Association between non-acute Traumatic Injury (TI) and Heart Rate Variability (HRV) in adults: A systematic review and meta-analysis

The Effects of Commando Training on Stress, Cognitive Performance, and Group Behavior in Military Personnel: An Exploratory Study

BACKGROUND

Military personnel are exposed to a high level of operational stress that degrades their psychophysiological and cognitive performance and could impact the mission. Commando training is a unique opportunity to assess psychological, physiological, and cognitive performance in an ecological setting.

METHODS

Psychological, physiological, and cognitive performance were evaluated at baseline, and before and after a 1-week commando training course consisting of exercises and night walks. Psychological factors (anxiety, subjective stress), physiological measures (heart rate variability, electrodermal conductance), cognitive behavior (cognitive bias, risk-taking, decision-making), and cognitive performance (the MindPulse neurophysiological test) were assessed. Volunteers were 39 young (mean age 21.6 years) French army officers.

RESULTS

Blind spot bias was found in all participants before training, except for the action-inaction bias. We observed a deterioration in parasympathetic functioning (Root Mean Square of Successive Differences, P = .05), an increase in subjective fatigue (P < .001), and impaired cognitive performance: reaction time (P = .02, F = 5.77), errors (P = .03, F = 4.97). Post-training, we observed an emerging group dynamic, notably an increase in avoidance (buck-passing) (P = .002, F = 10,43), a reduction of the action-inaction bias (P = .009, F = 7.59), ostrich effect (P = .008, F = 7.83) and stereotyping bias (P = .03, F = 5.11).

CONCLUSION

Commando training increases stress and impacts the cognitive performance of military personnel. Pre-deployment preparation could consider the need for physiological recovery, and the impact of deployment on cognitive performance.

Cardiac autonomic regulation during submaximal exercise in women with fibromyalgia

Fibromyalgia (FM) patients present impaired cardiac autonomic regulation during maximal exercise; however, it is unknown whether these alterations also manifest during submaximal exercise. The aim of this study was to compare the on-transient heart rate (HR) response and HR variability during a constant-load submaximal cycling exercise between FM and control (CON) women. Ten women with FM (age: 45.2±9.3 years) and 10 age-matched CON women (age: 48.4±6.1 years) performed a 15-min cycling exercise, with the work rate fixed at 50% of the individual peak power output attained in a maximal graded exercise test. The time intervals between consecutive heartbeats were recorded regularly during the exercise for subsequent analysis of on-transient HR response and HR variability indices. The on-transient HR time constant was similar (P=0.83) between the FM (41.0±14.1 sec) and CON (42.2±10.4 sec). During the 5-10 and 10-15 min of exercise, HR variability indices indicating sympathetic and parasympathetic activities were similar (P>0.05) between FM and CON groups. In conclusion, women with FM presented a normal cardiac autonomic response to submaximal cycling exercise. These findings have clinical relevance, as submaximal exercises are commonly prescribed for FM patients.

The Influence of Physical and Mental Health Mediators on the Relationship Between Combat-Related Traumatic Injury and Ultra-Short-Term Heart Rate Variability in a U.K. Military Cohort: A Structural Equation Modeling Approach

INTRODUCTION

Combat-related traumatic injury (CRTI) adversely affects heart rate variability (HRV). The mediating effect of mental and physical health factors on the relationship between CRTI, its severity and HRV has not been previously studied and investigated.

MATERIALS AND METHODS

A cross-sectional mediation analysis of the ArmeD SerVices TrAuma and RehabilitatioN OutComE (ADVANCE) prospective cohort study was performed. The sample consisted of injured and uninjured British male servicemen who were frequency-matched based on their age, rank, role-in-theater, and deployment to Afghanistan (2003-2014). CRTI and injury severity (the New Injury Severity Scores [NISS] [NISS < 25 and NISS ≥ 25]) were included as exposure variables. HRV was quantified using the root mean square of successive differences (RMSSD) obtained using pulse waveform analysis. Depression and anxiety mediators were quantified using the Patient Health Questionnaire and Generalized Anxiety Disorder, respectively. Body mass index and the 6-minute walk test (6MWT) represented physical health measures. Two mediation pathways between exposure and outcome variables were examined in comparison with the uninjured group using structural equation modeling.

RESULTS

Of 862 servicemen, 428 were injured and 434 were uninjured with the mean age at assessment of 33.9 ± 5.4 (range 23-59) years. Structural equation modeling revealed that depression, anxiety, and body mass index did not significantly mediate the relationship between injury/injury severity and RMSSD. However, the 6MWT significantly mediated the relationship between CRTI and RMSSD (27% mediation). The indirect effect of 6MWT on the relationship between injury severity (NISS ≥ 25 vs. uninjured) and RMSSD was -0.06 (95% CI: -0.12, -0.00, P < .05).

CONCLUSIONS

The findings suggest that greater physical function may improve HRV following CRTI. Longitudinal studies are warranted to further validate these findings.

The importance of self-regulation and mental health for effective recovery after traffic injuries: A comprehensive network analysis approach

OBJECTIVE

Traffic injuries significantly impact people's psychological, physical and social wellbeing, and involve complex self-regulation responses. Psychological impacts are seldom recognized and addressed holistically. This study employs network analysis to investigate the interconnectedness between different dimensions that influence mental health vulnerability and recovery after traffic injuries.

METHODS

120 adults with mild-to-moderate traffic injuries and 112 non-injured controls were recruited. The network investigation employed two main approaches. Four cross-sectional networks examined the interrelationships between self-regulation responses (cognitive and autonomic) and various health dimensions (psychological, physical, social) over time (1, 3, 6, 12 months). Three predictive networks explored influences of acute self-regulation responses (1 month) on long-term outcomes. Network analyses focused on between-group differences in overall connectivity and centrality measures (nodal strength).

RESULTS

An overall measure of psychological wellbeing consistently emerged as the most central (strongest) node in both groups' networks. Injured individuals showed higher overall connectivity and differences in the centrality of self-regulation nodes compared to controls, at 1-month and 12-months post-injury. These patterns were similarly observed in the predictive networks, including differences in cognitive and autonomic self-regulation influences.

CONCLUSIONS

Network analyses highlighted the crucial role of psychological health and self-regulation, in promoting optimal wellbeing and effective recovery. Post-traffic injury, increased connectivity indicated prolonged vulnerability for at least a year, underscoring the need of ongoing support beyond the initial improvements. A comprehensive approach that prioritizes psychological health and self-regulation through psychologically informed services, early psychological screening, and interventions promoting cognitive and autonomic self-regulation is crucial for mitigating morbidity and facilitating recovery.

TRIAL REGISTRATION

IMPRINT study, ACTRN 12616001445460.

Reliability of carotid-femoral arterial waveforms for the derivation of ultra-short term heart rate variability in injured British servicemen: An inter-rater reliability study

In this study, the comparative precision of carotid versus femoral arterial waveforms to measure ultra-short term heart rate variability (HRVUST) following traumatic injury was investigated for the first time. This was an inter-rater reliability study of 50 British servicemen (aged 23-44 years) with non-acute combat-related traumatic injury (CRTI). Paired continuous arterial waveform data for HRVUST analysis, were simultaneously sampled at the carotid and femoral arterial sites (14-16 seconds) during pulse wave velocity (PWV) measurement. HRVUST was reported as the root mean square of the successive differences (RMSSD). Following the determination of the superior sampling site (carotid versus femoral), the blinded inter-rater agreement in RMSSD for the preferred site was quantified using the Intra-class Correlation Coefficient (ICC) and the Bland-Altman plot. The mean age of participants was 34.06±4.88 years. The femoral site was superior to the carotid site with a significantly higher number of reliable signals obtained (Fisher's Exact test; p<0.001). The inter-rater agreement in femoral-derived RMSSD was excellent [ICC 0.99 (95%CI: 0.994-0.997)] with a moderate level of agreement (mean difference [bias]: 0.55; 95% CI: -0.13-1.24 ms). In this study, we demonstrated that the femoral artery is a more reliable site than the carotid artery for HRVUST measurement and post-trauma risk stratification following CRTI.