Pursed-lips Breathing and Dynamic Hyperinflation

Pulmonary function testing Lung function will be tested using an Easy One spirometer (NDD Medical Technologies Inc., Zurich, Switzerland), and calibration checked before each evaluation. Spirometry will be performed in accordance with ATS/ERS standards (Miller et al, 2005). The predicted values will be calculated from the equations proposed by Pereira et al. (2007).

Inspiratory capacity (IC) measurement IC will be measured with the patient in the sitting position, using an Easy One portable spirometer (NDD Medical Technologies Inc., Zurich, Switzerland), before and immediately after the tests, by the slow vital capacity maneuver starting from a stable end-expiratory volume, in accordance with ATS/ERS standards (Miller et al,2005). A minimum of three maneuvers (maximum of eight) will be performed and, in order to be considered reproducible, two curves could not vary by more than 5% or 150mL. The higher value of two reproducible curves will be used for analysis. DH is considered when the IC decreased 10% and/or 150mL or more compared to the basal value (O'Donnell et al, 2001).

Six-minute walk test The 6MWT will be performed according to the guidelines of the American Thoracic Society (2002). Pulse oxygen saturation (SpO2; Oxi-Go, Oximeter Plus, Roslyn Heights, New York, USA) and dyspnea (Borg CR10 scale) will be measured at the beginning and at the end of the test. Predicted values for walking distance will be calculated according to Iwama et al. (2009).

Glittre-ADL test The TGlittre consists of completing a circuit as follows: from a sitting position, the subject stands up and walks along a flat 10-m long course, in the middle of which there is a two-step ladder (each step 17 cm high x 27 cm deep) to be climbed; after completing the 10 m, the subject faces a shelf containing three 1-kg objects positioned on the top shelf (shoulder height) and moves them one by one to the bottom shelf (waist height) and then to the floor; the objects are then returned to the bottom shelf and finally to the top shelf again; the subject walks back, climbing up and down the steps, until reaching the starting point (chair), sits down and immediately begins the next lap. The subjects carry a weighted backpack (2.5 kg for women, 5.0 kg for men) and are instructed to complete five laps on this circuit as quickly as possible. SpO2 and dyspnea index (Borg CR10 scale) will be measured at the beginning of the test, at the end of each lap, and at the end of the test (Skumlien et al, 2006).

Inclusion criteria

• COPD GOLD stages 2, 3, and 4 of severity of airflow limitation
• history of smoking ≥ 20 pack-years
• clinical stability in the four weeks prior to the study protocol

Exclusion criteria

• long-term oxygen therapy
• current smoking
• any pulmonary disease other than COPD
• comorbidities that would compromise their ability to perform any of the evaluations in the study