Exercised-induced asthma is a narrowing of the airways in the lungs triggered by strenuous exercise. It causes shortness of breath, wheezing, coughing and other symptoms during or after exercise.
The preferred term for this condition is exercise-induced bronchoconstriction (brong-koh-kun-STRIK-shun). This term is more accurate because the exercise induces narrowing of airways (bronchoconstriction) but isn't a root cause of asthma. Among people with asthma, exercise is likely just one of several factors that may trigger breathing difficulties.
Most people with exercise-induced bronchoconstriction can continue to exercise and remain active by treating the symptoms with common asthma medications and taking preventive measures.
Signs and symptoms of exercise-induced bronchoconstriction may begin during or soon after exercise. These symptoms may last for 60 minutes or longer if left untreated. The signs and symptoms may include:
- Shortness of breath
- Chest tightness or pain
- Fatigue during exercise
- Poorer than expected athletic performance
- Avoidance of activity (a sign primarily among young children)
When to see a doctor
See your doctor if you experience any signs or symptoms of exercise-induced bronchoconstriction. A number of conditions can cause similar symptoms, making it important to get a prompt and accurate diagnosis.
Get emergency medical treatment if symptoms are getting worse, such as:
- Shortness of breath or wheezing that is quickly increasing, making it a struggle to breathe
- No improvement even after using a prescription inhaler for asthma attacks
It's not clear what causes exercise-induced bronchoconstriction. There may be more than one biological process involved. People with exercise-induced bronchoconstriction have inflammation and may have excess mucus production after strenuous exercise.
Exercise-induced bronchoconstriction is more likely to occur in:
- People with asthma. About 90 percent of people with asthma have exercise-induced bronchoconstriction. However, the condition can occur in people without asthma too.
- Elite athletes. Although anyone can experience exercise-induced bronchoconstriction, it's more common in high-level athletes.
Factors that may increase the risk of the condition or act as triggers include:
- Cold air
- Dry air
- Air pollution
- Chlorine in swimming pools
- Chemicals used with ice rink resurfacing equipment
- Activities with extended periods of deep breathing, such as long-distance running, swimming or soccer
Exercise-induced bronchoconstriction that is not treated can result in:
- A lack of beneficial exercise
- Poor performance in activities you would otherwise enjoy
- Serious or life-threatening breathing difficulties, particularly among people with poorly managed asthma
In addition to asking questions about your symptoms, your doctor will conduct a medical exam. Doctors typically order tests to assess your lung function and rule out other conditions that may be causing your symptoms.
Test of normal lung function
Your doctor will likely administer a spirometry (spy-ROM-uh-tree) test to assess how well your lungs function when you aren't exercising. A spirometer measures how much air you inhale, how much you exhale and how quickly you exhale.
After you do the test, your doctor may give you an inhaled medication to open your lungs (bronchodilator). You'll repeat the test, and your doctor will compare the results of the two measurements to see whether the bronchodilator improved your airflow. This initial lung function test is important for ruling out underlying chronic asthma as the cause of symptoms.
Exercise challenge tests
An additional test that enables your doctor to observe and assess symptoms is an exercise challenge. You will run on a treadmill or use other stationary exercise equipment that increases your breathing rate.
This exercise needs to be intense enough to trigger the symptoms you've experienced. If needed, you might be asked to perform a real-life exercise challenge, such as climbing stairs. Spirometry tests before and after the challenge can provide evidence of exercise-induced bronchoconstriction.
Alternate challenge test
As an alternative to the exercise challenge, your doctor may use an inhalation test that simulates the conditions that would likely trigger exercise-induced bronchoconstriction. If your airways respond to these stimuli, then the test should produce virtually the same lung function you have when exercising.
Spirometry tests before and after the challenge test provide information about changes in lung function. This challenge test is typically done using methacholine, an inhaled agent that interacts with certain smooth muscle cells in airways and results in bronchoconstriction.
Ruling out other conditions
Your doctor may order additional tests to rule out other conditions with symptoms similar to those of exercise-induced bronchoconstriction. These conditions include:
- Vocal cord dysfunction
- Other lung disease
- Gastroesophageal reflux disease
Your doctor may prescribe drugs to take shortly before exercise or to take daily for long-term control.
Your doctor may prescribe a drug that you take before exercise to minimize or prevent exercise-induced bronchoconstriction. Talk to your doctor about how much time you need between taking the drug and exercising. Drugs in this group include the following:
- Short-acting beta agonists are inhaled drugs that help open airways. These are the most commonly used and generally most effective pre-exercise medications. Daily use of these medications is not recommended, however, because you may develop a tolerance to the drugs. These drugs include albuterol (ProAir HFA, Proventil HFA, Ventolin HFA) and levalbuterol (Xopenex HFA).
- Ipratropium (Atrovent HFA) is an inhaled medication that relaxes the airways and may be effective for some people. A generic version of ipratropium also can be taken with a nebulizer.
Long-term control medications
Your doctor may prescribe a long-term control drug in addition to a daily pre-exercise medication, to manage underlying chronic asthma or to control symptoms when pre-exercise treatment alone isn't effective. These medications, usually taken daily, include the following:
- Inhaled corticosteroids help suppress inflammation in your airways. You may need to use this treatment for up to four weeks before it will have maximum benefit. Inhaled corticosteroid medications include fluticasone (Flovent Diskus, Flovent HFA), budesonide (Pulmicort Flexhaler), mometasone (Asmanex Twisthaler) and beclomethasone (Qvar).
- Combination inhalers contain a corticosteroid and a long-acting beta agonist (LABA), a drug that relaxes airways. While these inhalers are prescribed for long-term control, your doctor may recommend use prior to exercise. Combination inhalers include fluticasone and salmeterol (Advair Diskus), budesonide and formoterol (Symbicort), and mometasone and formoterol (Dulera).
Leukotriene modifiers are oral medications that may block inflammatory activity for some people. These drugs may be used daily or as a preventive treatment before exercise if taken at least two hours in advance. Examples include montelukast (Singulair), zafirlukast (Accolate) and zileuton (Zyflo, Zyflo CR).
Potential side effects of leukotriene modifiers include behavior and mood changes and suicidal thoughts. Talk to your doctor if you experience these signs or symptoms.
Don't rely only on quick-relief medications
You can also use pre-exercise drugs as a quick-relief treatment for symptoms. However, you shouldn't need to use your pre-exercise inhaler more often than your doctor recommends.
Keep a record of how many puffs you use each week, how often you use your pre-exercise inhaler for prevention and how often you use it to treat symptoms. If you use it daily or you frequently use it for symptom relief, your doctor may adjust your long-term control medication.
Exercise is an important part of a healthy lifestyle for everyone, including most people with exercise-induced bronchoconstriction. Steps you can take to prevent or minimize symptoms of exercise-induced bronchoconstriction include the following:
- If you have asthma, be sure to take your asthma medications as directed to keep your asthma under control.
- Do around 10 minutes of warm-up that varies in intensity before you begin regular exercise.
- Breathe through your nose to warm and humidify the air before it enters your lungs.
- Wear a face mask or scarf when exercising, especially in cold, dry weather.
- If you have allergies, avoid triggers. For example, don't exercise outside when pollen counts are high.
- Try to avoid areas with high levels of air pollution, such as roads with heavy traffic.
- Exercise regularly to stay in shape and promote good respiratory health.
Talk to your doctor about writing an action plan if your child experiences exercise-induced bronchoconstriction. This document provides step-by-step instructions for teachers, nurses and coaches that explain what treatments your child needs, when treatments should be administered and what to do if your child experiences symptoms.
There is limited clinical evidence that any alternative treatments benefit people with exercise-induced bronchoconstriction. For example, although it's been suggested that fish oil, vitamin C or vitamin C supplements can help prevent exercise-induced bronchoconstriction, there isn't enough evidence to show if they're useful or not.
You're likely to start by seeing your primary care doctor. He or she may refer you to a doctor who specializes in asthma (an allergist-immunologist or pulmonologist).
Be prepared to answer the following questions:
- What symptoms have you experienced?
- Do they start immediately when you start exercising, sometime during a workout or after?
- How long do the symptoms last?
- Do you experience breathing difficulties when you're not exercising?
- What are your typical workouts or recreational activities?
- Have you recently made changes to your exercise routine?
- Do the symptoms occur every time you exercise or only in certain environments?
- Have you been diagnosed with allergies or asthma?
- What other medical conditions do you have?
- What medications do you take? What is the dosage of each medication?
- What dietary supplements or herbal medications do you take?