Heart Rate Variability In Monitoring Special Forces Military Personnel: Preliminary Results Of A Cross-sectional Study

PURPOSE: Heart rate variability (HRV) is a simple, non-invasive, real-time and highly reproducible measurement that represents a significant indicator for assessing a health and physical condition, according to the protocols of the European Society of Cardiology (ESC) and the North American Society of Electrophysiological Stimulation (NASPE). Few studies so far on heart rate variability in active duty military personnel. METHODS: 112 male soldiers were enrolled, in the period between March and December 2019, and divided into six subgroups: office work (control group), internal night work, external night work, paratroopers, snipers with and without evaluation. Measurements were made with the Zephyr BioHarness 3 device. Raw data was analyzed with Kubios HRV software. RESULTS: The results of multi:le comparisons of the HRV parameters between the different subgroups showed significant differences for all the considered HRV parameters (p <0.05). Mean HR was significantly higher in skydivers and both subgroups of sharpshooters. Similarly, all the measured time and frequency-domain parameters, SDNN, RMSSD VLF, LF power, HF power, and PNS index were significantly higher in the control group than paratroopers and shooters but not compared to night work (both internal and external). Young age, as well as drug intake, relates with higher HRV levels. No associations were found between smoking habits and HRV parameters, possibly due to the ban on smoking during work. In spite of what was expected, as reported in the literature, night work did not affect HRV parameters, showing no statistically significant differences compared to the control group. CONCLUSIONS Highly demanding work tasks, such as paratroopers and sharpshooters, involve a significantly higher stress index and SNS index than the control group. The intake of non- steroidal anti-inflammatory drugs (NSAIDs) modifies cardiac regulation, linked to the sympathetic component, as evidenced by the reduction in the HR and SNS index.