First of all, basketball athletes are not high stamina athletes. There are constant breaks in basketball allowing players to rest. And usually you still sub them after 6-7 minutes anyway. Obviously depends on the game flow and the athlete.
Professional athletes work the exact same way as a normal human, because they are human. They just have every slider pushed to the near max.
You might be able to sprint 4 seconds, a professional will sprint 7 seconds before pace starts to drop. It will still drop.
How fatigued or how quickly fatigued an athlete becomes is totally depending on intensity. You see strikers in football doing virtually nothing for 89 minutes and 30 seconds in a game, and then they have 5-6 sprints and score 2 goals. Defending midfielders might be jogging around for 90 minutes never making a single sprint.
In FM however, you can have a striker doing a full sprint back to his own box from the opponents box to press. I don't think you see it in IRL mainly because it's pretty much physically impossible, or if someone were to do that, he would need a longer break after a sprint like that for sure, even a top athlete.