Long-term cardiopulmonary fitness and respiratory muscle recovery 12 months after COVID-19

Abstract Introduction Post-acute COVID-19 syndrome represents a considerable public health challenge, characterized by persistent symptoms that profoundly impact quality of life. Among the most common sequelae is cardiorespiratory dysfunction; however, its long-term trajectory of recovery is not well characterized. This study therefore aimed to evaluate the 12-month evolution of cardiorespiratory fitness and inspiratory muscle strength in individuals recovering from COVID-19. Methods We conducted a prospective cohort study with 29 adults previously diagnosed with post-acute COVID-19. Baseline data were collected during the acute phase of infection. Follow-up assessments, performed 12 months later, included cardiopulmonary exercise testing (CPET) on a cycle ergometer with a ramp protocol, spirometry and manovacuometry to measure maximal inspiratory pressure (MIP). Statistical analysis used paired t-tests or Wilcoxon tests, with calculation of effect size (Cohen's D). Results The mean age of the cohort was 55.0 ± 11.7 years. Most patients presented with severe (57%) and critical (31%) disease during the acute phase. After one-year, significant improvements were observed across several CPET parameters, including VE/MVV ratio (Cohen's D = 0.66), peak oxygen uptake (VO2peak) in both absolute and relative terms (ml/min: d = 0.67; and ml/kg/min: d = 0.45), oxygen uptake efficiency slope (OUES; D = 0.47) and a reduction in VE/VCO2 slope (D = 0.80). Pulmonary function improved with increases in % predicted forced expiratory volume in 1 s (FEV1; d = 0.67) and forced vital capacity (FVC; D = 0.67). MIP improved significantly (D = 0.67), and the prevalence of inspiratory muscle weakness decreased from 20.7% at baseline to 3.5% at follow-up. Conclusion Over the 12-month follow-up, patients recovering from COVID-19 demonstrated significant and multifaceted cardiorespiratory recovery. This was evidenced by a meaningful improvement in functional capacity, reflected in increased VO2peak, alongside enhanced ventilatory efficiency, indicated by a lower VE/VCO2 slope. Furthermore, a substantial rise in MIP and a marked decline in the prevalence of inspiratory muscle weakness confirm a robust restoration of respiratory muscle strength (Support FIPE-HCPA; CAPES; CNPq).