An Overview of Exercise-Induced Bronchospasm (EIB)

Exercise-induced bronchospasm (EIB) and exercise-induced asthma are often described as being the same condition. However, despite similar symptoms more recent research suggests that they are actually separate conditions. Individuals with exercise-induced asthma typically suffer from underlying asthma. This is not the case with EIB. In other words, people without asthma can have EIB.

Symptoms of EIB typically begin during exercise or shortly after stopping but can occur hours later in some cases.

Constriction (narrowing) of the airways during an episode of EIB typically causes some or all of the following symptoms:

• Coughing
• Difficulty breathing
• Wheezing (a distinct breathing noise that indicates distress and is also common in asthma)
• Fatigue and decreased athletic performance
• Chest tightness

The exact pathophysiology of exercise-induced bronchospasm is not completely understood. One theory is that the increased breathing rate during exercise causes the airways to dry out which sets in motion a series of reactions that leads to the release of inflammatory chemicals such as histamine and interleukins.

The type of air you are breathing during exercise may contribute.

Exercise-induced bronchospasm is common among elite level athletes and may affect anywhere from 5 percent to 20 percent of the population. Some factors may increase your risk of EIB including the type of exercise you participate in (swimming and long-distance running, for example, is high risk), or underlying conditions such as asthma, eczema or allergic rhinitis (when these three conditions exist together it is called atopia.)

In years past a diagnosis of exercise-induced bronchospasm may have been made based on self-reported symptoms. Recent research has shown this method to be highly inaccurate. Fortunately, several tests can help your doctor to make an accurate diagnosis of EIB including:

• Exercise challenge testing: This test starts out with some baseline breathing tests (spirometry) at rest after which you will be asked to participate in some form of exercise for approximately six to 10 minutes (often a treadmill). The tests are repeated to look for increased breathing difficulty.
• Surrogate provocation testing: This can be used instead of exercise challenge testing only if the proper laboratory facility is available. This test involves having you inhale a specific substance, usually histamine, mannitol, or methacholine, to see if the substance triggers bronchoconstriction. You may also be asked to breathe in very dry air containing 5 percent carbon dioxide, or hypertonic saline.
• Forced expiratory volume: Testing forced expiratory volume (FEV) before (to determine a baseline) and after exercise may be helpful in diagnosing EIB. It should be noted that testing peak inspiratory rates before and after exercise is not a test that is very accurate for diagnosing EIB although some doctors may choose this type of testing.

There are several ways to treat and manage EIB. Your doctor will help devise a treatment plan that works best for you.

Non-Pharmacologic Treatments

Individuals who have been diagnosed with exercise-induced bronchospasm should not stop exercising. In fact, increasing your cardiovascular endurance may actually improve your symptoms since it reduces minute ventilation.

When exercising in cold dry weather it is helpful to wear a loose-fitting scarf or mask over your mouth and nose to humidify and warm the air you're breathing. If you are a swimmer it may reduce your symptoms to use a pool that has a lower concentration of chloramines since these chemicals are known to exacerbate symptoms of EIB.

There is conflicting evidence regarding if warming up properly prior to exercise can reduce the symptoms of EIB. But, since there are other benefits including the prevention of injuries, proper warm-up before physical activity is recommended.

If you have pollen allergies it may be beneficial to workout indoors on days when pollen counts in your area are high.

A low-salt diet that is high in antioxidants may also help to reduce the symptoms of EIB.

Medications

The most commonly used medications to treat EIB are in a class of drugs known as short-acting beta-agonists including inhaled albuterol and levalbuterol. These medications are inhaled using a device called a spacer usually 15 to 20 minutes before exercise. Accurate instruction on using the inhaler/spacer is very important for effective relief of symptoms.

Albuterol is commonly prescribed, usually well-tolerated, and allowed by many athletic organizations. However, side effects may occur and include increased heart rate and anxiety. Tolerance to the medication and decreased effectiveness can occur with long term use.

Other medications sometimes used include formoterol, cromolyn sodium or terbutaline. These medications may not be allowed by some athletic associations.

Managing Underlying Conditions

If, in addition to EIB, you also have allergies, asthma, or both, managing these underlying conditions will be an important part of controlling symptoms of EIB.

People with underlying asthma should not avoid exercise and may benefit from using albuterol or a similar medication five to15 minutes before exercise.

Additionally, long term medications to control asthma are frequently used and may include: leukotriene antagonists such as Singulair (montelukast), or inhaled glucocorticoids such as beclomethasone or fluticasone. These medications may not be allowed or may be required to be "declared" by athletic associations.

If you have underlying allergies you may need to control your symptoms using medications such as antihistamines (diphenhydramine, cetirizine, loratadine, fexofenadine), or nasal sprays such as fluticasone, or mometasone.

Immunotherapy (allergy shots) may also be an option for treating underlying allergies. Working with a doctor who specializes in treating allergies, called an immunologist, can help you decide on the best treatment options for you and help you to get your allergies under control.