Why do you get out of breath?
The amount of oxygen you need depends on how hard your body is working. If you are resting, you need only a small amount. If you are running or playing badminton, you use up oxygen more quickly producing enough energy. An area in your brain automatically adjusts your breathing rate to make sure you get the oxygen you need, by breathing faster and more deeply.

Gasping for air
At rest, a 10-years-old takes in about 0.25 litre (15 cu in) of air with each breath. If you take deep breaths, you will take in seven times more air than this. If you work hard, you will force more air out of your lungs and take in ten time more air.