What causes exercise-induced asthma?
Environmental allergens, pollutants, or irritants inhaled during exercise may help trigger the symptoms. Prolonged, strenuous exercises without rest periods and exercising in cool, dry conditions can also bring on exercise-induced asthma. There are two theories to explain why this occurs. • Rapid breathing during exercise does not allow inspired air to be warmed and humidified by the nose. This cold, dry air cools the bronchial tubes, causing the muscles around the bronchial tubes to constrict (producing bronchospasm). After exercise, the bronchial tubes warm up. In asthma patients, warming up of the bronchial tubes causes the bronchial tubes to swell and become inflamed. This might explain why asthma occurs after exercise. This may be similar to what happens when previously cold fingers are warmed and they become red and swollen. • The second theory involves the loss of humidity surrounding the cells lining the bronchial tubes during rapid breathing. This drying induces the mast cells
