Exercise-induced asthma is an outdated phrase that makes little sense to an asthma specialist and that is confusing to boot! Exercise is a universal and common asthma trigger that is a cause of asthma symptoms when asthma is not optimally controlled. Any individual with inadequately controlled asthma will invariably experience variable cough, wheezing, and breathlessness with exertion and exercise. In the situation of poor asthma control, asthma symptoms are indeed exercise induced. In a subset of persons with asthma, however, exercise is the only precipitant of their asthma symptoms. Those persons have no symptoms of asthma and no decrease in lung function (peak flow or FEV1) in the absence of exercise.
The type of asthma arising only in the setting of exercise is classified as EIB for exercise-induced bronchoconstriction. Individuals with EIB experience respiratory symptoms—most commonly a dry, nagging cough—in the setting of aerobic exercise. In addition to the cough, symptoms may include wheezing, shortness of breath, endurance problems, and chest discomfort such as tightness or painful sensations. The symptoms develop during (or minutes after) vigorous exercise and peak 5–10 minutes after cessation of the activity. EIB lessens thereafter and abates 30–45 minutes later. Since symptoms and lung function findings tests are only present with exercise, confirming the diagnosis can be tricky! Many persons initially thought to have EIB actually have a diagnosis of usual asthma that needs to become better controlled; symptoms of their underlying asthma become triggered by exercise. The treating physician should suspect EIB when there is a pattern of asthma symptoms and lung function abnormality only during and immediately following exertion.
An exercise-challenge test may be helpful in establishing the diagnosis. Treatment of EIB includes proper attention to warm-up and cool-down maneuvers, as well as prescription medication. Medicines effective in the treatment of EIB include oral leukotriene modifiers and anti-inflammatory medicines, as well as inhalers such as inhaled short-acting β2 agonists, and/or inhaled cromolyn or nedocromil. When inhalers are prescribed, they should be used about 20 minutes prior to the warm-up routine as a preventive measure. Inhalers may otherwise be required after exercise to accelerate resolution of symptoms.
It is important to treat EIB in order to allow for full, symptom-free participation in sports, fitness, and recreational activities that are part of a healthy lifestyle. Many world-class athletes carry a diagnosis of EIB, proving that asthma is not a barrier to athletic achievement. Parents should notify teachers and coaches that a student has EIB; the youngster should take prescribed medication before sports and should take part in athletics and all physical education offerings.
A competitive athlete with EIB must disclose asthma medication use and should become familiar with the U.S. Anti-Doping Agency requirements, which are available at http://www.usantidoping.org. As of this writing and subject to change, use of some inhaled bronchodilator asthma medications (salmeterol, formoterol, salbuta-mol, terbutaline) requires that the athlete complete a therapeutic use exemption (TUE) form. Additionally, inhaled corticosteroid medication must be declared, and prescription of corticosteroid medication in pill (oral) form requires a TUE form.
In EIB, airway narrowing (bronchoconstriction) occurs secondary to vigorous exercise. The mechanism responsible for EIB implicates inhalation of cool dry air, specifically, fluxes in humidity and temperature within the airways during rapid breathing. EIB occurs more commonly with certain types of exercise, such as long-distance running. Competitive sports that require prolonged periods of strenuous activity, such as soccer, tennis, distance cycling, Nordic skiing, and cross-country running, will more often trigger EIB symptoms than activities such as baseball or swimming. EIB can occur in any weather, yet is more likely in cool and dry environments than in warmer, more humid ones.
Up to one quarter of Olympic winter sports athletes experience EIB, with the highest numbers (50%) in cross-country skiers. In contrast, the U.S. Olympic Committee deter-mined that 11.2% of athletes competing in the 1984 Summer Olympics experienced EIB. Although EIB requires treatment, it does not reflect inadequately con-trolled underlying asthma. Some physicians consider it a subtype of asthma while others view it as a possible precursor to asthma and continue to monitor their patients with EIB for the emergence of more usual forms of asthma as time goes by.
Gemma’s comment:
My daughter was not diagnosed with asthma until she was in her 20s, but she now feels that she had EIB as a teenager when she began running with school teams. Outdoors, and especially in cold weather, she would have trouble breathing while exercising, but when she stopped she would recover quickly and feel that the problem had gone away. She was, and is, very athletic, and particularly devoted to running. At the time, she didn’t complain of breathing problems and no coach ever noticed them. I should add that she is still an avid runner, but now she carries a bronchodilator with her and is careful about running in very cold weather or when the air seems especially polluted.