Inspiratory and Expiratory Muscle Strength Training for Persistent Dyspnea in Post-COVID-19

COVID-19 can create a viral-induced myopathy resulting in dyspnea. Respiratory muscle strength training has recently been reported to reduce persistent dyspnea in individuals with post-COVID-19 symptomology. This study aimed to determine the effectiveness of a 12-week home-based, respiratory muscle strength training program in reducing dyspnea and to determine its feasibility and acceptability. This single-group trial included adults > 4 weeks beyond the acute COVID illness. Participants were assessed in person at baseline, 6, and 12 weeks for dyspnea, pulmonary symptoms, quality of life, pulmonary function, and functional capacity. Participants received inspiratory and expiratory respiratory muscle strength trainers, diaries, weekly phone calls, and were shown how to perform the exercises using a return demonstration during the baseline appointment. Statistical analyses included descriptive statistics and the Friedman test to evaluate changes over time. There was a significant reduction in dyspnea (2.04-1.39, p = .005), pulmonary symptoms (17.6-11.7, p < .001), and a significant increase in the quality-of-life index score (0.682-0.752, p = .013) and visual analog scale (63.1-71.57, p = .004). Significant improvements in peak inspiratory flow (111.24-195.77 l, p < .001), forced expiratory volume over 1 s (291.29-345.42 l, p < .001), thoracic expansion (2.71-3.88 cm, p < .001) and the 6 min walk test (300.22-391.57 m, p < .001) were also found. Study adherence was >95% and feasibility and acceptability scores were high. Home-based respiratory muscle strength training may be an effective, acceptable strategy that can be used as a standalone treatment to reduce persistent dyspnea in post-COVID-19 survivors. This study was pre-registered with Clinical Trials.gov [NCT06091280]. Clinical Trial URL/ClinicalTrials.gov PRS: Record Summary NCT06091280. IRB approval was provided by the University of South Florida (006272).