Fatigue and perceived fatigability, not objective fatigability, are prevalent in people with post-COVID-19

Persistent symptoms after acute COVID-19 infection, termed post-COVID-19 fatigue, occur in 44-70% of patients. Characterizing fatigue in this population is vital to determine the etiology of post-COVID-19 fatigue symptoms and to assess the effectiveness of potential interventions. The purpose of this study was to assess differences in perceived and objective fatigability between people with post-COVID-19 symptoms (N = 29, 20 females) and people who had COVID-19 but are not experiencing persistent symptoms (N = 20, 12 females). Perceived fatigability, fatigue, pain, and quality of life were assessed with the Fatigue Severity Scale (FSS), Fatigue Assessment Scale (FAS), Visual Analog Scale for Pain (VAS), and the EQ-5D-5L, respectively. Objective fatigability was evaluated with torque and work fatigue indices (FI-T and FI-W), calculated via an isokinetic fatigue task. The results revealed that, the subjects with post-COVID-19 symptoms had significantly higher FAS (p < 0.01), FSS (p < 0.01), VAS (p < 0.01), and EQ-5D-5L VAS (p < 0.01) scores compared to subjects without post-COVID-19 symptoms, indicating greater fatigue and perceived fatigability, increased pain, and worse quality of life. However, there were no differences between the two groups for the FI-Ts (all p ≥ 0.07) or FI-W (all p ≥ 0.08), indicating no differences in objective fatigability. This study found that people with post-COVID-19 symptoms have increased fatigue and perceived fatigability, but not objective fatigability, compared to subjects without post-COVID-19 symptoms.