You can change effort values throughout the race to manage your endurance. "Energy Restore Phase" recovers a small amount of endurance but you run much slower. "Sprint" moves the fastest but you burn a lot more endurance. I Implemented this system using scriptable objects as a base to contain that data necessary for the states such as movement speed and animation speed. Those are then fed into the navigation system and mechanim system respectively. There is a custom endurance tracker that accurately tracks distance based on speed. Both the player and enemy runners inherit from a base "Running Entity" abstract class where they override the method "movement". Player movement is controlled by mouse position and the enemy runner's movement is automatically calculated by the navmesh system. The player uses the nav mesh system as well, but the destination is constantly set to the mouse position.
Here is the link to my GitHub Repo for the project
This was another prototype I made for sprinting. It functions similarly to the long distance simulator by using the Unity navigation system, but adds speed to the player every time the space button is pressed.