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Human body

Why do we breathe faster when we run?

Running makes you breathe fasterRunning makes you breathe fasterWhen you are doing increased physical activity, such as cycling, running or climbing, your breathing becomes faster. As well as bringing oxygen into the body more quickly, this speeds up the process of getting rid of carbon dioxide. Your brain—or, more specifically, the nucleus in the brainstem—sends out instructions to your body to increase the rate of respiration. This causes the excess carbon dioxide to be more quickly removed from the blood through the lungs. Once normal levels are reached, your breathing returns to normal.

Diagram of a glucose moleculeDiagram of a glucose molecule


Respiration is not the same as breathing (which is the mechanical action of getting air in and out of the lungs and is more correctly called ventilation). Respiration is the name for the chemical process that goes on all the time in your body cells to keep you functioning. During respiration, energy is released from glucose, a type of carbohydrate obtained through the digestion of food. In what is known as aerobic respiration, the blood delivers oxygen and glucose to the cells. The cells use this fuel to produce energy. The waste products, carbon dioxide and water, are taken away by the blood.

It is the amount of carbon dioxide in your blood that has the biggest influence on your breathing rate. As your activity level increases, your cells produce increased amounts of carbon dioxide. When the brain detects this, your breathing rate increases to get rid of it.
