Respiratory Muscle Training Enhances Pulmonary Function and Exercise Capacity in Long COVID Patients with Restrictive Lung Disease: A 4-week Intervention

Objectives: In South Korea, studies on “long COVID” are ongoing, but research on respiratory physical therapy are limited. In this study, we applied a respiratory muscle training program aimed at improving lung function in patients with long COVID who had restrictive lung disease. The program included 3 exercises: diaphragmatic breathing, respiratory muscle resistance training, and thoracic expansion exercises. Methods: This study investigated the effects of respiratory muscle training in 78 patients with long COVID who were characterized by restrictive lung disease. The training was conducted 3 times/week for 4 weeks, totaling 12 sessions. Changes in the forced expiratory volume in one second (FEV1), forced vital capacity (FVC), 6‐minute walk test (6 MWT) distance, and hand grip strength (HGS) were determined. Results: FVC values increased from 2.95 ± 0.59 ℓ to 3.73 ± 1.00 ℓ, exhibiting an increase of 0.78 ℓ. FEV1 values increased from 2.55 ± 0.59 ℓ to 3.03 ± 0.85 ℓ, showing an increase of 0.48 ℓ. The increase in FVC was more significant than that in FEV1. The 6 MWT demonstrated an improvement of 54 m. Furthermore, HGS increased by 1.19 kg compared with pre-respiratory training. Conclusion: This study demonstrated that respiratory muscle training improved pulmonary function and physical capacity in long COVID patients with respiratory symptoms. These findings provide evidence to guide treatment strategies for restrictive lung disease patterns in long COVID.