Respiratory Muscle Training Can Improve Cognitive, Lung Function, and Diaphragmatic Performance in Patients with Chronic Obstructive Pulmonary Disease: A Randomized Con-trolled Trial

Abstract

<b>Background:</b> Patients with chronic obstructive pulmonary disease (COPD) frequently comorbid with mild cognitive impairment (MCI). Although aerobic exercise has been demonstrated to improve cognitive function, whether adding expiratory muscle training (EMT) to inspiratory muscle training (IMT) is helpful remains unclear. <b>Methods:</b> We&nbsp;recruited 70 patients with COPD whose score of Mini-Mental State Examination (MMSE) were in the range of MCI. Patients were assigned into the full training group (EMT + IMT) or the simple training group (IMT); the patients practiced 30 breaths two times a day, 5 days a week, for a total of 8 weeks by using a threshold-type breathing trainer. The following parameters were measured: cognitive score, diaphragmatic performance examined through ultrasound, and dyspnea score, and the following tests were performed: pulmonary function test, cardiopulmonary exercise test, and 6-min walking test. <b>Results:</b> The results showed that respiratory muscle training (RMT) significantly improved maximal inspiratory pressure (MIP), diaphragmatic thickness fraction and excursion, lung function, and scores of the COPD assessment test (CAT), modified Medical Research Council (mMRC) scale, and MMSE in both groups; however, the between-group difference was not significant. Furthermore, the patients with forced expiratory volume in one second (FEV1) &gt;30% exhibited significant improvements in MIP, lung function, and cognitive function after RMT. <b>Conclusion:</b> Introduce RMT in COPD patients, especially in those with preserved lung function (FEV1 ≥ 30%),&nbsp;can improve physical parameters and&nbsp;cognitive function.