Discriminant analysis of non-linear heart rate variability features differentiates acute tactical stress induced by virtual and realistic shooting training

Acute tactical stress (ATS) might impair police officer’s (PO) decision-making, and ability to shoot accurately in self-defense situations on the street, with consequent incidents and lawsuit. Tactical shooting training (TST) is nowadays performed in virtual shooting ranges (VST) and in high stress real-world scenarios (hsRWST). This study aimed at assessing the level of ATS induced by VST and hsRWS. Methods: 26 POs were monitored before, during and after VST (Selex ES, Italy) and hsRWST. Anxiety was assessed with the State-Trait Anxiety Inventory-Trait. Discriminant Analysis (DA) of short-term heart rate variability (HRV) parameters was used to differentiate among the two kinds of ATS. Results: The majority of NL parameters significantly differed (p<0.05) between rest, VST and hsRWST. DA of TD and NL HRV features had high predictive accuracy (> 90%) in differentiating ATS induced by VSR and by hsRWS. Conclusions: DA of HRV parameters is highly efficient in differentiating between ATS induced in VSR and by hsRWS. Although TST in hsRWS is unrivalled to test individual capability to manage emotional reactions, its standardization is difficult. TST in VSR, on the contrary, provides objective correlation between tasks difficulty and performance, allows data storage for individual follow-up and retraining.