Exercise-induced asthma

Overview

Exercise-induced asthma is when the airways narrow or squeeze during hard physical activity. It causes shortness of breath, wheezing, coughing, and other symptoms during or after exercise.

The medical term for this condition is exercise-induced bronchoconstriction (brong-koh-kun-STRIK-shun). Many people with asthma have exercise-induced bronchoconstriction. But people without asthma also can have it.

Most people with exercise-induced bronchoconstriction can continue to exercise and remain active if they treat symptoms. Treatment includes asthma medicines and taking steps to prevent symptoms before physical activity starts.

Symptoms

Symptoms of exercise-induced bronchoconstriction usually begin during or soon after exercise. These symptoms can last for an hour or longer if untreated. Symptoms include:

• Coughing.
• Wheezing.
• Shortness of breath.
• Chest tightness or pain.
• Fatigue during exercise.
• Poorer than expected athletic performance.
• Avoiding activity, which happens mostly in young children.

When to see a doctor

See your health care provider if you have symptoms of exercise-induced bronchoconstriction. A few conditions can cause similar symptoms, so it's important to get a diagnosis as soon as you can.

Get emergency medical treatment if you have:

• Shortness of breath or wheezing that is quickly getting worse, making it hard to breathe.
• No improvement even after using a prescription inhaler for asthma attacks.

Causes

It's not exactly clear what causes exercise-induced bronchoconstriction. For a long time, the cause was thought to be cold air. However, recent studies found dry air to be a more likely culprit. Cold air contains less moisture than warm air. Breathing in cold, dry air dehydrates the air passages. This causes them to constrict, reducing air flow. Other factors, such as chlorine or other fumes, can irritate the lining of the airways and contribute to breathing difficulties as well.

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 also can occur in people without asthma.
• 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:

• Dry air.
• Cold air.
• Air pollution.
• Chlorine in swimming pools.
• In a gym setting, fumes from perfume, paint, new equipment or carpet.
• Activities with long 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

To diagnose exercise-induced bronchoconstriction, your health care provider first takes a medical history and does a physical exam. You may have tests to check your lung function and rule out other conditions.

Test of current lung function

Your provider will likely perform a spirometry (spy-ROM-uh-tree) test. This exam shows 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 provider might have you repeat the test after you take an inhaled medicine to open your lungs. This medicine is known as a bronchodilator. Your provider compares the results of the two measurements to see whether the bronchodilator improved your airflow. This initial lung function test is important for ruling out chronic asthma as the cause of symptoms.

Exercise challenge tests

During an exercise challenge test, you run on a treadmill or use other stationary exercise equipment to increase your breathing rate.

The 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.

Methacholine challenge breathing test

This test involves inhaling an agent, often methacholine, that narrows the airways in some people with exercise-induced bronchoconstriction. Afterward, a spirometry test checks lung function. This test mimics the conditions likely to trigger exercise-induced bronchoconstriction.

Treatment

Your health care provider might prescribe medicines to take shortly before exercise or to take daily for long-term control.

Preexercise medicines

If your provider prescribes a medicine to take before exercising, ask how much time you need between taking the medicine and starting the activity.

• Short-acting beta agonists (SABAs) are the most commonly prescribed medicines to take before exercising. These medicines include albuterol (ProAir HFA, Proventil-HFA, Ventolin HFA) and levalbuterol (Xopenex HFA). SABAs are inhaled medicines that help open airways. Do not use these medicines every day because it can make them less effective.
• Ipratropium (Atrovent HFA) is an inhaled medicine that relaxes the airways and may be effective for some people. A generic version of ipratropium also can be taken with a device called a nebulizer.

Long-term control medicines

Your provider may prescribe a long-term control medicine to manage underlying asthma or to control symptoms when preexercise treatment alone doesn't work. These medicines are usually taken daily. They include:

• Inhaled corticosteroids, which help calm inflammation in your airways. You take these medicines by breathing them in. You might need to use this treatment for up to four weeks before it will have maximum benefit.
• Combination inhalers, which contain a corticosteroid and a long-acting beta agonist (LABA), a medicine that relaxes airways. These inhalers are prescribed for long-term control, but your provider may recommend using it before you exercise.

• Leukotriene modifiers, which are medicines that block inflammatory activity for some people. These medicines are taken by mouth. They can be used daily or before exercise if taken at least two hours in advance.

  Possible side effects of leukotriene modifiers include behavior and mood changes and suicidal thoughts. Talk to your provider if you have these symptoms.

Don't rely only on quick-relief medicines

You also can use preexercise medicines as a quick-relief treatment for symptoms. However, you shouldn't need to use your preexercise inhaler more often than recommended.

Keep a record of:

• How many puffs you use each week.
• How often you use your preexercise inhaler for prevention.
• How often you use it to treat symptoms.

If you use your inhaler daily or you frequently use it for symptom relief, your provider might adjust your long-term control medication.

Self care

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

• Do about 15 minutes of warmup that varies in intensity before you begin regular exercise.
• Breathe through your nose to warm and humidify 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 health care provider 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.
• 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 your appointment

You're likely to start by seeing your primary health care provider. Your provider may refer you to someone who specializes in asthma, such as an allergist-immunologist or a 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?