Exercise helps keep you fit and healthy by strengthening your muscles and making your heart beat faster. Your muscles, lungs, and heart all work together to move your body and make sure you are getting enough oxygen. This results in an increase in your breathing rate, or rate of ventilation.
In order to reap the benefits of exercise, your heart and breathing rates must increase. Your muscles are pushing your blood back to your heart at a faster rate, so your heart must increase its rate of pumping to match. Some of the blood pumped by the heart travels to the lungs to get rid of carbon dioxide and pick up oxygen. The increase in heart rate stimulates your breathing rate. With an increase in heart rate, your blood pumps through your muscles at a faster rate, leaving less time for oxygen uptake. Having more oxygen available in the blood, from a faster breathing rate, helps the muscles get the amount they need.
Your muscles are working harder during exercise and that means their demand for oxygen increases. This happens because oxygen is needed to burn calories more efficiently. Since the blood picks up oxygen in the lungs, and the demand for oxygen increases during exercise, the lungs must work harder. With a faster breathing rate, more oxygen is picked up at the lungs for delivery to the working muscles.
Carbon Dioxide Removal
A by-product of metabolism is carbon dioxide. Part of the lungs’ function is to rid the blood of carbon dioxide. As exercise continues, or exercise intensity increases, more carbon dioxide is produced and needs to be removed. Increased breathing rate allows carbon dioxide to be expired more rapidly.
Another by-product of metabolism is heat. As your body temperature rises, signals are sent to the nerves and muscles of the respiratory system to increase breathing rate. The mechanism of this response is unknown, but increased ventilation is also often present accompanying fever.
At the onset of exercise, the brain signals increases in heart and breathing rates in anticipation of the increased need for oxygen and carbon dioxide exchange of exercise. Once exercise begins, circulating levels of the hormone epinephrine—also referred to as adrenaline—increase. This increase stimulates ventilation as well.