Exercise Induced Asthma (EIA) or Exercise Induced Bronchospasm (EIB) or exercise induced bronchoconstriction refers to asthma that occurs only with exercise. The reported incidence of EIA varies between 5% and 20% of the general population.

During start of exercise pulmonary functions tends to be normal, but within 5 to 10 minutes symptoms of asthma such as wheezing, breathlessness, tightness of chest appear. Patient may also feel extreme fatigue. After a rest period, the symptoms subside. But sometimes symptoms may become worse for a longer time.

Hyperventilation and airway cooling are the two most important triggers of EIA.

People with exercise induced asthma have airways that are sensitive towards changes of temperature and humidity. Hyperventilation during exercise is the primary event which causes cascade of events leading to EIA. Hyperventilation causes drying of the airway surface epithelium where by causing dehydration of the airway cells and increased intracellular osmolarity. The increased osmolarity results in the release of mediators from mast cells and damage airway epithelial. The mediators released during EIA include histamine, leukotrienes, cytokines, etc. All these events are called inflammatory reaction which is the root cause of asthma.

Other but less important cause of EIA is the airway cooling that is found with hyperventilation during exercise. During rest we breath through nose. Nose has a temperature and humidity control mechanism that makes air humid and at body temperature. When we exercise we breath through mouth, our respiration becomes rapid (hyperventilation). This forces cold and dry air into the airways. After the exercise is over, the small bronchiolar vessels around the tracheobronchial tree warm up, and this reactive hyperemia leads to exudation of serum into the interstitial fluid and release of mediators that subsequently causes airway muscles to contract and also walls of airways become inflamed resulting in narrowing of airways.

Diagnosis of EIA can easily be made symptomatic. Person is usually normal before exercise. During exercise he experiences shortness of breath and/or chest tightness, wheezing, and cough.
After a period of rest , the symptoms subside. Sometimes symptoms such as prolonged cough after exercise, chest pain and fatigue may last longer.

The diagnosis of EIB can also be confirmed by a variety of tests, such as exercise challenge, methacholine challenge, or eucapnic voluntary hyperpnea. The International Olympic Medical Commission recommends any or all of these tests, but in most cases the Eucapnic Voluntary Hyperventilation (EVH) test is the easiest to perform. If exercise challenge is to be performed, then this should be done in the athlete's sport.

"Pure" EIA and persistent asthma with an exercise exacerbation can be differentiated by spirometry. During rest if the forced expiratory volume in 1 second (FEV1) is not normal, patient is administered an inhaled beta-agonist and test is repeated after 15 minutes. If the FEV1 improves 12% or more, that is an indicator of mild persistent asthma, and the patient should be treated for the persistent asthma in addition to the EIA.

A 15% drop in FEV1 after 6 minutes of running or other exercise can be diagnostic of exercise induced asthma.

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Treatment of EIA is same as that of asthma. Short-acting beta-agonists, such as albuterol (salbutamol) are use full before exercise. Albuterol should be taken 15 minutes before exercise to reduce chances of EIA.

Inhaled steroids are also very effective for EIA but must be given daily and take about 2 weeks for effectiveness. Cromolyn and nedocromil can be given just prior to exercise like albuterol and work quite well.

Leukotriene modifiers, such as montelukast, are given as a daily pill and do help reduce EIA, but they are not as effective as the inhaled products. Some patients may benefit from anticholinergics, such as Ipratropium.

Many patients may require two or three medicines to treat EIA successfully.

High-intensity warm-up before the exercise is helpful for reducing the EIA. A low-salt diet and fish oil supplementation are other nonpharmacologic therapies that have been shown to reduce airway inflammation and reduce EIA.

What is the precaution I can take to prevent the attack?
With proper control of asthma, most adults  and children with asthma call participate fully in physical activities. If needed you should take 2 puffs of short acting reliever (one with blue cap) inhaler 15 minutes prior to exercise. This usually prevents the attack.

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Exercise reduces the risk of cardiovascular disease, diabetes, obesity and other health related  problems in asthmatic person as in any other person.
Aerobic exercise programs have shown to reduce  airway responsiveness   in patients who do them regularly.  Studies also suggests that asthma sufferers who exercise regularly have fewer exacerbations, use less medication, and miss less time from work and school.

The exercise goal for people who have asthma, as for most people, should be 20 to 30 minutes of activity that raises heart rate to 60% to 85% of maximum, four or five times a week.

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Which sports/ games are more suitable for EIA patients?

Aerobic exercises like swimming, running or biking or which exposes the exerciser to warm, humid and moist air that tempers the effect on the airways are more suitable for asthmatic patients. The sports that require short bursts of activity interspersed with breaks, are least likely to trigger asthma attack.
Some of the sports that are least likely to induce EIA are:

If you are wheezing, when allergies are particularly troubling, or when peak flow testing suggests a decline in lung function. These are signs that you have higher chances of having exercise induced asthma on that particular day.

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EIA is believed to be inflammatory in nature but another stimulus an allergic asthmatic reaction due to inhaled airborne allergens in the EIA patient with inhalant allergies may also be present. These two stimuli (exercise and inhaled allergens) may be additive or synergistic.
Exercising when pollen counts are high may cause more severe EIA in EIA patients allergic to pollens.

Also read <How to control asthma triggers>

Vocal cord dysfunction is a disease that mimics EIA. In vocal cord dysfunction the patient has inspiratory stridor because of partially closed vocal cords. Patients complain of throat tightness rather than a chest tightness. These patients also have the major symptom of dyspnea with little or no wheezing or cough.

In these patients the usual medications for EIA are not helpful. The diagnosis is best made by rhinolaryngoscopy after exercise, showing closure of the cords on inspiration. But vocal cord dysfunction may coexist with EIA making diagnosis difficult.

What do Jackie Joyner-Kersey, Dominique Wilkins, Nancy Hogshead, , Bill Koch, Greg Louganis, Jim Ryun and marathon runner and world record holder Haile Gebrselassie have in common?

They are world famous athlete who has asthma. They come from diverse fields: swimming, track and field, cross-country skiing, diving, basketball, and long-distance running. Studies have shown that up to 35% of students and 50% of elite cold weather athletes may have EIA. Properly following their Asthma Action Plan help them become winners.

Which sports are more likely to cause EIA:

Sports and games that are played in cold weather or require continuous exercise or activity are most likely to trigger an asthma attack.

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last modified: 22-2-2011

Approval of asthma medication during sports: