Background: Law enforcement officers (LEOs) must adhere to both public and institutional expectations. The evolving duties, stressful environments, and occupational hazards continuously challenge the LEO to correctly perceive and respond to threats in limited time frames. To reduce perceptual error, strategies to improve the officer’s ability to respond are desired. Purpose: The purpose of Arm 1 was to examine relationships between heart rate variability (HRV) versus tartle response time, and handgun mechanics in a simulated domestic ambush. The purpose of Arm 2 was to examine relationships between physical activity rating and morning HRV. Methods: Sixteen officers participated in HRV recording before a simulated domestic ambush in Arm 1. HRV was recorded before the simulated domestic ambush (HRV). all participants underwent two simulations; the control and a simulated domestic ambush. HRV was evaluated through z-score composite of the RR Interval, inRMSSD, and Low Frequency/ High Frequency Ratio. The LEOs startle response time (SRT) was measured by 1 – intialized by directional change in range of motion (ROM) and 2 – confirmed by high-speed camera. Additionally, handgun draw mechanics (HD) were measured with a high-speed camera and video editing software. In Arm 2, twenty-six officers correlations were assessed to examine the relationship with HRV metrics and estimated-VO2max. Results: Arm 1: The were no significant correlations between SRT, HD, and HRV. Arm 2: Analysis did not detect a correlation between HRV and estimated Vo2max. Conclusion: HRV was not correlated to handgun draw to the startle response. Furthermore, the data from our research does not help explain the potential of further exeggerated movements when the lethal threat was performed due to the assailant’s ambush threat. Additionally, no support is provided towards the increase of physical activity rating with higher HRV baseline readings in the morning. Further research is needed to provide a clear understanding if physical activity status is correlated in with morning HRV in LEOs.
