Why does minute ventilation increase after exercise?

Several factors contribute to the increase in minute ventilation after exercise:

Increased metabolic demand: Exercise places a greater demand on the body's energy systems, leading to an increase in metabolic rate. This increase in metabolic activity results in the production of more carbon dioxide (CO2) and heat.

Elevated body temperature: Exercise also causes an elevation in body temperature. As the body works harder, heat production increases, and the core temperature rises. This increase in temperature stimulates the respiratory centers in the brain, leading to an increase in breathing rate and depth.

Hypoxia: During intense exercise, the demand for oxygen by the muscles may exceed the oxygen supply. This can result in hypoxia, or a deficiency of oxygen in the tissues. Hypoxia stimulates the respiratory centers in the brain to increase minute ventilation in an effort to restore oxygen levels.

Acidosis: Lactic acid is a byproduct of anaerobic metabolism that occurs when the body's energy demands exceed the oxygen supply. During intense exercise, lactic acid accumulates in the muscles and bloodstream, leading to acidosis or a decrease in blood pH. Acidosis stimulates the respiratory centers to increase breathing and expel more CO2, which helps correct the pH balance.

Stimulation of stretch receptors: Exercise involves rhythmic movements of the limbs and respiratory muscles. These movements stimulate stretch receptors in the airways and lungs, which send signals to the respiratory centers in the brain. This stimulation contributes to the increase in minute ventilation during exercise.

The increase in minute ventilation after exercise is a physiological response that helps the body meet the increased metabolic demands, remove excess CO2 and heat, and restore oxygen and pH levels.