Associations of age, aerobic fitness, and body mass index with injury in an operational Army brigade

Efficacy of Army Combat Fitness Test 12-Week Exercise Program Among Females

INTRODUCTION

The dearth of research investigating the efficacy of virtual Army Combat Fitness Test (ACFT) training programs among female populations necessitates further exploration. This study aims to evaluate the effectiveness of a 12-week ACFT virtual exercise program among female participants.

MATERIALS AND METHODS

Nine female participants (age = 19.7 ± 1.3 years, height = 165.9 ± 4.9 cm, and body mass = 62.7 ± 5.9 kg) volunteered to complete 2 assessment sessions and the 12-week ACFT virtual exercise training program. In session 1, baseline height, body mass, body composition, and ACFT scores were collected. Upon completion of session 1, under supervisory guidance, all participants were scheduled to complete the 12-week exercise training program in-person. The ACFT exercise training program required participants to complete a warmup/cool down and exercise with suspension training straps 4 days per week, 60 minutes for 12 weeks. In session 2, post-assessments of body mass, body composition, and ACFT scores were collected. Statistical analyses were conducted utilizing paired sample t-tests to assess differences between pre- and post-intervention ACFT scores with P ≤ .05. Cohen's d was calculated to quantify the magnitude of the observed effect.

RESULTS

Overall mean ACFT pre-intervention scores (487.2 ± 66.5) increased significantly when compared to mean ACFT post-intervention scores (521.6 ± 44.0) (Cohen's d = 0.86, P = .03). No statistical differences were displayed among the individual mean ACFT pre- versus post-intervention scores. A consistent decline in adherence of 3.9% per week ensued from week 1 through week 12.

CONCLUSIONS

Following the intervention, female participants experienced a significant increase of approximately 7% in their overall ACFT scores, with upward trends observed across all 6 individual ACFT events. These findings suggest that 12-week virtual suspension training can be a valuable tool for enhancing physical fitness and performance among female participants, particularly within the context of military readiness.

Body mass index and physical training-related injuries in military personnel: a systematic review and meta-regression analysis

INTRODUCTION

Discrepancies exist in findings on how varying body mass index (BMI) levels impact physical training-related injuries across different studies. This systematic review and meta-analysis aimed to evaluate the relationship between BMI and physical training-related injuries both qualitatively and quantitatively.

METHODS

A comprehensive search of the MEDLINE, Cochrane and EMBASE databases was performed. The study selection followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A systematic review and meta-analysis were conducted using weighted data and a random-effects model. Subgroup analyses were based on gender and military service branches. Heterogeneity among the studies was assessed through the I2 statistic, indicating the proportion of total variation in effect size estimates. Funnel plots and Egger's test were employed to assess publication bias.

RESULTS

33 studies were included in the analysis, with abnormal BMI (underweight, overweight and obesity) identified as a clear risk factor for training-related injuries (overall RR=1.21, 95% CI 1.15 to 1.27; male RR=1.16, 95% CI 1.08 to 1.23; female RR=1.05, 95% CI 1.02 to 1.09). No significant heterogeneity was observed among navy, army and air force personnel (p=0.58), although abnormal BMI remained a notable risk factor in both the army and air force. Meta-regression analysis indicated that the lowest injury risk occurred at a BMI of 23 kg/m2. Obese individuals under the age of 27 and underweight individuals over the age of 27 were at high risk. Additionally, the highest injury risk was observed during the first 5 months of military training, with a gradual decline in subsequent months, stabilising by the 12th month.

CONCLUSION

Findings suggest that abnormal BMI increases the risk of training injuries among military personnel and that this risk varies with age and the duration of training. Emphasis should be placed on risk prevention in the early stages of military training and on enhanced protection for high-risk populations.

The Relationship Between Self-Efficacy, Aerobic Fitness, and Traditional Risk Factors for Musculoskeletal Injuries in Military Training: A Prospective Cohort Study

Background

The United States military strives to prepare soldiers physically and mentally for war while preventing injury and attrition. Previous research has focused on physical injury risk factors but has not prospectively examined psychological risk factors.

Purpose

This study's purpose was to investigate whether self-efficacy is a risk factor for musculoskeletal injury in an initial military training environment and compare it to other known risk factors.

Study Design

Prospective, Longitudinal Cohort Study.

Materials and Methods

Shortly after starting cadet basic training, new cadets rated self-efficacy by an 11-point questionnaire. Other risk factor data including injury history, sex, height, weight, body mass index, age, aerobic fitness, upper body muscular endurance, core muscular endurance and previous military experience were collected by self-report questionnaire and military fitness testing. The primary dependent variable was musculoskeletal injury that originated during the seven-week course. Independent variables were compared between participants who were and were not injured using Chi-squared test, t-tests, Cox regression analysis and time to injury was evaluated using Kaplan-Meyer survival analyses.

Results

Seven hundred eighty-one (65.1%) new cadets were eligible and consented to participate. Injured cadets had significantly lower self-efficacy scores (p=0.003 and p=<0.001), shorter height (p=<0.001), lower weight (p=0.036), lower push-up and plank performance (p=<0.001), slower two-mile run performance (p=<0.001), and females sustained a proportionally higher number of injuries than males (p=<0.001). Cadets with low self-efficacy, shorter height, lower hand release push-up performance, lower plank performance and slower two-mile run performance were at greater risk for musculoskeletal injury. Cadets with less self-efficacy were also less likely to continue uninjured throughout cadet basic training according to a Kaplan-Meier survival analysis (log rank test<0.002). Multivariable Cox regression revealed that only aerobic fitness predicted musculoskeletal injury (HR=1.005 [1.003-1.006], p=<0.001).

Conclusions

Participants with less self-efficacy sustained injuries earlier and more often than those with greater self-efficacy. However, aerobic fitness alone predicted future injury after controlling for all risk factors. Resolved prior injury was not a risk factor for future injury.

Level of Evidence 2b

Individual cohort study.

Why are we doing this Boss? Justification and implications of aerobic fitness testing in the military

BACKGROUND

Physical fitness is a key tenet of military organisations worldwide. Specifically, many consider aerobic fitness (AF) an essential physical attribute for ensuring optimal military performance and readiness. However, the intricate relationship between AF and various facets of military job performance necessitates comprehensive review to ascertain the appropriateness and effectiveness of its assessment.

OBJECTIVE

This narrative review aims to describe the relationship between AF and factors influencing individual military performance and readiness, and explores the implications of the enforcement of in-service, generic AF test standards in military populations.

METHODS

Databases (PubMed and Google Scholar) were searched for all relevant published peer-reviewed literature as at August 2023.

RESULTS

Inconsistent associations were found between AF and outcomes influencing individual military performance (physical capabilities, cognitive capabilities, presenteeism and productivity, resilience, and technical/tactical capabilities) and readiness (mental health and wellbeing and physical health). Consequently, the level of AF needed for acceptable or optimal military performance remains uncertain.

CONCLUSIONS

AF is a cornerstone of health and performance, yet linking generic AF test standards to job performance is complex, with multiple factors interacting to influence outcomes. From existing literatures, there does not appear to be a specific level of AF at, and/or above, which acceptable military performance is achieved. As such, the enforcement of and emphasis on in-service, pass/fail, generic AF test standards in military populations is questionable and requires thoughtful re-evaluation. Role/task-specific AF should be assessed through evidence-based PES and the use of generic AF tests limited to the monitoring and benchmarking of health-related fitness.

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.

Identifying special operative trainees at-risk for musculoskeletal injury using full body kinematics

Introduction: Non-combat musculoskeletal injuries (MSKIs) during military training significantly impede the US military's functionality, with an annual cost exceeding $3.7 billion. This study aimed to investigate the effectiveness of a markerless motion capture system and full-body biomechanical movement pattern assessments to predict MSKI risk among military trainees. Methods: A total of 156 male United States Air Force (USAF) airmen were screened using a validated markerless biomechanics system. Trainees performed multiple functional movements, and the resultant data underwent Principal Component Analysis and Uniform Manifold And Projection to reduce the dimensionality of the time-dependent data. Two approaches, semi-supervised and supervised, were then used to identify at-risk trainees. Results: The semi-supervised analysis highlighted two major clusters with trainees in the high-risk cluster having a nearly five times greater risk of MSKI compared to those in the low-risk cluster. In the supervised approach, an AUC of 0.74 was produced when predicting MSKI in a leave-one-out analysis. Discussion: The application of markerless motion capture systems to measure an individual's kinematic profile shows potential in identifying MSKI risk. This approach offers a novel way to proactively address one of the largest non-combat burdens on the US military. Further refinement and wider-scale implementation of these techniques could bring about substantial reductions in MSKI occurrence and the associated economic costs.

Relationship between Body Mass Index and Health and Occupational Performance among Law Enforcement Officers, Firefighters, and Military Personnel: A Systematic Review

The prevalence of overweight and obesity among tactical populations is estimated at 70%-75%, which may negatively impact health and performance. The relationship between BMI and health and performance is well established among the general population, however, literature on such relationships among tactical populations has yet to be reviewed and evaluated. The purpose of this study was to systematically review available literature on the relationship between BMI and health and occupational performance among law enforcement officer, firefighters, and military personnel. After reviewing the literature, 27 articles were included. Nine studies found BMI was positively associated with cardiovascular disease (CVD) risk factors. Studies involving BMI and cancer were lacking. One study found BMI was positively associated with type 2 diabetes (T2DM) risk. Five studies on occupational/physical performance and 12 studies on injury found a higher BMI was often indicative of decreased performance and increased risk of injury in general, but protective against stress fractures. Overall, higher BMI was often associated with negative health and performance outcomes among tactical populations, especially when beyond the overweight classification. Public health practitioners should focus efforts on improving nutrition and physical activity to promote a healthy BMI among these individuals.

Military Body Composition Standards and Physical Performance: Historical Perspectives and Future Directions

ABSTRACT

Harty, PS, Friedl, KE, Nindl, BC, Harry, JR, Vellers, HL, and Tinsley, GM. Military body composition standards and physical performance: historical perspectives and future directions. J Strength Cond Res 36(12): 3551-3561, 2022-US military physique and body composition standards have been formally used for more than 100 years. These metrics promote appropriate physical fitness, trim appearance, and long-term health habits in soldiers, although many specific aspects of these standards have evolved as evidence-based changes have emerged. Body composition variables have been shown to be related to many physical performance outcomes including aerobic capacity, muscular endurance, strength and power production, and specialized occupational tasks involving heavy lifting and load carriage. Although all these attributes are relevant, individuals seeking to improve military performance should consider emphasizing strength, hypertrophy, and power production as primary training goals, as these traits appear vital to success in the new Army Combat Fitness Test introduced in 2020. This fundamental change in physical training may require an adjustment in body composition standards and methods of measurement as physique changes in modern male and female soldiers. Current research in the field of digital anthropometry (i.e., 3-D body scanning) has the potential to dramatically improve performance prediction algorithms and potentially could be used to inform training interventions. Similarly, height-adjusted body composition metrics such as fat-free mass index might serve to identify normal weight personnel with inadequate muscle mass, allowing for effective targeted nutritional and training interventions. This review provides an overview of the origin and evolution of current US military body composition standards in relation to military physical readiness, summarizes current evidence relating body composition parameters to aspects of physical performance, and discusses issues relevant to the emerging modern male and female warrior.

Sensor-based intervention to enhance movement control of the spine in low back pain: Protocol for a quasi-randomized controlled trial

Introduction

Chronic low back pain is a common condition that imposes an enormous burden on individuals and society. Physical exercise with education is the most effective treatment, but generally results in small, albeit significant improvements. However, which type of exercise is most effective remains unknown. Core stability training is often used to improve muscle strength and spinal stability in these patients. The majority of the core stability exercises mentioned in intervention studies involve no spinal movements (static motor control exercises). It is questionable if these exercises would improve controlled movements of the spine. Sensor-based exergames controlled with spinal movements could help improve movement control of the spine. The primary aim of this study is to compare the effects of such sensor-based exergames to static motor control exercises on spinal movement control.

Methods and analysis

In this quasi-randomized controlled trial, 60 patients with chronic low back pain who are already enrolled in a multidisciplinary rehabilitation programme will be recruited. Patients will be randomly allocated into one of two groups: the Sensor-Based Movement Control group (n = 30) or the Static Motor Control group (n = 30). Both groups will receive 8 weeks of two supervised therapy sessions and four home exercises per week in addition to the rehabilitation programme. At baseline (week 1) and after the intervention (week 10), movement control of the spine will be assessed using a tracking task and clinical movement control test battery. Questionnaires on pain, disability, fear avoidance and quality of life will be taken at baseline, after intervention and at 6- and 12 months follow-up. Repeated measures ANOVAs will be used to evaluate if a significant Group x Time interaction effect exists for the movement control evaluations.

Discussion

Sensor-based spinal controlled exergames are a novel way to train spinal movement control using meaningful and engaging feedback. The results of this study will inform clinicians and researchers on the efficacy of movement control training for patients with low back pain.

Ethics and dissemination

Ethical approval for this study protocol was obtained from the METC Brabant (protocol number NL76811.028.21).

Trial registration

Open Science Framework Registries (https://osf.io/v3mw9/), registration number: 10.17605/OSF.IO/V3MW9, registered on 1 September 2021.

Demographic, psychosocial, and physical fitness predictors of successful graduation from U.S. Army Ranger School

U.S. Army Ranger School is an arduous 64-day leadership training course designed to simulate the stressors of combat. Although physical fitness has been shown to be an important predictor of successful graduation for Ranger School, psychosocial characteristics like self-efficacy and grit have not been examined. The purpose of this study is to identify personal, psychosocial, and fitness characteristics associated with successful completion of Ranger School. This study was a prospective cohort examining the association of baseline characteristics of Ranger School candidates with a primary outcome of graduation success. Multiple logistic regression was performed to determine the contribution of demographics, psychosocial, fitness and training characteristics to graduation success. Out of 958 eligible Ranger Candidates, this study obtained graduation status for 670 students, 270 (40%) of which graduated. Soldiers who graduated were younger, more likely to come from units with a higher proportion of previous Ranger School graduates, had higher self-efficacy and faster 2-mile run times. The results from this study suggest that Ranger students should arrive in optimal physical conditioning. Furthermore, training programs that optimize student self-efficacy and units with a high proportion of successful Ranger graduates may confer advantage for this challenging leadership course.

Association of deployment with maintenance of healthy weight among active duty service members in the Millennium Cohort Study

Objective

Understanding body size in relation to deployment readiness can inform Department of Defense fitness policies. This study examined longitudinal associations between deployment and changes in body mass index (BMI) among active duty service members.

Methods

Service branch-specific changes in BMI post-deployment were examined using logistic regression models among active duty Millennium Cohort Study participants without obesity at baseline (n = 22,995). BMI was categorized using self-reported height and weight as healthy weight (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), and obese (≥30 kg/m2). Number of deployments between baseline and follow-up and initial deployment lengths (in months, using service branch-specific deployment times) were examined.

Results

Among the pooled population and specifically Army and Marine Corps service members without obesity, those with longer deployments were significantly less likely to maintain a non-obese BMI than those deploying for shorter lengths. Each additional deployment increased the likelihood of maintaining a non-obese BMI post-deployment for personnel in the Army, Marine Corps, and within the pooled population.

Conclusions

Multiple deployments may support healthy weight maintenance; longer deployments may adversely impact weight maintenance. Future research should determine modifiable behaviors related to weight gain post-deployment to inform fitness policies designed to optimize service member readiness and deployability.

Profiling the New Zealand Police Trainee Physical Competency Test

Police officers require a certain amount of occupational fitness to successfully perform physically demanding tasks. As such, trainees are required to undergo training to develop their ability to perform such tasks. The physical competency test (PCT) is a 400 m obstacle course consisting of key police occupational physical tasks used to evaluate a trainee's ability to complete tasks that a police officer is expected to perform whilst on duty. The purpose of this study was to profile the PCT in a police recruit population to provide an indication of the current level of occupational fitness within a policing population to inform conditioning requirements. Retrospective data for 813 male (age = 27.41 ± 5.92 years, body mass = 83.98 ± 14.03 kg, height = 179.23 ± 10.50 cm, BMI = 25.85 ± 3.92 kg/m2) and 372 female (mean age = 27.01 ± 6.45 years, mean weight = 67.14 ± 8.60 kg, mean height = 168.14 ± 6.46 cm and mean BMI = 23.61 ± 2.52 kg/m2) police trainees from the New Zealand Police Constabulary Recruitment database were provided for analysis. Anthropometric data, including height, body mass, and BMI were provided, in addition to trainee PCT time. Data were split by sex and age. Significant differences were observed between sexes for all anthropometric measures and PCT time (p < 0.001). Generally, in both the male and female groups, younger recruits tended to perform better than the older recruits with results between the "under 20" and the 20-24-year-old-age groups performing significantly better than the 35-39-year-old-age group in both sexes, and the 25-29-year-old-age group performing significantly better than the 35-39-year-old-age group in female officers. The data provided in this study provides a profile for performance of male and female recruits of various ages on the PCT in preparation for entry, or re-entry following injury, into the NZ Police. However, given that the PCT is considered a measure of occupational task performance, consideration should be given to the use of sex and age neutral requirements as the occupational tasks performed by police officers exhibit the same traits regardless of sex or age. Older trainees may therefore need conditioning to improve PCT times and subsequently occupational performance.

Risk factors for musculoskeletal injuries in the military: a qualitative systematic review of the literature from the past two decades and a new prioritizing injury model

BACKGROUND

Musculoskeletal injuries (MSkIs) are a leading cause of health care utilization, as well as limited duty and disability in the US military and other armed forces. MSkIs affect members of the military during initial training, operational training, and deployment and have a direct negative impact on overall troop readiness. Currently, a systematic overview of all risk factors for MSkIs in the military is not available.

METHODS

A systematic literature search was carried out using the PubMed, Ovid/Medline, and Web of Science databases from January 1, 2000 to September 10, 2019. Additionally, a reference list scan was performed (using the "snowball method"). Thereafter, an international, multidisciplinary expert panel scored the level of evidence per risk factor, and a classification of modifiable/non-modifiable was made.

RESULTS

In total, 176 original papers and 3 meta-analyses were included in the review. A list of 57 reported potential risk factors was formed. For 21 risk factors, the level of evidence was considered moderate or strong. Based on this literature review and an in-depth analysis, the expert panel developed a model to display the most relevant risk factors identified, introducing the idea of the "order of importance" and including concepts that are modifiable/non-modifiable, as well as extrinsic/intrinsic risk factors.

CONCLUSIONS

This is the qualitative systematic review of studies on risk factors for MSkIs in the military that has attempted to be all-inclusive. A total of 57 different potential risk factors were identified, and a new, prioritizing injury model was developed. This model may help us to understand risk factors that can be addressed, and in which order they should be prioritized when planning intervention strategies within military groups.

Relationship Between Body Mass Index and Diagnosis of Obesity in the Military Health System Active Duty Population

OBJECTIVE

The overall rate of obesity is rising in the USA; this is also reflected in the military population. It is important that providers appropriately diagnose obesity and discuss treatment options with their patients.The purpose of this study was to investigate diagnosis of obesity compared to documented body mass index (BMI) in the military health system.

METHODS

Institutional review board approval was obtained by the 59th Medical Wing (Lackland Air Force Base, Texas) as an exempt study. This study included active duty military service members aged 18-65 years who sought outpatient care at a military treatment facility from September 2013 to August 2018 with a weight within the range of 31.8-226.8 kg and height between 121.9 and 215.9 cm. Data were collected from the Clinical Data Repository vitals and M2 encounter data to determine the percentage of each sub-population with a diagnosis of obesity according to BMI (≥30 kg/m2) and International Classification of Diseases diagnosis codes.

RESULTS

Using BMI, 19.2% of female and 26.8% of male service members can be diagnosed with obesity; however, only 42.2% and 35.1%, respectively, with a BMI ≥30 was diagnosed as such. This discrepancy was consistent among all service branches and BMI ranges.

CONCLUSION

This study demonstrates that obesity is underdiagnosed compared to BMI. This may result in insufficient resources being provided to patients to reduce weight. Further investigation is warranted to identify causes of underdiagnosis and potential barriers to diagnosis.

Experimental study protocol of the project "MOtor function and VItamin D: Toolkit for motor performance and risk Assessment (MOVIDA)"

Musculoskeletal injuries, a public health priority also in the military context, are ascribed to several risk factors, including: increased reaction forces; low/reduced muscle strength, endurance, body mass, Vitamin D level, and bone density; inadequate lifestyles and environment. The MOVIDA Project-funded by the Italian Ministry of Defence-aims at developing a transportable toolkit (assessment instrumentation, assessment protocols and reference/risk thresholds) which integrates motor function assessment with biological, environmental and behavioural factors to help characterizing the risk of stress fracture, stress injury or muscle fatigue due to mechanical overload. The MOVIDA study has been designed following the STROBE guidelines for observational cross-sectional studies addressing healthy adults, both militaries and civilians, with varying levels of physical fitness (sedentary people, recreational athletes, and competitive athletes). The protocol of the study has been designed and validated and is hereby reported. It allows to collect and analyse anamnestic, diagnostic and lifestyle-related data, environmental parameters, and functional parameters measured through portable and wearable instrumentation during adapted 6 minutes walking test. The t-test, one and two-way ANOVA with post-hoc corrections, and ANCOVA tests will be used to investigate relevant differences among the groups with respect to biomechanical parameters; non-parametric statistics will be rather used for non-normal continuous variables and for quantitative discrete variables. Generalized linear models will be used to account for risk and confounding factors.

The Use of Fitness Testing to Predict Occupational Performance in Tactical Personnel: A Critical Review

Tactical personnel work in an occupation that involves tasks requiring a high level of cardiovascular fitness as well as muscular strength and endurance. The aim of this literature review was to identify and critique studies investigating the relationship between physical fitness, quantified by fitness assessment measures, and occupational task performance. Databases were searched for relevant articles which assessed a fitness measure and a measure of occupational performance. A total of 15 articles were included and were deemed to be of acceptable methodological quality (8.4/12 on the Critical Appraisal Skills Programme checklist). Included articles assessed a variety of fitness attributes and occupational tasks. Across tactical groups, there appear to be no standardized fitness tests that can determine occupational performance, with aerobic fitness, anaerobic fitness, strength, endurance, power, and agility all being associated with occupational task performance. A wide range of fitness assessments appears to be required to predict occupational performance within tactical personnel. Efforts should be made to base fitness assessments on occupational demands unique to both the environment and requirements of each individual tactical unit.

Overuse-Related Injuries of the Musculoskeletal System: Systematic Review and Quantitative Synthesis of Injuries, Locations, Risk Factors and Assessment Techniques

Overuse-related musculoskeletal injuries mostly affect athletes, especially if involved in preseason conditioning, and military populations; they may also occur, however, when pathological or biological conditions render the musculoskeletal system inadequate to cope with a mechanical load, even if moderate. Within the MOVIDA (Motor function and Vitamin D: toolkit for risk Assessment and prediction) Project, funded by the Italian Ministry of Defence, a systematic review of the literature was conducted to support the development of a transportable toolkit (instrumentation, protocols and reference/risk thresholds) to help characterize the risk of overuse-related musculoskeletal injury. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach was used to analyze Review papers indexed in PubMed and published in the period 2010 to 2020. The search focused on stress (overuse) fracture or injuries, and muscle fatigue in the lower limbs in association with functional (biomechanical) or biological biomarkers. A total of 225 Review papers were retrieved: 115 were found eligible for full text analysis and led to another 141 research papers derived from a second-level search. A total of 183 papers were finally chosen for analysis: 74 were classified as introductory to the topics, 109 were analyzed in depth. Qualitative and, wherever possible, quantitative syntheses were carried out with respect to the literature review process and quality, injury epidemiology (type and location of injuries, and investigated populations), risk factors, assessment techniques and assessment protocols.

Comparison of Military Recruit and Incumbent Physical Characteristics and Performance: Potential Implications for Through-Career Individual Readiness and Occupational Performance

Drain, JR, Debenedictis, T, Bulmer, S, and Michael, S. comparison of military recruit and incumbent physical characteristics and performance: Potential implications for through-career individual readiness and occupational performance. J Strength Cond Res XX(X): 000-000, 2020-After basic military training, physical training practices among incumbent personnel differ substantially, potentially precipitating varied physical capacity and operational readiness. The purpose of this retrospective investigation was to compare physical characteristics and physical performance between recruits and incumbent personnel. Data were collected for 222 army recruits (REC: 197 men/25 women) nearing completion of basic training and 280 incumbent army personnel from combat arms (CA: 142 men) and noncombat arms trades (NCA: 113 men/25 women). Height, mass, and body mass index (BMI) were recorded together with performance measures including predicted V[Combining Dot Above]O2max and 1 repetition maximum box lift. Compared with REC, male incumbents were older (21.8 ± 0.6 vs. 27.6 ± 1.2 years; mean ± 95% confidence interval), had greater body mass (77.6 ± 1.3 vs. 82.6 ± 1.5 kg) and BMI (24.2 ± 0.3 vs. 25.8 ± 0.5 kg·m), similar relative V[Combining Dot Above]O2max, and lower box lift (49.7 ± 1.4 vs. 47.2 ± 2.4 kg). Male CA demonstrated greatest physical performance while male NCA demonstrated the highest BMI and poorest physical performance. Compared with REC, female incumbents were older (22.8 ± 1.6 vs. 31.9 ± 4.4 years), had similar body mass, higher BMI (24.1 ± 0.7 vs. 26.1 ± 2.4 kg·m), as well as lower V[Combining Dot Above]O2max (42.0 ± 1.3 vs. 37.9 ± 2.1 ml·kg··min) and box lift (27.8 ± 2.1 vs. 23.3 ± 2.4 kg). More than 97% of men and approximately 75% of women were able to achieve the box lift and V[Combining Dot Above]O2max baseline standards. The older age category (26 + vs. 18-25 years) typically demonstrated higher BMI and lower physical performance. Through-career maintenance of physical capacity is important for military personnel to support individual readiness and occupational performance, preserve health, and mitigate musculoskeletal injury risk.

No physiological or biomechanical sex-by-load interactions during treadmill-based load carriage

This study investigated whether physiological demand or gait mechanics differ between sexes during treadmill load carriage. Female (n = 15) and male (n = 15) military recruit-type participants with no load carriage experience completed three 10-minute walking trials at a self-selected speed with increasing relative body-borne loads (0%, 20%, and 40% body weight). A range of cardiorespiratory, perceptual and biomechanical variables were measured. Self-selected walking speed was similar between sexes (4.6-4.8 km·h^-1, p > .05) and there were no significant sex-by-load interactions for any variables. Absolute VO₂ and VCO₂ were greater in males (difference 175-178 mL·min^-1, p < .001), however, when relative to body mass, VO₂ was similar between sexes (p > .05). Across all loads, cadence was 7 ± 2 steps·min^-1 faster (p = .004) and stance time was 0.06 ± 0.02 s shorter (p = .013) in females. Increasing load resulted in greater physiological demand, cadence, % stance time, and step length (p < .05). Practitioner summary: Literature comparing physiological and biomechanical variables between sexes during load carriage is scarce. Physiological and biomechanical sex differences were limited to relative measures associated with physical size (height and mass). Future research may pool male and female participants when conducting trials up to ten minutes in length. Abbreviations: BW: body weight; COM: centre of mass; HR: heart rate; HR_max: maximum heart rate; RER: respiratory exchange ratio; RPE: rating of perceived exertion; VCO₂: volume of carbon dioxide; VE: ventilation; VO₂: volume of oxygen; VO_2max: maximum volume of oxygen.

Epidemiology and Financial Burden of Musculoskeletal Injuries as the Leading Health Problem in the Military

INTRODUCTION

Musculoskeletal injuries (MSIs) have direct impact on occupational readiness and task performance in military populations. Until this date, no epidemiologic data have been published concerning MSI incidence in the Netherlands Armed Forces (NAF). The aim of this study was to assess the MSI incidence and related costs in the NAF.

METHODS

In this descriptive epidemiologic study, we collected injury surveillance data from the electronic patient records of multiple military units of the NAF. Using data of all new consultations with a military physician from January 1, 2014 to December 31, 2016, we calculated MSI incidence rates per 100 person-years, with a 95% confidence interval (CI). Physician care costs were determined based on the number of physician consults and the charge per appointment. We used two methods to determine productivity costs; the top-down microcosting method and the friction cost method.

RESULTS

Our study sample included 22% (n = 8,847) of the total NAF population of 2016 (n =40,178). In this sample, consultations of MSIs accounted for 23.2% (n = 7,815) of all new consultations (n = 33,666). MSI incidence rates per unit ranged from 12.5 to53.3 per 100 person-years. In the total sample, MSI incidence rates were highest in the back (6.73, 95% CI 6.39-7.10), knee (5.04, 95% CI 4.74-5.35), and foot (4.79, 95% CI 4.50-5.10). The estimated costs for physician visits for MSIs in our sample were €0.69 million. Limited duty days accounted for €1.10 million productivity costs using top-down microcosting method.

CONCLUSION

Our study provided evidence that MSIs result in substantial financial burden. Injuries of the back, knee, and foot account for the majority of demands on curative care for MSIs.

The prevalence of overweight and obesity among Iranian military personnel: a systematic review and meta-analysis

Background

The overweight and obesity among military personnel, as an occupational group, beside the health issues, might affect their military performance. A systematic review and meta-analysis were conducted to estimate the pool prevalence of overweight and obesity among Iranian military personnel.

Methods

The national databases including Science Information Database, MagIran, and the following international databases; Web of Science, Medline via PubMed, and Scopus were searched, up to December 2017, for relevant published studies without time limitation.

Results

Totally,1431 studies were reterived and 10 studies included in meta-analysis. The pooled prevalence of overweight and obesity were 41% (95%CI:26, 57%) and 13% (95%CI:10, 17%), respectively. In the subgroup analyses, a lower and higher prevalence of overweight was reported in the ground (12%) and Navy (69%) forces military, recpectively. For the obesity, the air forces had the lowest prevalence (11%) and the ground and Navy forces military had highest prevalence (15%). The prevalence of overweight and obesity were slightly higher in studies conducted after 2014.

Conclusion

Our findings suggest a high prevalence of overweight and obesity in the military personnel as a high-risk occupational group. Owing to the high observed heterogeneity among the included studies, large representative studies are needed to estimate the prevalence of overweight and obesity in the military personnel.