Loads worn by soldiers predict episodes of low back pain during deployment to Afghanistan

Lifestyle factors and psychological factors are associated with central pain processing in service members with persistent low-back pain: A cross-sectional exploratory study

Persistent low-back pain (LBP) is highly prevalent in the military. Altered central pain processing is one of the mechanisms found to underlie persistent LBP. Our aim was to explore which factors are associated with altered pain processing in Dutch service members with persistent LBP. This knowledge may guide clinicians in what factors to address in the treatment of dysfunctional pain processing in service members with persistent LBP. Twenty-one service members with persistent LBP (mean age 34.0 years, 18 males) were included in this cross-sectional exploratory study. Participants completed questionnaires regarding lifestyle and psychological factors. Altered central pain processing was measured by temporal summation of pain to examine the function of the pain facilitatory system and by conditioned pain modulation to examine the pain inhibitory function. Univariable and multivariable linear regression analyses were performed. A higher local temporal summation of pain was associated with a longer sitting time, a higher level of physical activity and a higher level of pain catastrophizing. A higher local conditioned pain modulation was associated with a higher level of pain catastrophizing, anxiety and depression symptoms, and with a lower sleep quality. A higher remote conditioned pain modulation effect was associated with a higher level of physical activity, a higher body mass index and a shorter sitting time. This study succeeded in identifying lifestyle and psychological factors associated with altered pain processing in service members with persistent LBP. Prospective studies are needed to examine causality in these relationships.

Association Between Body Mass Index and Nonspecific Recurrent Low Back Pain in Over 600,000 Healthy Young Adults

An association between body mass index (BMI; weight (kg)/height (m)2) and low back pain (LBP) has long been debated, but inconsistent measurements of BMI and varying definitions of LBP have produced conflicting findings. We explored this association using measured BMI and physician documentation of recurrent LBP among healthy young adults. Data were extracted from the Israel Defense Forces electronic medical record system. All Israeli citizens with compulsory military service during January 2008-March 2019 were included (n = 705,840). Exclusion criteria were spine deformities, disc pathologies, spinal surgeries, arthropathies, connective tissue diseases, pain syndromes, low bone density disorders, cancers, and psychiatric illnesses. LBP was defined as electronic medical record system documentation of 1) 2 medical visits at least 6 weeks apart with a diagnosis of LBP or "LBP with radiation" or 2) 1 medical visit resulting in referral to an orthopedic surgeon. Logistic regression models were used to explore the association between BMI category and LBP; 619,969 (87.8%) individuals (mean age = 18.9 (standard deviation, 0.97) years; 56.9% male) were included. LBP prevalence was 9.2% (n = 56,918) and higher among males (9.7%) than females (8.5%). Overweight (odds ratio = 1.123, 95% confidence interval: 1.096, 1.151) and obesity (odds ratio = 1.137, 95% confidence interval: 1.096, 1.179) were associated with LBP. The association remained significant after accounting for various sociodemographic factors. Maintaining a healthy BMI may aid in the prevention of LBP in young adults.

A data-driven framework for assessing soldier performance, health, and survivability

Presented is a framework that uses pattern classification methods to incrementally morph whole-body movement patterns to investigate how personal (sex, military experience, and body mass) and load characteristics affect the survivability tradespace: performance, musculoskeletal health, and susceptibility to enemy action. Sixteen civilians and 12 soldiers performed eight military-based movement patterns under three body-borne loads: ∼5.5 kg, ∼22 kg, and ∼38 kg. Our framework reduces dimensionality using principal component analysis and uses linear discriminant analysis to classify groups and morph movement patterns. Our framework produces morphed whole-body movement patterns that emulate previously published changes to the survivability tradespace caused by body-borne loads. Additionally, we identified that personal characteristics can greatly impact the tradespace when carrying heavy body-borne loads. Using our framework, military leaders can make decisions based on objective information for armour procurement, employment of armour, and battlefield performance, which can positively impact operational readiness and increase overall mission success.

Mechanical Differences between Men and Women during Overground Load Carriage at Self-Selected Walking Speeds

Few studies have directly compared physical responses to relative loading strategies between men and women during overground walking. This study aimed to compare gait mechanics of men and women during overground load carriage. A total of 30 participants (15 male, 15 female) completed three 10-min walking trials while carrying external loads of 0%, 20% and 40% of body mass at a self-selected walking speed. Lower-body motion and ground reaction forces were collected using a three-dimensional motion capture system and force plates, respectively. Female participants walked with a higher cadence (p = 0.002) and spent less absolute time in stance (p = 0.010) but had similar self-selected walking speed (p = 0.750), which was likely due to the female participants being shorter than the male participants. Except for ankle plantarflexion moments, there were no sex differences in spatiotemporal, kinematic, or kinetic variables (p > 0.05). Increasing loads resulted in significantly lower self-selected walking speed, greater stance time, and changes in all joint kinematics and kinetics across the gait cycle (p < 0.05). In conclusion, there were few differences between sexes in walking mechanics during overground load carriage. The changes identified in this study may inform training programs to increase load carriage performance.

Self-reported pain or injury from equipment used on military deployment

BACKGROUND

Information about pain and injury from equipment on a particular deployment is not disaggregated in the literature; thus, the nature of the issue is unclear.

AIMS

To determine the prevalence of pain or injury during a particular deployment that military personnel attributed to equipment they used on this deployment; and to document the types of equipment they identified, the type of pain or injury and how they thought the pain or injury occurred.

METHODS

This paper analyses data from a deployment and health survey of Australian Defence Force personnel. The participants are 8932 personnel who deployed to Iraq and 6534 who deployed to Afghanistan. Participants indicated whether they experienced pain or injury from equipment they used on deployment and detailed their experiences in response to an open-ended question (n = 563).

RESULTS

Sixteen per cent of Iraq-deployed and 21% of Afghanistan-deployed participants reported pain or injury from equipment they used on deployment. Body armour was the most common equipment identified; however, a wide range of equipment was related to pain or injury. A new finding is that pain or injury related to armour was attributed to its wear in vehicles and during vehicle ingress or egress.

CONCLUSIONS

Knowledge of the nature of pain or injury related to equipment used on deployment may help inform improved designs and practices to reduce or prevent avoidable harm to serving personnel.

What Would it Take to Put a Chiropractor in Khakis? Effecting Chiropractors as Commissioned Officers in the U.S. Military-A Historical Brief

The purpose of this article is to provide a historical perspective on the commissioning of chiropractors within the U.S. Military and to propose a pathway by which this can be accomplished. A comprehensive review of Congressional actions proposed and enacted, and historical documents to create a chronology of actions that influence and support a proposed pathway for commissioning. The authority to commission chiropractors within the U.S. Military has long been provided to the Secretary of Defense, but it has never been acted upon despite decades of legislation. Chiropractors currently serve within the DoD as contractors or government employees; however, the direct association with the military in terms of commissioning has remained elusive. Musculoskeletal injuries are statistically one of the most prevalent combat-related injury classifications within the active duty military and subsequent veteran population. Chiropractic physicians serving within military medicine and veteran health care facilities routinely manage common and complex neurological and musculoskeletal injuries sustained by combat and non-combat servicemen and women. Patient satisfaction with chiropractic services within both the active duty and veteran population is high and routinely sought after. Chiropractic inclusion in the medical corps or medical service corps within the DoD is long overdue.

Identifying problems that female soldiers experience with current-issue body armour

Despite female soldiers representing a growing user population, military body armour systems are currently better suited to the anthropometric dimensions of male soldiers. The aim of this study was to explore issues that female soldiers experience with current Australian Defence Force (ADF)-issue body armour. Following a sequential exploratory design, an initial questionnaire was completed by 97 Australian female soldiers. Subsequently, 33 Australian female soldiers participated in one of three focus groups. Descriptive statistics of questionnaire data considered alongside thematic analysis of focus group transcripts revealed problems with the design (fit, form and function) of current ADF-issue body armour, as well as problems with the issuance and education surrounding use of the system. It is recommended that anthropometric data of female soldiers be better incorporated into future body armour designs, that these data inform processes surrounding both acquisition and issuance of body armour and that training protocols for body armour use be reviewed.

Risk factors for musculoskeletal injuries in military personnel: a systematic review with meta-analysis

OBJECTIVE

To investigate the risk factors for musculoskeletal injuries in military personnel.

METHODS

A systematic literature search was carried out in August 2019 and updated in July 2020 without language or time filters. The inclusion criteria were prospective studies that investigated the risk factors for injuries in military personnel. Only risk factors analyzed by at least ten studies were selected for the meta-analysis. For data analysis, the RevMan5.3 program was used to compare the number of participants with injuries between high- or low-risk groups. The measurement of dichotomous variables was one of the selected parameters for the analysis, as well as the Mantel-Haenszel statistical method, random-effects model, and analysis with a relative risk (RR) and 95% confidence interval for the included studies.

RESULTS

A total of 2,629 studies were identified through databases. Thirty-four studies met the inclusion criteria. The groups considered at risk were the oldest [RR = 1.22; (95% CI 1.06-1.41)], with overweight or obesity [RR = 1.27; (95% CI 1.08-1, 48)], with previous injuries [RR = 1.15; (95% CI 1.01-1.30)], and with the worst performance in running tests of 1,600-3,200 m [RR = 1.87; (95% CI 1.28-2.71)]. Gender, ethnicity, and smoking were not associated with injuries. However, a subgroup analysis showed that among studies with a follow-up of fewer than 12 months, women presented RR = 2.44 (95% CI 1.65-3.60) more likely to develop injuries.

CONCLUSION

Age, overweight or obesity, previous injuries, and performance in the 1600-3200 m run are associated with an increased risk of injury in the military.

The effect of physical training modality on exercise performance with police-related personal protective equipment

PURPOSE

To investigate the influence of aerobic capacity, muscle strength, and body composition on performance and metabolic demands of men wearing personal protective equipment (PPE).

METHODS

45 men were assigned to one of four groups which significantly differed in upright pull isometric strength (MVC ≤ 1325 N or ≥ 1531 N) and maximum oxygen uptake (VO₂max ≤ 51.9 mL min^-1·kg^-1 or ≥ 56.0 mL min^-1·kg^-1): endurance-trained (low MVC, high VO₂max), strength-trained (high MVC, low VO₂max), endurance- and strength-trained (high MVC, high VO₂max), and untrained (low MVC, low VO₂max). Each participant underwent two test series consisting of a repeated 10 m dummy drag and a graded exercise test wearing either sportswear or PPE of a German riot police unit weighing 20.9 kg (statistics: two-way repeated measures ANOVA, stepwise multiple linear regressions).

RESULTS

With PPE, dummy drag and running performance were impaired by 14 ± 9% and 58 ± 7%. Groups with high MVC dragged the dummy significantly faster than groups with low MVC (17.5 ± 1.8 s/17.6 ± 1.4 s vs. 23.4 ± 5.6 s/22.3 ± 3.5 s). Running distance was significantly higher in groups with high VO₂max (4.5 ± 0.8 km/4.4 ± 0.7 km vs. 3.1 ± 0.5 km/2.8 ± 0.5 km). Body composition variables partially correlated with performance (R ranging from -0.70 to 0.41), but were not significant predictors of the regression models in PPE.

CONCLUSIONS

Individuals who showed a certain degree of aerobic endurance, as well as muscle strength, performed consistently well during the test series. Therefore, none of these variables should be trained in isolation but optimized in combination to be capable in a variety of operational tasks.

Spine system changes in soldiers after load carriage training in a plateau environment: a prediction model research

BACKGROUND

Low back pain is the most common spinal disorder among soldiers, and load carriage training (LCT) is considered the main cause. We aimed to investigate changes in the spine system of soldiers after LCT at high altitudes and the change trend of the lumbar spine and surrounding soft tissues under different load conditions.

METHODS

Magnetic resonance imaging scans of the lumbar spines of nine soldiers from plateau troops were collected and processed. We used ImageJ and Surgimap software to analyze changes in the lumbar paraspinal muscles, intervertebral discs (IVDs), intervertebral foramina, and curvature. Furthermore, the multiple linear regression equation for spine injury owing to LCT at high altitudes was established as the mathematical prediction model using SPSS Statistics version 23.0 software.

RESULTS

In the paraspinal muscles, the cross-sectional area (CSA) increased significantly from 9126.4 ± 691.6 mm² to 9862.7 ± 456.4 mm², and the functional CSA (FCSA) increased significantly from 8089.6 ± 707.7 mm² to 8747.9 ± 426.2 mm² after LCT (P < 0.05); however, the FCSA/CSA was not significantly different. Regarding IVD, the total lumbar spine showed a decreasing trend after LCT with a significant difference (P < 0.05). Regarding the lumbar intervertebral foramen, the percentage of the effective intervertebral foraminal area of L₃/₄ significantly decreased from 91.6 ± 2.0 to 88.1% ± 2.9% (P < 0.05). For curvature, the lumbosacral angle after LCT (32.4° ± 6.8°) was significantly higher (P < 0.05) than that before LCT (26.6° ± 5.3°), while the lumbar lordosis angle increased significantly from 24.0° ± 7.1° to 30.6° ± 7.4° (P < 0.05). The linear regression equation of the change rate, △FCSA% = - 0.718 + 23.085 × load weight, was successfully established as a prediction model of spinal injury after LCT at high altitudes.

CONCLUSION

The spinal system encountered increased muscle volume, muscle congestion, tissue edema, IVD compression, decreased effective intervertebral foramen area, and increased lumbar curvature after LCT, which revealed important pathophysiological mechanisms of lumbar spinal disorders in soldiers following short-term and high-load weight training. The injury prediction model of the spinal system confirmed that a load weight < 60% of soldiers' weight cannot cause acute pathological injury after short-term LCT, providing a reference supporting the formulation of the load weight standard for LCT.

Are female soldiers satisfied with the fit and function of body armour?

Design and development of contemporary military body armour has traditionally focused primarily on male soldiers. As the anthropometric body dimensions of male and female soldiers differ, we aimed to determine whether current body armour was meeting fit and functional requirements of female soldiers. One-hundred and forty-seven female Australian Defence Force soldiers completed a 59-item questionnaire regarding the fit and function of current body armour. Most (68%) participants reported wearing ill-fitting body armour, which was associated with increased total musculoskeletal pain and discomfort, as well as pain at the shoulders, abdomen, and hips. Body armour that was too large was more likely to interfere with task performance when it was integrated with a combat belt, as well as when female soldiers performed operationally representative tasks. Modifying body armour design and sizing to cater to the anthropometric dimensions of female soldiers is recommended.

Conservative Interventions for Non-Specific Low Back Pain in Tactical Populations: A Systematic Review of Randomized Controlled Trials

Limited evidence exists about non-specific low back pain (NSLBP) interventions among tactical personnel (police officers, firefighters, or army forces). The aim was to identify and systematically review the findings of randomized control trials (RCTs) investigating conservative interventions for the treatment NSLBP in tactical personnel. A search of seven databases for randomized controlled trials RCTs were conducted. Two independent reviewers extracted data and assessed the risk of bias (PEDro scale). Five RCTs (n = 387 military subjects; median PEDro score = 7/10) were included. The trials were highly heterogeneous, differing in pain and disability outcome measures, duration of NSLBP symptoms (acute, nonacute, nonchronic, and chronic), types of intervention (exercise, manual therapy, and physical therapy), types of control groups, and intervention durations (4–12 weeks). Two studies reported that strengthening exercise interventions were not effective for reducing pain or disability in military personnel with chronic or nonacute NSLBP. Manual therapy treatment was more effective than usual activities in current pain and pain typical symptoms in soldiers with acute NSLBP after four weeks. A multidimensional intervention reduced disability in military personnel with non-chronic NSLBP after four weeks. Strong evidence does not exist for the efficacy of any conservative interventions in the reduction of pain and disability in tactical populations with NSLBP.

Physiological Factors of Importance for Load Carriage in Experienced and Inexperienced Men and Women

INTRODUCTION

The ability to carry heavy loads is an important and necessary task during numerous outdoor activities and especially in military operations. The aim of this study was to investigate factors associated with load-carrying ability in men and women with and without extensive load-carrying experience.

MATERIALS AND METHODS

The energy expenditure during carrying no load, 20, 35, and 50 kg at 2 walking speeds, 3 and 5 km h-1, was studied in 36 healthy participants, 19 men (30 ± 6 years, 82.5 ± 7.0 kg) and 17 women (29 ± 6 years, 66.1 ± 8.9 kg), experienced (>5 years) in carrying heavy loads (n = 16, 8 women) or with minor or no such experience (n = 20, 9 women). A standard backpack filled with weights to according carry load was used during the walks. Anthropometric data, leg muscle strength, as well as trunk muscle endurance and muscle fiber distribution of the thigh, were also obtained. Extra Load Index (ELI)-the oxygen uptake (VO2) during total load over unloaded walking-was used as a proxy for load-carrying ability at 20, 35, and 50 kg (ELI20, ELI35, and ELI50, respectively). In addition to analyzing factors of importance for the ELI values, we also conducted mediator analyses using sex and long-term carrying experience as causal variables for ELI as the outcome value. The study was approved by the Regional Ethics Committee in Stockholm, Sweden.

RESULTS

For the lowest load (20 kg), ELI20, was correlated with body mass but no other factors. Walking with 35 and 50 kg load at 5 km h-1 body mass, body height, leg muscle strength, and absolute VO2max were correlated, while relative VO2max, trunk muscle endurance, and leg muscle fiber distribution were not correlated to ELI35 and ELI50.ELI50 at 5 km h-1 differed between the sexes. This difference was only mediated by the difference in body mass. Neither muscle fiber distribution, leg muscle strength, trunk muscle endurance, and body height nor did absolute or relative VO2max explain the difference.Participants with long-term experience of heavy load carrying had significant lower ELI20 and ELI50 values than those with minor or no experience, but none of the above studied factors could explain this difference.

CONCLUSION

The study showed that body mass, without sex differences, and experience of carrying heavy loads are the dominant factors for the ability to carry heavy loads. Even though the effect of experience alludes to the need for extensive carrying training, no causality can be proven. Load carry training intervention studies is suggested for future investigations.

Musculoskeletal Injuries and United States Army Readiness Part I: Overview of Injuries and their Strategic Impact

Introduction

Noncombat injuries (“injuries”) greatly impact soldier health and United States (U.S.) Army readiness; they are the leading cause of outpatient medical encounters (more than two million annually) among active component (AC) soldiers. Noncombat musculoskeletal injuries (“MSKIs”) may account for nearly 60% of soldiers’ limited duty days and 65% of soldiers who cannot deploy for medical reasons. Injuries primarily affect readiness through increased limited duty days, decreased deployability rates, and increased medical separation rates. MSKIs are also responsible for exorbitant medical costs to the U.S. government, including service-connected disability compensation. A significant subset of soldiers develops chronic pain or long-term disability after injury; this may increase their risk for chronic disease or secondary health deficits potentially associated with MSKIs. The authors will review trends in U.S. Army MSKI rates, summarize MSKI readiness-related impacts, and highlight the importance of standardizing surveillance approaches, including injury definitions used in injury surveillance.

Materials/Methods

This review summarizes current reports and U.S. Department of Defense internal policy documents. MSKIs are defined as musculoskeletal disorders resulting from mechanical energy transfer, including traumatic and overuse injuries, which may cause pain and/or limit function. This review focuses on various U.S. Army populations, based on setting, sex, and age; the review excludes combat or battle injuries.

Results

More than half of all AC soldiers sustained at least one injury (MSKI or non-MSKI) in 2017. Overuse injuries comprise at least 70% of all injuries among AC soldiers. Female soldiers are at greater risk for MSKI than men. Female soldiers’ aerobic and muscular fitness performances are typically lower than men’s performances, which could account for their higher injury rates. Older soldiers are at greater injury risk than younger soldiers. Soldiers in noncombat arms units tend to have higher incidences of reported MSKIs, more limited duty days, and higher rates of limited duty days for chronic MSKIs than soldiers in combat arms units. MSKIs account for 65% of medically nondeployable AC soldiers. At any time, 4% of AC soldiers cannot deploy because of MSKIs. Once deployed, nonbattle injuries accounted for approximately 30% of all medical evacuations, and were the largest category of soldier evacuations from both recent major combat theaters (Iraq and Afghanistan). More than 85% of service members medically evacuated for MSKIs failed to return to the theater. MSKIs factored into (1) nearly 70% of medical disability discharges across the Army from 2011 through 2016 and (2) more than 90% of disability discharges within enlisted soldiers’ first year of service from 2010 to 2015. MSKI-related, service-connected (SC) disabilities account for 44% of all SC disabilities (more than any other body system) among compensated U.S. Global War on Terrorism veterans.

Conclusions

MSKIs significantly impact soldier health and U.S. Army readiness. MSKIs also figure prominently in medical disability discharges and long-term, service-connected disability costs. MSKI patterns and trends vary between trainees and soldiers in operational units and among military occupations and types of operational units. Coordinated injury surveillance efforts are needed to provide standardized metrics and accurately measure temporal changes in injury rates.

Relationship between individual payload weight and spondylolysis incidence in Turkish land forces

OBJECTIVEThe aim of this study was to investigate the relationship between lumbar spondylolysis and payload weight between different combat units of Turkish land forces (TLF).METHODThe authors reviewed clinical and radiological data of the military personnel with low-back pain (LBP) admitted to their clinic between July 2017 and July 2018. Age, BMI, average payload weight, and military service unit were recorded. CT scans were evaluated for pars interarticularis fractures and spondylolisthesis, whereas MRI studies were evaluated for spondylolisthesis, Modic-type endplate changes, or signal loss on T2-weighted images compatible with disc degeneration.RESULTFollowing exclusion, a total of 642 all-male military personnel were included. Of these personnel, 122 were commandos, 435 were infantry, and 85 were serving in the artillery units. Bilateral pars interarticularis fracture was noted in 42 commandos (34.42%) and 2 infantrymen (0.45%). There was no spondylolysis in the artillery units. There was no multiple-level spondylolysis and the most common level of spondylolysis was L5. Commandos had a significantly higher incidence of spondylolysis and more average payload weight (p < 0.001). Twelve patients (27.2%) with spondylolysis had accompanying MRI pathologies at the same level, whereas 32 patients (72.7%) had no accompanying MRI pathologies.CONCLUSIONSIncreased payload weight in military personnel is associated with spondylolysis, and commandos in the TLF have significantly heavier payloads, which causes an increased rate of spondylolysis compared to other units. Additionally, spondylolysis without adjacent-level changes on MRI could be undiagnosed. LBP in active military personnel who have a history of carrying heavy payloads should be evaluated extensively with both MRI and CT scans.

Lack of Prognostic Model Validation in Low Back Pain Prediction Studies: A Systematic Review

OBJECTIVE

The objective of this study was to investigate the frequency with which prediction studies for low back pain outcomes utilize prospective methods of prognostic model validation.

METHOD

Searches of Medline and Embase for terms "predict/predictor," "prognosis," or "prognostic factor." The search was limited to studies conducted in humans and reported in the English language. Included articles were all those published in 2 Spine specialty journals (Spine and The Spine Journal) over a 13-month period, January 2013 to January 2014. Conference papers, reviews, and letters were excluded. The initial screen identified 55 potential studies (44 in Spine, 11 in The Spine Journal); 34 were excluded because they were not primary data collection prediction studies; 23 were not prediction studies and 11 were review articles. This left 21 prognosis papers for review, 19 in Spine, 2 in The Spine Journal.

RESULTS

None of the 21 studies provided validation for the predictors that they documented (neither internal or external validation). On the basis of the study designs and lack of validation, only 2 studies used the correct terminology for describing associations/relationships between independent and dependent variables.

DISCUSSION

Unless researchers and clinicians consider sophisticated and rigorous methods of statistical/external validity for prediction/prognostic findings they will make incorrect assumptions and draw invalid conclusions regarding treatment effects and outcomes. Without proper validation methods, studies that claim to present prediction models actually describe only traits or characteristics of the studied sample.

A longitudinal observational study of back pain incidence, risk factors and occupational physical activity in Swedish marine trainees

OBJECTIVES

To evaluate the occurrence of low back pain (LBP) and LBP that limits work ability, to identify their potential early risks and to quantify occupational physical activity in Swedish Armed Forces (SwAF) marines during their basic 4 month marine training course.

DESIGN

Prospective observational cohort study with weekly follow-ups.

PARTICIPANTS

Fifty-three SwAF marines entering the training course.

OUTCOMES

Incident of LBP and its related effect on work-ability and associated early risks. Occupational physical activity, as monitored using accelerometers and self-reports.

RESULTS

During the training course, 68% of the marines experienced at least one episode of LBP. This yielded a LBP and LBP limiting work ability incidence rate of 13.5 (95% CI 10.4 to 17.8) and 6.3 (95% CI 4.2 to 10.0) episodes per 1000 person-days, respectively. Previous back pain and shorter body height (≤1.80 m) emerged as independent risks for LBP (HR 2.5, 95% CI 1.4 to 4.3; HR 2.0, 95% CI 1.2 to 3.3, respectively), as well as for LBP that limited work ability (HR 3.6, 95% CI 1.4 to 8.9; HR 4.5, 95% CI 2.0 to 10.0, respectively). Furthermore, managing fewer than four pull-ups emerged as a risk for LBP (HR 1.9, 95% CI 1.2 to 3.0), while physical training of fewer than three sessions per week emerged as a risk for LBP that limited work ability (HR 3.0, 95% CI 1.2 to 7.4). More than 80% of the work time measured was spent performing low levels of ambulation, however, combat equipment (≥17.5 kg) was carried for more than half of the work time.

CONCLUSIONS

Incidents of LBP are common in SwAF marines' early careers. The link between LBP and previous pain as well as low levels of exercise highlights the need for preventive actions early on in a marine's career. The role of body height on LBP needs further investigation, including its relationship with body-worn equipment, before it can effectively contribute to LBP prevention.

Prevalence and factors associated with low back pain among Malaysian army personnel stationed in Klang Valley

Study aim: The aims of this study were to examine the prevalence of low back pain (LBP) and explore possible factors associ­ated with LBP among Malaysian army personnel deployed in Klang Valley in the year 2018. Material and methods: A self-administered questionnaire on sociodemographic data, occupational background, occupational exposure and LBP evaluation was used in this study. A total of 330 respondents participated in this study and 321 (97%) of them completed and returned the questionnaires. Results: One hundred and fifty-seven respondents complained of LBP, giving a prevalence of 48.9%. LBP was found to be associated with smoking status, history of LBP, history of accident, military rank, category of regiment, lifting weights, push­ing weights, pulling weights and job-related physical activity. Logistic regression analysis identified four associated risk fac­tors of LBP: history of accident (OR = 4.42, 95% 2.29-8.55), history of LBP (OR=1.92, 95% 1.11-3.31), combat regiment (OR = 1.97, 95% 1.14-3.42) and high job-related physical activity (OR = 2.35, 95% 1.31-4.20). Conclusion: Almost half of Malaysian army personnel stationed in Klang Valley reported LBP symptoms. Smoking status, history of LBP, history of accident, junior non-commissioned officers (NCOs), combat regiments, manual handling of objects and moderate/high job-related physical activity are associated with LBP, but there is no evidence of a temporal relationship in the current study. Further exploration with a longitudinal study is needed to identify a cause and effect relationship between occupational exposure and LBP among Malaysian army personnel.

Bowel Control Strategies Used by Veterans With Long-Standing Spinal Cord Injuries

STUDY PURPOSE

The aim of the study was to describe strategies used by veterans with spinal cord injury to achieve control over bowel function and fit their bowel programs into their lifestyles in the years following the initial injury.

METHODS/DESIGN

Using a qualitative descriptive design, 18 outpatient veterans with spinal cord injuries were interviewed at a Veteran's Administration hospital. Recorded interviews were transcribed verbatim and analyzed to determine major themes.

FINDINGS/CONCLUSIONS

Fourteen of 18 participants had gained control over bowel function and led active lives. They emphasized the importance of positive attitudes, listening to their bodies, being physically active, taking charge, and using trial and error to find the best bowel control strategies. Findings also highlighted the value of peer support and the problem of military service connected back injury leading to spinal cord injury.

CLINICAL RELEVANCE

Participants provided practical advice for adapting strategies learned during rehabilitation for long-term bowel control after discharge home.

Reliability and agreement of the IsoKai isokinetic lift test - A test used for admission to the Swedish Armed Forces

This study was performed to evaluate the reliability and agreement of the IsoKai isokinetic lift test as it is currently administered in admission to the Swedish Armed Forces. The study included an intrarater (n = 534) and interrater reliability sample (n = 137), of Swedish male conscripts who performed the test on two test occasions about two hours apart. Two-to-four lifts were performed at each occasion, and the highest mean (IsoKai_MF) and peak force (IsoKai_PF) produced (N) were used for evaluation. All intraclass coefficients showed excellent reliability. The interrater analyses resulted in intraclass coefficients of 0.942 (95% CI; 0.920–0.959) and 0.858 (95% CI; 0.806–0.896) for the IsoKai_MF and IsoKai_PF, respectively, while the corresponding coefficients for the intrarater analyses were 0.935 (95% CI; 0.923–0.946) and 0.865 (95% CI; 0.842–0.886). Agreement, the capability of a test to detect changes, was assessed by the standard error of measurement (SEM/SEM%) and the smallest real difference (SRD/SRD%). These estimate indicated that it is possible to achieve measurements relevant to use in real practice with the IsoKai isokinetic lift test. Bland and Altman analyses revealed no systematic errors in either sample. Based on these findings, the IsoKai isokinetic lift test is suggested to be a highly reliable test for maximal dynamic muscular strength. The test could be of use in selection procedures in order to accurately evaluate maximal dynamic muscular strength, and for evaluating longitudinal changes in strength.

Assessment of chiropractic care on strength, balance, and endurance in active-duty U.S. military personnel with low back pain: a protocol for a randomized controlled trial

BACKGROUND

Low back pain (LBP) is a common cause of disability among U.S. military personnel. Approximately 20% of all diagnoses resulting in disability discharges are linked to back-related conditions. Because LBP can negatively influence trunk muscle strength, balance, and endurance, the military readiness of active-duty military personnel with LBP is potentially compromised. Chiropractic care may facilitate the strengthening of trunk muscles, the alteration of sensory and motor signaling, and a reduction in pain sensitivity, which may contribute to improving strength, balance, and endurance for individuals with LBP. This trial will assess the effects of chiropractic care on strength, balance, and endurance for active-duty military personnel with LBP.

METHODS/DESIGN

This randomized controlled trial will allocate 110 active-duty military service members aged 18-40 with non-surgical acute, subacute, or chronic LBP with pain severity of ≥2/10 within the past 24 h. All study procedures are conducted at a single military treatment facility within the continental United States. Participants are recruited through recruitment materials approved by the institutional review board, such as posters and flyers, as well as through provider referrals. Group assignment occurs through computer-generated random allocation to either the study intervention (chiropractic care) or the control group (waiting list) for a 4-week period. Chiropractic care consists primarily of spinal manipulation at a frequency and duration determined by a chiropractic practitioner. Strength, balance, and endurance outcomes are obtained at baseline and after 4 weeks. The primary outcome is a change between baseline and 4 weeks of peak isometric strength, which is measured by pulling on a bimanual handle in a semi-squat position. Secondary outcomes include balance time during a single-leg standing test and trunk muscle endurance with the Biering-Sorensen test. Patient-reported outcomes include pain severity, disability measured with the Roland Morris Disability Questionnaire, symptom bothersomeness, PROMIS-29, Fear Avoidance Beliefs Questionnaire, expectations of care, physical activity, and global improvement.

DISCUSSION

This trial may help inform further research on biological mechanisms related to manual therapies employed by chiropractic practitioners.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02670148 Registered on 1 February 2016.

Lumbar Muscle Structure Predicts Operational Postures in Active-Duty Marines

Background The relationship between lumbar spine posture and muscle structure is not well understood. Objectives To investigate the predictive capacity of muscle structure on lumbar spine posture in active-duty Marines. Methods Forty-three Marines were scanned in this cross-sectional study, using an upright magnetic resonance imaging scanner while standing without load and standing, sitting, and prone on elbows with body armor. Cobb, horizontal, and sacral angles were measured. Marines were then scanned while unloaded in supine using a supine magnetic resonance imaging scanner. The imaging protocol consisted of T2 intervertebral disc mapping; high-resolution, anatomical, fat-water separation, and diffusion tensor imaging to quantify disc hydration and muscle volume, fat fraction, and restricted diffusion profiles in the lumbar muscles. A stepwise multiple linear regression model was used to identify physiological measures predictive of lumbar spine posture. Results The multiple regression model demonstrated that fractional anisotropy of the erector spinae was a significant predictor of lumbar posture for 7 of 18 dependent variables measured, and explained 20% to 35% of the variance in each model. Decreased fractional anisotropy of the erector spinae predicted decreased lordosis, lumbosacral extension, and anterior pelvic tilt. Conclusion Fractional anisotropy is inversely related with muscle fiber size, which is associated with the isometric force-generating capacity of a muscle fiber. This suggests that stronger erector spinae muscles predict decreased lordosis, lumbosacral extension, and anterior pelvic tilt in a highly trained population. J Orthop Sports Phys Ther 2018;48(8):613-621. Epub 17 May 2018. doi:10.2519/jospt.2018.7865.

Musculoskeletal Pain and Headache in the Active Duty Military Population: An Integrative Review

BACKGROUND

Since 2001, the U.S. Armed Forces' training and deployment have greatly increased, escalating the risk of injury and pain-related issues both at home station and deployment environments.

AIMS

This integrative review examines the incidence, prevalence, and risk factors for musculoskeletal pain (MSP) and headaches in active duty (AD) military populations.

METHODS

Peer-reviewed research published between 2001 and 2016 was identified relevant to MSP and headache in AD military personnel using MeSH terms in key biomedical databases. Inclusion criteria were: epidemiological studies examining MSP or headache as primary or secondary outcome; samples that included AD populations; and studies conducted in the theater of operations, at home station, and in military treatment or Veterans Health Administration facilities.

RESULTS

Twenty-six articles met inclusion criteria. Low back pain (LBP) was the most prevalent MSP diagnosis. The incidence of LBP was 40.5 per 1,000 person-years and was comparable to nonmilitary populations. Inflammation and pain from overuse comprised the largest proportion of injury mechanism, accounting for about 82% of all injuries among nondeployed military personnel. The risk of MSP was greater for AD, female, Army, enlisted personnel, and those with greater time in a motor vehicle. Evidence suggests posttraumatic headache, occurring in up to 92% of military personnel who have sustained a mild traumatic brain injury, is associated with chronic daily headaches.

IMPLICATIONS

Nurses must recognize the consequences military service can have on the development of pain. Nurses have an opportunity to positively impact the health and well-being of military and veteran populations through early recognition and treatment of pain.

LINKING EVIDENCE TO ACTION

The findings from this review underscore considerable magnitude of MSP in military personnel and expose modifiable risk factors and potential targets for designing nurse-led interventions to improve pain and symptoms in military subpopulations.

Integrating a hip belt with body armour reduces the magnitude and changes the location of shoulder pressure and perceived discomfort in soldiers

Soldiers carry heavy loads that may cause general discomfort, shoulder pain and injury. This study assessed if new body armour designs that incorporated a hip belt reduced shoulder pressures and improved comfort. Twenty-one Australian soldiers completed treadmill walking trials wearing six different body armours with two different loads (15 and 30 kg). Contact pressures applied to the shoulders were measured using pressure pads, and qualitative assessment of comfort and usability were acquired from questionnaires administered after walking trials. Walking with hip belt compared to no hip belt armour resulted in decreased mean and maximum shoulder pressures (p < 0.005), and 30% fewer participants experiencing shoulder discomfort (p < 0.005) in best designs, although hip discomfort did increase. Laterally concentrated shoulder pressures were associated with 1.34-times greater likelihood of discomfort (p = 0.026). Results indicate body armour and backpack designs should integrate a hip belt and distribute load closer to shoulder midline to reduce load carriage discomfort and, potentially, injury risk. Practitioner Summary: Soldiers carry heavy loads that increase their risk of discomfort and injury. New body armour designs are thought to ease this burden by transferring the load to the hips. This study demonstrated that designs incorporating a hip belt reduced shoulder pressure and shoulder discomfort compared to the current armour design.

Biomechanics in Annulus Fibrosus Degeneration and Regeneration

Degenerative disc degeneration (DDD) is the major cause of low back pain, which seriously affects the life of patients. Current surgical and conservative treatments only relieve the pain temporarily, yet fail to restore the normal biomechanics and functions of healthy spine. Indeed, high recurrence of disc herniation commonly happens after discectomy. Degenerative changes in biomechanical and structural properties of the intervertebral disc (IVD), including fissures in annulus fibrosus (AF) and volume loss of nucleus pulposus (NP), mainly contribute to DDD development. AF plays a critical role in the biomechanical properties of IVD as it structural integrity is essential to confine NP and maintain physiological intradiscal pressure under loading. Maintaining the homeostasis of AF and NP, and thereby IVD, requires regulation of their biomechanics, which is also involved in the onset and subsequent development of AF degeneration. Therefore, it is essential to understand the biomechanical changes of AF during degeneration, which can also provide valuable insights into the repair and regeneration of AF. In this review, we focus on the biomechanical properties of AF tissue associated with its homeostasis and degeneration, and discuss the biomechanical stimulus required for regeneration of AF. We also provide an overview of recent strategies to target and modulate cell mechanics toward AF regeneration.

Effects of Training and Overtraining on Intervertebral Disc Proteoglycans

STUDY DESIGN

Animal experimental study.

OBJECTIVE

Evaluate the effect of physical activity and overtraining condition on glycosaminoglycan concentration on the intervertebral disc (IVD) using a rat running model.

SUMMARY OF BACKGROUND DATA

Some guidelines recommend the implementation of a physical exercise program as treatment for low back pain; however, cyclic loading impact on the health of the IVD and whether there is a dose-response relationship is still incompletely understood.

METHODS

Thirty-two rats ages 8 weeks were divided into four groups with eight animals each. The first 8 weeks were the adaptive phase, the overtraining phase was from the ninth to the eleventh week, which consisted of increasing the number of daily training sessions from 1 to 4 and the recovery phase was represented by the 12th and 13th weeks without training. Control group 1 (CG1) did not undergo any kind of training. Control group 2 (CG2) completed just the adaptive phase. Overtraining group 1 (OT1) completed the overtraining phase. Overtraining group 2 (OT2) completed the recovery phase. Running performance tests were used to assess the "overtraining" status of the animals. IVD glycosaminoglycans were extracted and quantified, and identified by electrophoresis.

RESULTS

Glycosaminoglycans showed a distribution between chondroitin sulfate and dermatan sulfate. Glycosaminoglycans quantification showed decreasing concentration at the following order: OT1 > CG2 > OT2 > CG1. Increased expression of dermatan sulfate was verified at the groups submitted to any training.

CONCLUSION

Overtraining condition, as assessed by muscle and cardiovascular endurance did not lessen glycosaminoglycan concentration in the IVD. In fact, physical exercise increased glycosaminoglycan concentration in the IVD in proportion to the training load, even at overtraining condition, returning to normal levels after the recovery phase and glycosaminoglycan production is a reversible acute positive response for mechanical stimulation of the IVD.

LEVEL OF EVIDENCE

N/A.

Lumbar spine postures in Marines during simulated operational positions

Low back pain has a 70% higher prevalence in members of the armed forces than in the general population, possibly due to the loads and positions soldiers experience during training and combat. Although the influence of heavy load carriage on standing lumbar spine posture in this population is known, postures in other operationally relevant positions are unknown. Therefore, the purpose of this study was to characterize the effect of simulated military operational positions under relevant loading conditions on global and local lumbar spine postures in active duty male US Marines. Secondary objectives were to evaluate if intervertebral disc degeneration and low back pain affect lumbar spine postures. Magnetic resonance images were acquired on an upright scanner in the following operational positions: Natural standing with no external load, standing with body armor (11.3 kg), sitting with body armor, and prone on elbows with body armor. Custom software was used to measure global lumbar spine posture: Lumbosacral flexion, sacral slope, lordosis, local measures of intervertebral angles, and intervertebral distances. Sitting resulted in decreased lumbar lordosis at all levels of the spine except L1-L2. When subjects were prone on elbows, a significant increase in local lordosis was observed only at L5-S1 compared with all other positions. Marines with disc degeneration (77%) or history of low back pain (72%) had decreased lumbar range of motion and less lumbar extension than healthy Marines. These results indicate that a male Marine's pathology undergoes a stereotypic set of postural changes during functional tasks, which may impair performance. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2145-2153, 2017.

Effect of Load Magnitude and Distribution on Lumbar Spine Posture in Active-duty Marines

STUDY DESIGN

Repeated measures.

OBJECTIVE

The purpose of this study was to quantify the effect of operationally relevant loads and distributions on lumbar spine (LS) in a group of active-duty Marines.

SUMMARY OF BACKGROUND DATA

Low-back pain has been associated with heavy load carriage among military personnel. Although there are data describing the LS posture in response to load, the effect of varying load characteristics on LS posture remains unknown.

METHODS

Magnetic resonance images of Marines (n = 12) were acquired when standing unloaded and when carrying 22, 33, and 45 kg of load distributed both 50% to 50% and 20% to 80% anteriorly and posteriorly. Images were used to measure LS and pelvic postures. Two-way repeated-measures ANOVA and posthoc tests were used to compare LS posture across load magnitudes and distributions (α = 0.05). This project was founded by the US Army Medical Research Acquisition Activity, Award No. W81XWH-13-2-0043, under Work Unit No. 1310.

RESULTS

No changes in LS posture were induced when load was evenly distributed. When load was carried in the 20% to 80% distribution lumbosacral flexion increased as a result of sacral anterior rotation and overall reduced lumbar lordosis. This pattern was greater as load was increased between 22 and 33 kg, but did not increase further between 33 and 45 kg. We observed that the inferior LS became uniformly less lordotic, independently of load magnitude. However, the superior LS became progressively more lordotic with increasing load magnitude CONCLUSION.: Postural adaptations were found only when load was carried with a posterior bias, suggesting that load-carriage limits based on postural changes are relevant when loads are nonuniformly distributed. Although the tendency would be to interpret that loads should be carried symmetrically to protect the spine, the relationship between postural changes and injury are not clear. Finally, the operational efficiency of carrying load in this distribution needs to be tested.

LEVEL OF EVIDENCE

3.

Activity-Limiting Musculoskeletal Conditions in US Veterans Compared to Non-Veterans: Results from the 2013 National Health Interview Survey

Past military service is associated with health outcomes, both positive and negative. In this study we use the 2013 National Health Interview Survey to examine the constellation of conditions referred to as musculoskeletal disorders (MSDs) for Veterans and non-veterans with health conditions that limit their daily activities. Multivariate logistic regression analysis reveal that Veterans are more likely to report MSDs like neck and back problems, fracture bone and joint problems as an activity limiting problem compared to non-veterans. The relationship between age and reports of activity limiting MSDs is moderated by Veteran status. Veterans in this sample report more activity limiting MSDs at younger ages compared to non-veterans and fewer MSDs at older ages. This research contributes to our understanding of potentially limiting health conditions at earlier ages for Veterans.

Loading of the lumbar spine during backpack carriage

Backpack carriage is significantly associated with a higher prevalence of low back pain. Elevated compression and shear forces in the lumbar intervertebral discs are known risk factors. A novel method of calculating the loads in the lumbar spine during backpack carriage is presented by combining physical and numerical modelling. The results revealed that to predict realistic lumbar compression forces, subject-specific lumbar curvature data were not necessary for loads up to 40 kg. In contrast, regarding shear forces, using subject-specific lumbar curvature data from upright MRI measurements as input for the rigid body model significantly altered lumbar joint force estimates.

Risk factors for back pain in marines; a prospective cohort study

Background

It is recognised that back pain (BP) is a debilitating medical problem in the soldier community, which limits operational readiness as well as work ability. As such, identification of risk factors is a necessity for effective preventive actions, but also regarded as important from a safety perspective. The aim of this prospective cohort study was therefore to identify risk factors for back pain and BP limiting work ability in active duty marines within a 6 and 12-month period.

Methods

Demographic characteristics, health-related factors and occupational exposure information, as gathered from questionnaires, as well as clinical test of movement control among 137 Swedish marines were regressed with multivariable logistic regressions, and strength of associations was presented as odds ratio (OR) with 95 % confidence intervals (CI). BP within 6 and 12 months were used as primary outcomes, whereas BP limiting work ability within 6 and 12 months served as secondary outcomes.

Results

Previous BP and tall body height (≥1.86 m) emerged as risk factors for back pain within 6 months (OR 2.99, 95 % CI 1.22–7.30; OR 2.81, 95 % CI 1.16– 6.84, respectively), and 12 months (OR 6.75, 95 % CI 2.30–19.80; 2.75, 95 % CI 1.21–6.29, respectively). Previous BP was also identified as risk factor for BP limiting work ability within 12 months (OR 6.64, 95 % CI 1.78–24.78), and tall body height emerged as a risk within both six (OR 4.30, 95 % CI 1.31–14.13) and 12 months (OR 4.55, 95 % CI 1.53–13.57) from baseline.

Conclusions

Marines with a history of BP are at risk of further BP episodes, which, thus, emphasise the importance of early BP preventive actions. Tall body height also emerged as an important risk which may reflect that personal equipment and work tasks are not adapted for the tallest marines. While this should be considered when introducing new work equipment, further studies are warranted to clarify the underlying mechanism of this association.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1172-y) contains supplementary material, which is available to authorized users.

Mechanics and biology in intervertebral disc degeneration: a vicious circle

Intervertebral disc degeneration is a major cause of low back pain. Despite its long history and large socio-economical impact in western societies, the initiation and progress of disc degeneration is not well understood and a generic disease model is lacking. In literature, mechanics and biology have both been implicated as the predominant inductive cause; here we argue that they are interconnected and amplify each other. This view is supported by the growing awareness that cellular physiology is strongly affected by mechanical loading. We propose a vicious circle of mechanical overloading, catabolic cell response, and degeneration of the water-binding extracellular matrix. Rather than simplifying the disease, the model illustrates the complexity of disc degeneration, because all factors are interrelated. It may however solve some of the controversy in the field, because the vicious circle can be entered at any point, eventually leading to the same pathology. The proposed disease model explains the comparable efficacy of very different animal models of disc degeneration, but also helps to consider the consequences of therapeutic interventions, either at the cellular, material or mechanical level.