The exercise test is used for the evaluation of bronchospasm induced by exercise.
Some patients show poor tolerance to physical exercise. This may be due to several conditions, one of which is the appearance of the so called exercise-induced bronchospasm.
The exercise may induce the contraction of the muscles in the bronchi, and thus cause narrowing of the airways and make it difficult to breathe. This can happen in some patients with asthma, and in some people who do not have bronchospasm apart from exercise.
First a study of the lung function is performed, then the patient makes a predefined exercise, usually between 5 and 8 minutes, in a stationary bicycle or a treadmill, and next the patient repeats the same lung function study at several time intervals. The results of the lung function are compared to the baseline result, to see if there is a decrease in lung function.
If there appears a significant decrease the patient is diagnosed with exercise-induced bronchospasm. If there is no decrease, other conditions may explain the symptoms.
One of the risks of the test is falling from the treadmill if the patient cannot keep the pace. As the patient is under continuous surveillance, the treadmill can be stopped before this happens. Another risk is the appearance of asthma symptoms. This is, precisely, the objective of the test, to check if symptoms appear due to a decrease in lung function.
The medication used for asthma may change the results of the test. If you are scheduled for an exercise test you should ask your doctor if you must withdraw the medication. The doctor might want to know the result of the test with no modification by the medication, but might also want to know if the medication is protecting you.
Angel Mazon MD, PhD