system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When playing in sports or doing anything tiresome on the body, what causes "second wind" ?
gpt
Okay your brain has a sort of limiter in it when it comes to physical activity. It says we better save some energy just in case we have to run away from a life threatening thing. So really when you feel dead tired and exhausted you actually have quite a bit left in the tank but your brain is lying to you to keep that energy in reserve. Every now and then though through excitement, Adrenalin whatever you can tap into some of that extra energy.