Exercised-induced asthma is a narrowing of the airways in the lungs that is 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 is not the root cause of asthma. Among people with asthma, exercise is likely just one of several factors that can induce breathing difficulties.
For most people with exercise-induced bronchoconstriction, treatment with common asthma medications and preventive measures enable them to exercise and remain active.
Signs and symptoms of exercise-induced bronchoconstriction may begin during or a few minutes after exercise, and they may persist for 30 minutes or longer if left untreated. The signs and symptoms may include:
See your doctor if you experience any signs or symptoms of exercise-induced bronchoconstriction. Because a number of conditions can cause similar symptoms, it's important to get a prompt and accurate diagnosis.
Get emergency medical treatment if you have worsening symptoms:
Medical researchers are exploring several ideas regarding the cause of exercise-induced bronchoconstriction. There may be more than one biological process that can lead to the condition. Researchers do know that in people who experience exercise-induced bronchoconstriction, strenuous exercise sets in motion molecular events that result in inflammation and the production of mucus in the airways.
Factors that may increase the risk of the condition or act as triggers include:
In addition to asking questions about your symptoms, your doctor will conduct a medical exam. He or she will also order tests to assess your lung function and rule out other conditions that may be causing your symptoms.
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.
After you do the test, your doctor may give you an inhaled medication to open your lungs (bronchodilator). You'll repeat the test, and 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.
An additional test that enables your doctor to observe and 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 the symptoms you've experienced. 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.
As an alternative to the exercise challenge, your doctor may 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.
Again spirometry tests before and after the challenge test provide information about changes in lung function. These challenge tests include the following:
Your doctor may order additional tests to rule out other conditions with symptoms similar to those of exercise-induced bronchoconstriction. These conditions include:
Exercise-induced bronchoconstriction that is not treated can result in:
There is limited clinical evidence of alternative therapies that may modify the severity of exercise-induced bronchoconstriction or provide additional benefit to standard treatments. Possible beneficial interventions include:
Steps you can take to prevent or minimize symptoms of exercise-induced bronchoconstriction include the following:
Talk to your doctor about writing an action plan if your child experiences exercise-induced bronchoconstriction. This document provides step-by-step instructions for teachers, nurses and coaches that explain what treatments your child needs, when treatments should be administered and what to do if your child experiences symptoms.