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Exercise Testing

by Noah Lechtzin, MD, MHS

Doctors may use exercise testing to evaluate people with a possible lung disorder. These tests are different from exercise stress tests done to diagnose heart disorders (see Stress Testing). The two most common forms of exercise testing are the 6-minute walk test and full cardiopulmonary exercise testing.

Six-minute walk test

This simple test measures the maximal distance that people can walk at their own pace in 6 minutes on a flat surface. The test assesses the person's overall function but, if the person's exercise capacity is reduced, does not tell which of the individual organs and systems (that is, the heart, lungs, muscles and bones, or other organs and systems) is the limiting factor. Neither does it assess the person's effort. This test is used before and after lung transplantation and lung volume reduction surgery, to monitor response to treatments and pulmonary rehabilitation, and to predict the risk of disability or death in people with heart and lung disorders.

Cardiopulmonary exercise testing

This computerized test analyzes heart function and provides information, such as how much air flows through the lungs, how much carbon dioxide is being produced, and how well the lungs are getting oxygen into the blood and removing carbon dioxide from it. The test is done while the person is at rest and while exercising on a treadmill or bicycle ergometer. The intensity of the exercise is increased gradually until symptoms prevent further exercise.

Cardiopulmonary exercise testing primarily determines whether a person's capacity to exercise is normal or reduced and if it is reduced, whether the reduction is because of heart and/or lung problems or deconditioning. The test detects problems at an earlier stage than would tests that are less comprehensive or done only at rest.

Doctors can also use cardiopulmonary exercise testing to monitor a person's response to treatment and guide exercise in pulmonary rehabilitation programs.