What does "taking time off the end of both men's careers" mean?

In the following paragraph," The fact that both UFC fighters were taken to the hospital immediately afterward gives credence to how much it took out of both of them, as well; it's easy to think that this war of attrition will wind up taking time off the end of both men's careers the same way the "Thrilla in Manilla" seemed to do to Ali and Frazier. After such a war, and no clear victor, a rematch has to happen."

Can anyone please tell me how to rephrase " taking time off the end of both men's careers"? Thanks a lot.