Combat Stress Decreases Memory of Warfighters in Action

Abstract

The present research aimed to analyze the effect of combat stress in the psychophysiological response and attention and memory of warfighters in a simulated combat situation. Variables of blood oxygen saturation, heart rate, blood glucose, blood lactate, body temperature, lower body muscular strength manifestation, cortical arousal, autonomic modulation, state anxiety and memory and attention through a postmission questionnaire were analyzed before and after a combat simulation in 20 male professional Spanish Army warfighters. The combat simulation produces a significant increase (p < 0.05) in explosive leg strength, rated perceived exertion, blood glucose, blood lactate, somatic anxiety, heart rate, and low frequency domain of the HRV (LF) and a significant decrease of high frequency domain of the heart rate variability (HF). The percentage of correct response in the postmission questionnaire parameters show that elements more related with a physical integrity threat are the most correctly remembered. There were significant differences in the postmission questionnaire variables when participants were divided by the cortical arousal post: sounds no response, mobile phone correct, mobile phone no response, odours correct. The correlation analysis showed positive correlations: LF post/body temperature post, HF post/correct sound, body temperature post/glucose post, CFFTpre/lactate post, CFFT post/wrong sound, glucose post/AC pre, AC post/wrong fusil, AS post/SC post and SC post/wrong olfactory; and negative correlations: LF post/correct sound, body temperature post/lactate post and glucose post/lactate post. This data suggest that combat stress actives fight-flight system of soldiers. As conclusion, Combat stress produces an increased psychophysiological response that cause a selective decrease of memory, depending on the nature, dangerous or harmless of the objects.

Higher use of techniques studied and performance in melee combat produce a higher psychophysiological stress response

“…In the present research, the significantly higher use of studied techniques (instinctive and basic techniques, with a technical component as low as possible for better learning) by the HPG allows them to obtain a higher task performance even with higher HR, because the low technical requirement allows it. Despite the high physiological activation of HPG, time perception was not negatively affected, result contrary with previous studies conducted in military population where different constructs of memory were negatively affected by combat stress (Delgado‐Moreno et al, ). Possibly the different contexts, training, and experience of the subjects analysed could be the explanation but allow us to think that present operative training could be an optimal tool to improve cognitive impairment due to combat stress.…”

“…In order to complete the Objective 1, before and immediately after the simulation, the following parameters were measured in the following order as in previous studies (Clemente‐Suárez et al, ; Clemente‐Suárez et al, ; Clemente‐Suárez et al, ; R. Delgado‐Moreno et al, ; Sánchez‐Molina et al, ; Tornero‐Aguilera et al, ): Rated of perceived exertion by the Borg 6–20 scale Stress subjective perception by a 0–100 scale. Body temperature (BT) with a digital infrared thermometer (Temp Touch; Xilas Medical, San Antonio, TX). Blood oxygen saturation (BOS) and HR by a pulse oximeter (PO 30 Beurer Medical). Blood lactate concentration taking a sample of 5‐μl capillary blood from a finger of subjects and analysed with the Lactate Pro Arkay, Inc. system (Kyoto, Japan). Cortical arousal trough the Critical Flicker Fusion Threshold (CFFT) in a viewing chamber (Lafayette Instrument Flicker Fusion Control Unit Model 12021) following the procedures conducted in previous studies (Fuentes et al, ). Lower body muscular strength manifestation by means of a vertical jump test. We used the Sensorize FreePowerJump system (SANRO Electromedicina, Madrid, Spain), which recorded flight time (s) and jump height (cm) to evaluate three vertical types of jump.…”

“…The study of psychophysiological response in combat situations, specifically in military and police populations, showed an increase in stress response that causes an anxiety state, decreased cortical arousal, and central nervous system fatigue (Clemente‐Suárez et al, ; Clemente‐Suárez, Delgado‐Moreno, González‐Gómez, & Robles‐Pérez, ; Clemente‐Suarez & Robles‐Pérez, ; Clemente‐Suarez, Robles‐Pérez, Herrera‐Mendoza, Herrera‐Tapias, & Fernández‐Lucas, ; Sánchez‐Molina et al, ; Tornero‐Aguilera, Robles‐Pérez, & Clemente‐Suárez, ). The anxiety response increases the allocation of attention to threat‐related stimuli reducing attentional focus and negatively affect working memory (Delgado‐Moreno, Robles‐Pérez, & Clemente‐Suárez, ). These results showed the necessity of specific training to endure stress in their habitual work demands, fact important to improve personnel performance and health, since the prolonged exposition to stress environment without a correct preparation was related with posttraumatic stress disorders (Villarreal et al, ).…”

Effectiveness of an applied high intensity interval training as a specific operative training

“…Nerveless, these values were lower than the evaluated metabolic response, probably due to soldiers were not aware of the physiological requirement of the training, as well as the response found in combat simulations [5,7]. In the same line, stress perception increased after the training, not affecting memory capacity of soldier, in contras of previous studies conducted in asymmetrical combat [30]. This could be due to the lack of combat stress, since present research only analyze an operative training not combat simulation.…”

“…Despite the decrease in cortical arousal, the lower body strength manifestation (horizontal jump) was not affected, increasing after the operative HIIT. Probably, this increase was due to the increase in sympathetic nervous system activation produced in the HIIT, which produce a greater number of cortex eferences to muscles [30]. About the rating of perceived exertion during the operative HIIT, we found a significant increase in RPE.…”