Since its introduction by the American Thoracic Society in 2002, 6-Minute Walk Test became one of the most common and validated measurements of endurance and exercise capacity in patients with pulmonary diseases. The test is simple and performed in controlled environment by highly trained staff at TruDoc Medical Pulmonary Function Testing Laboratory. During the test, whether the patient walks or rests, the timer does not stop. The principle is to measure how much distance someone can cover for a period of 6 minutes. The results are compared to reference matched ranges gathered from healthy people of the same background, height, and weight of the patient. These comparisons allow the physician to know if the disease had affected the patient’s exercise capacity and also permit for monitoring of progression or improvement overtime.