Correlation between lung function and functional capacity after inspiratory muscle training in post-COVID-19

<bold>Introduction:</bold> Patients after COVID-19 infection, in addition to respiratory impairment, also present weakened physical condition, reducing their exercise capacity and activities of daily living. <bold>Aim:</bold> To correlate lung function with functional capacity after inspiratory muscle training (IMT) in patients post-COVID-19 infection. <bold>Methods:</bold> 28 participants of both sexes, post-COVID-19, were divided into two groups: Inspiratory Muscle Training (IMTG), with outpatient rehabilitation and IMT, and Conventional (CG), with only outpatient rehabilitation. IMT occurred twice a week for five weeks, totaling 10 sessions, consisting of two sets of 15 inspiratory efforts with a load of 30% of the maximal inspiratory pressure. Patients underwent spirometry evaluation, obtaining FVC and FEV1 values. The number of step-ups during the 6-minute step test (nTD6) was also assessed. All participants were evaluated before and after the rehabilitation period. Findings were correlated using Pearson's correlation coefficient, with significance set at p≤0.05. <bold>Results:</bold> Regarding the IMTG, after five weeks, a significant moderate correlation was observed between FVC and nTD6 (pre: r=0.40, p=0.15; post: r=0.52, p=0.05), and a low correlation between FEV1 and nTD6 (pre: r=0.43, p=0.12; post: r=0.47, p=0.08). For the CG, low and non-significant correlations were observed between FVC and nTD6 (pre: r=0.34, p=0.22; post: r=0.30, p=0.28) and between FEV1 and nTD6 (pre: r=0.27, p=0.34; post: r=0.20, p=0.49). <bold>Conclusions:</bold> The results showed a positive and significant correlation between FVC and nTD6 in the IMTG, suggesting a possible influence of IMT on pulmonary and functional recovery after COVID-19 infection.