The Effect of Individual Stress Zones on Car-Racing Performance 논문 내용중.

자동차경주 잘아시는분 도와주세요 ㅜ

RACE FORMAT인거같은데..