system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What happens to your body when you get winded?

Just saw a video of a guy falling down and getting winded. What's going on that causes the inability to breathe?
gpt
You know how walking uphill is harder than walking downhill? Or, how it's more difficult to stretch a spring, and it snaps back to place on its own? For the same reasons, inhaling is more difficult than exhaling. Not so difficult that it requires a lot of effort, but a part of the equation is that empty lungs is your breathing cycles neutral mode.

The larger part of the equation is you need to understand what happens when you hold your breath. You know the burning feeling that is telling you to breathe? It's not as much that your body is oxygen-starved, but that it is desperate to expel the carbon dioxide accumulating in your lungs.

People get winded because a sudden jolt to the body empties the lungs very quickly. It's a spooky feeling because you stop breathing, but you don't feel like you are suffocating (no oxygen in your lungs means that carbon dioxide isn't building-up). To begin the breathing cycle again, you need to inhale forcefully because your diaphram (the muscles that make your lungs inflate and deflate) is quite content to sit empty. Your normal inhale isn't enough. A person recognizes they aren't breathing, get alarmed, and it's only when they gasp, or start to panic and suck-in hard, that the cycles starts again. It's confusing and jarring.