Autonomic myocardial influences as a factor determining inter-task consistency of heart rate reactivity.

Abstract

ABSTRACTThis study assessed the consistency of subjects’relative heart rate (HR) responsivity across four tasks and examined the role played by autonomic myocardial influences on this consistency. HR responses across tasks were predicted to covary to the extent that they reflected a similar autonomic mediation, assessed by measurement of pulse transit time (PTT).Forty‐eight male subjects performed two sensory intake (Tones and Lights RT) and two sensory rejection (Mental Arithmetic and Word Formation) tasks. Consistency of HR responsivity was revealed by significant positive correlations observed between HR changes during all task pairs. High HR reactors in rejection tasks displayed HR decreases during an intake task (Tones), whereas low reactors displayed the expected bradycardia. Significant correlations between HR and PTT changes suggested that SNS influences were evoked by mental arithmetic, whereas a dissociation of these indices in the Tones task implied a predominance of PNS influence in that task. Nevertheless, HR changes covaried reliably between these tasks, suggesting that HR responsivity is consistent across situations evoking different patterns of autonomic influence on the heart.