Your Officers Need to Be Anaerobically Fit

Heart rate variability data from a real SWAT unit shows why short-duration, high-intensity fitness predicts autonomic reserve during tactical task

Publication

Tomes, C., Schram, B., Canetti, E.F.D., & Orr, R. (2024). Heart rate variability monitoring in Special Emergency Response Team anaerobic-based tasks and training. Safety, 10(4), Article 84. https://doi.org/10.3390/safety10040084

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What Was the Issue?

SWAT teams operate in environments that simultaneously demand physical performance and precise fine-motor control under extreme stress. Heart rate variability (HRV) – the variation in timing between successive heartbeats – is a well-established marker of autonomic nervous system regulation and physiological stress load. Most HRV research in law enforcement has focused on aerobic fitness. This study asked whether anaerobic fitness was a better predictor of HRV in SWAT operators, and whether HRV could practically serve as a readiness monitoring tool in small tactical units.

How Did They Look at It?

Fifteen male SWAT operators from an Australian law enforcement agency underwent ECG recording at three time points: baseline (prior to the duty day, seated at rest), immediately following annual firearms qualification, and immediately following a physically demanding training exercise. HRV was calculated across time-domain measures (HR, RMSSD, SDNN), frequency-domain measures (total power, low-frequency, high-frequency), and non-linear measures (SD1, SD2). Just think of these as a lot of different ways to measure HRV. Officers also completed an anaerobic obstacle course two weeks before the HRV testing; completion time served as the independent predictor variable in linear regression models.

What Did They Find?

Firearms qualification alone did not suppress HRV. The qualification event, while cognitively demanding, was not physically taxing enough to measurably alter autonomic function.

Training did suppress HRV. Significant decreases from baseline to post-training were found for HR, SDNN, total power, high-frequency HRV, and SD2, reflecting the genuine physiological cost of the more demanding training exercise.

Obstacle course time significantly predicted every HRV measure after qualification, with r-squared values ranging from 0.52 to 0.67 (r-squared is the amount of variance explained by the variables in the model. It ranges from 0 to 1. A .67 means that 67% of the variance in HRV can be explained by the times on the obstacle course). Officers who completed the course faster had substantially better HRV going into the study.

More anaerobically fit operators experienced greater drops in HRV during training, but they started from a higher baseline and maintained more reserve than less fit counterparts. When the group was split at the median obstacle course time, the top half showed post-training HRV values above the smallest worthwhile change threshold – meaning autonomic function was preserved. The bottom half showed those same measures below threshold – autonomic function was suppressed.

So What?

The authors argue that HRV can serve as a practical readiness monitoring tool for SWAT units even when cohort size is small. The connection between anaerobic fitness and HRV reserve supports prioritizing short-duration, high-intensity training in SWAT fitness programming over aerobic conditioning alone. Officers who can complete the physical demands of the job faster have more autonomic buffer when the precision task begins.

My $.02

We have to be careful reading too much into this study because the sample size is quite small (15 SWAT operators), but the findings are still interesting.

I to emphasize the move away from heart rate (HR) as a good indicator of performance or capacity. When I first started studying this area, it was really the only thing we had. More recent research has found the HRV is a much better predictor.

HR tells you someone is activated. Many highly trained athletes and professionals can still function effectively even with very high HR. Formula 1 drivers, for example, have average heart rates from 160 to 180 beats per minute during races and can peak at 200 yet still drive effectively.

HRV tells you how much buffer is left. Low HRV means that the performer doesn’t have much capacity left. A training program that produces chronically low resting HRV is depleting officers’ capacity.

ECG-based measurement (as used here) is more accurate than wrist-based consumer devices, but wrist-based monitors are cheap and widely available now. The question for any agency running a SWAT unit is whether readiness monitoring is worth the modest investment it would take to do it.

For training programmers: the takeaway is not just “get officers fit.” The type of fitness matters. Short-duration, high-intensity anaerobic capacity seems to buffer autonomic function during close-range, high-stakes, fine-motor, under-stress situations. HRV can be used to see if trainees have recovered before the next heavy training session is conducted.