This study is unique and timely because it applies heart rate variability (HRV) monitoring, a relatively new and advanced method, to evaluate stress in a highly demanding police training environment. In 2024, with increasing awareness of mental and physical health in high-stress jobs, this research stands out by offering a practical way to monitor and understand the stress levels of police officers during selection courses. The potential impact of this work is significant. By providing a holistic view of how candidates respond to extreme conditions, HRV monitoring could revolutionize the selection process for elite police units. It allows trainers and decision-makers to better assess not only the physical but also the mental resilience of candidates. This could lead to more effective training programs, better-prepared officers, and ultimately, a safer and more capable police force. Given the growing emphasis on occupational health and risk management, particularly amongst first responders, this study's insights are particularly relevant and could attract widespread interest from both scientific and professional communities.