Cardiorespiratory Fitness and Neuromuscular Performance in Patients Recovered from COVID-19

Frazao, M.; Santos, A. d. C.; Cacau, L. d. A. P.; Silva, P. E.; Petrucci, T. R.; Assis, M. C.; Leal, R. d. A.; Forjaz, C. L. d. M.; Brasileiro-Santos, M. d. S.

Objective: COVID-19 affects cardiorespiratory and muscular systems, causing dysfunctions that may persist after recovery from the acute infection and treatment. The aim of this study was to evaluate cardiorespiratory fitness and neuromuscular performance in these patients. Methods: Patients recovered from mild (n=31) and severe (n=17) COVID-19 were evaluated and compared to healthy subjects (n=15). All volunteers underwent a maximal cardiopulmonary exercise test with simultaneous acquisition of electromyography (EMG). Power output, oxygen uptake (VO2), pulse oxygen (O2Pulse), cardiovascular efficiency ({Delta}HR/{Delta}VO2), ventilation (VE), breathing reserve (BR) and ventilatory efficiency (VE/VCO2 slope) were analyzed. From EMG, power output for type Ia and IIa activation as well as total neuromuscular efficiency ({Delta}watts/{Delta}%RMS) were determined. Results: Patients with severe COVID-19 presented lower VO2, O2Pulse and VE than mild COVID-19 patients and healthy subjects (p < 0.05 for all comparisons). No differences in {Delta}HR/{Delta}VO2, BR or VE/VCO2 slope were observed among the groups (p > 0.05 for all comparisons). Type IIa and IIb fibers were activated at lower power output in severe than in mild COVID-19 patients and healthy subjects (p < 0.05). {Delta}watts/{Delta}%RMS was lower in severe than in mild COVID-19 patients and healthy subjects (p < 0.05). Conclusion: Patients recovered from severe COVID-19 present low cardiorespiratory fitness, activate glycolytic fibers at low power outputs, and show low neuromuscular efficiency; while patients recovered from mild COVID-19 do not present these sequels.