PP035 - STANDARDIZED PHASE ANGLE PREDICTS BASELINE FATIGUE BUT NOT POST-EXERTIONAL MALAISE IN LONG COVID

PP035

STANDARDIZED PHASE ANGLE PREDICTS BASELINE FATIGUE BUT NOT POST-EXERTIONAL MALAISE IN LONG COVID

S. M. Bomans^1,2,*, D. Beckwée ², B. G. Jimenez Garcia^1,2, P. Janssens³, L. Leemans^1,2, E. De Waele¹

¹Clinical Nutrition, Universitair Ziekenhuis Brussel, ²Rehabilitation Research, Vrije Universiteit Brussel, ³Nephrology, Universitair Ziekenhuis Brussel, Brussels, Belgium

Rationale: Post-exertional malaise (PEM) is a core symptom of Long COVID and is characterized by worsening fatigue following exertion, yet the role of body composition in fatigue and PEM remains unclear. This secondary observational analysis within a cross-over study (NCT06933017) examined associations between body composition and fatigue severity in patients suffering from Long COVID with PEM.

Methods: Body composition was assessed using bioelectrical impedance analysis¹. Standardized phase angle (SPhA), skeletal muscle index (SMI), fat mass index (FMI), and fat-free mass index (FFMI) were included. Participants completed a two-day cardiopulmonary exercise test leading to PEM. Fatigue was assessed using the Revised Piper Fatigue Scale (RPFS) at baseline and 24 hours later. Degree of PEM was measured as ΔRPFS (24h – baseline). Body mass index (BMI) was included as a covariate. Linear regression analyses examined whether body composition parameters predicted baseline fatigue and PEM.

Results: 25 participants (age 49 ±10,3 years; 72% females) were included in the analyses. The model predicting baseline fatigue was significant (F(2,22) = 4.39, p = 0.025) and explained approximately 29% of the variance in RPFS scores. SPhA was the only outcome positively associated with baseline fatigue (B=1.21, β=0.47, p=0.019), while BMI did not significantly contribute to the model. No body composition parameters were associated with PEM.

Conclusion: SPhA predicts baseline fatigue in Long COVID, accounting for nearly one-third of its variance. In contrast, no body composition parameters were associated with PEM. This suggests cellular health may influence resting fatigue, whereas PEM likely involves other mechanisms.

References: ¹Lukaski, Henry C., and Jose Manuel Garcia-Almeida. "Phase angle in applications of bioimpedance in health and disease." Reviews in Endocrine and Metabolic Disorders 24.3 (2023): 367-370.

Disclosure of Interest: None declared