eli5 why is exercise supposed to make you tired if atp is not stored?

Question

I read that atp is produced constantly as needed and that you can only store about a minutes worth, so how is exercise supposed to make you tired and sleepy if you’re not using up your energy?

In: 19

Answer 1

Exercising produces this goop in your body called lactic acid. This is produced when your body breaks down carbs. Think of it like this: When you need energy you eat bread, but bread makes you also thirsty and you drink some milk. It’s easy to swim in water, but swimming in milk would be hard, so until your body flushes out all the milk you’re tired.