Abstract
BACKGROUND: Non-invasive ventilation (NIV) reduces respiratory load and demands on peripheral muscles. METHODS: This study aims to evaluate the acute effects of bi-level NIV on peripheral muscle function during isokinetic exercise and aerobic performance in chronic obstructive pulmonary disease (COPD) patients. This is a pilot crossover study performed with a non-probabilistic sample of 14 moderate to very severe COPD patients. Procedures carried out in two days. Dyspnea, quality of life, lung function, respiratory muscle strength, functional capacity (6-min walk test-6MWT), and isokinetic assessment of the quadriceps were assessed. Blood samples (lactate, lactate dehydrogenase, and creatine kinase concentration) were also collected. Right after, NIV was performed for 30 min (bi-level or placebo, according to randomization) followed by new blood sample collection, 6MWT, and isokinetic dynamometer tests. Before and after evaluations, the subjective perception of dyspnea and fatigue in the lower limbs was quantified. After a wash-out period of seven days, participants returned, and all assessments were performed again. RESULTS: NIV showed improvements in perceived exertion and dyspnea after isokinetic exercise (p < 0.02 and p < 0.05, respectively). CONCLUSIONS: NIV improves the perception of dyspnea and fatigue during the isokinetic exercise.