The resting pulmonary and cardiac function testing cannot reliably predict exercise performance and functional capacity. Cardiopulmonary exercise testing (CPET) provides to assessment of the pulmonary, cardiovascular, hematopoietic, neuropsychological, and skeletal muscle systems. Thus, CPET has gained increasing popularity for the evaluation of undiagnosed exercise intolerance and exercise related symptoms, and to reveal functional capacity and impairment.