Diagnosis

Your doctor will conduct a medical exam and order tests to assess your lung function and rule out other conditions that can cause your symptoms.

Test of normal lung function

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.

Your doctor might have you repeat the test after you take an inhaled medication to open your lungs (bronchodilator). 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.

Exercise challenge tests

An additional test that enables your doctor to 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 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.

Alternate challenge test

As an alternative to the exercise challenge, your doctor might 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.

Spirometry tests before and after the challenge test provide information about changes in lung function. This challenge test is typically done using methacholine, an inhaled agent that causes bronchoconstriction.