EXERCISE-INDUCED ASTHMA OVERVIEW — Exercise-induced asthma occurs when the airways narrow as a result of exercise. The preferred term for this condition is exercise-induced bronchoconstriction (EIB); exercise does not cause asthma, but is frequently an asthma trigger.
A person may have asthma symptoms that become worse with exercise (more common) or may have only exercise-induced bronchoconstriction, without symptoms at other times. If a person’s asthma is triggered only during vigorous exercise (exercise-induced bronchoconstriction), they are considered to have mild intermittent asthma. Separate topic reviews discuss asthma in children and adults. (See “Patient information: Asthma treatment in adolescents and adults” and “Patient information: Asthma symptoms and diagnosis in children”.)
EXERCISE-INDUCED ASTHMA SYMPTOMS — Typical symptoms are shortness of breath, chest tightness, and cough. Exercise-triggered symptoms typically develop 10 to 15 minutes after a brief episode of exercise or about 15 minutes into prolonged exercise. Symptoms typically resolve with rest over 30 to 60 minutes. Exercise-induced symptoms occur more commonly and are more intense when the inhaled air is cold, probably due to changes in the airways that are triggered by the large amounts of relatively cool, dry air inhaled during vigorous activity. (See “Patient information: Trigger avoidance in asthma”.)
EIB is different than simple shortness of breath related to exercise, which generally resolves within five minutes of stopping exercise.
EXERCISE-INDUCED ASTHMA PREVENTION — Preventing exercise-induced bronchoconstriction usually includes use of an inhaled medication. Several options are available.
Rapid-acting bronchodilator — Inhalation of a rapid-acting bronchodilator (eg, two puffs of albuterol or 1 inhaled formoterol capsule) may be taken approximately 10 minutes before exercise. (See “Patient information: Asthma inhaler techniques in children” and “Patient information: Asthma inhaler techniques in adults”.)
Cromolyn sodium — Inhaled cromolyn sodium (Intal®) may be used before exercise, sometimes in combination with a rapid-acting inhaled bronchodilator. When taken via metered dose inhaler, the dose of cromolyn is two puffs, 15 to 20 minutes before exercising. However, in the United States, cromolyn is only available as a nebulizer solution.
Cromolyn sodium works by decreasing the activity of allergy cells. This medicine has no side effects. It is sometimes less effective than albuterol, although some patients prefer it due to the lack of side effects. It is important to understand that cromolyn sodium is used for prevention of symptoms ONLY. Cromolyn does NOT relieve symptoms once they have developed. If asthma symptoms develop despite pretreatment with cromolyn, a rapid-acting bronchodilator (eg, albuterol) should be used.
For children or active adults — Some adults and most children exercise intermittently throughout the day, making it hard to use a preventive treatment before each episode of activity. In this case, a long-acting inhaled bronchodilator (eg, salmeterol or formoterol) or a leukotriene modifier (eg, montelukast or zafirlukast) may be recommended to provide day-long protection (see ‘Leukotriene modifiers’ below).
Long-acting bronchodilators — Long-acting bronchodilators (LABAs) such as salmeterol and formoterol work for a longer period than rapid-acting bronchodilators. LABAs are not recommended as a single treatment for asthma, but should instead be used with an inhaled glucocorticoid or a leukotriene modifier. Inhalers that contain both a LABA and a glucocorticoid are recommended (eg, Advair®, Seretide® in Europe, Symbicort). Salmeterol should be taken at least 30 minutes and formoterol at least 5 minutes before exercise. Do not repeat these more frequently than every 12 hours.
Leukotriene modifiers — Leukotriene modifiers work by decreasing airway narrowing, inflammation, and mucus production. Examples of leukotriene modifiers include montelukast (Singulair®) and zafirlukast (Accolate®). These are taken in pill form by mouth once daily (montelukast) or twice daily (zafirlukast), and have few side effects. Taken regularly, either of these medications is useful in preventing exercise-induced bronchospasm.
Leukotriene modifiers may be used as an alternative to rapid-acting bronchodilators to prevent exercise-induced bronchoconstriction for patients who prefer or need all-day protection or have difficulty using inhalers.
Montelukast is approved for use as needed before exercise for patients who do not require daily medication. Montelukast should be taken at least two hours before the start of exercise; protection lasts for approximately 12 hours. The medication should only be taken once in 24 hours.
Leukotriene modifiers are used for prevention of symptoms, NOT for relief of symptoms once they have developed. If asthma symptoms develop despite pretreatment with a leukotriene modifier, a rapid-acting bronchodilator (eg, albuterol) should be used.
ASTHMA ATTACK TREATMENT — The term “asthma attack” is somewhat confusing because it does not distinguish between a mild increase in symptoms and a life-threatening episode. Asthma symptoms may develop during exercise despite pretreatment and may sometimes be more severe than expected. Exercise induced asthma symptoms may be aggravated by changes in air quality, common colds, exposure to allergens, or changes in the weather. These triggers can cause mild, moderate, or severe symptoms to develop. Any of these changes could be considered an asthma “attack.”
Some people have periodic, mild attacks that never require emergency care, while others have severe and sudden attacks that require a call for emergency medical services.
Emergency care plan — A patient or parent should work with a healthcare provider to formulate an emergency care plan that explains specifically what to do if symptoms worsen.
- Mild attacks: Take two puffs of a rescue medication (eg, inhaled rapid-acting bronchodilator, such as albuterol). This may be repeated twenty minutes later, and then periodically (every two to four hours) until symptoms are improved. People who take controller medications, such as inhaled glucocorticoids, should also increase the dose of these and contact their provider for further instruction.
- Severe attack: Take two to six puffs of a rescue medication, depending upon how much the individual can tolerate at once without becoming too jittery. For patients with home nebulizer machines, two treatments can be given, 20 minutes apart.
If symptoms worsen or do not improve after initial use of a rescue medication, someone should immediately call for emergency medical assistance. Severe asthma attacks can be fatal if not treated promptly.
In most areas of the United States, emergency medical assistance is available by calling 911. Patients should not attempt to drive to the hospital and should not ask someone else to drive. Calling 911 is safer than driving for two reasons:
- From the moment EMS personnel arrive, they can begin evaluating and treating asthma. When driving in a car, treatment cannot begin until the person arrives in the emergency department.
- If a dangerous complication of asthma occurs on the way to the hospital, EMS personnel may be able to treat the problem immediately.
Following a severe asthma attack, the patient is usually given a three to ten day course of an oral glucocorticoid medication (eg, prednisone, prednisolone). This treatment helps to reduce the risk of a second asthma attack.
Wear medical identification — Many people with medical conditions wear a bracelet, necklace, or similar alert tag at all times. If an accident occurs and the person cannot explain their condition, this will help responders provide appropriate care