Low fitness, low body mass and prior injury predict injury risk during military recruit training: a prospective cohort study in the British Army

Associations Between Self-Reported Injury History, Physical Complaints, and Medical Attention Injury During Army Basic Military Training

INTRODUCTION

Effective and easily implementable methods to reduce the incidence and burden of injury during Army basic military training (BMT) are desirable. This study therefore investigated (1) the association between prior injury history and medical attention (MA) injury and (2) the association and accuracy of daily self-reported physical complaints on the incidence of MA injury, during Army BMT.

MATERIALS AND METHODS

Recruits (n = 625, male = 524; female = 101; age: 22 ± 6 years [range: 17-55 years]) completed a 12-month prior injury history questionnaire during week 1 and throughout BMT reported physical complaints daily, using a modified Oslo Sports Trauma Research Centre Questionnaire on Health Problems (OSTRC-H). Medical attention injuries were recorded via physiotherapy reports. Cox proportional hazard regressions explored the association between prior injury and MA injury. Generalized linear mixed-effects models were used to model the association between OSTRC-H responses and an MA incident injury within 7 days. The predictive ability and accuracy of OSTRC-H responses were also assessed.

RESULTS

Prior injury was not significantly associated with a greater risk of MA injury during BMT. Self-reported physical complaints effecting "participation" ("Full participation, but with injury/illness": OR = 2.23, 95% CI 1.97-2.52; "Reduced participation due to injury/illness": OR = 3.19, 95% CI 2.54-4.00), "severity" ("To a mild extent": OR = 2.19, 95% CI 1.91-2.51; "To a moderate extent": OR = 2.83, 95% CI 2.38-3.36; "To a severe extent": OR = 4.50, 95% CI 3.26-6.21), and "location" (OR = 2.19, 95% CI 1.96-2.45) were significantly associated with greater odds of MA incident injury within 7 days. Spine (OR = 4.39, 95% CI 3.07-6.30), upper extremity (OR = 2.45, 95% CI 1.76-3.40), and lower extremity (OR = 2.73, 95% CI 2.40-3.40) physical complaints were significantly associated with an MA incident injury to the corresponding general body region within 7 days. Using the presence of a physical complaint to indicate the occurrence of an MA incident injury within 7 days resulted in a high number of false positives and false negatives (area under the curve: 0.51-0.66).

CONCLUSIONS

Independently, self-reported 12-month prior injury was not significantly associated with a greater risk of an MA injury during BMT. Daily self-reported physical complaints may however flag increased MA injury risk, which could help prevent more severe injuries.

Cardiorespiratory demands of firearms training instruction and 15m shuttle tests in British law enforcement

OBJECTIVES

Law enforcement agencies require minimum fitness standards to safeguard their officers and training staff. Firearms instructors (FI) are expected to maintain the same standards as their operational counterparts. This study aimed to quantify the daily physiological demands placed on FI.

METHODS

19 FI (45 ± 5 years) completed occupational tasks whilst wearing heart rate (HR) monitors for a minimum 10 days. Maximal oxygen consumption (VO2max) testing was conducted on FI during a treadmill test (TT) and a multistage shuttle test (ST). Linear regression models were used to model the relationship between VO2 and HR throughout the TT. This model was applied to HR data from occupational tasks to infer oxygen consumption. Repeated Measures ANOVAs were used to compare time spent in VO2max equivalent zones throughout.

RESULTS

The VO2max achieved during ST (45.1 ± 5.6 ml/kg/min) was significantly higher than TT (39 ± 3 ml/kg/min) (p = 0.014). Time to exhaustion (TTE) was sooner on ST (06:26 min) compared to TT (13:16 min) (p < .001). FI spent ~85% of occupational time with an oxygen demand ≤20 ml/kg/min (p < .005). The most intense occupational tasks saw FI achieve VO2max ≥30 ml/kg/min, but <40 ml/kg/min.

CONCLUSION

Using ST to assess cardiorespiratory fitness resulted in a quicker TTE and a higher VO2max. Predominantly, FI occupational tasks are low intensity with sporadic exposures requiring a VO2max of >40 ml/kg/min. To safeguard FI from occupational-related cardiorespiratory or long-term health issues, it is intuitive to suggest fitness standards should exceed a VO2max of 40 ml/kg/min.

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 Value of Strength as a Predictor of Musculoskeletal Injury in Canadian Armed Forces Basic Infantry Candidates

INTRODUCTION

Musculoskeletal injuries (MSKI) impact military organizations by threatening their operational readiness, warranting investigation into relevant factors to inform risk reduction strategies. While several self-reported and physical performance measures have been associated with MSKI among military personnel, few have been validated and none have been reported in Canadian basic infantry candidates. The purpose of this study was to investigate associations between self-reported and physical performance measures and MSKI, and determine their validity as predictors of MSKI, in Canadian basic infantry candidates.

METHODS

This was a planned secondary analysis of a study tracking MSKI at a basic infantry training facility in Ontario, Canada approved by Defence Research & Development Canada. Before the basic infantry training, consenting candidates completed a baseline testing session including self-reported questionnaires, measures of anthropometry, and physical performance previously associated with MSKI (ankle dorsiflexion test, Y-Balance Test, Isometric Mid-Thigh Pull, and the Fitness for Operational Requirements of CAF Employment (FORCE) evaluation). All MSKI reported by candidates were diagnosed by licensed healthcare providers. From a total sample of 129 candidates, 76% (n = 98) were used to determine any associations between baseline testing variables and MSKI and to develop a predictive model (Development Sample), while 24% (n = 33) were used to offer preliminary validation of the same predictive model (Validation Sample). The binary logistic regression and independent sample t-testing determined independent associations with MSKI in the Development Sample. All continuous variables and dichotomous variables previously associated with MSKI risk (Smoker Yes/No, previous history of MSKI, and physical inactivity) were entered into a backward stepwise logistic regression analysis to assess the predictive association with MSKI incidence in the Development Sample. The regression model was then applied to the Validation Sample.

RESULTS

A total of 35 MSKI were diagnosed by Health Services Centre staff. The majority of the MSKI were acute (63%), sustained to the hip, knee, and ankle (74%). The most common diagnoses were strains and sprains (71%). Uninjured participants performed significantly better on the Relative Isometric Mid-Thigh Pull, FORCE 20 mR, FORCE ILS, and FORCE Estimated VO2peak compared to injured participants. Logistic regression analysis showed that the only variable with significant independent association with diagnosed MSKI incidence was self-reported previous history of MSKI. However, the backward stepwise logistic regression analysis retained self-reported previous history of MSKI, FORCE SBD, FORCE Estimated VO2peak, and Isometric Mid-Thigh Pull Peak Force as predictors of MKSI. The logistic regression model including these variables could predict MSKI with an accuracy of 79% in the Development Sample and 67% in the Validation Sample.

CONCLUSION

This study provides preliminary support for the value of measures of absolute muscular strength and cardiorespiratory fitness as predictors of MSKI in Canadian basic infantry candidates. Given the associations between physical performance measures and MSKI, and their necessity during occupational tasks, it is recommended that Canadian basic infantry training facilities integrate resistance training with external loads to best prepare their candidates to meet their occupational demands and potentially minimize MSKI. Further investigations to confirm the predictive capacity of these variables in a larger sample across additional facilities are warranted.

Efficacy of neuromuscular exercises to promote movement quality and reduce musculoskeletal injury during initial military training in Royal Navy recruits

INTRODUCTION

Musculoskeletal injuries (MSKIs) are a significant problem in the Royal Navy, contributing to 48% of all medical discharges from service between 2019 and 2020. The objective of the study was to assess efficacy of implementing a neuromuscular training intervention to improve movement quality and reduce MSKIs in Royal Navy recruits undertaking initial military training.

METHODS

Neuromuscular training (pre-activation exercises, focusing on hip control) was integrated into the warm-up exercise regimen preceding physical training during the 10-week initial naval training (recruits) programme (January-March 2020) at HMS Raleigh (intervention group; n=162). A control group comprised (n=90) of recruits entering training from January 2019, who completed the standard warm-up programme prior to physical training. Movement control of the intervention group (intervention) was assessed before and after the 10-week programme using the Hip and Lower-Limb Movement Screen (HLLMS). Injury incidence proportion for both groups was determined retrospectively by review of medical notes.

RESULTS

The control group's MSKI incidence proportion was 31%, which was higher (p<0.05) than the 8% reported in the intervention group. The majority of MSKIs were of the lower limb, and were reported in weeks 1, 2 and 5 of the 10-week training programme. Movement control, as assessed by the HLLMS score, improved (pretraining (week 1) and post-training (week 10) HLLMS score (mean (SD) pre: 11.2 (5.6); post: 8.4 (3.9); t=5.829, p<0.001) following the neuromuscular training in the intervention group but was not assessed in the control group.

CONCLUSION

A neuromuscular control intervention was successfully implemented during the initial military training in the Royal Navy. The cohort undertaking the intervention demonstrated lower injury incidence compared with an equivalent cohort of recruits who undertook standard training. Movement control improved following the intervention, indicating better movement quality. Continued use of the programme may reduce military training attrition in the Royal Navy.

Beyond change scores: Employing an improved statistical approach to analyze the impact of entry fitness on physical performance during British Army basic training in men and women

The aim was to use a robust statistical approach to examine whether physical fitness at entry influences performance changes between men and women undertaking British Army basic training (BT). Performance of 2 km run, seated medicine ball throw (MBT) and isometric mid-thigh pull (MTP) were assessed at entry and completion of Standard Entry (SE), Junior Entry-Short (JE-Short), and Junior Entry-Long (JE-Long) training for 2350 (272 women) recruits. Performance change was analyzed with entry performance as a covariate (ANCOVA), with an additional interaction term allowing different slopes for courses and genders (p < 0.05). Overall, BT courses saw average improvements in 2 km run performance (SE: -6.8% [-0.62 min], JE-Short: -4.6% [-0.43 min], JE-Long: -7.7% [-0.70 min]; all p < 0.001) and MBT (1.0-8.8% [0.04-0.34 m]; all p < 0.05) and MTP (4.5-26.9% [6.5-28.8 kg]; all p < 0.001). Regression models indicate an expected form of "regression to the mean" whereby test performance change was negatively associated with entry fitness in each course (those with low baseline fitness exhibit larger training improvements; all interaction effects: p < 0.001,η p 2 $$ {\eta}_{\mathrm{p}}^2 $$  > 0.006), particularly for women. However, when matched for entry fitness, men displayed considerable improvements in all tests, relative to women. Training courses were effective in developing recruit physical fitness, whereby the level of improvement is, in large part, dependent on entry fitness. Factors including age, physical maturity, course length, and physical training, could also contribute to the variability in training response between genders and should be considered when analyzing and/or developing physical fitness in these cohorts for future success of military job-task performance.

Introducing a new method to record injuries during military training: a prospective study among 296 young Norwegian conscripts

INTRODUCTION

Most epidemiological studies in the field of military medicine have been based on data from medical records and registries. The aims of this study were to test a self-reporting injury surveillance system commonly used in sports medicine in a military setting, and to describe the injury pattern among Norwegian army conscripts during a period of military training.

METHOD

A total of 296 conscripts in His Majesty the King's Guard were asked to report all injuries each week for 12 weeks, using a modification of the Oslo Sports Trauma Research Center Questionnaire on Health Problems (OSTRC-H2). We recorded all injuries irrespective of their need for medical attention or consequences for military participation. In addition, we retrieved data on injuries recorded by military physicians in the medical record from the Norwegian Armed Forces Health Register.

RESULTS

The mean weekly response rate was 74%. A total of 357 injuries were recorded, of which 82% were only captured through the OSTRC-H2 and 3% only in the medical records. The average weekly prevalence of injury was 28% (95% CI: 25% to 31%), and 10% (95% CI: 8% to 12%) experienced injuries with a substantial negative impact on training and performance. The greatest injury burden was caused by lower limb injuries, with knee and foot injuries as the predominant injury locations.

CONCLUSION

The OSTRC-H2 is suitable for use in a military setting and records substantially more injuries than the standard medical record. The prevalence of injuries among conscripts is high and comparable with many elite sports.

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.

A Comprehensive Analysis of Injuries During Army Basic Military Training

INTRODUCTION

The injury definitions and surveillance methods commonly used in Army basic military training (BMT) research may underestimate the extent of injury. This study therefore aims to obtain a comprehensive understanding of injuries sustained during BMT by employing recording methods to capture all physical complaints.

MATERIALS AND METHODS

Six hundred and forty-six recruits were assessed over the 12-week Australian Army BMT course. Throughout BMT injury, data were recorded via (1) physiotherapy reports following recruit consultation, (2) a member of the research team (third party) present at physical training sessions, and (3) recruit daily self-reports.

RESULTS

Two hundred and thirty-five recruits had ≥1 incident injury recorded by physiotherapists, 365 recruits had ≥1 incident injury recorded by the third party, and 542 recruits reported ≥1 injury-related problems via the self-reported health questionnaire. Six hundred twenty-one, six hundred eighty-seven, and two thousand nine hundred sixty-four incident injuries were recorded from a total of 997 physiotherapy reports, 1,937 third-party reports, and 13,181 self-reported injury-related problems, respectively. The lower extremity was the most commonly injured general body region as indicated by all three recording methods. Overuse accounted for 79% and 76% of documented incident injuries from physiotherapists and the third party, respectively.

CONCLUSIONS

This study highlights that injury recording methods impact injury reporting during BMT. The present findings suggest that traditional injury surveillance methods, which rely on medical encounters, underestimate the injury profile during BMT. Considering accurate injury surveillance is fundamental in the sequence of injury prevention, implementing additional injury recording methods during BMT may thus improve injury surveillance and better inform training modifications and injury prevention programs.

Influence of combat boot types on in-shoe forces and perceived comfort during unloaded and loaded walking

INTRODUCTION

Combat boots are essential protective gear for military personnel. The purposes of the present study were to examine (1) the influence of combat boot type on ground reaction force (GRF) variables and perceived comfort during unloaded and loaded walking and (2) the relationship between comfort and biomechanical measurements.

METHODS

Four types of combat boots with different physical features (eg, mass, thickness) and mechanical properties (eg, cushioning, rigidity) were compared across 61 male participants with experience in military marching while carrying heavy loads. In each boot type, participants completed a 10-m walk under an unloaded and a 20-kg loaded conditions at their preferred speeds. Peak force and loading rate during walking were measured using the loadsol wireless in-shoe sensor system. Comfort level was assessed using a 7-point Likert scale. Difference between loaded and unloaded walking, and across boot types were statistically compared. Correlation analyses were performed between comfort and GRF variables.

RESULTS

On average across all boot types, participants walked 2.1% slower when carrying 20-kg loads while experiencing 24.3% higher peak force and 20.8% higher loading rate. Boot D was perceived as most comfortable, followed by boots C, B and A (χ2(2)=115.4, p<0.001). Participants walked slightly faster (p=0.022, ηp 2 = 0.052) and displayed higher loading rates (p<0.001, ηp 2=0.194) in the two more comfortable boots (C and D) than the less comfortable boots (A and B). No significant correlations were found between perceived comfort and any GRF variables.

CONCLUSIONS

Combat boot features can influence perceived comfort ratings substantially during walking, whereas biomechanical differences among boot types are more subtle regardless of load conditions. The lack of relationship between comfort and force variables suggests that both subjective and objective measurements should be considered for comprehensive evaluation of combat boots.

Diagnostic and Therapeutic Challenges in a Military Recruit Training Center of the Hellenic Navy: A Retrospective Analysis of the Poros Registry Serving as a Quality Improvement Project for Medical Officers

INTRODUCTION

Basic military training (BMT) has been associated with increased morbidity burden. Nevertheless, the exact epidemiology of the encountered cases in the BMT of Greek recruits has never been assessed. The aim of this quality improvement project was to investigate for the first time the clinical patterns, rates, and severity of symptoms leading recruits to visit the infirmary of a recruit training center and use this knowledge to provide a practical guidance for the physicians in charge.

MATERIALS AND METHODS

All medical cases which were consecutively examined for the time range from November 2021 to September 2022 at the infirmary of the Hellenic Naval recruit training center in Poros, Greece, were retrospectively analyzed. Logistic regression analyses were performed to identify independent predictors of "severe clinical status" (i.e., overnight sick bay confinement and/or transfer to a tertiary hospital within 24 h) and absence from BMT for at least 1 day.

RESULTS

A total of 2,623 medical cases were examined during four recruit seasons from November 2021 to September 2022. Upper respiratory tract infections (URTIs) and musculoskeletal injuries were the most frequent reasons for a recruit's visit to the infirmary (33.9% and 30.2%, respectively). 6.7% of the total cases were identified as having "severe clinical status." Specifically, in psychiatric, urological, and cardiovascular cases, febrile events were all independently associated with increased risk of "severe clinical status." There was a positive association between training week and absence from BMT, while febrile events and spring recruit season were also independently linked with increased probability of absence from BMT for at least 1 day.

CONCLUSIONS

URTIs and musculoskeletal complaints were the primary reasons for recruits' presentation at the infirmary of a Greek recruit training center, leading to severe rates of attrition. Further registries and quality improvement projects are warranted to reach specific conclusions and reduce BMT-related morbidity and its subsequent implications.

Profiling injuries sustained following implementation of a progressive load carriage program in United States marine corps recruit training

BACKGROUND

Load carriage tasks during United States Marine Corps (USMC) recruit training can cause injury. Load carriage conditioning, if optimized, can reduce injury risk.

OBJECTIVE

To compare injuries sustained by USMC recruits following participation in either the Original Load Carriage (OLC) program or a Modified Load Carriage (MLC) program.

METHODS

Retrospective musculoskeletal injury data were drawn from the USMC San Diego Sports Medicine injury database for recruits completing the OLC (n = 2,363) and MLC (n = 681) programs. Data were expressed as descriptive statistics and a population estimate of the OLC:MLC relative risk ratio (RR) was calculated.

RESULTS

The proportion of injuries sustained in the MLC cohort (n = 268; 39% : OLC cohort, n = 1,372 : 58%) was lower, as was the RR (0.68, 95% CI 0.61- 0.75). The leading nature of injury for both cohorts was sprains and strains (OLC n = 396, 29%; MLC n = 66; 25%). Stress reactions were proportionally higher in MLC (n = 17, 6%; OLC n = 4, 0.3%), while stress fractures were proportionately lower (MLC n = 9, 3%; OLC n = 114, 8%). Overuse injuries were lower in MLC (- 7%). The knee, lower leg, ankle, and foot were the top four bodily sites of injuries and the Small Unit Leadership Evaluation (SULE), Crucible, overuse-nonspecific, running, and conditioning hikes were within the top five most common events causing injury. The prevalence rates of moderate severity injury were similar (MLC = 23%; OLC = 24%), although MLC presented both a higher proportion and prevalence of severe injuries (MLC = 6%; OLC = 3%, respectively).

CONCLUSION

A periodized load carriage program concurrently increased exposure to load carriage hikes while reducing injuries both during the load carriage hikes and overall.

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.

Vitamin D Metabolites Are Associated With Musculoskeletal Injury in Young Adults: A Prospective Cohort Study

The relationship between vitamin D metabolites and lower body (pelvis and lower limb) overuse injury is unclear. In a prospective cohort study, we investigated the association between vitamin D metabolites and incidence of lower body overuse musculoskeletal and bone stress injury in young adults undergoing initial military training during all seasons. In 1637 men and 530 women (aged 22.6 ± 7.5 years; body mass index [BMI], 24.0 ± 2.6 kg/m- 2 ; 94.3% white ethnicity), we measured serum 25-hydroxyvitamin D (25(OH)D) and 24,25-dihydroxyvitamin D (24,25(OH)2 D) by high-performance liquid chromatography tandem mass spectrometry, and 1,25-dihydroxyvitamin D (1,25(OH)2 D) by immunoassay during week 1 of training. We examined whether the relationship between 25(OH)D and 1,25(OH)2 D:24,25(OH)2 D ratio was associated with overuse injury. During 12 weeks of training, 21.0% sustained ≥1 overuse musculoskeletal injury, and 5.6% sustained ≥1 bone stress injury. After controlling for sex, BMI, 2.4 km run time, smoking, bone injury history, and Army training course (Officer, standard, or Infantry), lower body overuse musculoskeletal injury incidence was higher for participants within the second lowest versus highest quartile of 24,25(OH)2 D (odds ratio [OR] = 1.62; 95% confidence interval [CI] 1.13-2.32; p = 0.009) and lowest versus highest cluster of 25(OH)D and 1,25(OH)2 D:24,25(OH)2 D (OR = 6.30; 95% CI 1.89-21.2; p = 0.003). Lower body bone stress injury incidence was higher for participants within the lowest versus highest quartile of 24,25(OH)2 D (OR = 4.02; 95% CI 1.82-8.87; p < 0.001) and lowest versus highest cluster of 25(OH)D and 1,25(OH)2 D:24,25(OH)2 D (OR = 22.08; 95% CI 3.26-149.4; p = 0.001), after controlling for the same covariates. Greater conversion of 25(OH)D to 24,25(OH)2 D, relative to 1,25(OH)2 D (ie, low 1,25(OH)2 D:24,25(OH)2 D), and higher serum 24,25(OH)2 D were associated with a lower incidence of lower body overuse musculoskeletal and bone stress injury. Serum 24,25(OH)2 D may have a role in preventing overuse injury in young adults undertaking arduous physical training. © 2023 Crown copyright and The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). This article is published with the permission of the Controller of HMSO and the King's Printer for Scotland.

Assessment of Training Load, Sleep, Injuries, and Operational Physical Performance During Basic Military Qualification

INTRODUCTION

Optimizing training load (TL) and sleep is essential to maximize physical performance and prevent musculoskeletal injuries (MSKIs) for Canadian forces recruits during the 10-week basic military qualification (BMQ) course. The purpose of this study was to assess the TL, sleep duration, the occurrence of MSKIs during the BMQ, and the operation fitness performance during the BMQ.

MATERIALS AND METHODS

Forty Canadian recruits, eight females and 32 males, (age 24 ± 5 years; height 176.4 ± 10.4 cm), were monitored with an accelerometer (GENEActiv) on their wrist between weeks 1 and 9 to evaluate the TL and sleep duration. During weeks 2 and 10, the recruits completed an operational fitness evaluation. Injury surveillance was performed over 10 weeks.

RESULTS

TL intensity was significantly different (P = 0.0001) from week to week. The weekly average total time of moderate and vigorous physical activity was 189.7 ± 48.1 min and 44.7 ± 15.2 min, respectively. The average sleep duration was 5.4 ± 0.4 h per night and decreased to 4.2 h ± 0.4 during field exercises. A significant difference in sleep duration was observed between recruits with and without a MSKI. The recruits accumulated a total of 95 days under medical restrictions with an average of 3.8 consecutive days. The VO2peak estimated from the Fitness for Operational Requirements of Canadian Armed Forces Employment job-based simulation test significantly improved from weeks 2 to 10 (pre, 47.1 ± 6.3; post: 50.2 ± 5.8; P = 0.001).

CONCLUSIONS

TL is of high magnitude and varies from week to week. The reported mean sleep duration per week may perhaps negatively impact the occurrence of MSKI. No significant improvement was detected in operational fitness by the end of the BMQ.

Influence of smoking status on acute biomarker responses to successive days of arduous military training

INTRODUCTION

Habitual smoking is highly prevalent in military populations despite its association with poorer training outcomes. Smoking imposes challenges on the immune and endocrine systems which could alter how smokers acutely respond to, and recover from, intensive exercise particularly over multiple days of training.

METHODS

Over a two-day period, 35 male British Army recruits (age 22±3 years; mass 76.9±8.0 kg; height 1.78±0.06 m; 15 smokers) completed a 16.1 km loaded march (19.1 kg additional mass) on the first morning and a best-effort 3.2 km 'log race' (carrying a 60 kg log between six and eight people) on the subsequent morning. Blood samples were obtained on waking and immediately postexercise on both days and analysed for C reactive protein (CRP), interleukin 6 (IL-6), testosterone to cortisol ratio and insulin-like growth factor 1 (IGF-1).

RESULTS

Independent of smoking group, the exercise bouts on both days evoked significant increases in IL-6 (p<0.001) and decreases in testosterone to cortisol ratio (p<0.05). CRP concentrations on day 2 were significantly higher than both time points on day 1 (p<0.001), and a 9% decline in IGF-1 occurred over the two-day period, but was not significant (p=0.063). No significant differences were observed between smokers and non-smokers (p>0.05).

CONCLUSIONS

Military-specific tasks elicited inflammatory and endocrine responses, with systemic CRP and IGF-1 indicating that the physiological stress generated during the first training day was still evident on the second day. Despite the well-established impacts of smoking on resting levels of the markers examined, responses to two days of arduous military-specific training did not differ by smoking status.

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.

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.

The Influence of Previous Lifestyle on Occupational Physical Fitness in the Context of Military Service

The Estonian Defense Forces are the basis of military service, mandatory for all male citizens of the Republic of Estonia who are at least 17 years old. The physical load in military service, especially in the first stage, is significantly greater than for men in everyday life. Therefore, it is important to know if health promotion in civilian life adequately prepares young people for military service and to what extent pre-military health behaviors affect physical performance during service. The purpose of this work was to examine conscripts' physical fitness at different stages of military service and its relationships with previous lifestyle. Soldiers' physical fitness was estimated three times during military service using three tests: sit-ups, push-ups and 2-mile run. Lifestyle and socio-economic background data was collected by a web-based questionnaire (n = 235). Linear regression analysis was performed using Army Physical Fitness Test (APFT) scores as dependent variables and questionnaire data as independent variables. The socio-economic background variables had no effect on physical fitness scores throughout the training period (p > 0.05). Young men that were physically more active daily, did sports, had healthier diet and did not smoke before entering military service showed better physical fitness test results throughout the period of service (p < 0.05). The effect of participation in sports was evident, as the conscripts with previous sports experiences demonstrated higher fitness tests scores (p < 0.01). These findings show that health promotion initiatives or programs for promoting physical activity and healthy diet, and preventing obesity and tobacco use, can also have a positive effect on the physical performance of young men during military service.

Sex-related Differences in Functional Movement Screen Scores Among Reserve Officers' Training Corps Cadets

INTRODUCTION

The primary aim of Reserve Officers' Training Corps (ROTC) programs is to prepare cadets for future military service. To successfully complete one of these programs and perform active duty responsibilities, cadets must be able to complete a variety of physical tasks. Therefore, performing movement screening may be useful for identifying potential movement disparities that could lead to injury. The purpose of this investigation was to determine whether sex-related differences in movement patterns exist on the Functional Movement Screen (FMS). The FMS is a tool that uses seven functional movements to assess movement pattern deficits and asymmetries; deep squat, hurdle step, inline lunge (ILL), shoulder mobility, active straight-leg raise (ASLR), trunk stability pushup (TSPU), and rotary stability.

MATERIALS AND METHODS

Archived data for 93 (male, n = 69; female n = 24) ROTC cadets were provided to the primary investigators for analysis. Independent t-tests (P < .05) were conducted to analyze differences in assessments between sexes.

RESULTS

Significant differences between sexes were observed on the ILL (P = .014), ASLR (P < .001), and TSPU (P < .001). Females scored higher on both the ILL (2.13 ± 0.54) and ASLR (2.04 ± 0.69) compared with males (1.81 ± 0.52 and 1.48 ± 0.58). Males scored significantly higher (P ≤ .001) on the TSPU (2.57 ± .581) compared with females (2.00 ± .417). No significant differences were observed in the deep squat (P = .865), hurdle step (P = .829), shoulder mobility (P = .342), and rotary stability (P = .230) assessments.

CONCLUSIONS

Sex differences in the ILL, ASLR, and TSPU may be because of greater mobility in the ankle and hamstrings and reduced upper-body muscle mass for females compared with males. Males performed better than females on the TSPU test. In conclusion, sex-related differences in FMS performance do exist within the ROTC population. Additionally, these differences should be taken into consideration when designing specific exercise programs for ROTC cadets.

Changes in eating pathology symptoms during initial military training in men and women and associations with BMI and injury risk

Nutritional fitness, which comprises food choices, meal timing, and dietary intake behaviors, is an important component of military service member health and performance that has garnered recent attention. This study utilized generalized linear mixed effects modeling (GLMM) to investigate changes in eating pathology symptoms in men and women during initial military training (Marine Corps Officer Candidates School (OCS)). Associations among eating pathology, musculoskeletal injury risk and BMI were also assessed. This investigation includes data from the Eating Pathology Symptoms Inventory (EPSI) and BMI at the start of OCS (n = 598: Male n = 469, Female n = 129) and end of the 10-week program (n = 413: Male n = 329, Female n = 84), and injury surveillance throughout. At baseline, female candidates presented with greater body dissatisfaction, binge eating, purging, and restricting, but lower negative attitudes toward obesity compared to male candidates (p < 0.001). Eating symptoms changed during military training indicated by decreased body dissatisfaction in women (p = 0.003), decreased excessive exercise and negative attitudes toward obesity in men (p < 0.001), decreased cognitive restraint (p < 0.001), restricting (p < 0.001), purging (p = 0.013), and muscle building (p < 0.001) and increased binge eating (p < 0.001) in both sexes. Changes in restricting were significantly related to changes in BMI during training (p < 0.05). The likelihood of future injury was 108 % higher in female candidates than males and decreased by 5 % for each unit increase in excessive exercise. Eating attitudes and behaviors change during military training environments and are associated with military health and readiness outcomes including BMI and injury risk.

Comprehensive Physical Activity Assessment During U.S. Army Basic Combat Training

ABSTRACT

Alemany, JA, Pierce, JR, Bornstein, DB, Grier, TL, Jones, BH, and Glover, SH. Comprehensive physical activity assessment during U.S. Army Basic Combat Training. J Strength Cond Res 36(12): 3505-3512, 2022-Physical activity (PA) volume, intensity, and qualitative contextual information regarding activity type and loads carried are limited during U.S. Army Basic Combat Training (BCT). The purpose of this study was to characterize daily (05:00-20:00 hours) PA during BCT using a comprehensive approach. During 2 10-week BCT cycles ( n = 40 trainees per cycle), pedometers, accelerometers, and direct observation were used to estimate daily step count, PA volume, and intensity. Physical activity intensity was categorized by metabolic equivalents (METs) such as "sedentary" (1-2 METs), "light" (2-3 METs), "moderate" (3-6 METs), or "vigorous" (≥6 METs). Daily PA data were analyzed longitudinally using linear mixed models, with significance set at p ≤ 0.05. The mean daily step count was 13,459 ± 4,376 steps, and the mean daily accelerometer-assessed PA volume and intensity were as follows: sedentary: 505 ± 98 minutes, light: 190 ± 78 minutes, moderate: 168 ± 51 minutes, and vigorous: 14 ± 14 minutes, with no differences between cycles for all measures ( p > 0.50). Cumulative time on feet (∼50%) and sitting (20-25%) accounted for most daily activity types during both cycles. Trainees, on average, carried between 3 and 9 kg, and ≥9 kg, for 60% and 10% of the monitored day, respectively. Basic Combat Training's physical demands are high, where trainees achieved 1.7 to 2.7 times greater daily ambulation and 6 times the recommended weekly moderate-to-vigorous PA compared with civilian counterparts and performed weight-bearing load carriage for nearly half of the day. Basic Combat Training-associated PA may increase injury risk among trainees unaccustomed to arduous PA and exercise. Implementing national PA policies to improve physical fitness and facilitate acclimatization to BCT's high physical demands could reduce public health burdens and military nonreadiness.

Quantification of Recruit Training Demands and Subjective Wellbeing during Basic Military Training

Purpose: Assess and describe the physical demands and changes in subjective wellbeing of recruits completing the 12 week Australian Army Basic Military Training (BMT) course. Methods: Thirty-five recruits (24.8 ± 6.8 y; 177.4 ± 10.1 cm, 75.6 ± 14.7 kg) consented to daily activity monitoring and weekly measures of subjective wellbeing (Multi-component Training Distress Scale, MTDS). The physical demands of training were assessed via wrist worn activity monitors (Actigraph GT9X accelerometer). Physical fitness changes were assessed by push-ups, sit-ups and multi-stage shuttle run in weeks 2 and 8. Results: All objective and subjective measures significantly changed (p < 0.05) across the 12 week BMT course. In parallel, there was a significant improvement in measures of physical fitness from weeks 2 to 8 (p < 0.001). The greatest disturbance to subjective wellbeing occurred during week 10, which was a period of field training. Weeks 6 and 12 provided opportunities for recovery as reflected by improved wellbeing. Conclusions: The physical demands of training varied across the Australian Army 12 week BMT course and reflected the intended periodization of workload and recovery. Physical fitness improved from week 2 to 8, indicating a positive training response to BMT. Consistent with findings in sport, wellbeing measures were sensitive to fluctuations in training stress and appear to have utility for individual management of personnel in the military training environment.

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

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

Unsupervised Clustering Techniques Identify Movement Strategies in the Countermovement Jump Associated With Musculoskeletal Injury Risk During US Marine Corps Officer Candidates School

Musculoskeletal injuries (MSKI) are a significant burden on the military healthcare system. Movement strategies, genetics, and fitness level have been identified as potential contributors to MSKI risk. Screening measures associated with MSKI risk are emerging, including novel technologies, such as markerless motion capture (mMoCap) and force plates (FP) and allow for field expedient measures in dynamic military settings. The aim of the current study was to evaluate movement strategies (i.e., describe variables) of the countermovement jump (CMJ) in Marine officer candidates (MOCs) via mMoCap and FP technology by clustering variables to create distinct movement strategies associated with MSKI sustained during Officer Candidates School (OCS). 728 MOCs were tested and 668 MOCs (Male MOCs = 547, Female MOCs = 121) were used for analysis. MOCs performed 3 maximal CMJs in a mMoCap space with FP embedded into the system. De-identified MSKI data was acquired from internal OCS reports for those who presented to the OCS Physical Therapy department for MSKI treatment during the 10 weeks of OCS training. Three distinct clusters were formed with variables relating to CMJ kinetics and kinematics from the mMoCap and FPs. Proportions of MOCs with a lower extremity and torso MSKI across clusters were significantly different (p < 0.001), with the high-risk cluster having the highest proportions (30.5%), followed by moderate-risk cluster (22.5%) and low-risk cluster (13.8%). Kinetics, including braking rate of force development (BRFD), braking net impulse and propulsive net impulse, were higher in low-risk cluster compared to the high-risk cluster (p < 0.001). Lesser degrees of flexion and shorter CMJ phase durations (braking phase and propulsive phase) were observed in low-risk cluster compared to both moderate-risk and high-risk clusters. Male MOCs were distributed equally across clusters while female MOCs were primarily distributed in the high-risk cluster. Movement strategies (i.e., clusters), as quantified by mMoCap and FPs, were successfully described with MOCs MSKI risk proportions between clusters. These results provide actionable thresholds of key performance indicators for practitioners to use for screening measures in classifying greater MSKI risk. These tools may add value in creating modifiable strength and conditioning training programs before or during military training.

Profiles of Recruits Entering Army Basic Training in New Zealand

INTRODUCTION

A high incidence of musculoskeletal injuries is sustained by army recruits during basic training. Describing recruits' personal, lifestyle, and physical performance characteristics at the entry to training can help identify existing intrinsic risk factors that may predispose some recruits to injury. Identifying modifiable and preventable intrinsic risk factors may contribute to lower recruit injury and associated burdens during the course of basic training. The aim of this study was to therefore describe the profile of New Zealand Army recruits upon entry to basic training using personal, lifestyle, and physical performance characteristics.

METHODS

New Zealand Army male and female recruits from two intakes in the same year were invited to participate. Recruits' data on personal (sex, age, height, and weight), lifestyle (self-reported responses to the Military Pre-training Questionnaire comprising physical and injury history, diet, alcohol, and smoking status) and physical performance characteristics (2.4-km timed run, weight-bearing dorsiflexion lunge test, and the Y Balance TestTM for lower limb dynamic stability) were collected and analyzed.

RESULTS

Participants included 248 New Zealand Army recruits: 228 males (91.9%), 20 females (8.1%), average age of 20.3 ± 2.8 years. Findings indicated 30.9% of recruits reported injury in the 12 months prior to training commencing, with 44.8% of those injuries in the lower limbs. Pre-entry alcohol consumption was higher than recommended and 20.1% of recruits identified as current smokers. Recruits who passed the 2.4-km timed run included 53.8% of males and 28.6% of females. Weight-bearing dorsiflexion lunge test performance was within a normal range (right = 10.3 ± 3.3 cm), however limb asymmetry (>1.5 cm) was present with 30.9% of recruits. For the Y Balance TestTM for dynamic lower limb stability, 70% of female recruits had high posterolateral reach asymmetry (8.1 ± 6.0 cm), while normalized composite reach scores were low (right) for male (92.2 ± 8.1%) and female recruits (89.0 ± 7.5%).

CONCLUSIONS

New Zealand Army recruits entering basic training were predominantly active young males, reported few injuries in the previous year, had higher than recommended alcohol consumption and a minority were smokers. The majority of recruits had low aerobic fitness, average ankle dorsiflexion range, and low dynamic lower limb stability. While a number of adverse characteristics identified are potentially modifiable, more research is required to identify an association to musculoskeletal injury risk in New Zealand Army recruits. Describing the profile of recruits entering training, particularly recruits at risk of injury is one of the first steps in injury prevention.

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.

Tibial Bone Geometry Is Associated With Bone Stress Injury During Military Training in Men and Women

Bone stress injuries (BSI) are a common musculoskeletal condition among exercising and military populations and present a major burden to military readiness. The purpose of this investigation was to determine whether baseline measures of bone density, geometry, and strength, as assessed via peripheral quantitative computed tomography (pQCT), are predictive of tibial BSI during Marine Officer Candidates School training. Tibial pQCT scans were conducted prior to the start of physical training (n = 504; Male n = 382; Female n = 122) to measure volumetric bone mineral density (vBMD), geometry, robustness, and estimates of bone strength. Bone parameters were assessed at three tibial sites including the distal metaphysis (4% of tibial length measured from the distal endplate), mid-diaphysis (38% of tibial length measured from the distal endplate), and proximal diaphysis (66% of tibial length measured from the distal endplate). Injury surveillance data was collected throughout training. Four percent (n = 21) of the sample were diagnosed with a BSI at any anatomical site during training, 10 injuries were of the tibia. Baseline bone parameters were then tested for associations with the development of a tibial BSI during training and it was determined that cortical bone measures at diaphyseal (38 and 66%) sites were significant predictors of a prospective tibial BSI. At the mid-diaphysis (38% site), in a simple model and after adjusting for sex, age, and body size, total area [Odds Ratio (OR): 0.987, 0.983], endosteal circumference (OR: 0.853, 0.857), periosteal circumference (OR: 0.863, 0.824), and estimated bending strength (SSI; OR: 0.998, 0.997) were significant predictors of a BSI during training, respectively, such that lower values were associated with an increased likelihood of injury. Similarly, at the proximal diaphysis (66% site), total area (OR: 0.989, 0.985), endosteal circumference (OR: 0.855, 0.854), periosteal circumference (OR: 0.867, 0.823), robustness (OR: 0.007, 0.003), and SSI (OR: 0.998, 0.998) were also significant predictors of BSI in the simple and adjusted models, respectively, such that lower values were associated with an increased likelihood of injury. Results from this investigation support that narrower bones, with reduced circumference, lower total area, and lower estimated strength are associated with increased risk for tibial BSI during military training.

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.

Prevalence of Musculoskeletal Injuries in New Zealand Army Recruits as Defined by Physical Therapy Service Presentations

INTRODUCTION

Army recruit injuries occurring during basic training can lead to high personal and organizational burdens potentially threatening deployment capability. Previous military surveillance describing recruit injury as defined by physical therapy presentations is limited to 1-year duration or includes only male infantry recruits or trained personnel. Research describing injury incidence and trends specific to New Zealand Army basic training recruits over a longer period will better inform future injury prevention programs.

AIMS

To identify the incidence and patterns of injuries reported from physical therapy presentations for New Zealand Army recruits undertaking basic training over a 4-year period.

MATERIALS AND METHODS

This retrospective observational study identified injuries from physical therapy service presentations in New Zealand Army recruits from 2008 to 2011. All male and female New Zealand Army recruits who presented to physical therapy, following medical triage, were included. Recruit physical therapy presentations for injury and respiratory and other conditions were collated. Injury incidence was grouped by body region (upper limbs, lower limbs, and combined spinal regions) and site (joint or segment), and cumulative and injury incidence rates were calculated.

RESULTS

One thousand eight hundred and ninety-six (1,697 males and 199 females) New Zealand Army recruits commenced basic training between 2008 and 2011. One thousand six hundred and eighty-three physical therapy presentations occurred for recruit injury during New Zealand Army basic training over 4 years. Lower limb injuries accounted for over 75% (n = 1,285) of the overall demand for physical therapy service during recruit basic training. Injuries sustained at the knee and below accounted for 67% of all reported injury presentations.

CONCLUSION

Four years of injury surveillance using physical therapy presentations identified the lower limb, with the knee and below as the most commonly injured regions in New Zealand Army recruits. Injury prevention interventions for New Zealand Army recruits should aim to reduce lower limb injuries. Future research on injury surveillance would benefit from incorporating clear injury and severity definitions, established injury classification systems, and standardized incidence calculations.

Soldier Load Carriage, Injuries, Rehabilitation and Physical Conditioning: An International Approach

Soldiers are often required to carry heavy loads that can exceed 45 kg. The physiological costs and biomechanical responses to these loads, whilst varying with the contexts in which they are carried, have led to soldier injuries. These injuries can range from musculoskeletal injuries (e.g., joint/ligamentous injuries and stress fractures) to neurological injuries (e.g., paresthesias), and impact on both the soldier and the army in which they serve. Following treatment to facilitate initial recovery from injuries, soldiers must be progressively reconditioned for load carriage. Optimal conditioning and reconditioning practices include load carriage sessions with a frequency of one session every 10-14 days in conjunction with a program of both resistance and aerobic training. Speed of march and grade and type of terrain covered are factors that can be adjusted to manipulate load carriage intensity, limiting the need to adjust load weight alone. Factors external to the load carriage program, such as other military duties, can also impart physical loading and must be considered as part of any load carriage conditioning/reconditioning program.

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.

Despite an improved aerobic endurance, still high attrition rates in initially low-fit recruits-results of a randomised controlled trial

Background

Low baseline fitness of recruits entering basic military training (BMT) is associated with an increased risk of musculoskeletal injuries (MSIs) and attrition from training.

Objective

To determine the effects of a pre-training conditioning program (PCP) on aerobic endurance, incidence of musculoskeletal injuries (MSIs), and attrition rates in BMT of a special infantry unit of the Netherlands Armed Forces.

Participants

Recruits were considered eligible for this study when they were ‘low-fit’ at the start of BMT (time to complete a 2.7-km run ≥ 12′23″).

Interventions

‘Low-fit’ recruits were deferred to a seven to twelve week—depending on the time between two consecutive training platoons—PCP consisting of functional training to improve several fitness domains. The control (CON) group started regular BMT without delay.

Results

Forty-nine recruits were included in this study; 26 in the PCP-group and 23 in the CON-group. Recruits who followed the PCP started BMT with better aerobic endurance than the CON-group who started BMT immediately (2.7 km run timings: PCP 11′32″, CON 13′16″). The risk of dropout was lower in the PCP-group (incidence density ratio (IDR) 0.63, 95%CI 0.32; 1.26), but dropout due to training-related MSIs was more frequent (IDR 1.23, 95%CI 0.32; 4.76 (per-protocol 0.94, 95%CI 0.24; 3.63), without statistically significant differences between the groups.

Conclusion

Although a PCP was effective to improve aerobic endurance in low-fit recruits to return to meet pre-enlistment fitness criteria, we could not demonstrate an effect on dropout from military training.

Trial registration

Dutch trial register Trial NL6791 (NTR6977) https://www.trialregister.nl/trial/6791.

•

Low baseline fitness of recruits is associated with musculoskeletal injuries and dropout from military training.

•

A pre-training conditioning program was capable of improving physical fitness in low-fit recruits.

•

However, dropout from training remained high, perhaps due to common other causes.

•

Future research should focus on identifying these physical, social and mental factors, and their interactions.

Worldwide epidemiology of foot and ankle injuries during military training: a systematic review

INTRODUCTION

Musculoskeletal foot and ankle injuries are commonly experienced by soldiers during military training. We performed a systematic review to assess epidemiological patterns of foot and ankle injuries occurring during military training.

METHODS

A review of the literature was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search, done on 14 February 2019, resulted in 1603 reports on PubMed, 565 on Embase and 3 on the Cochrane Library. After reading the remaining full-text articles, we included 91 studies.

RESULTS

Among a population of 8 092 281 soldiers from 15 countries, 788 469 (9.74%) foot and ankle injuries were recorded. Among the 49 studies that reported on length of training, there were 36 770/295 040 (18.17%) injuries recorded among women and 248 660/1 501 672 (16.56%) injuries recorded among men over a pooled mean (±SD) training period of 4.51±2.34 months. Ankle injuries were roughly 7 times more common than foot injuries, and acute injuries were roughly 24 times more common than non-acute injuries. Our findings indicated that, during a 3-month training period, soldiers have a 3.14% chance of sustaining a foot and ankle injury. The incidence of foot or ankle injury during military parachutist training was 3.1 injuries per thousand jumps.

CONCLUSIONS

Our findings provide an overview of epidemiological patterns of foot and ankle injuries during military training. These data can be used to compare incidence rates of foot and ankle injuries due to acute or non-acute mechanisms during training. Cost-effective methods of preventing acute ankle injuries and non-acute foot injuries are needed to address this problem.

Musculoskeletal complaints in military recruits during their basic training

INTRODUCTION

Overuse injuries often start with a musculoskeletal complaint, which can progress over time to an injury. Little or no information is known about the development and severity of overuse injuries in military recruits. This study describes the musculoskeletal complaints in Dutch military recruits during their basic training and examines potential predictive factors for dropout due to injury.

METHODS

In this prospective cohort study, Dutch military recruits reported complaints of the lower body weekly using a Numeric Rating Scale (NRS) pain score chart during their basic training. Number, location and severity of complaints during each of the first 12 weeks of basic training were analysed.

RESULTS

Of the 930 recruits, 61% reported an NRS pain score of 3 or higher and 34% reported an NRS pain score of 5 or higher at least once. Complaints were mostly reported in the foot and ankle region and least reported in the upper leg region. Injury dropouts (11%) showed significantly higher proportions of complaints and higher maximal pain scores throughout most weeks of basic training. The maximal NRS pain score of the first two weeks was the strongest predictor of dropping out due to injury.

CONCLUSIONS

Recruits who drop out due to injury report more severe complaints throughout basic training. Focusing on musculoskeletal complaints in the first phase of training seems helpful to identify recruits who are at risk of developing an injury.

Electrical Stimulation Therapies for Active Duty Military with Patellofemoral Pain Syndrome: A Randomized Trial

INTRODUCTION

Patellofemoral pain syndrome (PFPS) is a common musculoskeletal disorder among military service members that causes knee pain, quadriceps strength loss, and impaired motor performance in otherwise healthy individuals. PFPS poses a threat to the health, fitness, and subsequent readiness of the total force. The goal of rehabilitation for military service members with PFPS is to regain physical capacity of strength and function and to reduce pain, in order to restore readiness in this population. The randomized controlled trial reported here compared an active home exercise program (HEP) alone with three different electrical stimulation treatment regimens implemented concurrently with HEP postulated improvements in lower extremity strength and physical functional performance while also reducing pain in active duty military diagnosed with PFPS.

MATERIALS AND METHODS

After baseline testing, 130 active duty military members with PFPS were randomized to 1 of 4 treatment groups: (1) neuromuscular electrical stimulation (NMES) with HEP; (2) transcutaneous electrical nerve stimulation (TENS) with HEP; (3) combined NMES/TENS with HEP; (4) active HEP only. The primary outcome measure was degree of change in knee flexion and extension strength over 9 weeks. Secondary outcomes were physical functional performance and knee pain. The primary analyses used repeated measures, linear mixed-effects models with a random effect for subject, time as a continuous variable, group as a categorical variable, and a group and time interaction to test for differences in change over time among the groups.

RESULTS

All three electrical stimulation treatment groups improved in knee extension strength in the PFPS limb to a greater extent than the HEP alone group over the 9-week treatment period. The NMES and NMES/TENS groups improved to a greater extent than the HEP alone group in knee flexion strength in the PFPS limb. The reported pain improved over time for all treatment groups with no significant group differences. All three stimulation groups performed better on the 6-min walk test than the HEP alone group.

CONCLUSION

The findings from this study showed that all three electrical stimulation with HEP treatment groups showed greater improvement in strength compared to the HEP alone group. These findings could offer alternative forms of rehabilitation for AD military with PFPS as these treatment regimens can be easily implemented at home station or during deployment.

Musculoskeletal disorders and their associations with health- and work-related factors: a cross-sectional comparison between Swedish air force personnel and army soldiers

BACKGROUND

The high numbers of musculoskeletal disorders (MSD) among soldiers in the Swedish Armed Forces has led to the implementation of an effective prevention program, the musculoskeletal screening protocol (MSP), including questionnaires, physical tests and individual intervention of their MSD. A corresponding MSP for the Swedish Air Force is also needed due to earlier reported high prevalence of MSD. We therefore investigated the prevalence of MSD in Swedish Air Force personnel (AF) and compared this to Swedish Army deployed soldiers (DS). Individual, health- and work-related factors associated with MSD were also investigated.

METHODS

Cross-sectional questionnaire-based study on 166 male AF and 185 DS. AF consisted of fighter pilots, helicopter pilots and rear crew from one Swedish air base.

RESULTS

The one-year and point prevalence, respectively, of MSD were significantly higher for AF compared to DS with regard to both the upper quarter of the body (i.e. neck, shoulder and thoracic regions) (AF = 54.8 and 31.3%, DS = 26.1 and 13.6%, p = 0.01) and the lumbar region (AF = 38.0 and 18.7%, DS = 22.2 and 7.1%, p = 0.00). No significant differences were present between fighter pilots, helicopter pilots and rear crew regarding MSD prevalence. Factors significantly associated with having both upper quarter and lumbar regions MSD were group (i.e. greater odds for AF than DS) and self-reported physical health as less than excellent. Additionally, being older and taller were also factors associated with lumbar region MSD.

DISCUSSION

Despite a generally healthy lifestyle, MSD were commonly reported by AF and DS, with generally higher prevalence in AF who mainly reported MSD in the upper quarter of the body. The results from this study indicate that the MSP can be a meaningful tool to prevent MSD in air force personnel and that questions regarding general health and MSD in specific body regions should be included in screening protocols. The development of the preventive program MSP is therefore recommended for the Swedish Air Force.

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 test-retest reliability of the Military Physical Loading Questionnaire (MPLQ)

INTRODUCTION

Despite the high prevalence of musculoskeletal injuries, there is a shortage of data quantifying the risk factors attributable to cumulative occupational demands among UK Military personnel. We developed a new comprehensive questionnaire that examines occupational and operational physical loading during military service. The aim of this study was to examine the test-retest reliability of the Military Physical Loading Questionnaire (MPLQ).

METHODS

Intraclass correlation coefficients (ICC) were used to evaluate the test-retest reliability (4-week interval) of the MPLQ on 18 occupational and 18 operational items in 50 male (mean age: 36 years; SD ±7.9) UK military personnel. A stratified analysis based on duration of Service (0-10 years, 11-20 years and ≥21 years) was conducted to assess whether stability of task items was dependent on participant length of recall. Internal consistency was assessed by Cronbach's alpha (α) coefficients.

RESULTS

Reliability of individual operational items ranged from fair to almost perfect agreement (ICC range: 0.37-0.89; α range: 0.53-0.94) with most items demonstrating moderate to substantial reliability. Overall scores related to occupational items showed substantial to almost perfect agreement between administrations (ICC range: 0.73-0.94; α range: 0.84-0.96). Stratifying by duration of Service showed similar within group reliability to the entire sample and no pattern of decreasing or increasing reliability with length of recall period was observed.

CONCLUSIONS

It is essential that data used in planning UK military policy and health services are as accurate as possible. This study provides preliminary support for the MPLQ as a reliable self-report instrument for assessing the cumulative lifelong effects of occupational loading in UK military personnel. Further validation studies using larger and more demographically diverse military populations will support its interpretation in future epidemiological research.

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.

Functional Movement Screen (FMS™) Scores and Demographics of US Army Pre-Ranger Candidates

Introduction

The United States Army Rangers are a unique population whose training requirements are intensive, and physically and mentally demanding. The Functional Movement Screen (FMS) is a movement screening tool designed to assess movement quality and asymmetries in movement with the potential to identify injury risk. This study was a descriptive, cross-sectional investigation examining associations between FMS scores and the various measures of health and performance of active duty soldiers in light infantry units who were involved in the U.S. Army Pre-Ranger Course (PRC).

Materials and Methods

Before the PRC, 491 male soldiers (mean age = 24.0 ± 3.8 years; mean height = 176.6 ± 7.2 cm; mean body mass = 80.2 ± 9.8 kg) completed a questionnaire which included items on self-assessed physical fitness, last Army physical fitness test (APFT) score, tobacco use, and injury history. The soldiers then completed the FMS, which consisted of seven movements and three clearing tests. From the FMS results, a determination of asymmetries (i.e., differences in FMS scores between the right and left side of the body) was made. Differences between groups were analyzed via an independent sample t-test, a one-way analysis of variance, or a chi-square as appropriate. Significance was set at 0.05 a priori.

Results

The average composite FMS score was 16.4 (±1.9) points. Soldiers reporting ≥290 APFT points achieved a higher FMS score than those reporting lower APFT scores (16.5 ± 2.0 vs 16.1 ± 2.0 points, P = 0.03). Soldiers reporting either tobacco use or a previous musculoskeletal injury had lower FMS scores than those not reporting these (tobacco: 16.1 ± 2.1 vs 16.5 ± 1.8 points, P = 0.02; injury: 16.0 ± 2.2 vs 16.6 ± 1.8 points, P &lt; 0.01). FMS asymmetries were not related to APFT scores, tobacco use, or self-rated fitness. As self-rated fitness increased so did APFT scores.

Conclusions

Active duty soldiers of a light infantry division achieved FMS scores similar to other military populations tested, and the composite FMS score was related to higher APFT scores, absence of tobacco use, and absence of previous musculoskeletal injuries. Improving PRC candidate healthy habits through highlighting the negative associations between poorer fitness, cigarette tobacco use and movement quality, may reduce injury risk and increase PRC completion potential.

Self-Managed Strength Training for Active Duty Military With a Knee Injury: A Randomized Controlled Pilot Trial

INTRODUCTION

Knee injuries among active duty military are one of the most frequent musculoskeletal injuries and are often caused by exercise or intense physical activity or combat training. These injuries pose a threat to force readiness. Our objective was to assess feasibility (including recruitment and retention rates) of three self-managed strengthening strategies for knee injuries and determine if they resulted in improvements in lower extremity strength, function, pain, and activity compared to usual physical therapy (PT) in military members.

METHODS

A pilot study using a randomized controlled trial was conducted at three outpatient military medical treatment facilities. After baseline testing, 78 active duty military members with a knee injury were randomized to 1-4 trial arms: (1) neuromuscular electrical stimulation (NMES) applied to the quadriceps muscle; (2) graduated strength walking using a weighted vest (WALK); (3) combined NMES with strength walking (COMBO); (4) usual PT alone. All groups received usual PT. The primary outcome was the rates of change in knee extensor and flexor strength over 18 weeks. Secondary outcomes explored the rates of change in functional performance, pain, and activities of daily living scale (ADLS). The primary analysis for the endpoints used repeated measures, linear mixed-effects models. This study was approved by Institutional Review Boards at all facilities.

RESULTS

The randomized sample (N = 78) included 19 participants in the PT-only, 20 in the WALK, 19 in the NMES and 20 in the COMBO groups. At baseline, there were no group differences. Fifty of the participants completed the 18-week study. The completers and non-completers differed at baseline on injury mechanism, with more completers injured during sports (45% vs 29%), and more non-completers during military training (36% vs 18%). Also, they differed in uninjured knee extension (completers 28% weaker), and uninjured knee flexion (completers 22% weaker). Adherence for self-reported daily step logs showed that the WALK group was 15% below goal and COMBO group 6% below goal. The 300 PV muscle stimulator showed the NMES group completed 34% of recommended stimulation sessions and the COMBO group 30%.Knee extension strength in the injured knee found only the COMBO group having a statistically higher improvement compared to PT-only (Change over 18 weeks: 10.6 kg in COMBO; 2.1 kg in PT-only). For the injured knee flexion changes, only the COMBO showed significant difference from PT-only (Change over 18 weeks: 7.5 kg in COMBO; -0.2 kg in PT-only). Similarly, for the uninjured knee, only the COMBO showed significant difference from PT-only in knee extension (Change over 18 weeks: 14.7 Kg in COMBO; 2.7 kg in PT-only) and knee flexion (Change over 18 weeks: 6.5 kg in COMBO; -0.2 kg in PT-only). Overall pain improved during the study for all groups with no significant group differences. Similarly, function and ADLS significantly improved over 18 weeks, with no significant group differences.

CONCLUSIONS

Knee extensor strength improvements in the COMBO group were significantly higher compared to usual PT. Pain, functional measures, and ADLS all improved during the study with no group differences. Further research is required to confirm these findings.

A pre-training conditioning program to increase physical fitness and reduce attrition due to injuries in Dutch Airmobile recruits: Study protocol for a randomised controlled trial

BACKGROUND

Low baseline fitness of recruits entering basic military training is shown to be associated with an increased risk of musculoskeletal injuries (MSIs) and attrition of military training. This in turn leads to an increased demand for health care, increased health care costs and decreased personnel occupancy rate of military units.

DESIGN

Study protocol for a randomised controlled trial.

OBJECTIVE

To determine the effects of a pre-training conditioning program on cardiovascular endurance, incidence of overuse injuries, and attrition rates in Dutch Airmobile recruits undertaking initial military training.

SETTING

Royal Netherlands Army, Air Assault Brigade military training course.

PARTICIPANTS

Recruits are considered eligible for this study when they are 'low-fit' at the start of the initial military training. Time to complete a 2700 m run test in ≥12'23'' is used as selection criteria.

INTERVENTIONS

We use a complex system approach to cover multiple domains of MSI prevention and optimise intervention circumstance; a pre-training conditioning program, training staff support, process-focused culture and health accountability. The pre-training conditioning program contains functional training to improve mobility, power, agility, lower and upper body strength and cardiovascular endurance. Cardiovascular endurance will be targeted both by endurance training and high intensity interval training.

MAIN OUTCOME MEASUREMENTS

Outcome measures include cardiovascular endurance, injury incidence, attrition rates, lost training days due to injuries, and implementation fidelity of the PCP.

TRIAL STATUS

Recruitment of participants commenced April 18, 2018 and final results are expected in August 2019.

TRIAL REGISTRATION

Dutch trial register www.trialregister.nl/=trial/6791.

Effects of a contoured foot orthosis and flat insole on plantar pressure and tibial acceleration while walking in defence boots

This study investigated the effects of a contoured, prefabricated foot orthosis and a flat insole on plantar pressure and tibial acceleration while walking in defence boots. Twenty-eight adults walked along an 8-metre walkway in a: (i) defence boot (control condition), (ii) defence boot with a flat insole, and (iii) defence boot with a contoured foot orthosis. Plantar pressure data were collected using the pedar-X in-shoe system and tibial accelerations were measured with an accelerometer. In relation to plantar pressure under the rearfoot, the contoured foot orthosis, compared to the defence boot, decreased peak pressure and maximum force, and increased contact area. Under the medial midfoot, the contoured foot orthosis and flat insole increased peak pressure, maximum force and contact area. Under the medial forefoot, the contoured foot orthosis and flat insole increased maximum force. Under the lateral forefoot, the contoured foot orthosis and flat insole increased contact area, with the flat insole also increasing maximum force. In relation to tibial acceleration, the contoured foot orthosis, compared to the defence boot, decreased tibial peak positive acceleration. These findings provide novel biomechanical evidence for the effects of contoured foot orthoses in defence boots.

Injuries in Australian Army full-time and part-time personnel undertaking basic training

Background

Musculoskeletal injuries are a problem in military personnel as they detract from force readiness and may prevent deployment. Injuries occur during basic training at three times the rate observed in post-training military service and more commonly in part time (PT) when compared to full time (FT) army personnel. The purpose of this study was to examine differences in rates and patterns of reported injuries between full time (FT) and part time (PT) personnel undertaking army basic training.

Methods

A retrospective cohort study was conducted to determine and compare rates and patterns of injuries which occurred during basic training in PT and FT personnel. Injury data from the period 01 July 2012 to 30 June 2014 was obtained in a non-identifiable format from the Workplace Health, Safety, Compensation and Reporting (WHSCAR) database of the Australian Department of Defence. Analysis included descriptive statistics and the calculation of injury rates and injury rate ratios.

Results

A total of 1385 injuries were reported across FT and PT cohorts, with an injury rate ratio for FT:PT of 1.06 [0.80–1.40], when accounting for exposure. In FT personnel, 1192 (90%) were Minor Personal Injuries (MPIs) and 43 (3.2%) Serious Personal Injuries (SPIs). In PT personnel, 147 (94.8%) were MPIs and three (1.9%) SPIs. In both FT and PT personnel, injuries most commonly: occurred during Physical Training (41.7% FT, 515 MPIs, 10 SPIs, 32% PT. 48 MPIs, 1 SPI); affected the knee (FT 41.7% 159 MPIs, 7 SPIs, PT 36.0%, 22 MPIs, 0 SPIs); involved soft tissue damage (FT 60.9%, 744 MPIs, 8 SPIs, PT 69.3%, 103 MPIs, 1 SPI); and were due to muscular stress (FT 41.7%, 509 MPIs, 6 SPIs, PT 36%, 54 MPIs, 0 SPIs).

Conclusions

FT and PT recruits exhibited similar injury profiles, with mechanisms, sites and types of injuries in agreement with other research. Given these similarities, effective interventions that reduce injury risks in either population will likely benefit both.

Risk Factors Associated With Musculoskeletal Injury: A Prospective Study of British Infantry Recruits

Background:

Musculoskeletal Injury (MSKI), a common problem in both military and physically active civilian populations, has been suggested to result from both extrinsic and intrinsic factors.

Objective:

To investigate prospectively whether gait biomechanics, aerobic fitness levels and smoking status as well as entry military selection test variables can be used to predict MSKI development during recruit training.

Methods:

British infantry male recruits (n = 562) were selected for the study. Plantar pressure variables, smoking habit, aerobic fitness as measured by a 1.5 mile run time and initial military selection test (combination of fitness, Trainability score) were collected prior to commencement of infantry recruit training. Injury data were collected during the 26 week training period.

Results:

Incidence rate of MSKI over a 26 week training period was 41.28% (95 % CI: 37.28 - 45.40%). The injured group had a higher medial plantar pressure (p < 0.03), shorter time to peak heel rotation (p < 0.02), current smoking status (p < 0.001) and a slower 1.5 mile run time (p < 0.03). In contrast, there were no significant differences (p > 0.23) in lateral heel pressure, age, weight, height, BMI and military selection test. A logistic regression model predicted MSKI significantly (p= 0.03) with an accuracy of 34.50% of all MSK injury and 76.70% of the non-injured group with an overall accuracy of 69.50%.

Conclusion:

The logistic regression model combining the three risk factors was capable of predicting 34.5% of all MSKI. A specific biomechanical profile, slow 1.5 mile run time and current smoking status were identified as predictors of subsequent MSKI development. The proposed model could include evaluation of other potential risk factors and if validated then further enhance the specificity, sensitivity and applicability.