What is it?

• If you cough, wheeze or feel out of breath during or after exercise, it may be more than exertion causing your symptoms. You might have exercise-induced asthma. As with asthma triggered by other things, exercise-induced asthma symptoms occur when your airways tighten and produce extra mucus.
• If you have exercise-induced asthma — also called exercise-induced bronchospasm— physical exertion may be the only thing that triggers your symptoms. Or, exercise may be just one of several things that trigger your asthma. But having exercise-induced asthma doesn't mean you shouldn't exercise. Proper treatment and precautions can keep you active — whether you're strolling through the park or competing for Olympic gold.

Symptoms

Mechanism of asthmaExercise-induced asthma symptoms can include:

• Coughing
• Wheezing
• Shortness of breath
• Chest tightness or pain
• Fatigue during exercise
• Poor athletic performance

Exercise-induced asthma symptoms may start a few minutes after you begin exercising. Some people have symptoms 10 to 15 minutes after finishing a workout. It's possible to have symptoms both during and after exercise.

Feeling a little short of breath or fatigued when you work out is normal, especially if you aren't in great shape. But with exercise-induced asthma, these symptoms can be more severe.

For many people, exercise is just one of a few asthma triggers. Others can include pollen, pet dander and other airborne allergens.

Causes

It isn't clear exactly what causes exercise-induced asthma, and why some people get it and others don't. In susceptible individuals, symptoms may be triggered by drying or cooling of the airways during heavy breathing.

Factors that can trigger or worsen exercise-induced asthma include:

• Cold air
• Dry air
• Air pollution such as smoke or smog
• High pollen counts
• Having a respiratory infection such as a cold
• Being out of shape
• Chemicals such as chlorine, paint, fertilizers or herbicides

There's no particular exercise you must avoid when you have exercise-induced asthma, but activities that make you breathe hard are more likely to trigger symptoms. For example, aerobic exercise, such as running or playing basketball, hockey or soccer, is more likely to trigger symptoms than is weightlifting, golfing or moderate-paced walking. Likewise, exercising in cold weather also can increase asthma symptoms because you're breathing in a lot of cold, dry air.

But don't let that discourage you. With proper treatment, you can do intense aerobic activities — and cold-weather workouts — without asthma symptoms slowing you down.

Risk factors

Exercise-induced asthma can occur in people of any age and activity level, but certain people are more likely to be diagnosed with the condition than others. Factors that increase your risk include:

• Already having asthma triggered by other things
• Having hay fever or other allergies
• Having a blood relative, such as a parent or sibling, with asthma
• Living in a large urban area, especially the inner city, which may increase exposure to air pollution
• Smoking or exposure to secondhand smoke
• Exposure to occupational triggers, such as chemicals used in farming and hairdressing, and in paint, steel, plastics and electronics manufacturing
• Being very overweight (obese)
• Participating in winter sports, such as figure skating, ice hockey or cross-country skiing
• Being a child — children are generally more active than adults

Complications

Asthma of any kind — including exercise-induced asthma — may cause a number of complications. Proper treatment can help you avoid them. Possible asthma complications include:

• Poor athletic performance
• Permanent narrowing of the airways (bronchial tubes), which causes difficulty breathing
• Emergency room visits and hospitalizations for severe asthma attacks

Diagnosis

Your doctor will probably start by doing a physical exam that includes your ears, nose, throat and chest and may ask you a number of questions.

You may need one or more tests to see what's going on and to make sure your symptoms aren't caused by something other than exercise-induced asthma. If you do have asthma, your doctor may want to do tests to determine how well your lungs are working and if something other than exercise also triggers your symptoms.

However, extensive testing isn't always needed to diagnose exercise-induced asthma. Your doctor may give you an inhaler to try before exercise. If it works, you probably do have asthma. For many people with exercise-induced asthma, taking one or two puffs of albuterol or another inhaled medication before exercise is enough to ease symptoms.

Ruling out other conditions

If it isn't clear whether asthma's causing your symptoms, your doctor may do tests to see whether your symptoms may be caused by something else. Other health problems that can mimic exercise-induced asthma include:

• Being out of shape
• Heart disease or heart failure
• Lung disorders
• Side effects of certain medications
• Central airway obstruction
• Vocal cord dysfunction (also called paradoxical vocal fold motion disorder)
• Hay fever or other allergies

Lung function tests

To see how well your lungs are working, and to see whether you show signs of asthma, you may need lung function tests that may include:

• Spirometry. This test, which measures how well you breathe, is the preferred test for diagnosing asthma. During this 10- to 15-minute test, you take deep breaths and forcefully exhale into a tube connected to a machine called a spirometer. If certain key measurements are below normal for a person your age and sex, your airways may be blocked by inflammation (obstructed). This is a key sign of asthma. Your doctor may ask you to inhale a bronchodilator drug used in asthma treatment to open your airways. Then you retake the spirometry test. If your breathing improves significantly, it's likely you have asthma.
• Exercise challenge. This test is used to see how exertion affects your lung function. With this test, your doctor may have you do a lung function test before and after you exercise. Exercise is usually done for six to eight minutes on a treadmill or other stationary workout machine. For competitive athletes, exercise challenge tests are sometimes done in the sporting environment.
• Peak flow measurement. To determine if you have asthma, and how well your lungs work, your doctor may ask you to carry a peak flow meter. This small, hand-held device measures how fast you can force air out of your lungs. The slower you exhale, the worse your asthma. You'll likely be asked to use your peak flow meter at certain times, such as during or following exercise.
• Nitric oxide test. This test is used to see how much nitric oxide gas is in your breath. High levels of nitric oxide are a sign of asthma.
• Methacholine challenge. During a methacholine (meth-uh-KOH-leen) challenge test, you inhale a small amount of methacholine mist to see if it causes asthma symptoms. Your lung function is tested before and after the methacholine is given to see how much it affects your ability to breathe. Challenge testing may also be done using cold air or histamine. These tests are done only at specialized clinics.
• Allergy skin tests. During a skin test, your skin is pricked with purified allergy extracts and observed for signs of an allergic reaction. These tests may be useful to see whether you have a reaction to things other than exercise, such as animal dander, mold, dust mites or latex. 

Treatments and drugs

For many people, a few puffs from a quick-relief inhaler right before exercise is enough to control asthma symptoms. These bronchodilator (brong-koh-DIE-lay-tur) medications — albuterol, for example — quickly open the airways and can help control symptoms for several hours.

However, some people also need to take additional medications to control asthma symptoms. You may need daily long-term control medications if you have frequent asthma symptoms when you're not exercising, or if using a medication before exercise doesn't keep your symptoms under control.

Long-term control medications

In most cases, these medications need to be taken every day. Types of long-term control medications include:

• Inhaled corticosteroids. These medications include fluticasone (Flovent Diskus, Flovent HFA), budesonide (Pulmicort Flexhaler), mometasone (Asmanex), triamcinolone (Azmacort), flunisolide (Aerobid), beclomethasone (Qvar) and others. They are the most commonly prescribed type of long-term asthma medication. You may need to use these medications for several days to weeks before they reach their maximum benefit. Unlike oral corticosteroids, these corticosteroid medications have a relatively low risk of side effects and are generally safe for long-term use.
• Leukotriene modifiers. These oral medications include montelukast (Singulair), zafirlukast (Accolate) and zileuton (Zyflo, Zyflo CR). They help prevent asthma symptoms for up to 24 hours. In rare cases, these medications have been linked to psychological reactions, such as agitation, aggression, hallucinations, depression and suicidal thinking. Seek medical advice right away for any unusual reaction.
• Theophylline. This is a daily pill that helps keep the airways open (bronchodilator). Theophylline (Theo-24, Elixophyllin, others) relaxes the muscles around the airways to make breathing easier. It's not used as often now as in past years.
• Long-acting beta agonists (LABAs). These inhaled medications include salmeterol (Serevent Diskus) and formoterol (Foradil Aerolizer). Taken 30 minutes before exercise, long-acting beta agonists can prevent symptoms of exercise-induced asthma for up to 12 hours. However, they've been linked to severe asthma attacks. LABAs should always be taken only in combination with an inhaled corticosteroid.
• Combination inhalers such as fluticasone and salmeterol (Advair Diskus) and budesonide and formoterol (Symbicort). These medications contain a LABA along with a corticosteroid. Like other LABA medications, these medications may increase your risk of a severe asthma attack and need to be used with caution.

Quick-relief medications

Also called rescue medications, quick-relief medications are used as needed for rapid, short-term symptom relief during an asthma attack — or before exercise if your doctor recommends it. Types of quick-relief medications include:

• Short-acting beta agonists. These inhaled bronchodilator medications include albuterol (ProAir HFA, Ventolin HFA, others), levalbuterol (Xopenex HFA) and pirbuterol (Maxair Autohaler). For most people, one to two puffs of albuterol or another inhaled short-acting beta agonist 10 to 15 minutes before exercise is enough to prevent symptoms for up to four hours. These inhaled bronchodilator medications can rapidly ease symptoms during an asthma attack.
• Ipratropium (Atrovent). Your doctor might prescribe this inhaled medication for immediate relief of your symptoms. Like other bronchodilators, ipratropium relaxes the airways, making it easier to breathe. Ipratropium is mostly used for emphysema and chronic bronchitis, but it's sometimes used to treat asthma attacks.
• Oral and intravenous corticosteroids. These medications relieve airway inflammation caused by severe asthma. Examples include prednisone and methylprednisolone. They can cause serious side effects when used long term, so they're only used to treat severe asthma symptoms on a short-term basis.

Treatment for allergy-induced asthma

If your asthma is triggered or worsened by allergies, you may benefit from allergy treatment as well. Allergy treatments include:

• Omalizumab (Xolair). This medication is specifically for people who have allergies and asthma. It reduces the immune system's reaction to allergy-causing substances, such as pollen, dust mites or pet dander. Xolair is delivered by injection every two to four weeks.
• Allergy medications. These include oral and nasal spray antihistamines and decongestants as well as corticosteroid, cromolyn and ipratropium nasal sprays.
• Allergy shots (immunotherapy). Immunotherapy injections are generally given once a week for a few months, then once a month for a period of three to five years. Over time, they gradually reduce your immune system reaction to specific allergens.

Don't rely only on quick-relief medications

If you've been prescribed long-term asthma control medications — such as inhaled corticosteroids — you shouldn't need to use your quick-relief inhaler more often than your doctor recommends. Keep a record of how many puffs you use each week. If you frequently need to use your quick-relief inhaler, see your doctor. You probably need to adjust your long-term control medication. 

Prevention

There's no way to keep from getting exercise-induced asthma. But you can take steps to keep symptoms under control:

• Warm up for 15 minutes before strenuous exercise.
• Do your best to avoid colds and other respiratory infections. Don't do strenuous exercise when you have a cold.
• Choose a humid environment for your workout, such as a trail alongside a lake or a gym with an indoor pool.
• Avoid allergens when exercising if they worsen your symptoms. Examples include air pollution, pollen or pet dander.
• Learn to breathe through your nose to warm air before it goes into your lungs.
• Keep your mouth and nose covered during exercise in cold weather.
• Don't avoid exercise because you have asthma. Staying in good shape can ease asthma symptoms in the long run.

References:

https://en.wikipedia.org/wiki/Exercise-induced_bronchoconstriction

http://www.aafa.org/page/exercise-induced-asthma.aspx

http://www.emedicinehealth.com/exercise-induced_asthma/article_em.htm

http://acaai.org/asthma/exercise-induced-asthma-eib

http://emedicine.medscape.com/article/1938228-treatment