Hyperpnea

Hyperpnea is an increase in the depth and often the rate of breathing that raises ventilation in response to increased metabolic demand. It is commonly seen during exercise, when working muscles consume more oxygen and produce more carbon dioxide. Hyperpnea can therefore be a normal physiological response rather than a sign of abnormal breathing .^1,2

During hyperpnea, minute ventilation, the total volume of air moved into and out of the lungs each minute, increases because breaths become deeper, more frequent, or both. During mild to moderate exercise in healthy people, alveolar ventilation rises closely with carbon dioxide production. This matching allows the lungs to remove the additional carbon dioxide generated by metabolism while arterial carbon dioxide levels remain relatively stable .²

Hyperpnea is distinct from hyperventilation. Both involve increased ventilation, but hyperventilation means that alveolar ventilation exceeds that required for the current rate of carbon dioxide production and therefore tends to lower arterial carbon dioxide. Hyperpnea, by contrast, describes increased breathing associated with increased metabolic demand without necessarily causing a fall in arterial carbon dioxide. It is also distinct from tachypnea, which refers specifically to an increased breathing rate and does not by itself describe breathing depth or the relationship between ventilation and metabolism .^1,2

The control of exercise hyperpnea involves coordinated neural and metabolic signals. Evidence supports contributions from feedforward signals associated with movement, sensory feedback from working muscles, and signals associated with metabolic activity, although precisely how these inputs are integrated remains an active area of physiological research .²