Sport Asthma

Exercise-induced asthma

What is exercise-induced asthma?

Exercise-induced asthma (EIA) describes the narrowing of airways that occurs in association with physical exertion. EIA occurs in 90% of asthma sufferers, but also affects a proportion of otherwise "healthy" individuals and appears to be very common in athletes. Current estimates suggest that up to 50% of athletes may be affected.
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Why is it important?

In athletes, the diagnosis of EIA is particularly important because of potential implications on performance and health. EIA is a recognized cause of sudden death in sport and, untreated, may have long-term implications for structure and function of the airways.
In addition, strict regulations concerning the use of medications by competitive athletes mean that ensuring accurate diagnosis is crucial.
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Recognizing EIA

Surprisingly, symptoms during exercise (e.g. wheeziness and tight chest) are a poor indicator of actual airway narrowing. Since diagnosis of EIA is often made on symptoms alone this could potentially result in a peculiar situation where EIA is:

  • overdiagnosed in athletes who report symptoms but who do not have airway narrowing


  • underdiagnosed in athletes with no symptoms (asymptomatic) but who have narrowing of the airways that can still affect their performance

Studies in elite athletes support this and have led to many top sports teams screening their athletes for EIA (e.g. Australian and British Olympic Teams).
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Screening for EIA

Performance

From the point of view of the athlete, the main reason to screen for EIA is that the condition may have detrimental effects on athletic performance. EIA is already known to reduce exercise capacity, particularly peak VO2 and running speed in cold environments and may compromise not only performance during competition but capacity to train effectively.
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Health

Supporters of screening also argue that correctly diagnosing EIA has important implications for the health of athletes, with one study showing asthma as a significant risk factor for unexplained death. In addition, a high proportion of asthma-related deaths occur in athletes during, or soon after, a sporting event.
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Diagnosis of EIA

Currently, eucapnic voluntary hyperpnea (EVH) is the diagnostic method favored by the IOC-MC. EVH has a very high specificity for diagnosis. It also provides a measure of the degree of airway narrowing and can be used to establish the effectiveness of treatment.
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Treatment of EIA

Pharmacological and nonpharmacological therapies have been used successfully in the treatment of EIA. Medications shown to improve FEV1 response include inhaled β2-agonists, inhaled corticosteroids, cromolyn compounds, and leukotriene modifiers. Other studies have also highlighted the importance of dietary manipulation as an adjunctive intervention.

However, there is no clear consensus as to the optimum treatment. Nevertheless, it is generally acknowledged that β2-agonist medication should be accompanied by an inhaled corticosteroid, because this helps to prevent persistent use of β2-agonist therapy and also work against potential airway remodeling that may occur.
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