IMT in Ventilatory Muscle Metaboreflex in COPD

Patients will be selected from the Hospital de Clinicas de Porto Alegre's COPD ambulatory, by convenience. Afterwards, patients will be submitted to pulmonary function test (spirometry) and cardiopulmonary exercise tests (incremental and submaximal), maximal inspiratory pressure evaluation and induction of the inspiratory muscle metaboreflex through venous occlusion plethysmography. Disease specific health related quality of life questionnaire (Saint George Respiratory Questionnaire) and daily life dyspnea questionnaire (Baseline Dyspnea Index and Transitional Dyspnea Index) will be administered at the first and last visit of each subject. Patients will undergo inspiratory muscle training for 30 minutes per day, 7 times a week, for 8 weeks, with Inspiratory Muscle Trainer device (PowerBreath Inc.). There will be a weekly follow up at the institution's Clinical Research Center, where maximal inspiratory pressure (PImax) and inspiratory training techniques will be reevaluated. After this period, tests of pulmonary function, questionnaires exercise tolerance and induction of the inspiratory muscle metaboreflex will be reevaluated.