The energy systems

Consider the energy systems an 800m track athlete would use during a race. In a scenario where the runner has completed an adequate warm-up, their aerobic system is heightened and meeting the energy demands they’re putting on their body, prior to beginning the race.

During the first 400m of the race, they feel strong and quick, why? What are the energy systems their body is using? (Hint: there are 3, remember they have completed a warm-up).

As the runner approaches the last 200m of the race, they begin to slow down. Why?