Heart rate variability is reduced in COVID‐19 survivors and associated with physical activity and fatigue

Abstract

AbstractReduced heart rate variability (HRV) and fatigue are common after COVID‐19 infection and both are potentially influenced by physical activity (PA). We compared resting HRV, PA from accelerometers and questionnaires, and self‐reported fatigue in 41 COVID‐19 survivors (~8 months postinfection, 38 ± 17 years) with 41 matched controls. Differences in HRV were observed on acceleration capacity (p = 0.041), deceleration capacity (p = 0.032), high‐frequency peak frequency (p = 0.019), absolute low‐frequency power (p = 0.042), relative very low‐frequency power (p = 0.012), SD2 (from Poincare plot; p = 0.047), and DFA2 (slope of long‐term detrended fluctuation analysis; p = 0.004). Fatigue was greater in COVID‐19 survivors (p < 0.001) with no differences in PA. Moderate‐vigorous physical activity (MVPA) (Standardized Beta = −0.427, p = 0.003) and steps per day (Standardized Beta = −0.402, p = 0.007) were associated with DFA2 in COVID‐19 survivors after controlling for age, sex, and body fat percentage. Fatigue was correlated to less MVPA (Spearman's rho = 0.342, p = 0.031) and fewer steps per day (rho = 0.329, p = 0.038) in COVID‐19 survivors, and was indirectly linked to HRV through these PA mediators (Estimate = −0.20; p = 0.040). We present a model showing the complex relations between HRV, PA, and fatigue that provides the foundation for strategies to improve outcomes and rehabilitation after COVID‐19 infection.