Heart Rate Variability Monitoring in Special Emergency Response Team Anaerobic-Based Tasks and Training

The Law enforcement profession is known to impart high stress. Members of Special Weapons and Tactics (SWAT) teams are allocated particularly demanding law enforcement operations and may therefore attain high fitness levels but may accumulate excessive stress. Heart rate variability (HRV), an assessment of time differences between heartbeats, likely indicates holistic load in field settings. To date, though, little research measuring HRV has been conducted involving SWAT units. The purpose of this study was to explore HRV measurements following (1) annual firearms qualification and (2) potential stress exposure with respect to completion time on an anaerobically taxing obstacle course. Officers with greater obstacle course performance were hypothesized to also exhibit greater HRV. HRV was also expected to stratify personnel more effectively than heart rate. Prospective 3-lead ECGs were obtained from a cohort of male SWAT operators (n = 15) with 5.2 ± 4.3 years of experience at three time points throughout one training day. HRV was assessed by time, frequency, and non-linear domains. Differences between baseline and post-training values were significant as assessed by the Wilcoxon signed-ranks test for heart rate, SDRR, LF, HF, and SD2. An enter-method linear regression model predicted post-training HF HRV by obstacle course time; r2 = 0.617, F (1,6) = 9.652, p = 0.021. Anaerobic performance may be highly valuable in SWAT units. HRV analysis may also be beneficial in measuring the psychophysiological impact of SWAT activities.