Effects of respiratory muscular training in post-covid-19 patients: a systematic review and meta-analysis of randomized controlled trials

Post-Covid-19 syndrome is defined as non-self-sustaining signs and/or symptoms lasting more than 12 weeks, occurring during or after a Covid-19 infection. The primary outcome was the analysis of the respiratory muscle training (RMT) result in respiratory muscle strength, (maximum inspiratory pressure (MIP) e maximum expiratory pressure (MEP)); and the secondary results were the analysis of lung function, dyspnea, quality of life (QoL), fatigue and functional performance. The PICO description for this research was: P: patients diagnosed with post-Covid-19; I: RMT; C: Sham or simulated inspiratory or expiratory muscle training and usual care; O: MIP, MEP, Lung Function, level of dyspnea, QoL and functional performance. On January 15, 2024, the following databases were consulted: PubMed, Lilacs, Cochrane Library, PEDro and EMBASE. Randomized clinical trials were included without restrictions on year of publication or language. The data selection and extraction steps were carried out by two independent reviewers. The search in the databases resulted in a total of 14,216 studies, and after the eligibility process, 7 studies were included with a sample of 527 patients. The MIP results suffered a statistically significant increase, that is, the RMT was favorable to improve the MIP (MD = 29.55cmH O IC 95%: 7.56cmH O to 51.54cmH O, p = 0,00001). For the MEP outcome, the results were statistically significant in favor of RMT (MD = 10.93cmH2O CI 95%: 3.65cmH O to 18.21cmH O, p = 0.00001). We also noticed a significant improvement for the group that received the RMT in the distance covered in the 6-Minute Walk Test (6MWT) MD = 40.70 m CI 95%: 18.23 m to 65.17 m%, p = 0.01). We noticed that RMT is being used in patients with respiratory diseases, including post-Covid-19. Our systematic review observed that this training provides an increase in inspiratory and expiratory muscle strength, a reduction in dyspnea levels, and an increase in the distance covered in the 6MWT and improved QoL in post-covid patients after intervention.