Exercise induced bronchoconstriction in adults: evidence based diagnosis and management.

EIB is defined as “the transient narrowing of the lower airway following exercise in the presence or absence of clinically recognized asthma.” Bronchoconstriction typically develops within 15 minutes after exercise and spontaneously resolves within 60 minutes. After an episode of EIB, there is often a refractory period of about 1-3 hours in which, if exercise is repeated, the bronchoconstriction is less emphasised in 40-50% of patients. 3 EIB can also occur during exercise. 5 The term “exercise induced bronchoconstriction” is preferred to that of “exercise induced asthma” since asthma is a chronic condition which is not induced by a single bout of exercise. EIB is more likely in people with asthma, but it also occurs in individuals without asthma. 6 EIB is characterised by falls in forced expiratory volume in one second (FEV1) after exercise, while in people with asthma there is persistent airway inflammation and recurrent symptoms outside of exercise (that is, with allergen exposure or upper respiratory infections). Often, at baseline there is evidence of reversible lower airway obstruction. Pharmacological management for persistent asthma requires daily anti-inflammatory, preventive medications. However, airway inflammation and remodelling also occur in cold weather athletes with and without asthma and EIB.