Mitigating the risk of musculoskeletal injury: A systematic review of the most effective injury prevention strategies for military personnel

Prior Musculoskeletal Injury and Components of Physical Fitness in Military Personnel: A Systematic Review with Meta-analysis

INTRODUCTION

Military personnel confront heightened risks of musculoskeletal injuries (MSIs) because of the demanding nature of their duties, contributing to restricted active duty and financial burdens. Although preventable factors like training and physical fitness influence some injuries, understanding the enduring effects of previous MSIs on physical fitness in military personnel remains a critical gap. This study aimed to systematically review and meta-analyze this impact.

MATERIALS AND METHODS

In accordance with PRISMA guidelines, a systematic review with meta-analysis was conducted, focusing on military personnel with and without a history of MSIs. Physical fitness components were assessed via observational studies, with isokinetic peak torque values as primary metrics. Quality assessments utilized the NIH Quality Assessment Tool and GRADE framework.

RESULTS

Out of 36 papers, 6 met inclusion criteria, with 4 included in the meta-analysis. Across 1,267 participants, individuals with prior MSIs exhibited a significant reduction in the pooled effect size for isokinetic peak muscle force, with d+ = -0.25 (95% CI: -0.36 to -0.13), notably affecting knee and shoulder regions. These findings underscore the pervasive impact of MSIs on military personnel's physical performance, necessitating targeted interventions.

CONCLUSION

Military personnel with prior MSIs exhibit enduring deficits in isokinetic peak muscle force, particularly in knee and shoulder regions. However, evidence on the impact of previous injuries on other physical fitness components remains limited. Further research is crucial to understanding the multifaceted impact of MSIs on diverse aspects of physical performance, informing comprehensive injury prevention strategies and optimizing performance outcomes among military personnel.

A whole system approach to promoting health and human performance in military settings as vital prerequisites for force readiness and operational capability

The military role and associated occupation-specific training contribute to a high musculoskeletal injury (MSKI) incidence and poor health burden. A fit Force is better prepared for achieving mission success, as well as being more resilient to operational physical and cognitive demands. Conversely, MSKI and ill-health reduce Force readiness. Internationally, militaries have common workforce capacity and capability challenges, where more is being asked of fewer personnel. Unhealthy body composition, low aerobic fitness, poor movement control and poor health behaviours interact to adversely impact human performance. The military workplace-including leadership prioritisation and resource allocation-has generally not strategically managed and supported health and performance interventions to maximise people outcomes. Efforts have focused on the individual and their capabilities to address their ill-health or poor performance. Only through system-based thinking-adopting a Whole System Approach (WSA)-can effective evidence-based interventions to promote health and human performance be: holistically developed; successfully implemented at scale across geographically dispersed organisations to realise meaningful and enduring outcomes; and impacts measured and evaluated. This paper provides a synthesis of scientific and practice-based evidence to operationalise system-thinking in developing integrated WSA workplace interventions for military health and human performance, and measure effect and return on investment. Whilst militaries are recognising the need for a paradigm shift to realise the benefits of effective health and performance interventions, persuasive financial arguments could assist with overcoming large-organisation inertia. Moreover, system-based thinking-addressing individual and organisational factors-could maximise military health and performance, foster resilience and deliver operational effectiveness.

Perceived barriers and facilitators to implementation of injury prevention programs in the military: Feedback from inside the trenches

BACKGROUND

Musculoskeletal injuries enact a substantial burden in military settings, incurring high costs, long-term disability, and impacting military readiness. This has led to a prioritization of injury prevention programs. Understanding the challenges faced by those trying to implement these programs could help standardize and better inform future efforts. The purpose was to capture perceptions of barriers and facilitators to implementation of injury prevention programs in the US Armed Forces.

METHODS

A cross-sectional survey with open-ended questions was circulated to relevant stakeholders; key themes were derived using conceptual content analysis. Four questions were asked concerning injury prevention programs: 1) barriers, 2) facilitators, 3) how can leadership best support, and 4) how can subject matter experts best collaborate to make these programs successful?

RESULTS

The survey reached at least 300 individuals working with the armed services worldwide; 91 completed the survey. The mean (SD) time working with military service members was 11.5 (8.2) years; 93 % worked with active-duty service members, 71.4 % were licensed healthcare providers, and 55 % worked in settings with established injury prevention programs. Only 45.2 % of participants believed an appropriate, clear way to measure program success currently exists. Nearly 85 % believed that lacking standardization of definitions and metrics hinders program assessment. Wide variability existed in opinions regarding who should be primarily responsible for promoting/supporting injury prevention efforts. Key themes included resources as both a facilitator (when present) and barrier (when absent), organizational culture, and leadership support. Leadership can best help by prioritizing the programs and valuing the programming through modeling the desired behavior. Program staff can collaborate by focusing on enabling change, integrating into organizational/unit culture and collaborating with leaders to change policy.

CONCLUSIONS

Factors leading to incidence and recovery of musculoskeletal injuries are multifactorial, requiring collaborative multidisciplinary approaches for optimal injury prevention program development and implementation. Leadership support/prioritization, unit-level cultural acceptance and sufficient resources are essential facilitators to implementing prevention programs. Developing standardized, relevant metrics for assessing program effectiveness and establishing organizational best practices are necessary for long term program viability and lasting change.

Effects of prevention programmes on injury risk in military personnel: a systematic review with meta-analysis

INTRODUCTION

Exercise programmes have been used to prevent injuries in military personnel, as they can reduce modifiable risk factors for injuries. Our aim was to review the literature to evaluate the effects of different exercise protocols on the prevention of injuries in military personnel.

METHODS

A systematic literature review examined the effects of different exercise protocols on the prevention of musculoskeletal injuries in the military. Several databases were explored to find experimental studies that investigated the effects of prevention programmes on the risk of injury. We have extracted from the studies: profile of participants, sample size, study design and characteristics of the control group (CG), the type of intervention and the relative risk (RR) in the experimental group and CG, with their significance levels. For data analysis, we used the RevMan V.5.3 software. The measure of RR was investigated. The risk of publication bias was analysed with Begg's test.

RESULTS

A total of 13 694 titles and studies were recovered from the databases and by manual search. After the removal of duplicate titles and studies that did not meet the eligibility criteria, 17 studies were selected. The protocols were composed of neuromuscular training, stretching, agility training or combined exercises. The meta-analysis showed that injury prevention exercise programmes reduced the risk of musculoskeletal injuries in military personnel by 14% (RR=0.86; 95% CI=0.76 to 0.98).

CONCLUSION

Injury prevention exercise programmes promoted a slight reduction in the risk of musculoskeletal injuries in military personnel.

LEVEL OF EVIDENCE

Very low.

TRIAL REGISTRATION NUMBER

CRD 42017077946.

MSKI reduction strategies: evidence-based interventions to reduce musculoskeletal injuries in military service members

Musculoskeletal injuries (MSKI) are one of the biggest challenges for military services globally, contributing to substantial financial burdens and lost training and working days. Effective evidence-based intervention strategies are essential to reduce MSKI incidence, and research has shown the positive effect of both nutritional interventions and physical training (PT) interventions on reducing MSKI incidence. Levels of vitamin D metabolites have been associated with MSKI and bone stress fracture risk, while calcium and vitamin D supplementation has been shown to reduce the incidence of stress fractures during military training. Protein and carbohydrate supplementation during arduous military training (high volume, high intensity) has also been shown to reduce MSKI risk and the number of limited/missed duty days. PT has played a key role in soldier development to meet the occupational demands of serving in the armed forces. Paradoxically, while PT is fundamental to enhancing soldier readiness, PT can also be a major contributor to MSKI; emerging evidence suggests that the nature of the PT being performed is a risk factor for MSKI. However, strategies like reducing training load and implementing PT programmes using evidence-based training principles can reduce MSKI incidence among military service members by 33-62%, and reduce the financial burdens for military services. This review provides a summary of effective MSKI reduction interventions and provides strategies to enhance the success and adoption of such interventions.

Viability of Structured Gait Retraining for Improving Clinical Outcomes Following Running-related Injury in Active Duty Service Members

INTRODUCTION

All branches of the U.S. Military have a running component of their physical readiness testing battery. Running-related musculoskeletal injuries affect 20 to 40% of DoD Service Members each year. Running form has not historically been addressed with military running-related injuries. To assess the utility of a structured gait retaining protocol designed to treat the onset of running-related pain and/or injury by correcting identified biomechanical risk factors for injury and improve clinical outcomes.

STUDY DESIGN

Case series.

MATERIALS AND METHODS

A total of 160 Active Duty Service Members (ADSMs) with running-related lower-body musculoskeletal injuries were referred by a physical therapist for a multisession gait retraining program termed "Run with CLASS" (Cadence, Lean, Alignment, Soft-landing, Strike). Run with CLASS utilized various drills to emphasize impact progression, proximal strengthening, and proprioception and spatial awareness.

RESULTS

Results revealed that the implemented gait retraining protocol significantly improved running parameters following lower-body injury as evidenced by increased cadence, improved functional assessment scores, and a marked transition from predominantly heel strike to forefoot strike patterns during running.

CONCLUSIONS

A 3-week supervised gait retraining program focused on the gait retraining program termed "Run with CLASS" (Cadence, Lean, Alignment, Soft-landing, Strike) was successful in altering biomechanics of self-selected running gait by increasing cadence and transitioning ADSMs to a forefoot foot strike. Additionally, ADSMs reported significant improvements on the self-reported functional scores on the University of Wisconsin Running Injury and Recovery Index and Single Assessment Numerical Evaluation.

LEVEL OF EVIDENCE

4.

Risk Factors Associated with Musculoskeletal Injuries within the Crew of the Leopard 2 A6 Main Battle Tank Using Inertial Movement Unit Sensors: A Pilot Study

This study aims to assess the musculoskeletal risk of military personnel on a Leopard 2 A6 main battle tank crew and to identify associated factors for future prevention and mitigation strategies. A sample of 57 Portuguese military personnel, who are or were part of the Leopard 2 A6 main battle tank crew, answered a questionnaire on their perception of task performance, considering muscle demands, comfort, posture, movements, and associated symptoms. A subsample of four soldiers from the Armoured Squadron of the Portuguese Mechanized Brigade were assessed using an inertial measurement unit system and underwent a whole-body kinematic analysis coupled with a Rapid Entire Body Assessment during a simulated two-hour mission. The results indicate that soldiers accurately perceive their roles within the crew and that, overall, there is a high risk of musculoskeletal injuries in all tasks. However, tasks directly related to the crew's primary duties carry consistently high risk when considering the time spent on their tasks. This study highlights the need for targeted preventive measures to reduce the incidence and severity of injuries among the crew of the Leopard 2 A6 main battle tank.

Management and prevention strategies for osteoarthritis in tactical athletes

Osteoarthritis (OA) affects over 600 million worldwide, is one of the leading causes of disability and has a significant burden of morbidity. There are multiple modifiable and non-modifiable risk factors, with professional and tactical athletes at higher risk than other occupational groups. Without specific anti-OA pharmacological agents, clinicians may feel helpless. However, primary, secondary and tertiary preventative strategies can slow or prevent OA development or progression. There are many modifiable risk factors which, if targeted, can contribute to an improvement in the experience of people living with OA. Radiological features of OA may signify the presence of 'the disease'; however, the pain and symptoms experienced may be more accurately described as 'the illness'. Targeting both, using a combination of the medical and biopsychosocial models of care, will improve the overall experience.This paper outlines some easily adoptable general and specific strategies to help manage this common and disabling condition, focused on improving joint healthspan, not just joint lifespan. They include education and communication, empowering individuals to confidently self-manage their condition with access to healthcare resources when required. A holistic package, including support for sleep, diet and weight loss, physical activity and specific home-based exercise routines, with appropriate analgesia when needed, can all improve OA illness and potentially slow OA disease development or progression. Clinicians should feel confident that there are many opportunities to intervene and mitigate the risk factors of OA, using various preventative strategies, especially in a young, physically active population with functional occupational or recreational demands.

Musculoskeletal injury in military specialists: a 2-year retrospective study

BACKGROUND

Military specialists are elite personnel who are trained to work across diverse operational environments where a high level of physical conditioning is a prerequisite for their role. Anecdotally, personnel are acknowledged to be at high risk of developing musculoskeletal injuries (MSKIs). However, there are presently no published data on this UK military population to support this view. This is the first (2-year) retrospective epidemiological study to identify the MSKI sustained by this military population.

METHODS

All MSKI reported over a 2-year period (January 2018-December 2019) were recorded to identify the incidence, frequency, nature, onset, cause, location and reporting times. Injuries were described using injury count and relative frequency (percentage). Time at risk for each personnel day was calculated as 365 days.

RESULTS

A total of 199 personnel reported 229 injuries over the reporting periods. The injury incidence rates were 26.8 personnel per 100 person years (2018) and 27.7 personnel per 100 person years (2019), respectively. Military training accounted for the highest number of injuries (32%), followed by 'other injuries' (28%), personal training (28%) and sport (12%). The leading activity associated with injury was weight training (15%), followed by running (11%) and military exercise (10%). Lower extremity injuries accounted for the highest number of injuries (40%), followed by trunk (36%) and upper extremity (24%) injuries.

CONCLUSION

This study identifies the MSKI profile of a military specialist population over a 2-year period. Areas where modifiable risk factors may be identified to reduce risk of injury are highlighted. Recommendations for further research include investigating injury burden and the impact of injury on operational readiness.

High Physical Exposure During Female Recruits' Basic Military Training in Sweden-A Descriptive Study

INTRODUCTION

There is a knowledge gap concerning the occurrence of physical complaints/injuries, i.e., musculoskeletal disorders (MSD), among Swedish women who undergo basic military training (BMT). The aims were to describe prevalence and factors related to MSD and explore physical exposure and performance in Swedish female recruits during BMT.

MATERIALS AND METHODS

A total of 144 females (mean age 22 years) who underwent BMT in 2016 participated in this cross-sectional study. Data regarding self-reported MSD, physical performance, physical activity and exercise, motivation and mental and physical preparation, and physical exposure during BMT and perceived health were collected at the end of BMT through the Musculoskeletal Screening Protocol questionnaire. Additional data on muscle strength were retrieved from IsoKai isokinetic lift tests. Descriptive and analytic (paired samples t-test and logistic binary regression) statistics were used.

RESULTS

The prevalence of MSD was high, with 33% (n = 48) reporting MSD before BMT, 78% (n = 113) during, and 50% (n = 72) at the end of BMT. Knee and upper back were the most frequently reported MSD locations. Forty-four (30%) participants felt insufficiently physically prepared for BMT. The physical exposure was high with loaded marches/runs and carrying heavy loads as the most demanding tasks. The longest walking distance was reportedly 55 km, and the reported maximum load was 50 kg. Forty-five participants (31%) had carried a load representing over 50% of their body weight. Most participants reported good to excellent health at the end of BMT. There was a small (8 N) but significant (P = 0.045) increase in mean force over time. Two variables, MSD before BMT (odds ratio 2.24, P = 0.03) and being physically unprepared (odds ratio 3.03, P < 0.01), were associated with MSD at the end of BMT.

CONCLUSION

This study showed that the prevalence of MSD in Swedish female recruits was high before, during, and at the end of BMT, with knee and upper back as the most frequent locations. Although the physical exposure during BMT was occasionally high, self-rated health was mainly perceived as good to excellent at the end of BMT. Previous MSD and being physically unprepared were related to MSD at the end of BMT. These important and relevant findings indicate the necessity for implementing interventions to increase physical fitness and treat MSD at the beginning of BMT.

Barriers and facilitators to implementation of musculoskeletal injury mitigation programmes for military service members around the world: a scoping review

INTRODUCTION

Musculoskeletal injury (MSK-I) mitigation and prevention programmes (MSK-IMPPs) have been developed and implemented across militaries worldwide. Although programme efficacy is often reported, development and implementation details are often overlooked, limiting their scalability, sustainability and effectiveness. This scoping review aimed to identify the following in military populations: (1) barriers and facilitators to implementing and scaling MSK-IMPPs; (2) gaps in MSK-IMPP research and (3) future research priorities.

METHODS

A scoping review assessed literature from inception to April 2022 that included studies on MSK-IMPP implementation and/or effectiveness in military populations. Barriers and facilitators to implementing these programmes were identified.

RESULTS

From 132 articles, most were primary research studies (90; 68.2%); the remainder were review papers (42; 31.8%). Among primary studies, 3 (3.3%) investigated only women, 62 (69%) only men and 25 (27.8%) both. Barriers included limited resources, lack of stakeholder engagement, competing military priorities and equipment-related factors. Facilitators included strong stakeholder engagement, targeted programme design, involvement/proximity of MSK-I experts, providing MSK-I mitigation education, low burden on resources and emphasising end-user acceptability. Research gaps included variability in reported MSK-I outcomes and no consensus on relevant surveillance metrics and definitions.

CONCLUSION

Despite a robust body of literature, there is a dearth of information about programme implementation; specifically, barriers or facilitators to success. Additionally, variability in outcomes and lack of consensus on MSK-I definitions may affect the development, implementation evaluation and comparison of MSK-IMPPs. There is a need for international consensus on definitions and optimal data reporting elements when conducting injury risk mitigation research in the military.

Musculoskeletal injuries in UK Service Personnel and the impact of in-theatre rehabilitation during Cold Weather Warfare training: Exercise CETUS 2020

INTRODUCTION

The Royal Marines provide the lead Service for UK Defence Mountain and Cold Weather Warfare capability. This is the first prospective study addressing musculoskeletal injury rates sustained during Cold Weather Warfare training, with the aim of informing injury mitigation interventions and assist military medical planning with respect to delivering primary care rehabilitation in theatre.

METHODS

All musculoskeletal injuries were surveyed by the Forward Rehabilitation Team (Nov 2019-Mar 2020) during a Cold Weather Deployment to Norway (Ex CETUS 2019/20). The frequency, nature of injury (new or recurrent), onset (sudden or gradual), cause, location and exercise/treatment outcome were recorded.

RESULTS

Eleven per cent (n=136 cases) of the deployed population (n=1179) reported a musculoskeletal injury, which were mainly 'new' (62%), and with a 'sudden' onset (64%). Injury rate was 17.8 injuries per 10 000 personnel days. The majority of injuries occurred due to military training (88%), specifically during ski-related (61%) and load carriage (10%) activities.The average Service Person treated by the Forward Rehabilitation Team improved from 'injured with restricted duties' to 'fully fit', and with an improvement in their self-reported Musculoskeletal Health Questionnaire from 33 to 45 over an average of two rehabilitation sessions. One hundred and seventeen Service Personnel were able to continue on Ex CETUS with rehabilitation in theatre, thus negating the requirement for aeromedical evacuation for continuation of rehabilitation in the UK. Nineteen patients were unable to continue their Cold Weather Deployment due to the nature of their musculoskeletal injury and returned to the UK for continued care in firm base rehabilitation centres.

CONCLUSION

This study identifies the nature, causation and injury location. It demonstrates the effectiveness of in-theatre rehabilitation and the ability to treat patients when deployed. Recommendations are presented to support strategies to mitigate musculoskeletal injury risk during future Cold Weather Warfare deployments to Norway.

Increased Barefoot Stride Variability Might Be Predictor Rather than Risk Factor for Overuse Injury in the Military

Footwear usage could be a promising focus in reducing musculoskeletal injury risk in lower extremities commonly observed among the military. The goal of this research was to find potential gait-related risk factors for lower leg overuse injuries. Cases (n = 32) were active-duty infantry soldiers who had suffered an overuse injury in the previous six months of service before enrolling in the study. The control group (n = 32) included infantry soldiers of the same age and gender who did not have a history of lower leg overuse injury. In the gait laboratory, individuals were asked to walk on a 5-m walkway. Rearfoot eversion, ankle plantar/dorsiflexion and stride parameters were evaluated for barefoot and shod conditions. Barefoot walking was associated with higher stride time variability among cases. According to the conditional regression analysis, stride time variability greater than 1.95% (AUC = 0.77, 95% CI (0.648 to 0.883), p < 0.001) during barefoot gait could predict lower leg overuse injury. Increased barefoot gait variability should be considered as a possible predictive factor for lower leg overuse injury in the military, and gait with military boots masked stride-related differences between soldiers with and without lower leg overuse injury.

Efficacy of Army Combat Fitness Test 12-Week Virtual Exercise Program

INTRODUCTION

The Army Combat Fitness Test (ACFT) is the fitness assessment used by the Army launched in April of 2022. The ACFT consists of six physically demanding motor movements that parallel to the stressors experienced by the modern-day combat soldier. The aim of this study is to determine the efficacy of a 12-week virtual exercise program on the individual and their overall ACFT scores.

MATERIALS AND METHODS

Thirteen soldiers from the Army National Guard (age = 29.8 ± 6.2 years; height = 175.7 ± 6.1 cm; service experience ≥ 18 months to 18 years) volunteered to complete three sessions. In session 1, baseline height, body mass, body composition, and ACFT scores were collected. Session 2 consisted of a suspension trainer (ST) tutorial in which all participants familiarized themselves with the set-up and utilization of the suspension training tool kit. Upon completion of session 2, a TRX Elite ACFT Kit containing one suspension trainer, four resistance bands, and the 12-week virtual exercise training program available via iphone operating system and Android were given to all participants. In session 3, post-assessments of body mass, body composition, and ACFT scores were collected. Data were statistically analyzed using a paired-sample t-test with a Bonferroni correction (P < .00065) to adjust for multiple comparisons.

RESULTS

There were no significant changes in mean body mass (83.8 ± 16.5 kg vs. 83.9 ± 16.6 kg; P = .752); however, there was a significant reduction in mean percentage body fat (19.5 ± 6.4% vs. 18.3 ± 6.5%; P < .0001). Mean scores from four of the six individual ACFT assessments, specifically, deadlift, standing power throw, hand-release push-ups, and sprint-drag-carry, displayed improvements, but did not attain statistical significance. The overall mean ACFT scores displayed significant improvements (319.4 ± 39.9 vs. 390.4 ± 68.5; P < .0001).

CONCLUSIONS

The TRX Elite ACFT Kit which includes one suspension trainer, four varying resistance bands, and on-demand access to a stepwise 12-week virtual exercise program was deemed effective by increasing the overall mean ACFT scores among participants. From a practitioner's perspective, the TRX Elite ACFT Kit should be widely distributed to all Army units and recruiting commands to provide vital assistance for recruits and soldiers to train and prepare for the ACFT. Moreover, given the ease and portability of the TRX Elite ACFT Kit, recruits and soldiers will be able to effectively train anytime, anywhere.

Physical fitness and anthropometrics in Finnish soldiers during their early career: prospective changes during a 3-year follow-up

INTRODUCTION

Physical fitness is a fundamental capability required of military personnel, but studies focusing on longitudinal changes in physical fitness and anthropometrics in soldiers are lacking. The aim was to evaluate physical fitness and anthropometrics in soldiers during their early career.

METHODS

A 3-year prospective study included 180 male soldiers (baseline age 26±2 years) with measures of a 12 min running test, standing long jump, sit-up and push-up tests, and body mass, height and waist circumference (WC). Baseline data were stratified into tertiles, and the changes within each tertile were analysed using dependent t-tests and analysis of variance.

RESULTS

12 min running test distance decreased on average by 2% (-54 m), sit-up performance 3% (-1.5 repetitions (reps)/min), push-up performance 4% (-1.9 reps/min) and standing long jump performance 1% (-2.1 cm) over the 3-year period (p<0.05). Both aerobic and muscular fitness decreased consistently among the highest baseline tertile (12 min running test: -70 m, sit-ups: -3.2 reps/min, push-ups: -7.5 reps/min, standing long jump: -5.5 cm; p<0.001), whereas both aerobic and muscular fitness levels were maintained and push-up performance was improved (p<0.05) in the lowest baseline tertiles. Body mass increased on average by 4% (+3.4 kg) and WC by 4% (+3.9 cm) (p<0.001), and these increases were observed for all baseline tertiles (p<0.05).

CONCLUSIONS

Small decrements in physical fitness and anthropometrics exist during the early career of soldiers. The changes in physical fitness differed according to baseline fitness levels. The results indicate that support for exercise training may be needed even in a soldier's early career.

Concussion history is associated with increased lower-extremity injury incidence in Reserve Officers' Training Corps cadets

INTRODUCTION

Concussions have been associated with an increased risk of lower-extremity musculoskeletal injury (LE-MSI) in athletes and US Army soldiers, creating an added economic, physical and social burden. Yet, there is a paucity of evidence on this relationship among Reserve Officers' Training Corps (ROTC) cadets, a group which engages in activities with high-injury risk and will subsequently commission as active duty officers. This study aimed to examine the association between concussions and LE-MSI in ROTC cadets.

METHODS

125 (83 were male) Army and Air Force ROTC cadets (19.8±2.0 years) from two large state universities' Army and Air Force ROTC programmes participated in this study. Cadets completed a reliable injury history questionnaire to ascertain the following variables of interest: (1) any concussion history, (2) reported concussions, (3) undiagnosed concussions, and (4) potentially unrecognised concussion history and LE-MSI history (eg, ankle sprain, knee sprain or muscle strain). Data were analysed using a χ² test for association and binary logistic regression to determine ORs.

RESULTS

Cadets with any concussion history (n=42) had a significantly (p=0.035) higher association with LE-MSI (OR 2.47, 95% CI 1.05 to 5.83) than those without. Cadets who had a reported concussion (n=33) had a significantly (p=0.026) higher association with LE-MSI (OR 2.95, 95% CI 1.11 to 7.84) compared to cadets without.

CONCLUSIONS

ROTC cadets with a history of diagnosed concussion were more likely to have suffered an LE-MSI than cadets without a concussion history. ROTC cadre should be aware of this relationship and incorporate injury prevention protocols.

Understanding the musculoskeletal injury risk of women in combat: the effect of infantry training and sex on musculoskeletal injury incidence during British Army basic training

INTRODUCTION

Until recently, women were excluded from British combat roles. Their risk for musculoskeletal injury during basic training is two to three times higher than men. To better understand the musculoskeletal injury risk of women in British Army infantry basic training, we compared injury incidence between (1) men in standard entry training and men in infantry training, to assess the risk of infantry training; and (2) men and women in both standard entry and officer basic training, to assess the risk in women compared with men.

METHODS

The incidence of musculoskeletal injury was determined from defence medical records for all men entering infantry training, and for all men and women entering standard entry and officer training, between April 2015 and March 2016.

RESULTS

7390 men (standard entry, n=4229; infantry, n=2683; officer, n=478) and 696 women (standard entry, n=626; officer, n=70) entered basic training. Men in infantry training had a lower incidence of musculoskeletal injury (391 vs 417 per 1000 personnel, OR 0.90 (95% CI 0.81 to 0.99), p=0.028) and a higher incidence of stress fracture (14 vs 5 per 1000 personnel, OR 2.80 (95% CI 1.64 to 4.80), p<0.001) than men in standard entry training. Women had a higher incidence of musculoskeletal injury than men in standard entry training (522 vs 417 per 1000 personnel, OR 1.53 (95% CI 1.29 to 1.81), p<0.001) and a higher incidence of stress fracture than men in officer training (114 vs 19 per 1000 personnel, OR 6.72 (95% CI 2.50 to 18.07), p<0.001).

CONCLUSION

Women in infantry training may be at similar risk for musculoskeletal injury, but at higher risk for stress fracture, compared with their non-infantry counterparts. Women in infantry training may be at higher risk for musculoskeletal injury and stress fracture compared with men in infantry training.

Effect of sex and combat employment on musculoskeletal injuries and medical downgrading in trained military personnel: an observational cohort study

INTRODUCTION

Following the opening of all combat roles to women across the UK Armed Forces, there is a requirement to understand the risk of injury to these female personnel. Women injure at a higher rate than men during basic military training, but fewer data are published from individuals who have passed military training.

METHODS

A bespoke survey was designed to investigate differences in injury prevalence and medical downgrading between sexes and career employment groups (ie, job roles) in the UK Armed Forces.

RESULTS

Questionnaire data were evaluated from 847 service personnel (87% men) employed in combat roles (Royal Marines, Infantry, Royal Armoured Corps, Royal Air Force Regiment (all men)) and non-combat roles (Royal Regiment of Artillery, Corps of Royal Engineers, Royal Logistic Corps and Combat Service Support Corps who were attached to one of the participating units (men and women)). Women reported more total (OR 1.64 (95% CI: 1.03 to 2.59), p=0.035), lower limb (OR 1.92 (95% CI: 1.23 to 2.98), p=0.004) and hip (OR 2.99 (95% CI: 1.59 to 5.62), p<0.001) musculoskeletal injuries in the previous 12 months than men, but there were no sex differences in the prevalence of current or career medical downgrading due to musculoskeletal injury (both p>0.05). There were no differences in 12-month musculoskeletal injury prevalence between men in combat roles and men in non-combat roles (all p>0.05), but men in non-combat roles were more likely to be currently medically downgraded (OR 1.88 (95% CI: 1.27 to 2.78), p=0.001) and medically downgraded during their career (OR 1.49 (95% CI: 1.11 to 2.00), p=0.008) due to musculoskeletal injury than men in combat roles. More time in service and quicker 1.5-mile run times were associated with increased prevalence of total musculoskeletal injuries, and female sex was a predictor of hip injury.

CONCLUSIONS

Although women are at greater risk of injury than men, we have no evidence that combat employment is more injurious than non-combat employment. The prevention of hip injuries should form a specific focus of mitigation efforts for women.

Gender data gap in military research: a review of the participation of men and women in military musculoskeletal injury studies

Servicewomen are at increased risk of musculoskeletal injuries compared with their male counterparts, but women are under-represented in sports medicine research. The aim of this review was to assess the representation of women in military musculoskeletal injury studies. PubMed was searched for human original research studies using the terms Military OR Army OR Navy OR 'Air Force' AND 'musculoskeletal injury' Each study was categorised as epidemiology (basic training), epidemiology (trained personnel), risk factors, interventions and other. The number of male and female participants was retrieved from each study. A total of 262 studies were included: 98 (37%) studies only included men, 17 (6%) studies only included women and 147 (56%) studies included both men and women. A total of 8 051 778 participants were included in these studies (men: 6 711 082, 83%; women: 1 340 696, 17%). The study theme with the greatest proportion of women was musculoskeletal injury epidemiology studies in a basic training population (20% of participants) with the lowest proportion of women in intervention trials (6% of participants). These data suggest women are not under-represented in military musculoskeletal injury studies when considering the gender representation of most militaries. Our data are, however, biased by large epidemiological trials and women were under-represented in intervention trials. The under-representation of women in intervention trials could be due to difficulties in controlling for the effects of female sex steroids on musculoskeletal outcomes, or a focus on interventions in the most arduous military roles where injury risk is highest and women have been previously excluded.

Prevention of Lower Extremity Musculoskeletal Injuries in Tactical and First Responder Populations: A Systematic Review and Meta-Analysis of Randomized Trials From 1955 to 2020

ABSTRACT

Sinnott, AM, Krajewski, KT, LaGoy, AD, Beckner, ME, Proessl, F, Canino, MC, Nindl, BC, Turner, RL, Lovalekar, MT, Connaboy, C, and Flanagan, SD. Prevention of lower extremity musculoskeletal injuries in tactical and first responder populations: A systematic review and meta-analysis of randomized trials from 1955 to 2020. J Strength Cond Res 37(1): 239-252, 2023-Lower extremity musculoskeletal injuries (LEMSIs) impose a significant burden on tactical and first responder populations. To determine the effectiveness of LEMSI prevention strategies, we performed a systematic review and meta-analysis of randomized controlled trials published in English from 1955 to 2020 (PROSPERO: CRD42018081799). MEDLINE, EMBASE, Cochrane, CINAHL, ProQuest, and DTIC databases were searched for trials that assigned military service members, police, firefighters, or paramedics to LEMSI prevention interventions with a minimum surveillance period of 12 weeks. Evidence was synthesized as odds ratios (OR) for LEMSI occurrence between individuals assigned to interventions and those assigned to standard activities. Risk of bias was assessed with the Cochrane Risk of Bias tool 2.0. Random-effects meta-analyses were conducted for (a) physical training and (b) footwear modifications to reduce LEMSI and (c) footwear modifications to reduce stress fractures specifically. Certainty in the body of evidence was determined with the GRADE approach. Of 28,499 records, 18 trials comprised of more than 11,000 subjects were synthesized. Interventions included physical training (8, N = 6,838), footwear modifications (8, N = 3,792), nutritional supplementation (1, N = 324), and training modifications (1, N = 350). Overall risk of bias was generally moderate ( N = 7 of 18) or high ( N = 9 of 18). Physical training (OR = 0.87, 95% CI [0.71, 1.08], p = 0.22, I 2 = 58.4%) and footwear modification (OR = 1.13, 95% CI [0.85, 1.49], p = 0.42, I 2 = 0.0%) did not reduce LEMSI or stress fractures (OR = 0.76, 95% CI [0.45, 1.28], p = 0.30, I 2 = 70.7%). Our results indicate that there is weak evidence to support current LEMSI prevention strategies. Future efforts will benefit from longer surveillance periods, assessment of women and nonmilitary populations, improved methodological rigor, and a greater breadth of approaches.

Epidemiology of Musculoskeletal Injuries in the Navy: A Systematic Review

Objectives: This study aimed to critically review the results of recent studies that investigated the epidemiology of noncombat-related musculoskeletal injuries (MSIs) in the Navy. Methods: A systematic search was conducted of three major databases (Pubmed, Embase, and Cochrane) to identify epidemiological studies on MSIs in the Navy. Study selection and risk of bias assessment were conducted. Results: The overall prevalence of MSIs ranged from 12.69% to 48.81%. And the prevalence of head and face injuries, upper extremity injuries, spine injuries, chest injuries, and lower extremity injuries were 0.11%-0.66%, 0.53%-11.47%, 0.75%-12.09%, 0.43%-0.95%, and 0.4%-21.17%, respectively. For the specific MSIs, the incidence ranged from 0.03/1000 person-years to 32.3/1000 person-years in the Navy and Marines. The ankle-foot, lumbopelvic, knee and lower leg, and shoulder were identified as the most frequent location for MSIs. Conclusion: This systematic review summarized that the Navy population had a high prevalence of MSIs. And different risk factors for MSIs varied from different anatomic locations. This systematic review also provided valuable information on MSIs for sports medicine specialists.

Test-Retest Reliability and Translation of the Musculoskeletal Screening Protocol Questionnaire Used in the Swedish Armed Forces

INTRODUCTION

Musculoskeletal disorders (MSDs) in military personnel are common, and it is important to identify those at risk so that appropriate preventive and rehabilitative strategies can be undertaken. The Musculoskeletal Screening Protocol (MSP) questionnaire is part of the implemented prevention strategy to reduce MSDs in the Swedish Armed Forces. The aims of this study were to evaluate the questionnaire's reliability and to translate it into English.

MATERIALS AND METHODS

One-week test-retest reliability of the questionnaire was evaluated in a sample of 35 Swedish military personnel. Reliability was evaluated by calculations of Cohen's kappa or quadratic-weighted kappa. Percent agreement was used as a parameter for measurement error. Translation into English included forward and backward translations and expert committee discussions.

RESULTS

Kappa values relating to physical complaints/injuries were excellent (>0.75) except for knee and lower leg MSDs and for the intensity ratings, where Kappa values were mostly interpreted as fair-to-good (0.4-0.75). Kappa values of items pertaining physical performance, physical activity and exercise, eating and tobacco habits, sleep, and perceived health ranged between 0.72 and 1. Kappa values for feeling mentally or physical prepared were 0.47 and 0.65, respectively. Most percentage agreement values ranged between 90% and 100%. The English version was found to be satisfactorily equivalent to the Swedish MSP questionnaire.

CONCLUSION

The Swedish MSP questionnaire was found to be highly reliable and was satisfactorily translated into English. This provides support for the questionnaire's ability to trustworthily capture the prevalence of MSDs and perceived health in military personnel. Future research is warranted on the psychometric properties of the English MSP questionnaire.

A Career Life-Cycle Perspective on Women's Health and Safety: Insights From the Defense Health Board Report on Military Women's Health

OBJECTIVE

Women's health has demanded more attention from employers as women integrated into the workforce. Traditionally male-dominant fields and occupations require special attention to workplace design, physical standards for entry, employment practices, equipment, and health monitoring. This editorial summarizes the Defense Health Board's (DHB) review of Active Duty Women's Health and its recommendations grounded in a woman's career life-cycle.

METHODS

The DHB reviewed the Department of Defense and foreign militaries' current women's health services, relevant policies and practices, peer-reviewed scientific literature, and subject matter expert interviews.

RESULTS

The DHB's recommendations centered on a comprehensive approach to education, health care access and treatment, professional workforce development, workplace standards and equipment, and accountable outcomes metrics to guide improvement.

CONCLUSIONS

Employers can learn how to reduce morbidity, leading to a healthier and more productive female workforce.

One out of four recruits drops out from elite military training due to musculoskeletal injuries in the Netherlands Armed Forces

INTRODUCTION

Musculoskeletal injuries (MSIs) are among the main causes of dropout from military training. The main purpose of this study was to provide an overview of dropout rates and MSI incidence rates during elite military training. Second, this study aimed to explore restricted training days due to MSIs and to describe MSI-care by military physicians.

METHODS

In a retrospective observational study, we collected dropout rates and injury surveillance data from the electronic patient records of two elite units of the Netherlands Armed Forces (NAF): the Royal Netherlands Marine Corps (RNLMC) and the Airmobile Brigade (AMB), from 1 January 2015 until 31 December 2017.

RESULTS

In the RNLMC, total dropout rate was 53.9% and dropout due to MSIs was 23%. The most frequently affected locations were foot, knee and leg. In the AMB total dropout rate was 52.6% and dropout due to MSIs was 25%. In the AMB, the most frequently affected locations were back, knee and leg. Average restricted training days due to MSIs ranged between 8.3 and 20.8 days/injury. MSI-care by military physicians consisted mostly of the provision of injury-specific information and (self-)management options, imposing a specific activity restriction and referral to physiotherapy.

CONCLUSION

Our study findings showed that one out of four recruits who dropout from elite military training in the NAF, do so due to MSIs. Redesigning training programmes with the objective to reduce MSIs should be given high priority, as this may reduce dropout substantially.

Low Back Biomechanics during Repetitive Deadlifts: A Narrative Review

OCCUPATIONAL APPLICATIONSHeavy deadlifting is used as a screening tool or training protocol for recruitment and retention in physically-demanding occupations, especially in the military. Spinal loads experienced during heavy deadlifts, particularly shearing forces, are well above recommended thresholds for lumbar spine injury in occupational settings. Although members of the noted occupation likely have stronger musculoskeletal systems compared to the general population, experiencing shearing forces that are 2 to 4 times larger than the threshold of injury, particularly under repetitive deadlift, may transform a screening tool or training protocol to an occupationally-harmful physical activity.

Weighted vests in CrossFit increase physiological stress during walking and running without changes in spatiotemporal gait parameters

This study quantified the physiological and biomechanical effects of the 20 lb (9.07 kg, males) and 14 lb (6.35 kg, females) weighted vest used in CrossFit, and whether they were predisposed to injury. Twenty subjects (10 males, 10 females) undertook walking (0%, 5% and 10% gradient) and running trials in two randomised study visits (weighted vest/no weighted vest). Physiological demand during walking was increased with the vest at 10% but not 5% or 0% with no change in gait variables. In the running trial, the weighted vest increased oxygen uptake (males; females) (+0.22L/min, p < 0.01; +0.07 L/min, p < 0.05), heart rate (+11bpm, p < 0.01; +11bpm, p < 0.05), carbohydrate oxidation (+0.6 g/min, p < 0.001; +0.2 g/min, p < 0.01), and energy expenditure (+3.8 kJ/min, p < 0.001; +1.5 kJ/min, p < 0.05) whilst blood lactate was increased only in males (+0.6 mmol/L, p < 0.05). There was no change in stride length or frequency. Weighted vest training increases physiological stress and carbohydrate oxidation without affecting measured gait parameters. Practitioner summary: We examined the effect of weighted vest training prescribed in CrossFit (20 lb/9.07 kg, males and 14 lb/6.35 kg, females) in a randomised controlled trial. We found that physiological stress is increased in both sexes, although three-fold greater in males, but with no change in biomechanical gait that predisposes to lower-limb injury.

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.

Musculoskeletal Injuries Among Females in the Military: A Scoping Review

INTRODUCTION

Musculoskeletal injuries (MSKi) are a common challenge for those in military careers. Compared to their male peers, reports indicate that female military members and recruits are at greater risk of suffering MSKi during training and deployment. The objectives of this study were to identify the types and causes of MSKi among female military personnel and to explore the various risk factors associated with MSKi.

MATERIALS AND METHODS

A scoping review was conducted over a 4-month time frame of English language, peer-reviewed studies published from 1946 to 2019. Search strategies for major biomedical databases (e.g., MEDLINE; Embase Classic + Embase; and the following EBM Reviews-Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Health Technology Assessment, and the NHS Economic Evaluation Database) were developed by a senior medical information specialist and included 2,891 titles/abstracts. Study selection and data collection were designed according to the Population, Concept, and Context framework. Studies were included if the study population provided stratified data for females in a military context.

RESULTS

From a total of 2,287 citations captured from the literature searches, 168 peer-reviewed publications (144 unique studies) were eligible for inclusion. Studies were identified from across 10 countries and published between 1977 and 2019. Study designs were primarily prospective and retrospective cohorts. Most studies assessed both prevalence/incidence and risk factors for MSKi (62.50%), with few studies assessing cause (13.69%). For MSKi of female recruits compared to active female members, the prevalence was higher (19.7%-58.3% vs. 5.5%-56.6%), but the incidence (0.02%-57.7% vs. 13.5%-71.9%) was lower. The incidence of stress fractures was found to be much higher in female recruits than in active members (1.6%-23.9% vs. 2.7%). For anthropometric risk factors, increased body fat was a predictor of MSKi, but not stress fractures. For physiological risk factors for both female military groups, being less physically fit, later menarche, and having no/irregular menses were predictors of MSKi and stress fractures. For biomechanical risk factors, among female recruits, longer tibial length and femoral neck diameter increased the risk of stress fractures, and low foot arch increased risk of an ankle sprain. For female active military members, differences in shoulder rotation and bone strength were associated with risk of MSKi. For biological sex, being female compared to male was associated with an increased risk of MSKi, stress fractures, and general injuries. The consequences of experiencing MSKi for active military included limited duties, time off, and discharge. For recruits, these included missed training days, limited duty days, and release.

CONCLUSIONS

This scoping review provides insight into the current state of the evidence regarding the types and causes of MSKi, as well as the factors that influence MSKi among females in the military. Future research endeavors should focus on randomized controlled trials examining training paradigms to see if women are more susceptible. The data presented in the scoping review could potentially be used to develop training strategies to mitigate some of the identified barriers that negatively impact women from pursuing careers in the military.

Applying Force Plate Technology to Inform Human Performance Programming in Tactical Populations

Force plate assessments, such as countermovement jumps and isometric mid-thigh pulls, examine performances (e.g., jump height, force, power) and movement strategies (e.g., asymmetries, durations), and are best suited to characterize and monitor physical capabilities, not predict injuries. To begin applying force plate technologies, users must first; (1) develop a data management plan to visualize and capture data over time; (2) select appropriate force plates for their scenario; (3) design appropriate testing protocols to ensure valid and reliable data. Force plate assessments may be added to existing testing, serve as separate testing batteries for annual profile testing to compare individuals and understand initial physical capabilities, or for more frequent testing (i.e., monthly or weekly) to monitor training-related adaptations or neuromuscular fatigue. Although these assessments inform evidence-based program designs, human performance practitioners must understand the considerations for conducting appropriate force plate testing, as well as proper visualizations and management of force plate data. Thus, the aim of this review is to provide evidence-based practices for utilizing force plates in tactical populations (e.g., military, firefighters, police). This includes best practices to implement testing for performance profiling, training adaptations, and monitoring neuromuscular fatigue and force asymmetries. Of note, due to the large amount of force-time metrics to choose from, this article provides general examples of important metrics to monitor and training recommendations based on changes to these force-time metrics, followed by specific examples in three case studies.

Kinetic and Kinematic Analysis of Various Drop Jump Performances in Army Reserve Officer Training Corps Cadets

ABSTRACT

Merrigan, JJ, O'Toole, KB, Wutzke, CJ, and Jones, MT. Kinetic and kinematic analysis of various drop jump performances in army reserve officer training corps cadets. J Strength Cond Res XX(X): 000-000, 2021-The purpose was to examine effects of sex, drop height, and external loads on drop jump mechanics in Reserve Officer Training Corps cadets and whether findings were associated with strength. Males (n = 14) and females (n = 12) completed maximal isokinetic concentric (slow-C and fast-C) and eccentric (slow-E and fast-E) knee extensions and flexions at 60°·s-1 and 180°·s-1. After 72 hours, 3 drop jumps were performed under 3 conditions, (i.e., 30 cm unloaded [30UL], 30 cm loaded 15 kg [30L], and 60 cm unloaded [60UL]). No sex × condition interactions existed for any metric (p > 0.05). The 30L condition resulted in slower eccentric and concentric center of mass (COM) and angular velocities, reduced concentric vertical ground reaction forces (vGRF), and lower jump performances. Although 60UL resulted in greater eccentric COM and angular velocities, peak vGRF, impulse, and rate of force development (p < 0.008), no differences existed in jump performances. Males had faster COM and angular concentric velocities and smaller knee valgus angles, but no different vGRF compared with females. The change in the peak hip angle, because of 60UL, was associated with knee extension eccentric and concentric strength, whereas changes in knee angles were associated with eccentric strength. Likewise, eccentric strength influenced the effects of 30L on landing vGRF more so than concentric strength. Initial strength training is recommended, specifically emphasizing eccentric actions, before performing loaded (15 kg) drop jumps to reduce the increase of landing forces. However, caution may be required when performing drops from 60 cm because of increased forces, although no decline in jump performances were noted.

Dimensionality Reduction Differentiates Sensitive Force-Time Characteristics from Loaded and Unloaded Conditions throughout Competitive Military Training

The purpose was to evaluate neuromuscular fatigue’s effect on unloaded and loaded countermovement jump (CMJ) force-time characteristics during high-intensity tactical training. Eighteen male and sixteen female Marines completed two maximal effort CMJs, in unloaded (PVC pipe) and loaded (10 kg weight vest and 20 kg barbell) conditions, prior to, and 24, 48, and 72 h after starting the 4-day event. The top three variables from three principal components (PC) were analyzed using mixed-effects modeling (PC1—concentric mean power, eccentric peak force, and modified reactive strength index; PC2—countermovement depth, eccentric mean power, and eccentric mean velocity; PC3—braking duration, jump height, peak power). Metrics from PC1 and PC3 were reduced across training and from both loading conditions. Metrics from PC2 were similarly affected by external loading but were less influenced by training-induced fatigue. Jump performances with the barbell and with shallower countermovement depths did not change throughout training. Thus, 20 kg loaded CMJs are stable neuromuscular measures suitable for tracking chronic training adaptations. Monitoring unloaded and 10 kg loaded CMJ performances, along with movement strategies (i.e., countermovement rates and depth), may help identify moments of accumulated fatigue to inform training and recovery adjustments and improve the sustainability of personnel.

Does Protein Supplementation Support Adaptations to Arduous Concurrent Exercise Training? A Systematic Review and Meta-Analysis with Military Based Applications

We evaluated the impact of protein supplementation on adaptations to arduous concurrent training in healthy adults with potential applications to individuals undergoing military training. Peer-reviewed papers published in English meeting the population, intervention, comparison and outcome criteria were included. Database searches were completed in PubMed, Web of science and SPORTDiscus. Study quality was evaluated using the COnsensus based standards for the selection of health status measurement instruments checklist. Of 11 studies included, nine focused on performance, six on body composition and four on muscle recovery. Cohen's d effect sizes showed that protein supplementation improved performance outcomes in response to concurrent training (ES = 0.89, 95% CI = 0.08-1.70). When analysed separately, improvements in muscle strength (SMD = +4.92 kg, 95% CI = -2.70-12.54 kg) were found, but not in aerobic endurance. Gains in fat-free mass (SMD = +0.75 kg, 95% CI = 0.44-1.06 kg) and reductions in fat-mass (SMD = -0.99, 95% CI = -1.43-0.23 kg) were greater with protein supplementation. Most studies did not report protein turnover, nitrogen balance and/or total daily protein intake. Therefore, further research is warranted. However, our findings infer that protein supplementation may support lean-mass accretion and strength gains during arduous concurrent training in physical active populations, including military recruits.

Nonexercise Interventions for Prevention of Musculoskeletal Injuries in Armed Forces: A Systematic Review and Meta-Analysis

CONTEXT

This study evaluates the effect of nonexercise interventions on the reduction of risk for musculoskeletal injuries in armed forces.

EVIDENCE ACQUISITION

A database search was conducted in PubMed/MEDLINE, Embase, Cochrane Library, CINAHL, SPORTdiscus, Greylit, Open Grey, the WHO trial registry, and the reference lists of included articles up to July 2019. RCTs and cluster RCTs evaluating nonexercise interventions for the prevention of musculoskeletal injuries in armed forces compared with any other intervention(s) or no intervention were eligible for inclusion. Data extraction and risk of bias assessment were done by 2 authors independently, followed by meta-analysis and Grading of Recommendations Assessment, Development, and Evaluation assessment, if appropriate.

EVIDENCE SYNTHESIS

This study included 27 articles with a total number of 25,593 participants, examining nutritional supplementation, prophylactic medication, and equipment modifications with mostly high or unclear risk of bias. Meta-analysis and Grading of Recommendations Assessment, Development, and Evaluation assessment could be performed for 3 comparisons: custom-made insoles versus no insoles, tropical/hot-weather boots versus leather boots, and shock-absorbing insoles versus nonshock-absorbing insoles interventions, all showing the very low quality of evidence. Some evidence was found to support the preventive effect of shock-absorbing insoles, basketball shoes, padded polyester socks, calcium with vitamin D supplementation, only calcium supplementation, protein supplementation, and dynamic patellofemoral braces.

CONCLUSIONS

Although an evidence base for the efficacy of preventive interventions for musculoskeletal injuries in armed forces is weak, there are some indications for the preventive effect of shock-absorbing insoles, basketball shoes, padded polyester socks, supplementation of calcium alone or combined with vitamin D, protein supplementation, and dynamic patellofemoral braces on the incidence of musculoskeletal injuries.

Identifying Reliable and Relatable Force-Time Metrics in Athletes-Considerations for the Isometric Mid-Thigh Pull and Countermovement Jump

The purpose of this study was to evaluate intrasession reliability of countermovement jump (CMJ) and isometric mid-thigh pull (IMTP) force-time characteristics, as well as relationships between CMJ and IMTP metrics. Division I sport and club athletes (n = 112) completed two maximal effort CMJ and IMTP trials, in that order, on force plates. Relative and absolute reliability were assessed using intraclass correlation coefficients (ICCs) > 0.80 and coefficients of variation (CVs) < 10%. Intrasession reliability was acceptable for the majority of the CMJ force-time metrics except for concentric rate of force development (RFD), eccentric impulse and RFD, and lower limb stiffness. The IMTP's time to peak force, instantaneous force at 150 ms, instantaneous net force, and RFD measures were not reliable. Statistically significant weak to moderate relationships (r = 0.20-0.46) existed between allometrically scaled CMJ and IMTP metrics, with the exception of CMJ eccentric mean power not being related with IMTP performances. A majority of CMJ and IMTP metrics met acceptable reliability standards, except RFD measures which should be used with caution. Provided CMJs and IMTPs are indicative of distinct physical fitness capabilities, it is suggested to monitor athlete performance in both tests via changes in those variables that demonstrate the greatest degree of reliability.

Monitoring Neuromuscular Performance in Military Personnel

A necessarily high standard for physical readiness in tactical environments is often accompanied by high incidences of injury due to overaccumulations of neuromuscular fatigue (NMF). To account for instances of overtraining stimulated by NMF, close monitoring of neuromuscular performance is warranted. Previously validated tests, such as the countermovement jump, are useful means for monitoring performance adaptations, resiliency to fatigue, and risk for injury. Performing such tests on force plates provides an understanding of the movement strategy used to obtain the resulting outcome (e.g., jump height). Further, force plates afford numerous objective tests that are valid and reliable for monitoring upper and lower extremity muscular strength and power (thus sensitive to NMF) with less fatiguing and safer methods than traditional one-repetition maximum assessments. Force plates provide numerous software and testing application options that can be applied to military's training but, to be effective, requires the practitioners to have sufficient knowledge of their functions. Therefore, this review aims to explain the functions of force plate testing as well as current best practices for utilizing force plates in military settings and disseminate protocols for valid and reliable testing to collect key variables that translate to physical performance capacities.

Exercise Programs to Reduce the Risk of Musculoskeletal Injuries in Military Personnel: A Systematic Review and Meta-Analysis

Objective

To evaluate the effect of exercise programs on reduction of musculoskeletal injury (MSI) risk in military populations.

Design

Systematic review and meta‐analysis.

Literature Survey

A database search was conducted in PubMed/MEDLINE, EMBASE, Cochrane Library, CINAHL, SPORTdiscus, WHO International Clinical Trials Registry Platform Search Portal, Open Gray, National Technical Reports Library, and reference lists of included articles up to July 2019. Randomized and cluster‐randomized controlled trials evaluating exercise programs as preventive interventions for MSIs in armed forces compared to other exercise programs or to usual practice were eligible for inclusion.

Methodology

Two authors independently assessed risk of bias and extracted data. Data were adjusted for clustering if necessary and pooled using the random‐effects model when appropriate.

Synthesis

We included 15 trials in this review, with a total number of 14 370 participants. None of the included trials appeared to be free of any risk of bias. Meta‐analysis and Grading of Recommendations, Assessment, Development and Evaluations (GRADE) assessment could be performed for static stretching compared to no stretching (3532 participants), showing low quality of evidence indicating no favorable effect of stretching. Gait retraining, an anterior knee‐pain targeted program, and resistance exercises showed cautious favorable effects on reducing injury risk in military personnel.

Conclusion

The current evidence base for exercise‐based MSI prevention strategies in the military is of low quality. Areas worthy of further exploration include the effects of gait retraining, anterior knee‐pain targeted programs, agility training, and resistance training programs, on medial tibial stress syndrome incidence, anterior knee pain incidence, attrition due to injuries and any type of MSI, respectively.

The Overtraining Syndrome in Soldiers: Insights from the Sports Domain

INTRODUCTION

Soldiers are exposed to extreme training regimens in order to optimally prepare for real battle. High attrition rates are a known issue during training courses, especially for elite troops. An underlying factor might be the disbalance between stress/strain and recovery. The aim of this review is to give insight in the current knowledge about functional overreaching (FOR), non-FOR (NFOR), and the overtraining syndrome (OTS) in the military.

MATERIALS AND METHODS

A systematic literature review was conducted. PubMed, IngentaConnect, Science Direct, and Web of Science were screened for the following keywords and combinations of search terms; military, personnel, OT, soldier.

RESULTS

Seven studies investigating the effects of OT during training courses were selected. The definitions used for OT varied widely and there is no systematic use of markers to determine FOR, NFOR, or the OTS in the military.

CONCLUSIONS

Much research on NFOR/OTS has been conducted in the sports domain and the military could make use of these insights to promote a more efficient balance between training load and recovery. It is suggested to regularly test soldiers on physical performance, psychomotor speed and mood using ideally a military-specific test or the 1.5-mile run, psychomotor vigilance test and Profile of Mood States. The two-bout exercise test can be used as a specific test if previous testing indicates the development of NFOR/OTS and can be combined with metabolic and immunological testing to exclude pathological causes.

Sex differences in dietary intake in British Army recruits undergoing phase one training

Background

British Army Phase One training exposes men and women to challenging distances of 13.5 km·d^− 1 vs. 11.8 km·d^− 1 and energy expenditures of ~ 4000 kcal·d^− 1 and ~ 3000 kcal·d^− 1, respectively. As such, it is essential that adequate nutrition is provided to support training demands. However, to date, there is a paucity of data on habitual dietary intake of British Army recruits. The aims of this study were to: (i) compare habitual dietary intake in British Army recruits undergoing Phase One training to Military Dietary Reference Values (MDRVs), and (ii) establish if there was a relative sex difference in dietary intake between men and women.

Method

Researcher led weighed food records and food diaries were used to assess dietary intake in twenty-eight women (age 21.4 ± 3.0 yrs., height: 163.7 ± 5.0 cm, body mass 65.0 ± 6.7 kg), and seventeen men (age 20.4 ± 2.3 yrs., height: 178.0 ± 7.9 cm, body mass 74.6 ± 8.1 kg) at the Army Training Centre, Pirbright for 8-days in week ten of training. Macro and micronutrient content were estimated using dietary analysis software (Nutritics, Dublin) and assessed via an independent sample t-test to establish if there was a sex difference in daily energy, macro or micronutrient intakes.

Results

Estimated daily energy intake was less than the MDRV for both men and women, with men consuming a greater amount of energy compared with women (2846 ± 573 vs. 2207 ± 585 kcal·day^− 1, p < 0.001). Both sexes under consumed carbohydrate (CHO) when data was expressed relative to body mass with men consuming a greater amount than women (4.8 ± 1.3 vs. 3.8 ± 1.4 g·kg^− 1·day^− 1, p = 0.025, ES = 0.74). Both sexes also failed to meet MDRVs for protein intake with men consuming more than women (1.5 ± 0.3 vs. 1.3 ± 0.3 g·kg^− 1·day^− 1, p > 0.030, ES = 0.67). There were no differences in dietary fat intake between men and women (1.5 ± 0.2 vs. 1.5 ± 0.5 g·kg^− 1·day^− 1, p = 0.483, ES = 0.00).

Conclusions

Daily EI in men and women in Phase One training does not meet MDRVs. Interventions to increase macronutrient intakes should be considered along with research investigating the potential benefits for increasing different macronutrient intakes on training adaptations.

Prevention of exertional lower body musculoskeletal injury in tactical populations: protocol for a systematic review and planned meta-analysis of prospective studies from 1955 to 2018

BACKGROUND

Exertional lower body musculoskeletal injuries (ELBI) cost billions of dollars and compromise the readiness and job performance of military service and public safety workers (i.e., tactical populations). The prevalence and burden of such injuries underscores the importance of prevention efforts during activities necessary to sustain core occupational competencies. Attempts to synthesize prevention techniques specific to tactical populations have provided limited insight on the comparative efficacy of interventions that do not modify physical training practices. There is also a need to assess the influence of sex, exposure, injury classification scheme, and study design. Thus, the primary purpose of the systematic review and planned meta-analysis detailed in this protocol is to evaluate the comparative efficacy of ELBI prevention strategies in tactical populations.

METHODS

A systematic search strategy will be implemented in MEDLINE, EMBASE, Cochrane, and CINAHL. A multi-tiered process will be used to capture randomized controlled trials and prospective cohort studies that directly assess the prevention of ELBI in tactical population(s). Extracted data will be used to compare prevention strategies and assess the influence of heterogeneity related to occupation, sex, exposure, injury characteristics, and study quality. In addition, individual risk of bias, meta-bias, and the quality of the body of evidence will be rigorously tested.

DISCUSSION

This systematic review and planned meta-analysis will comprehensively evaluate ELBI mitigation strategies in tactical populations, elucidate factors that influence responses to treatment, and assess the overall quality of the body of research. Results of this work will guide the prioritization of ELBI prevention strategies and direct future research efforts, with direct relevance to tactical, health and rehabilitation science, and human performance optimization stakeholders.

SYSTEMATIC REVIEW REGISTRATION

The systematic review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) on 3 Jan 2018 (registration number CRD42018081799 ).