The Effects of a Positive Expiratory Pressure (PEP) on Dyspnea and Dynamic Hyperinflation During Exercise in Chronic Obstructive Pulmonary Disease (COPD) Patients

From the relationship between pathophysiology of chronic obstructive pulmonary disease (COPD), dyspnea, and dynamic hyperinflation during ventilatory increasing, the investigators hypothesize that 1. Positive expiratory pressure (PEP) breathing will reduce dyspnea more than normal breathing during exercise in mild to moderate COPD patients. 2. PEP breathing will improve dynamic hyperinflation during exercise more than normal breathing in mild to moderate COPD patients. 3. PEP breathing will improve cardiorespiratory function during exercise than normal breathing in mild to moderate COPD patients.