Why does your breathing change after you exercise?

Your body needs oxygen to breathe, which it takes from the air around you, into your lungs, to your heart - where it is pumped to your muscles and organs. When the oxygen is used by your muscles, carbon dioxide is produced, which needs to be removed. So as the new oxygen goes into your muscles, the carbon dioxide from the last pump is taken out, where it is sent all the way back round to the heart, and then back to your lungs, and out of your mouth, back into the air.

When you exercise, your muscles need more oxygen to cope with the increased levels of activity (the oxgen is used up quicker, by your working muscles, and so becomes carbon dioxide quicker) and so your breathing rate needs to increase. During exercise, your breathing will be increased more than normal.

So when you stop exercising, your breathing rate slows back down, as your body is able to remove the carbon dioxide from your muscles more easily, and so less oxygen is needed to exchange for carbon dioxide.

This explanation is a very simplified version - the acidity of carbon dioxide is also a factor as to why it is removed, etc.

Hope that helps.

KK