Bronchospasm, Exercise-Induced

Exercise-induced bronchospasm (EIB) is a well-understood medical condition of the lungs and airways that affects respiratory function and consequent athletic performance. EIB is caused by a narrowing of the passages within the lungs; EIB is a reversible constriction of the airway structures.

As air is inhaled into the respiratory system through either the mouth or the nose, the air travels through the throat and the trachea (windpipe), which divides into the left and right bronchi, the bronchial tubes that lead to each lung. If observed in isolation, the bronchi have the appearance of a branch or the spreading roots of a tree, proceeding from the thick stem nearest the trachea, to the tiny passages in which air travels to the equally minute alveoli, the clusters of air sacs within the lung, each supplied by the capillaries that receive oxygen from the inhaled air, and return carbon dioxide from the cardiovascular system to be exhaled through the lungs. These exchanges of air are a microscopic process, as there are up to 300 million alveoli attached to the surface of the lungs of a typical person.

Asthma is a common condition of the bronchial passages. Asthma occurs when the cells of the bronchial tubes become swollen and inflamed, restricting the passages of air into the lungs. Asthma is believed to have a genetic origin, and it is a condition often aggravated by smoke, pollution, airborne pollens, and exercise.

EIB may arise in asthmatic persons, but it is distinct from asthma as a condition (exercise-induced asthma is a distinct subscript of asthma). EIB arises where vigorous exercise triggers a wheezing, painful cough, often associated with the sensation of a tight chest in the individual. Symptoms of EIB will usually be present between five minutes and twenty minutes after exercise begins. Persons with previously determined asthmatic conditions, exercise that takes place in cold or dry air, and a vulnerability to airborne allergies heighten the risk of developing EIB. As the colder and drier air passes along the bronchial tubes, the cells exposed to this air tend to tighten, causing the constriction of the passages. Sports where the duration of any exercise segment is less than five minutes tend not to aggravate or promote the onset of EIB.

EIB is not a barrier to either general exercise participation, overall physical fitness, or competitive sports. However, care must be taken in the management of any symptoms that arise. Medications delivered into the bronchial airways by way of a bronchodilator ("puffer"), which is an inhaler device designed to deliver medication directly to the affected areas of the bronchi, are often very effective. A common active ingredient in these medications is the class of drugs known as B₂-agonists, which relax the muscles of the airways to promote ease of breathing.

see also Cardiorespiratory function; Prescription medications and athletic performance; Upper respiratory tract infection.