Impact of respiratory muscle training on clinical and functional parameters in COVID-19 recovered patients

Introduction: early respiratory rehabilitation is required for patients with coronavirus virus disease 2019 (COVID-19) sequelae to reduce the risk of serious disabilities after hospital discharge. Methods: it was a comparative prospective study including patients with persistent symptoms one month after discharge. The patients were hospitalized at the pneumology department D of Abderahman Mami hospital for COVID-19 pneumonia. The study involved two groups: (G1) included patients who participated in respiratory muscle training program (twice a week during 6 weeks), and a control group (G2). The groups were matched based on age, sex and body mass index (BMI). Persistent symptoms and pulmonary lung function (forced vital capacity (FVC), forced expiratory volume in one second (FEV1), total lung capacity (TLC) and diffusion capacity for carbon monoxide (DLCO), maximal inspiratory pressure (PI max) and maximal expiratory pressure (PE max), 6 Minute Walk distance (6-MWD) at baseline and after 6 weeks were compared between the two groups. Results: the two groups of patients were comparable in terms of age, sex, BMI, comorbidities, and extent of lung computed tomography (CT) lesions. Compared to G2, a significant improvement of persistent symptoms was noted in G1, including dry cough (p=0.002), dyspnea (p=0.001), chest pain (p=0.002), and fatigue (p=0.001). The mean of percutaneous oxygen saturation (SpO2) increased from 96.68% to 97.93% (p<0.01) in G1. A significant improvement in the percentages of change of FEV1 (p=0.005), FVC (p=0.003), TLC (p<0.001), DLCO (p<0.001), and 6-MWD (p=0.015) was also noted in G1 after this program. Nevertheless, only the percentage of FEV1 (p=0.02) increased in the control group. No impact of respiratory muscle training on PI max and PE max was noted. Conclusion: the present study demonstrated a significant improvement of persistent symptoms and exercise tolerance after short-term respiratory muscle training in patients suffering from COVID-19 sequelae.