HEART RATE RECOVERY IN EXHAUSTION DISORDER : quadratic vagal interaction predicting work ability?

Abstract: Exhaustion disorder (ED) is a Swedish criteria-based medical diagnosis related to burnout, that often requires long term rehabilitation and sick leave. Comorbidity of functional gastrointestinal (GI) problems and ED has been reported and may be mediated by dysregulated vagal function. This study aimed to explore whether vagus nerve regulation evaluated with the vagal estimate Heart rate recovery (HRR60s), is quadratically associated with severity of ED, affective, GI symptoms/diagnoses, and work ability, using data from a randomized controlled trial. On baseline 16.1% of participants (n = 155) showed attenuated (<25 beats/minute) or fast HRR60s (>51 beats/minute) (82.6/17.4% women/men; N = 161; M = 43yrs; SD = 8.5). Controlling for effects of BMI, fitness (Vo2max), age and sex all subjects were in the HRR60s range defined as normal (27-47, n = 152). The explanatory power of cross-sectional correlations where similar using a quadratic and a linear model. The main hypothesis was therefore not supported. Within-subject analyses showed a tendency that longitudinal increase in HRR60s was associated with a decrease in burnout symptoms up to a certain tip-point, where it contrariwise was associated with higher ratings. Lower prevalence of GI symptoms/diagnoses than in earlier publications indicate that these may be underreported in data. In conclusion preliminary results suggest that evaluating HRR60s in ED using an inverted U-shaped model of cardiac vagal regulation may add information of stage, degree of severity of ED and progress of treatment on an individual basis, which may not be transparent in cross-sectional analysis.