Heightened trait and state-level Fatigue and Fatigability in patients with post COVID across cognitive, motor, and emotional domains.

Fatigue (self-reported exhaustion) and Fatigability (performance decline) are core symptoms of post COVID but remain poorly understood due to their multidimensional nature. It is unclear how the symptoms manifest at state and trait levels across cognitive, motor, and emotional domains. Our test paradigm included questionnaires addressing cognitively, emotionally and physically perceived Fatigue, and we assessed alertness (cognitive Fatigability), and hand grip strength (motor Fatigability). These were administered before and after experiencing either cognitive (attention tasks) or emotional (short films) load, or relaxation (breathing, virtual reality nature). Compared to healthy controls, patients exhibited significantly elevated trait Fatigue and Fatigability levels, with substantial intra-individual variability in the extent of symptoms. While healthy controls (n = 58) responded to acute load with domain-congruent Fatigue, patients with post COVID (n = 73) showed amplified state Fatigue and Fatigability interacting across domains, and after either type of loads and relaxation. Our multidimensional paradigm demonstrated that post COVID involves a generalized vulnerability to diverse tasks, even when exposed to relaxing stimuli. To better address symptom heterogeneity, current frameworks of clinical assessments and treatment should differentiate between state and trait Fatigue and Fatigability across cognitive, motor, and emotional domains, while accounting for intra-individual variability through multiple assessments.