Physical fitness and depressive symptoms during army basic combat training

Determining the Changes in Law Enforcement Recruit Aerobic Fitness Using the 2.4-km Run and 20-m Multistage Fitness Test. Does the Type of Test Matter?

ABSTRACT

Campbell, P, Maupin, D, Lockie, RG, Dawes, JJ, Simas, V, Canetti, E, Schram, B, and Orr, R. Determining the changes in law enforcement recruit aerobic fitness using the 2.4-km run and 20-m multistage fitness test. Does the type of test matter? J Strength Cond Res 38(6): 1111-1117, 2024-Aerobic fitness is linked with academy graduation, employment, and the long-term health of law enforcement officers and is often used as a training outcome. However, different tests can be used, and aerobic improvements may differ according to the test used. The aim of this study was to determine whether recruits improved to a greater extent in 1 aerobic test compared with the other. Retrospective data from 5 law enforcement recruit cohorts (males = 741; females = 353) who underwent 18 weeks of academy training were analyzed. Initial 20-m multistage fitness test (20MSFT) and 2.4-km run assessments were completed during weeks 4 and 5 of training, with final testing completed during weeks 16 and 17, respectively. A repeated-measures analysis of variance ( p < 0.05) with a Bonferroni post hoc analysis determined changes in aerobic fitness in the 20MSFT and 2.4-km run between male and female recruits. A mean difference of 9.27 (95% confidence intervals [CI] 14.8-10.9; d = 0.63; p < 0.001) shuttle increase in 20MSFT performance and 20.1 (95% CI 16.0-24.2; d = 0.49; p < 0.001) second improvement in 2.4-km run time were demonstrated when averaged across sex, yielding a larger performance improvement for the 20MSFT compared with the 2.4-km run. Conversely, there was a smaller magnitude of change in aerobic fitness between male recruits and female recruits for the 20MSFT ( d = 0.47) compared with the 2.4-km run ( d = 0.50). The findings indicate that current academy training results in improvements to aerobic fitness and to a greater magnitude in the 20MSFT compared with the 2.4-km run. These results may affect policy considerations for law enforcement agencies regarding aerobic test selection.

Evaluating the Variability Between 20-m Multistage Fitness Test Estimating Equations in Law Enforcement Recruits

ABSTRACT

Campbell, P, Maupin, D, Lockie, RG, Dawes, JJ, Simas, V, Canetti, E, Schram, B, and Orr, R. Evaluating the variability between 20-m multistage fitness test estimating equations in law enforcement recruits. J Strength Cond Res 38(4): 742-748, 2024-The 20-m multistage fitness test (20MSFT) is commonly used by law enforcement agencies to measure aerobic fitness and to estimate maximal aerobic consumption (V̇ o2 max). These measures are an important occupational variable with aerobic fitness levels linked to employment status, occupational performance, and long-term health in law enforcement officers. There are a multitude of predictive equations used to provide an estimate of V̇ o2 max, with the extent of variability in the estimated V̇ o2 max currently unknown in this population. This has consequences for comparisons between, and across, differing agencies, and in capabilities of deriving normative data. The aim of this investigation was to compare the variability in estimated V̇ o2 max scores derived from different 20MSFT predictive equations. The 20-m multistage fitness test data from 1,094 law enforcement recruits (male n = 741, 25.2 ± 6.3 years; female: n = 353, 25.6 ± 5.6 years) from a single agency were retrospectively analyzed. The 20MSFT scores were transformed into estimated V̇ o2 max scores using 6 different predictive equations. Significance was set at p < 0.05. Results demonstrated significantly different V̇ o2 max scores between each predictive equation ( p < 0.001; d = 0.25-1.53) and between male and female recruits ( p < 0.001, r = 0.55). All estimated V̇ o2 max equations showed small to very strong correlations with each other ( p < 0.001; r = 0.32-0.99). The findings indicate considerable dispersion of V̇ o2 max scores when using differing equations, suggesting raw 20MSFT variables (e.g., shuttles or distance completed) should be preferred to measure and apply results from aerobic fitness tests if standardized approaches are not developed within law enforcement.

Four-Year Training Course for Police Officers (CFOP) and Fitness Outcomes of Police Academy Cadets: A Cohort Study from 2004 to 2020

This study examines the effect of gender, age, and a 4-year training course for police officers (CFOP) on the physical fitness attributes of Portuguese police academy cadets. This longitudinal cohort study considered 686 police cadets (female, n = 131; male, n = 555 male), corresponding to 2578 fitness assessments (female, n = 509; male, n = 2069). The database of police cadets' physical fitness evaluations (from 2004/2005 to 2019/2020) comprises body size, speed, agility, strength, flexibility, and aerobic capacity first assessment (T0) and evaluations at the end of the first four years of the CFOP (T1, T2, T3, T4). Results showed that (i) female cadets are younger (p < 0.05), shorter, lighter, less fast, less agile, less strong, and perform worse in aerobic capacity assessments than male cadets (all, p < 0.001) but perform better in the flexibility assessment (p < 0.001); (ii) female cadets > 29 years are significantly heavier, slower, jump less, perform fewer sit-ups, and perform less on the Cooper test (but they have more handgrip strength), and male cadets > 29 years are significantly heavier, slower, jump less, perform fewer sit-ups, and have less flexibility and aerobic capacity (still, they have superior back and lumbar strength and handgrip strength); and (iii) from T0 to T4 (Δ), female cadets are significantly faster (60 m, -0.32 s; slalom, -0.78 s), jump further (+4 cm), have more abdominal strength endurance (+2.6 repetitions) and more back and lumbar strength (+89.8 kg), and male cadets are significantly heavier (+3.27 kg), faster (60 m, -0.23 s; 30 m, -0.15 s; slalom, -0.91 s), jump further (+8 cm), complete more repetitions in the sit-ups (+4.9 repetitions) and in pull-ups (+2.5 repetitions) and have more back and lumbar strength (+92.1 kg) and handgrip strength (+8.6 kg) but a lower aerobic capacity (Cooper test, -74.8 m; VO2max, -1.3 mL/kg/min) when compared to T0. The study's findings lead to widely accepted conclusions within the discipline. Nevertheless, this work provides valuable insights into the impact of various factors on the physical fitness of Portuguese police academy cadets, i.e.: (i) it is an essential study with practical implications for recruitment, training, and the ongoing development of Portuguese police academy cadets and police officers; and (ii) these results can also assist in tailoring training programs to different age groups and genders, which is crucial in police training.

Adaptation in Young Military Recruits: Protocol for the Advancing Research on Mechanisms of Resilience (ARMOR) Prospective Longitudinal Study

BACKGROUND

Military services provide a unique opportunity for studying resilience, a dynamic process of successful adaptation (ie, doing well in terms of functioning and symptoms) in response to significant adversity. Despite the tremendous interest in positive adaptation among military service members, little is known about the processes underlying their resilience. Understanding the neurobiological, cognitive, and social mechanisms underlying adaptive functioning following military stressor exposure is essential for enhancing the resilience of military service members.

OBJECTIVE

The primary objective of the Advancing Research on Mechanisms of Resilience (ARMOR) longitudinal study is to characterize the trajectories of positive adaptation among young military recruits in response to basic combat training (BCT), a well-defined, uniform, and 10-week period of intense stress (aim 1), and identify promotive and protective processes contributing to individual variations in resilience (aim 2). The secondary objective is to investigate the pathways by which neurobehavioral markers of self-regulation assessed using electroencephalography and magnetic resonance imaging contribute to adaptive trajectories (aim 3).

METHODS

ARMOR is an ongoing, prospective longitudinal cohort study of young military recruits who recently joined the National Guard but have not yet shipped out for BCT. Participants (N=1201) are assessed at 5 time points over the initial >2 years of military service beginning before BCT (baseline) and followed up at 2 weeks and 6, 12, and 18 months after BCT. Participants complete web-based questionnaires assessing vulnerability and protective factors, mental health, and socioemotional functioning at each time point and a battery of neurocognitive tests at time 0. A subset of participants also complete structured diagnostic interviews and additional self-report measures and perform neurobehavioral tasks before and after BCT during electroencephalography sessions and before BCT only during magnetic resonance imaging sessions.

RESULTS

This UG3/UH3 project was initially funded in August 2017, with the UG3 pilot work completed at the end of 2018. The UH3 phase of the project was funded in March 2019. Study enrollment for the UH3 phase began on April 14, 2019, and ended on October 16, 2021. A total of 1201 participants are enrolled in the study. Follow-up data collection for the UH3 phase is ongoing and projected to continue through February 2024. We will disseminate the findings through conferences, webinars, open access publications, and communications with participants and stakeholders.

CONCLUSIONS

The ARMOR study provides a rich data set to identify the predictors and mechanisms of resilient and nonresilient outcomes in the context of military stressors, which are intended to empirically inform the development of prevention and intervention strategies to enhance the resilience of military trainees and potentially other young people facing significant life challenges.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/51235.

Predicting Postoperative Injury and Military Discharge Status After Knee Surgery in the US Army

BACKGROUND

Researchers have assessed postoperative injury or disability predictors in the military setting but typically focused on 1 type of surgical procedure at a time, used relatively small sample sizes, or investigated mixed cohorts with civilian populations.

PURPOSE

To identify the relationship between baseline variables and injury incidence or military discharge status in US Army soldiers after knee surgery.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Data were obtained from a repository containing personnel, performance, and medical records for all active-duty US Army soldiers. Multivariate logistic regressions were used to estimate the effects of numerous variables on postoperative injury or on medical discharge. Variable selection and model validation were conducted using the k-fold method.

RESULTS

A total of 7567 soldiers underwent knee surgery between 2017 and 2019. Meniscal procedures were the most common type of surgery (39%), and approximately 71% of the cohort had a postoperative injury. Significant predictors for sustaining a postoperative injury included having a previous nonknee injury (odds ratio [OR], 1.5), female sex (OR, 1.3), and Black race (OR, 1.2). Within 4 years after surgery, 17% of soldiers were discharged from the military because of knee-related disability. Significant predictors for discharge from duty included enlisted rank (OR, 2.3), recent fitness test failure (OR, 1.9), number of previous knee surgeries (OR, 1.7), and having a previous nonknee injury (OR, 1.6).

CONCLUSION

After knee surgery, nearly three-fourths of the soldiers in this cohort sustained a postoperative injury and almost one-fifth of soldiers were medically discharged from the military within 4 years. This study identified variables that indicate statistically increased risk for these postoperative outcomes and highlighted potentially modifiable factors.

Advancing Research on Mechanisms of Resilience (ARMOR) Prospective Longitudinal Study of Adaptation in Young Military Recruits: Protocol and rationale for methods and measures

Background

Military service provides a unique opportunity for studying resilience, a dynamic process of successful adaptation (i.e., doing well in terms of functioning and symptoms) in response to significant adversity. Despite tremendous interest in positive adaptation among military service members, little is known about the processes underlying their resilience. Understanding neurobiological, cognitive, and social mechanisms underlying adaptive functioning following military stressor exposure is essential to enhance the resilience of military service members.

Objectives

The primary objective of the Advancing Research on Mechanisms of Resilience (ARMOR) longitudinal study is to characterize trajectories of positive adaptation among young military recruits in response to Basic Combat Training (BCT), a well-defined, uniform, 10-week period of intense stress (Aim 1) and identify promotive and protective processes contributing to individual variations in resilience (Aim 2). The secondary objective is to investigate pathways by which neurobehavioral markers of self-regulation assessed by electroencephalography (EEG) and magnetic resonance imaging (MRI) contribute to adaptive trajectories (Aim 3).

Methods

ARMOR is an ongoing, prospective longitudinal cohort study of young military recruits who recently joined the National Guard but have not yet shipped for BCT. Participants (N=1,201) are assessed at five timepoints over the initial 2+ years of military service beginning before BCT (baseline) and followed up at 2 weeks, 6, 12, and 18 months post-BCT. At each time point, participants complete online questionnaires assessing vulnerability and protective factors, mental health and social-emotional functioning, and, at Time 0 only, a battery of neurocognitive tests. A subset of participants also complete structured diagnostic interviews, additional self-report measures, and perform neurobehavioral tasks before and after BCT during EEG sessions, and, at pre-BCT only, during MRI sessions.

Results

Study enrollment began April 14, 2019 and ended in October 16, 2021. A total of 1,201 participants are enrolled in the study (68.9% male; mean age = 18.9, SD = 3.0). Follow-up data-collection is ongoing and projected to continue through March 2024. We will disseminate findings through conferences, webinars, open access publications, and communications with participants and stakeholders.

Conclusions

Results are expected to elucidate how young military recruits adapt to military stressors during the initial years of military service. Understanding positive adaptation of military recruits in the face of BCT has implications for developing prevention and intervention strategies to enhance resilience of military trainees and potentially other young people facing significant life challenges.

Assessment of physical activity among adolescents: a guide to the literature

Purpose

The aim of this article is to systematically review articles and annual reports concerning young peoples' physical activity (PA) and linking this to considerations of the state and national defense.

Method

A systematic search of the literature included an analysis of publications accessible in global databases and other available books, student papers, and projects. The articles and reports were categorized based on year of publication, methods used, age of respondents, sample size, country, and digital object identifier (DOI).

Results

The result of this search is an overview of the extent and manner in which the worldwide scientific community is addressing the current situation and the long-term development of the physical fitness of adolescents. This publication also maps to what extent professional publications and articles are addressing PA from the perspective of the needs of armies and armed forces of various countries around the world.

Conclusions

The article provides a systematic overview of methods used to measure PA, and an overview of articles dealing with assessing PA. The examined articles indicate that from the perspective of not only national defense, but also health and overall quality of life, in particular, we need initiatives to encourage and motivate young people to increase their everyday PA. The research therefore also includes an overview of factors that may considerably influence PA. The results ascertained in this publication will be used, i.a. for investigating a longitudinal defense research project of the Ministry of Defense of the Czech Republic in which the authors are participating.

Predictors of combat training attrition in Israel Defense Forces soldiers

BACKGROUND

Attrition from combat service carries significant organizational and personal ramifications, but predicting factors associated with attrition remains challenging.

AIMS

To evaluate medical and psychosocial factors associated with attrition from basic combat training (BCT) in the Israel Defense Forces (IDF). In addition, we identify subsets of the recruit population which exhibit certain trends in terms of medical corresponding with a high risk of attrition.

METHODS

A cross-sectional study of IDF combat trainees undergoing infantry BCT between 2012 and 2017. Data were collected from the soldiers' electronic medical and administrative records. We used multivariable logistic regression and the SAS® decision-tree tool to analyse key predictive factors for attrition.

RESULTS

A total of 46 472 soldiers enlisted to BCT during the research period. The mean body mass index (BMI) was 21.8 (SD 3.54). The overall attrition rate was 10%. The following factors were associated with attrition from BCT: ethnicity (P < 0.01), BMI (P < 0.01), pre-enlisting motivation score (P < 0.01) and the number of mental health officer visits (P < 0.01). Using a decision-tree model, we found a high attrition rate among soldiers who had >5.2 to primary care physician visits (11% attrition rate versus 3%) or more than 11 sick leave days (59% versus 19%).

CONCLUSIONS

This study sheds light on unique measures relating to attrition. Attrition is associated with several demographic and psychosocial factors. Early prediction of motivation and monitoring of healthcare utilization may enable early identification and focused interventions targeting soldiers at high risk for attrition. These findings need to be further translated into actionable directives and further investigations.

Comprehensive evaluation of military training-induced fatigue among soldiers in China: A Delphi consensus study

Objective

Military training-induced fatigue (MIF) often results into non-combat attrition. However, standard evaluation of MIF is unavailable. This study aimed to provide credible suggestions about MIF-evaluation.

Methods

A 3-round Delphi study was performed. The authority of the experts was assessed by the authority coefficient (Aa). In round 1, categories of indicators were collected via anonymous survey of experts, then potential indicators were selected via literature search. In round 2, experts should evaluate the clinical implication, practical value, and importance of each potential indicators, or recommend new indicators based on feedback of round 1. Indicators with recommendation proportions ≥ 70% and new recommended indicators would be included in round 3 to be rated on a 5-point Likert scale. "Consensus in" was achieved when coefficient of concordance (Kendall's W) of a round was between 0.2 and 0.5 and the coefficient of variation (CV) of each aspect for an indicator was < 0.5. If round 3 could not achieve "consensus in," more rounds would be conducted iteratively based on round 3. Indicators included in the recommendation set were ultimately classified into grade I (highly recommended) or grade II (recommended) according to the mean score and CV of the aspects.

Results

Twenty-three experts participated with credible authority coefficient (mean Aa = 0.733). "Consensus in" was achieved in round 3 (Kendall's W = 0.435, p < 0.001; all CV < 0.5). Round 1 recommended 10 categories with 73 indicators identified from 2,971 articles. After 3-round consultation, consensus was reached on 28 indicators focusing on the cardiovascular system (n = 4), oxygen transport system (n = 5), energy metabolism/metabolite level (n = 6), muscle/tissue damage level (n = 3), neurological function (n = 2), neuropsychological/psychological function (n = 3), endocrine function (n = 3), and exercise capacity (n = 2). Among these, 11 indicators were recommended as grade I: basic heart rate, heart-rate recovery time, heart rate variability, hemoglobin, blood lactic acid, urine protein, creatine kinase, reaction time, Borg Rating of Perceived Exertion Scale, testosterone/cortisol, and vertical jump height.

Conclusion

This study developed a reliable foundation for the comprehensive evaluation of MIF among soldiers.

Profiling the Typical Training Load of a Law Enforcement Recruit Class

Law enforcement academies, designed to prepare recruits for their prospective career, represent periods of high physical and mental stress, potentially contributing to recruits' injuries. Managing stress via monitoring training loads may mitigate injuries while ensuring adequate preparation. However, it is vital to first understand an academy's typical training load. The aim of this study was to profile the typical training load of law enforcement recruits over the course of 22 weeks. Data were prospectively collected using global positioning system (GPS) units placed on recruits during a portion of the academy training, while a desktop analysis was retrospectively applied to six other classes. A Bland-Altman plot was conducted to assess the agreement between the two methods. A linear mixed model was conducted to analyse the difference in distances covered per week, while other variables were presented graphically. Adequate agreement between the desktop analysis and GPS units was observed. Significant differences (p-value < 0.01) in distance covered (9.64 to 11.65 km) exist between weeks during early academy stages, which coincide with increases (~6 h) in physical training. Significant decreases in distances were experienced during the last five weeks of academy training. Most acute:chronic workload ratios stayed between the proposed 0.8 to 1.3 optimal range. Results from this study indicate that large increases in training occur early in the academy, potentially influencing injuries. Utilizing a desktop analysis is a pragmatic and reliable approach for instructors to measure load.

Effects of long-term exercise training on physiological signals and personality traits in women in law enforcement

Law enforcement teams across the globe experience the highest occupational stress and stress-related diseases. Physical exercise and an active lifestyle are recommended as part of their profession to equip them to fight stress and related health adversities. The research is carried out using objective measures of Heart Rate Variability (HRV), Electro Dermal Activity (EDA), Heart Rate Recovery (HRR), and subjective questionnaires. HRV was generated with an electrocardiogram (ECG) signal acquired using NI myRIO 1900 interfaced with the Vernier EKG sensor. HRR was acquired with the help of a Polar chest strap exercise heart rate monitor and EDA acquisition was carried out with Mindfield E-Sense electrodes. Then statistical features are extracted from the collected data, and feed to the AQCNN (Aquila convolution neural network) classifier to predict the stress. Signal analyses were done in Kubios 4.0, Ledalab V3.x in a MATLAB environment. The results pointed out that exercise training is effective in increasing the vagal tone of the Autonomic Nervous System (ANS) and hence improves the recovery potential of the cardiovascular system from stress. The proposed AQCNN method improves the accuracy of 95.12% which is 93.13%, 85.36% and 80.13% better than MANOVA technique, CNN and ML-SVM respectively. The findings have the potential to influence decision-making in the selection and training of recruits in high-stress positions, hence optimizing the cost and time of training by identifying maladaptive recruits early.

Opposite effect of basic combat training on mood state of recruits with different physical fitness: A study from perspective of fatigue

Objective

Basic combat training (BCT) is a kind of necessary high-intensity training to help each military recruit convert into a qualified soldier. In China, both the physical fatigue and passive psychological state have been observed in new recruits during BCT. However, after same-intensity training, the degree of fatigue and passive mood vary among recruits. Therefore, this study aimed to explore the effect of BCT on mood state of recruits with different physical fitness levels from a perspective of fatigue.

Materials and methods

Before and after BCT, the degree of fatigue and mood state of participants were evaluated via the Borg Rating of Perceived Exertion Scale and Profile of Mood States Questionnaire immediately after 20 push-ups as RPE and POMS scores [total mood disturbance (TMD), passive mood (T_tension, T_anger, T_fatigue, T_depression, and T_confusion) and positive mood (T_vigour and T_esteem)]. The participants were divided into two groups according to the RPE score measured after BCT: (1) group 1: RPE score after BCT < 13 and (2) group 2: RPE score after BCT ≥ 13.

Result

A total of 564 recruits were included (group 1: 456/564, 80.85%; group 2: 108/564, 19.15%). After BCT, in group 1, TMD (from 95.65 ± 17.89 to 87.52 ± 17.63) and passive mood T_tension (from 4.46 ± 3.18 to 3.79 ± 3.14), T_fatigue (from 4.94 ± 3.58 to 3.12 ± 3.04), T_depression (from 2.86 ± 3.41 to 2.01 ± 2.75), T_confusion (3.12 ± 2.72 to 2.42 ± 2.57) declined significantly (all within-group p < 0.001), but positive mood both increased significantly (T_vigour: from 13.21 ± 4.59 to 15.44 ± 5.42, T_esteem: from 9.18 ± 3.36 to 11.04 ± 3.67; both within-group p < 0.001); while in group 2, only T_anger (from 4.27 ± 4.16 to 6.22 ± 5.94, within-group p = 0.001) and T_esteem (from 8.36 ± 3.15 to 9.07 ± 3.67, within-group p = 0.031) increased significantly.

Conclusion

BCT could alleviate passive mood and add to positive mood for recruits with better physical fitness, while had no ameliorative effects on or even deteriorate most of the passive mood for recruits with worse physical fitness.

Factors Predicting Training Delays and Attrition of Recruits during Basic Military Training

Ensuring a balance between training demands and recovery during basic military training (BMT) is necessary for avoiding maladaptive training responses (e.g., illness or injury). These can lead to delays in training completion and to training attrition. Previously identified predictors of injury and attrition during BMT include demographic and performance data, which are typically collected at a single time point. The aim of this study was to determine individual risk factors for injury and training delays from a suite of measures collected across BMT. A total of 46 male and female recruits undertaking the 12-week Australian Army BMT course consented to this study. Injury, illness, attrition, and demographic data were collected across BMT. Objective measures included salivary cortisol and testosterone, step counts, cardiorespiratory fitness, and muscular endurance. Perceptions of well-being, recovery, workload, fatigue, and sleep were assessed with questionnaires. Baseline and mean scores across BMT were evaluated as predictors of injury and attrition using generalized linear regressions, while repeated-measures ANOVA was used for the group comparisons. From the 46 recruits, 36 recruits completed BMT on time; 10 were delayed in completion or discharged. Multiple risk factors for injury during BMT included higher subjective ratings of training load, fatigue, and stress, lower sleep quality, and higher cortisol concentrations. Higher ratings of depression, anxiety, and stress, and more injuries were associated with a higher risk of delayed completion. Higher concentrations of testosterone and higher levels of fitness upon entry to BMT were associated with reduced risk of injury and delayed completion of BMT. Ongoing monitoring with a suite of easily administered measures may have utility in forewarning risk of training maladaptation in recruits and may complement strategies to address previously identified demographic and performance-based risk factors to mitigate injury, training delays, and attrition.

Exercise and Occupational Stress among Firefighters

The aim of our study was to evaluate the potential association between physical activity and occupational stress among firefighters. Data were collected from Cypriot firefighters through a web-based battery of internationally validated questionnaires completed anonymously (COPSOQ, DASS). A total of 430 firefighters (response rate 68%) completed the survey (age range: 21-60 years). More than half of the firefighters (54%) reported either no or minimal physical activity. A total of 11% of firefighters reported moderate to extremely severe stress based on the DASS-S scale. Using multivariable-adjusted logistic regression models, we showed that firefighters who exercised had 50% lower risk of occupational stress, and using a categorical model, we found that every hour per week of increased physical activity among firefighters was associated with 16% lower risk of occupational stress after adjusting for age, education, smoking, and body mass index (OR = 1.16; p = 0.05). In addition, our findings suggest an inverse dose-response relationship between physical activity and occupational stress among firefighters. Physical activity appears to be inversely associated with occupational stress and serves as an important mitigating factor of occupational stress in firefighters. Further research is warranted to evaluate the potential effect of exercise interventions on occupational stress, and the overall mental health of firefighters and other occupational groups.

Moving Past the One-Size-Fits-All Education-Training Model of Police Academies to the Self-Prescribed Individualized Exercise Prescription Model

Law enforcement agencies generally employ the "one-size-fits-all" education-training model. Its effectiveness compared to alternative training models has been under scrutiny. Physical fitness scores of Serbian male (n = 98) and female (n = 79) police cadets during their yearly evaluation were compared. Cadets trained for the first 3 years with the "one-size-fits-all" model. In the fourth year, they self-prescribed an individualized exercise program based on the obtained curriculum knowledge. A two-way MANOVA revealed a significant effect of academic years on combined variables (p < 0.001) and significant differences between academic years for deadlift, half squat, standing long jump, sit-ups and 12-min Cooper test time (p < 0.001). Sex also had a significant main effect on combined variables (p < 0.001) with males outscoring females on all of the fitness assessments. For pull-ups, there was a significant year * sex interaction (p = 0.01) with the third year to be pivotal for female and male performance, respectively. In conclusion, the use of a "one-size-fits-all" model, presented differences in physical fitness scores between the years one to three, pointing to its questionable effectiveness. On the contrary, the self-prescribed individualized exercise program of the fourth year elicited greater fitness scores, indicating the need to evaluate the applicability of such a training model more.

Studying the Health and Performance of Shipboard Sailors: An Evidence Map

INTRODUCTION

It is estimated that sailors who are assigned to surface ships and submarines are deployed for more than 1 year across their careers and they spend 15% to 23% of their time away from home. Research suggests that shipboard sailors experience rates of behavioral health issues similar to those with ground combat experiences. Despite the rigorous operational tempo and the unique shipboard environment experienced by these service members, little military health research has examined the health outcomes of sailors serving aboard ships. The objectives of this study were to develop an evidence map of the peer-reviewed literature to (1) identify potential threats to the health and readiness of shipboard sailors, (2) identify health and performance issues experienced by this population, and (3) identify gaps in the current peer-reviewed published literature on shipboard health and performance.

MATERIALS AND METHODS

A systematic review of the existing peer-reviewed literature pertaining to the health, experiences, and performance of shipboard service members was conducted. Comprehensive search terms were used to identify articles published between January 2000 and April 2018. Identified articles were subject to a two-level review process. Study characteristics for all articles selected for final review were extracted, and articles were categorized into 13 content areas that were selected a priori. Findings are presented in an evidence map.

RESULTS

The initial literature search yielded 8,858 unique articles, 90 of which were eligible for full review. Most articles primarily examined active duty sailors from the U.S. or other foreign militaries (88.9%). A total of 60 articles (67.8%) included information about the type of ship studied; the most frequently examined were submarines (29.5%) and aircraft carriers (27.9%). Most of the included studies used cross-sectional (63.3%) or longitudinal (24.4%) designs. Only 7.8% (n = 7) of articles described interventions. The most commonly examined focal areas included physical health issues, such as viral infections and injuries (56.7%), and health behaviors, such as substance use/misuse (40.0%). Other frequently addressed content areas were occupational stress (38.9%), interpersonal issues (32.2%), ship conditions (30.0%), and mental health (28.9%). Most articles (73.3%) addressed more than one content area. There was a high degree of variation in the measurement tools used; self-report surveys were the most common (48.9%), followed by objective physical, biological, or cognitive measures (32.2%) and medical and personnel record reviews (31.1%).

CONCLUSIONS

The evidence map identified various gaps in the research pertaining to the health and performance of shipboard sailors. These gaps included a lack of research on the risk factors for common health and performance issues experienced by sailors and on the relationship between stressors of shipboard life and sailors' health, performance, and readiness. The results of this evidence map should be used to inform the development, implementation, and evaluation of interventions to improve the shipboard environment and/or the preventive health behaviors used by sailors while underway or deployed.

Association of Psychological Stress with Physical Fitness in a Military Cohort: The CHIEF Study

INTRODUCTION

Psychological stress is associated with sedentary behavior, which may impair exercise performance. The aim of our study was to examine the association between psychological stress and physical fitness in military personnel.

METHOD

A military cohort of 4080 subjects in Taiwan was used for the analysis. The Brief Symptoms Rating Scale (BSRS-5) includes items of anxiety, depression, hostility, interpersonal sensitivity, and insomnia measured by a five-point Likert-type scale of 0-4. Psychological stress was defined as normal (n = 3657), slight (n = 314), and great (n = 109) by BSRS-5 score ≤5, 6-9, and ≥10, respectively. Aerobic fitness and anaerobic fitness were evaluated by the time of 3000-meter running and the numbers of 2-min sit-ups and 2-min push-ups, respectively. Multiple linear and logistic regression analyses were used to determine the relationship.

RESULTS

As compared with normal stress, slight and great stress were positive dose-dependently correlated with 3000-meter running time (β = 9.09 and 14.44; P = 0.0032 and 0.048, respectively) after adjusting for age, sex, service specialty, body mass index, systolic blood pressure, cigarette smoking, alcohol intake, hemoglobin levels, and exercise frequency. Similarly, those with slight stress were more likely to be the worst 10% performers in the 3000-meter run test relative to the normal individuals (odds ratio and 95% confidence intervals: 1.50, 1.00-2.24). By contrast, there was no relationship of psychological stress with the numbers of 2-min sit-ups and 2-min push-ups.

CONCLUSIONS

Our findings suggest that the presence of higher psychological stress on military personnel may reduce their cardiorespiratory fitness but not affect the anaerobic fitness.

Grip strength and depressive symptoms in a large-scale adult population: The TCLSIH cohort study

BACKGROUND

Previous studies suggest that muscle-derived cytokines (myokines) are linked with brain function. Although muscle strength measured by handgrip strength is a prognostic indicator of functional decline, epidemiological studies directly examining the association between grip strength and mental health remain scarce. The aim of this study is to clarify the association between grip strength and depressive symptoms in the general adult population.

METHODS

This is a cross-sectional study of 24,109 Chinese adults (41. 5  ± 11.9 years; 46.0% females). Grip strength was measured by dynamometer and the greatest force was normalized to body weight (NGS, kg/kg). Depressive symptoms were assessed using the Self-Rating Depression Scale (SDS). Models of logistic regression were conducted to assess the association between NGS and depressive symptoms, with adjustment for established confounding factors.

RESULTS

Of the 24,109 participants, the prevalence of depressive symptoms (SDS ≥45) was 16.8% (males 15.7%, females 18.0%). After adjusting for multiple confounding factors, the odds ratios and 95% confidence interval for depressive symptoms in the quartiles of NGS were 1.00, 0.96 (0.84-1.10), 0.91 (0.79-1.05), and 0.91 (0.78-1.07) (P = 0.03) in males; 1.00, 0.92 (0.80-1.06), 0.90 (0.77-1.04), and 0.80 (0.69-0.94) (P = 0.0002) in females, respectively.

LIMITATIONS

This cross-sectional study cannot determine causality.

CONCLUSIONS

Grip strength was inversely associated with depressive symptoms, with stronger association observed among females than males.  Further prospective studies or randomized trials are required to clarify these findings.

Associations between inflammatory markers and well-being during 12 weeks of basic military training

PURPOSE

Stress, anxiety and physical exertion are all closely linked to well-being, and each can alter immune function. Diminished well-being has been observed during military training, however there is mixed evidence regarding whether concomitant changes in inflammatory markers occur, with these phenomena indicating potential maladaptive responses to imposed training loads. The aims of this project were (1) assess changes in inflammation and subjective well-being across a 12-week basic military training (BMT) program, and (2) evaluate relationships between circulating inflammatory markers and well-being.

METHODS

A total of 37 men and women undergoing 12 weeks of BMT in Australia were recruited. Well-being was assessed via questionnaire (DASS-21), and plasma samples were collected for the analysis of inflammatory cytokines [interleukin (IL)-4, IL-6, IL-1β, IL-8, IL-10, and tumor necrosis factor (TNF)-α] at weeks 1, 4, 8 and 12. Data were analysed using general linear mixed models.

RESULTS

Depression, anxiety and stress subscale scores all significantly improved (all P ≤ 0.001), and TNF-α decreased (P = 0.031) across time. Compared to baseline (week 1), significant decreases in associations between depression and IL-10, anxiety and IL-10, and stress and IL-10, IL-4 IL-6 and TNF-α (all P < 0.05), were detected across BMT.

CONCLUSION

The BMT program appears to support improved well-being over the 12 weeks, with minimal perturbation to inflammatory markers. Biomarkers and well-being displayed consistent associations and may have utility as psychophysiological indicators of health status in military research, however for now, subjective measures may represent more cost-effective proxies for ongoing monitoring of military personnel.

The Role of Military Training in Improving Psychological Resilience and Reducing Depression Among College Freshmen

Background: Military training plays an important protective role in enhancing mental health. However, the effects of military training on psychological resilience and depression among college freshmen in China remain unclear. The present study aimed to evaluate changes in psychological resilience and depression through military training among college freshmen, and to investigate associated psychosocial factors including childhood trauma that may influence its effects on psychological resilience. Methods: A prospective and self-comparison study design was employed. College freshmen who received 3 weeks of military training were recruited. Socio-demographic variables were collected and childhood trauma exposure was estimated by the Childhood Trauma Questionnaire (CTQ). The Connor-Davidson Resilience Scale (CD-RISC) and Patient Health Questionnaire (PHQ-9) were used to assess psychological resilience and depression before and after the military-style training. Results: The military training significantly increased the total and subscale scores of CD-RISC (p < 0.001), and decreased the PHQ-9 score (p < 0.001). The proportion of students with clinical depression reduced from 10.5% at baseline to 7.2% after the training (p < 0.001). Improvement of CD-RISC scores was positively affected by male gender and urban area, while negatively affected by older age, and higher baseline scores of PHQ-9 and CTQ. A significant correlation was found between changes in scores of CD-RISC and PHQ-9 through the training (r = -0.238, p < 0.001). Conclusions: Military training may have a positive effect on increasing psychological resilience and reducing depressive symptoms among college freshmen, especially in male students and those from an urban area, while older age, childhood trauma, higher depression levels, and resilience at baseline may weaken, or even mask its positive effect. Follow-up research should be considered for the long-term effects of military-style training.

Physical Fitness Level and Mood State Changes in Basic Military Training

The purpose of this study was to investigate the change of fitness level and mood states in the basic military training (BMT) for midshipmen using latent growth model analysis. A total of 285 midshipmen were selected as participants in BMT. The results were as follow: First, the slope of low initial fitness level increase higher than high initial fitness level. Second, there is no significant on relation between the slope of total mood disturbance score (TMD) and initial TMD level. Third, initial fitness level might increase the difference in participants’ mood state. To Sum up, participants in low initial fitness level scored lower on the results of initial TMD than people in high initial fitness level, and the rate of change in TMD of the stronger participants was larger than the others. Thus, we suggested that to consideration not only fitness level but also psychological, social aspect during in BMT.

The association between cardiorespiratory fitness and the incidence of common mental health disorders: A systematic review and meta-analysis

BACKGROUND

Physical activity is associated with a lower incidence of common mental health disorder, but less is known about the impact of cardiorespiratory fitness (CRF).

METHODS

In this review, we systematically evaluated the relationship between CRF and the incidence of common mental health disorders in prospective cohort studies. We systematically searched six major electronic databases from inception to 23rd of May 2019. We assessed study quality using the Newcastle-Ottawa scale.

RESULTS

We were able to pool the hazard ratios (HRs) and 95% confidence intervals (CIs) of four studies including at least 27,733,154 person-years of data. We found that low CRF (HR = 1.47, [95% CI 1.23 - 1.76] p < 0.001 I2 = 85.1) and medium CRF (HR = 1.23, [95% CI 1.09 - 1.38] p < 0.001 I2 = 87.20) CRF are associated with a 47% and 23% greater risk of a common mental health disorders respectively, compared with high CRF. We found evidence to suggest a dose-response relationship between CRF and the risk of common mental health disorders.

LIMITATIONS

We were only able to identify a small number of eligible studies from our search and heterogeneity was substantial in the subsequent meta-analysis.

CONCLUSIONS

Our findings indicate that there is a longitudinal association between CRF levels and the risk of a common mental health disorder. CRF levels could be useful for identifying and preventing common mental health disorders at a population-level.