Evaluation of stress-related heart-rate variability in police officers during operational training for high-risk tactical tasks

Emotional stress reaction to perceived danger induce autonomic survival adaptation ("fight-or-flight reflex"). Little information is available about the interaction between emotional response in police officers (POs), during demanding tactical tasks (DTTs) and the effects of stress on tactical efficiency. We studied operational efficiency (OE) of POs using realistic training scenarios (RTS) implying the use of deadly force, by measuring heart rate (HR) and its variability (HRV) as indexes of reaction to psychological stress (PS). 110 POs were studied during RTS. All had a normal heart. 12-lead Holter ECG and wrist blood pressure were recorded 2 hours before to 1 hour after RTS. OE and behaviour were TV-monitored. Subjective PS was rated by a questionnaire. HR rose above 150 bpm in all POs during expectation of danger, and even above 190 bpm during DTTs. HR above 180 bpm was often associated with irrational behaviour and poor situational control. HRV parameters were consistent with stress-induced loss of heart coherence. DTTs might imply severe cardiovascular strain especially when PS is associated with physical effort. Abnormal HRV was associated with higher individual stress, behavioural impairment and tactical inefficacy. This should be taken into account in fitness-for-duty evaluation and planning training standards for POs education