When law enforcement officers (LEOs) face a spontaneous act of lethal force, there is no “warning or foreperiod” as in typical assessments of motor response, causing a startle response to occur. The firearm draw has been tested in controlled settings; however, such an analysis when under duress has not been examined for motor response. PURPOSE: The purpose of the present study was to evaluate LEOs firearm draw and motor response following a spontaneous presentation of lethal force in a training scenario. METHODS: A total of 22 active duty LEOs engaged in training scenario under the ruse of a “communication experiment.” The LEOs were instructed to take a report from a woman that was struck by her husband. The first trial was terminated with a whistle blow at approximately 1 minute. In the second trial, a door in the back of the room slammed and a husband entered the room yelling. When the husband entered the visual field of the LEO (~20 ft away), he drew and fired a training pistol armed with training ammunition at the LEO. The LEOs were video recorded (via GoPro) and their kinematics were measured using wearable sensors (OPALs). A third gun draw trial, not under duress, was recorded to act as a control. RESULTS: The threat of lethal force evoked a startle response of 0.78 ± 0.44 s with the most common startle responses characterized by shielding of the body with the non-shooting arm and flexion of the neck and/or back to “dodge” the gun shot. Initiation of the tactical response, i.e., moving to draw their weapon to return gun fire, occurred during the startle suggesting the startle is an open-loop motor program and the tactical responses is a close loop motor program. Draw times were 0.35 ± 0.29 s slower under duress vs. the control trial (t=3.40, p=0.003, d=1.05). The elbow kinematic profiles of the practice draw were observed being more efficient and faster, whereas the ambush draw displayed characteristics of over emphasizing each phase of the gun draw kinematic profile, causing the gun draw to take longer (r= -0.111, p=0.622). CONCLUSION: More dynamic environment training in ambush-type situations is recommended based on our findings that suggest no performance or kinematic efficiency carry over to the ambush trial compared to the practice draw, due to the novel observation of the startle response and firearm draw overlapping.



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