In patients with COPD, although lip retraction breathing helps to reduce the patient’s respiratory rate at rest and improves oxygen saturation, there is insufficient evidence on the effect of this training modality on lung filling and exercise endurance under dynamic conditions. Therefore, in order to evaluate the effects of lip retraction breathing on exercise tolerance, breathing patterns, lung hyperinflation and arterial oxygen saturation during intense exercise in patients with chronic obstructive pulmonary disease, Guimaraes et al. from the Federal University of Rio de Janeiro, Brazil, designed a study and published the results in Eur J Phys Rehabil Med The results were published in the February 2015 online issue of Eur J Phys Rehabil Med. The study was a randomized crossover study, conducted in the Respiratory Physiology Laboratory of the Federal University of Rio de Janeiro. The investigators included 40 subjects in the stable phase of chronic obstructive pulmonary disease, aged between 40 and 75 years, with FEV1 < 60%. < p=""> Subjects performed lip retraction breathing training and respiratory control training while exercising at a constant intensity on an electric power bicycle. The assessment then included the patient’s dynamic lung inflation, oxygen saturation, and respiratory pattern recorded at rest and at the moment of peak exercise, respectively. Nine subjects showed an increase in endurance time of more than 25% during lip retractor training, and these patients were classified in the improvement group. These patients had a lower peak expiratory flow rate (EPF) compared to subjects in the non-improved group. subject work curve analysis of EPF suggested that its sensitivity and specificity in differentiating the improved and non-improved groups was best when the percentage of predicted value was used as the threshold. The investigators observed that at 47.7% of the predicted EPF value, the sensitivity and specificity were 61% and 88%, respectively. In subjects in the improvement group, lip retraction breathing increased inspiratory volume and oxygen saturation while decreasing the patient’s respiratory rate when compared to the breathing control training modality when the isochrones were reached. In contrast, in subjects in the non-improved group, asynchrony of the thoracoabdominal rhythm occurs during lip retraction breathing. At the peak of training, lip retraction improved arterial oxygen saturation for subjects in the improvement group, without significant changes in respiratory pattern. The results of this study suggest that lip retraction training reduces lung overfilling during submaximal training and improves exercise tolerance, respiratory pattern, and arterial oxygen saturation in patients with chronic obstructive pulmonary disease with low PEF. The clinical value of the results of this study is that the use of lip reduction breathing exercises can improve exercise tolerance in some patients with COPD, and that PEF measurements can help predict the appropriateness of lip reduction breathing exercises for patients.