What Increases Lung Ventilation During Exercise?

It is obvious to every child on the playground and every marathon runner that exercise makes you breathe hard. And the harder you work, the more you breathe. But your body requires no conscious effort to match your lung ventilation with exercise. The balance is based on internal sensors that detect the rate at which your muscles use oxygen, make carbon dioxide, and respond to hormones and environmental stimuli. Don't worry, you won't forget to breathe.

Oxygen Consumption

Muscular work consumes oxygen to convert sugar in your blood and fat stored in your tissues into raw energy. Researchers at the Human Performance Laboratory of the Department of Health and Kinesiology at Texas A&M University documented that oxygen consumption in the breathing muscles increases with rising ventilatory effort during exercise. The carotid bodies, special sense organs in your carotid arteries that detect oxygen in the arterial blood, respond to a decrease in oxygen content. At high altitudes, where air is thinner and oxygen more scarce, or during extreme exercise, when your body uses more oxygen than your breathing can replace, your carotid bodies signal your brain to increase ventilatory efforts.

Carbon Dioxide Production

Oxygen used in muscular exercise adds the metabolic waste product carbon dioxide, or CO2, to your blood. As the concentration increases, the CO2 is converted into carbonic acid, which stimulates acid-sensitive cells in your medulla oblongata, a part of the brain that controls lung ventilation. Those nerve cells then fire faster to stimulate your rib cage muscles and diaphragm to make you breathe faster and deeper. The resulting increased lung ventilation lowers the CO2 concentration in your lungs and blood in a drive to keep it normal.

Adrenalin

The release of stress hormones adrenalin and nor-adrenalin, in response to pain or psychological challenges, regulates the physiologically heightened state commonly called "fight or flight." Among your body's responses to these hormones is increased lung ventilation, which can add O2 to your blood and remove CO2 in readiness for sudden exertion.

Emotional Factors

Excitement, whether of a positive or negative nature, increases lung ventilation. This is relatively common knowledge, but it reflects neurological control of breathing beyond the control mediated by the medullary brain centers. Emotions bring both conscious and subconscious factors, mediated in the higher brain centers, including the frontal cortex and the deeper hypothalamus and amygdala, in the control of lung ventilation. These emotional triggers for increased lung ventilation are also measured in the use of the polygraph, or lie detector.