This was a prospective, randomized, and crossover
trial. To establish the COPD population, a total of 30
subjects of both genders were screened, including
patients with stable and moderate to severe COPD5,
among whom fifteen subjects (8 men and 7 women)
were selected for inclusion in the study. The selected
subjects had a documented medical history of COPD,
were receiving medical therapy with pulmonary
drugs, were smokers or former smokers, and none
had any clinical or physiological features of bronchial
asthma. The exclusion criteria were age over 80 years,
obesity, history of recent exacerbation, uncontrolled
arterial hypertension, and need for home oxygen
therapy.