Exercise-induced asthma

Exercise-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 can trigger breathing difficulties.

Most people with exercise-induced bronchoconstriction can continue to exercise and remain active by treating the symptoms with asthma medications and taking preventive measures.

Symptoms

Signs and symptoms of exercise-induced bronchoconstriction usually begin during or soon after exercise. These symptoms can last for 60 minutes or longer if untreated. The signs and symptoms can include:

• Coughing
• Wheezing
• 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 have 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 you have:

• 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

Causes

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 might produce excess mucus after hard exercise.

Risk factors

Exercise-induced bronchoconstriction is more likely to occur in:

• People with asthma. About 90% of people with asthma have exercise-induced bronchoconstriction. However, the condition can occur in people without asthma too.
• Elite athletes. Although anyone can have exercise-induced bronchoconstriction, it's more common in high-level athletes.

Factors that can increase the risk of the condition or act as triggers include:

• Cold air
• Dry air
• Air pollution
• Chlorine in swimming pools
• Chemicals from ice cleaning equipment
• Activities with extended periods of deep breathing, such as long-distance running, swimming or soccer

Complications

If not treated, exercise-induced bronchoconstriction can result in:

• Serious or life-threatening breathing difficulties, particularly among people with poorly managed asthma
• Lower quality of life because of inability to exercise

Diagnosis

Your doctor will conduct a medical exam and order tests to assess your lung function and rule out other conditions that can cause 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.

Your doctor might have you repeat the test after you take an inhaled medication to open your lungs (bronchodilator). 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 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 your symptoms. 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 might 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 causes bronchoconstriction.

Treatment

Your doctor might prescribe drugs to take shortly before exercise or to take daily for long-term control.

Pre-exercise medications

If your doctor prescribes a drug that you take before exercise to minimize or prevent exercise-induced bronchoconstriction, ask how much time you need between taking the drug and exercising. Drugs in this group include:

• Short-acting beta agonists, which 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 can develop a tolerance to them. These drugs include albuterol (ProAir HFA, Proventil-HFA, Ventolin HFA) and levalbuterol (Xopenex HFA).
• Ipratropium (Atrovent HFA), 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 might also prescribe a long-term control drug to manage underlying chronic asthma or to control symptoms when pre-exercise treatment alone isn't effective. These medications, usually taken daily, include:

• Inhaled corticosteroids, which help suppress inflammation in your airways. You might 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 Redihaler).
• Combination inhalers, which 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, which are oral medications that block inflammatory activity for some people. These drugs can 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 have 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 might adjust your long-term control medication.

Lifestyle and home remedies

Exercise is an important part of a healthy lifestyle for everyone, including most people with exercise-induced bronchoconstriction. Besides taking your medication, steps you can take to prevent or minimize symptoms of exercise-induced bronchoconstriction include the following:

• Do around 15 minutes of warmup 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.

At school

If your child has exercise-induced bronchoconstriction, talk to your doctor about providing an action plan. This document provides step-by-step instructions for teachers, nurses and coaches that explain what treatments your child needs, when treatments should be given and what to do if your child has symptoms.

Alternative medicine

There is limited clinical evidence that any alternative treatments benefit people with exercise-induced bronchoconstriction. For example, it's been suggested that fish oil, vitamin C or vitamin C supplements can help prevent exercise-induced bronchoconstriction, but there isn't enough evidence to show if they're useful.

Preparing for an appointment

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 had?
• Do they start immediately when you start exercising, sometime during a workout or after?
• How long do the symptoms last?
• Do you have 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?

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