Physical fitness and psychological hardiness as predictors of parasympathetic control in response to stress: a Norwegian police simulator training study

The individual biopsychological response to a specific stressor is the result of a complex interplay between many different factors including physiology, behavior, and personality. The goal of the present study was to explore the potential link between physical fitness, hardiness (Kobasa 1979), and the individual autonomic stress arousal experienced during a stressful police training situation (active shooter). Eighty-four police students participated in the study and were randomly assigned to either a high-stress or a low-stress testing condition. Hardiness was measured with the Dispositional Resilience Scale (Hystad et al. 2010). Physical fitness was assessed with V˙O2max . Parasympathetic control was measured using heart rate variability (HRV), i.e., the root mean square successive difference (RMSSD). Regression analysis showed that psychological hardiness had a negative main effect on change in parasympathetic activity from baseline to the testing phase (B = − 1.43, t = − 2.81, p = 0.007). Larger withdrawal of parasympathetic activation for high-hardy individuals in this phase of the study can be interpreted as an adaptive adjustment to the task set in front of them. A second regression analysis showed that both psychological hardiness (B = − 1.47, t = 3.68, p