Question 1. What is the mechanism of exercise-induced asthma?

From Chapter 8 of the Philippine Consensus Report on Asthma 2004 by the Philippine College of Chest Physicians.
This guideline starts below.

What is the mechanism of exercise-induced asthma?

Answer

The heat exchange theory is currently one of the top theories for bronchoconstriction associated with exercise.

During exercise, the humidification and heating function of the nose is bypassed and cold air reaches the airways, which in turn produces bronchial spasm. This theory also suggests that the cold air may produce a humoral effect or a nerve reaction in the small airways that leads to bronchospasm. Neurohormonal transmitters like leukotrienes have also been implicated in mediating a portion of the airway narrowing.

Leukotrienes have been found to play a role in airway refractoriness with repeated bouts of exercise. They may act through release of inhibitory prostaglandins or by inhibiting other mediator release.