Cardio-Respiratory Fitness and Fatigue in Post-COVID-19 Syndrome-A Three-Year Update.

Post-COVID-19 syndrome (PCS) is defined as the persistence of symptoms 3 months after acute SARS-CoV-2 infection. The long-term prevalence and clinical progression of PCS has not been established. Our aim was to investigate the symptoms in PCS patients, explore the degree of physical activity, according to the fatigue severity score, and analyze its association with basic cardio-pulmonary exercise testing (CPET) parameters. A total of 192 subjects with history of SARSCoV-2 infection were included. They filled in the Chronic Fatigue Syndrome Questionnaire (CFSQ) and were divided into symptomatic and asymptomatic groups. Forty-seven had persistent post-COVID complaints-reduced physical capacity, fatigue, dyspnea, sleep disturbances, muscle pain. CPET was performed and the pathophysiological parameters in the different fatigue severity groups were compared. Subjects with persistent long-term PCS were divided into two groups-mild (20) and moderate-severe (27), depending on the CFSQ score; forty-eight PCS subjects without complaints served as a control group. The average period between the acute illness and the study was 1028 ± 214 days. Subjects with moderate-severe PCS had more symptoms during CPET (73.6% vs. 24.8% vs. 17.4%), as compared to mild/asymptomatic. The rate of perceived effort was subjective and did not correspond to the workload, heart, or breathing rate in the symptomatic group. These subjects were unable to reach the anaerobic threshold, compared to mild/asymptomatic subjects (51.8% vs. 25%, vs. 12.5%). Patients with moderate-severe PCS showed lower peak VO (24.13 ± 6.1 mL/min/kg vs. 26.73 ± 5.9 mL/min/kg, vs. 27.01 ± 6.3 mL/min/kg), as compared to mild/asymptomatic subjects. Long-term PCS is still present in up to 24% of the general population, more than thirty months after the acute episode. It is characterized by increased perception of symptom burden and diminished aerobic metabolism. A third of the long-term PCS exhibit lower cardio-respiratory fitness, independently from the severity of the symptoms.