exercise-induced asthma

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A form of asthma induced by physical activity. All asthmatics have their symptoms, such as wheezing (see stridor), exaggerated by exercise. However, exercise appears to actually precipitate an asthmatic attack in some people. It is believed that exercise and hyperventilation with dry air, dries the mucous membrane lining the airway, leading to the release of chemicals that cause the bronchioles to constrict (exercise-induced bronchospasm). Normally, bronchioles in the airways are dilated during exercise, but in exercise-induced asthma (EIA) they constrict either during or a few minutes after cessation of the activity, making breathing difficult. The same level of exertion may produce different degrees of asthmatic attack depending on the nature of the activity. Running tends to provoke worse attacks than cycling, and both running and cycling provoke worse attacks than swimming, which is among the best sports for asthmatics. Factors that increase the risk of an asthmatic attack include activity performed in cold weather or a smoky environment; continuous exercise running; high intensity exercise; poor physical fitness; cold, dry air; air pollutants; pollens and grass; recent respiratory infection; and taking Beta blockers. Factors that tend to decrease the risk include intermittent exercise; swimming; low exercise intensity; good physical fitness; and warm, moist air. Beta2 agonists are administered to relieve and treat exercise-induced asthma. All such agonsists and their D- and L-isomers are on the World Anti-Doping Agency's 2005 Prohibited List. Their use by athletes requires a Therapeutic Use Exemption (TUE). However, as exceptions, formoterol, salbutamol, salmeterol and terbutaline, when administered by inhalation to treat EIA, require an abbreviated TUE. See also exercise test, vocal cord dysfunction.

Subjects: Sports and Exercise Medicine.

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