BMI and Lower Extremity Injury in U.S. Army Soldiers, 2001-2011

Utilization of antiobesity medications within the Military Health System

OBJECTIVE

The prevalence of overweight and obesity among beneficiaries of the Military Health System (MHS) is 41.6% and 30.5%, respectively. This incurs significant medical, fiscal, and military readiness costs. It is not currently known how the utilization of antiobesity medications (AOMs) within the MHS compares with that in the Veterans Health Administration or the private sector. Our aim was to assess the utilization of AOMs within the MHS.

METHODS

A cross-sectional study was conducted using data gathered from the MHS Data Repository and the inclusion of all adult TRICARE Prime and Plus beneficiaries ages 18 to 64 years who were prescribed at least one TRICARE-approved AOM during the years 2018 to 2022.

RESULTS

The total study population included 4,414,127 beneficiaries, of whom 1,871,780 were active-duty service members. The utilization of AOMs among the eligible population was 0.56% (0.44% among active-duty personnel). Liraglutide was the most-prescribed AOM (36% of the total). Female sex, age greater than or equal to 30 but less than 60 years, and enlisted or warrant officer rank were all associated with statistically significant higher odds of receiving AOMs.

CONCLUSIONS

Comparable with the US private sector, the MHS significantly underutilizes AOMs, including among active-duty service members, despite coverage of AOMs since 2018.

An Approach to Reduce the Incidence of Submarine Medical Evacuations by Identifying Individual Risk Characteristics: Preliminary Findings

INTRODUCTION

Military medical evacuations (MEDEVACs) are resource intensive and can disrupt operations and decrease readiness. Medical evacuations are a concern for the submarine force because of the limited medical resources onboard, the impact of manpower loss on smaller crews, and the compromise of operational stealth. Although some medical emergencies cannot be avoided, some MEDEVACs may be preventable. However, there is limited knowledge of the underlying causes and risk factors associated with submarine MEDEVACs. This work describes an approach to identify individual characteristics associated with submarine MEDEVACs by presenting preliminary results and next steps. Identifying those most at risk for a MEDEVAC will foster prevention strategies that lead to fewer MEDEVACs, military operation disruptions, missed work and limited duty days, unplanned losses, early separations, and disability compensation claims among navy submariners.

MATERIALS AND METHODS

This retrospective study examines MEDEVACs from U.S. Navy submarines from January 1, 2012 to December 31, 2020. Medical evacuation causes were classified by 3 major diagnostic categories: Injury, psychiatric, and medical (i.e., all other non-injury medical events, including dental issues). Diagnostic subcategories were grouped by body region (for injuries) and body system (for non-injuries). Identifiable information from MEDEVAC records were linked to personnel files to capture demographic and occupational variables. Trends across the years were examined, and frequencies and percentages of MEDEVAC cases by both major and sub-diagnostic categories were presented. For cases where both the major diagnostic categories and characteristics were both available, we assessed associations between major diagnostic categories and demographic and occupational characteristics, using Pearson's χ2 test for proportions and Fisher Freeman-Halton exact tests. Pairwise z-tests for proportions were used to determine which proportions differed significantly.

RESULTS

A total of 1,283 MEDEVACs were confirmed from 2012 to 2020, with an annual average of 143. Across the years, 24.3% were caused by psychiatric issues (e.g., suicidal ideation), 18.4% were caused by injuries (e.g., blunt trauma), and the remaining 57.3% were caused by other medical emergencies (e.g., gastrointestinal issues). Among the cases linked to personnel files, the major diagnostic category was associated with age, rank, department, and submarine qualification status (group size varied). By age (n = 973), large differences in MEDEVAC causes were seen among submariners 21 to 25 years old who represented 52.4% of psychiatric versus 37.5% of medical MEDEVACs. In contrast, those 35 and older represented 17.0% medical versus 2.7% psychiatric MEDEVACs.

CONCLUSIONS

Medical, non-injury cases were the most common cause for a MEDEVAC. There were proportionately more psychiatric than medical cases among younger, less experienced submariners. Conversely, there were proportionately more medical than psychiatric cases among older submariners. A centralized approach to collecting MEDEVAC data is needed. This is the most comprehensive study examining risk factors associated with submarine MEDEVACs. Follow-on work will include adding prior medical waiver requests, health indicators, and confirmed diagnoses to the dataset to conduct a risk analysis. Considering submarines have smaller crews than most surface ships, limited medical assets, and often operate in austere environments, examination of submarine MEDEVACs should be distinct from other navy and military MEDEVACs.

Neuromuscular Strength and Power Predict Musculoskeletal Injury and Attrition During Marine Corps Recruit Training

INTRODUCTION

Elevated rates of musculoskeletal injuries (MSIs) and attrition are documented in military recruit training. By identifying and addressing modifiable risk factors, the rate of successful training completion and military readiness can be enhanced. Despite their impact, the causes of MSIs and attrition among U.S. Marine Corps (USMC) recruits remain underexplored. This study investigates demographic, psychological, and physiological predictors of MSIs and attrition among USMC recruits.

MATERIALS AND METHODS

In this prospective cohort study, we evaluated USMC recruits at Marine Corps Recruit Depot, Parris Island and San Diego. Recruits were briefed and invited to volunteer. All recruits who were medically cleared to participate in recruit training were eligible to participate in the study. We gathered baseline data on potential predictors at the start of training, with follow-up data on MSIs and attrition collected post-training. Analyzed predictors encompassed dynamic and static strength measures from countermovement jumps, isometric mid-thigh pulls; and participant surveys. We employed multiple logistic regression to discern risk factors for MSI and attrition.

RESULTS

Our study comprised 584 USMC recruits (183 female recruits, 19.49 ± 1.88 years, 160.10 ± 7.17 cm, 61.19 ± 8.05 kg; 401 males, 18.94 ± 1.92 years, 172.97 ± 7.26 cm, 73.86 ± 11.04 kg). We observed 193 MSIs in 135 recruits, with 80.31% affecting the lower extremity (LE). Notably, lower relative peak power (odds ratio [OR] 0.91 [0.89, 0.94], P < .001) and shorter eccentric deceleration duration (OR 0.99 [0.99, 1.00], P = .005) were significant predictors of MSIs. Specifically, for LE MSIs, similar trends were noted for relative peak power and eccentric deceleration duration, with additional risks associated with lower body mass index (OR 0.93 [0.86, 0.99], P = .036) and previous LE MSIs (OR 2.25 [1.18, 4.27], P = .013). Attrition was more likely with a reduced eccentric deceleration impulse (OR 0.98 [0.97, 0.99], P < .001) and prolonged time to peak force (OR 1.36 [1.17, 1.59], P < .001) and cigarette use (OR 2.12 [1.01, 4.43], P = .046).

CONCLUSIONS

MSIs and attrition during USMC recruit training significantly undermine force readiness and escalate costs. Our research has pinpointed several modifiable risk factors, chiefly reduced muscular power and cigarette smoking. We advocate for neuromuscular training programs to bolster strength and power, integrated nutrition and exercise strategies for optimal body composition, and support for smoking cessation to alleviate the incidence of MSIs and curtail attrition. Initiating training with a gradual increase in activity intensity can provide a critical window to correct pre-existing neuromuscular imbalances and weaknesses, particularly those stemming from prior MSIs. Effectively addressing these risk factors is pivotal for diminishing the rates of MSIs and attrition among recruits, thereby enhancing overall military readiness and operational efficiency.

The Medical Burden of Obesity and Overweight in the US Military: Association of BMI with Clinically Diagnosed Medical Conditions in United States Military Service Members

BACKGROUND

A high BMI is associated with various medical conditions, notably type 2 diabetes, cardiovascular disease, and mental health disorders. In the US military, BMI increased linearly between 1975 and 2015.

OBJECTIVE

This cross-sectional study investigated the associations between BMI and a comprehensive range of clinically diagnosed medical conditions (CDMCs) in US military service members (SMs).

METHODS

A stratified random sample of SMs (n=26,177) completed an online questionnaire reporting their height, weight, and demographic/lifestyle characteristics. Medical conditions for 6 mo before questionnaire completion were obtained from a comprehensive military electronic medical surveillance system and grouped into 39 CDMCs covering both broad (largely systemic) and specific medical conditions. BMI was calculated as weight/height2 (kg/m2). The prevalence of CDMCs was compared among normal weight (<25.0 kg/m2), overweight (25.0-29.9 kg/m2), and obese (≥30 kg/m2) SMs.

RESULTS

After multivariable adjustment for demographic/lifestyle characteristics, higher BMI was associated with higher odds of a diagnosed medical condition in 30 of 39 CDMCs, with all 30 displaying dose-response relationships. The 5 major CDMCs with the largest odds ratios comparing obese to normal weight were endocrine/nutritional/metabolic diseases (OR=2.67, 95%CI=2.24-3.15), nervous system diseases (odds ratio [OR]=2.59, 95%CI=2.32-2.90), circulatory system diseases (OR=2.56, 95%CI=2.15-3.06), musculoskeletal system diseases (OR=1.92, 95%CI=1.76-2.09), and mental/behavioral disorders (OR=1.69, 95%CI=1.51-1.90). Compared with normal weight SMs, overweight or obese SMs had a higher number of CDMCs (1.8±1.9 vs. 2.0±2.0 and 2.5±2.3, mean ± standard deviation, respectively, P<0.01).

CONCLUSIONS

In a young, physically active population, higher BMI was associated with a host of medical conditions, even after adjustment for demographic/lifestyle characteristics. The US Department of Defense should improve nutrition education and modify other factors that contribute to overweight and obesity. This study demonstrates that the medical burden of obesity is substantial in overweight and obese SMs.

Risk factors for musculoskeletal-related occupational disability among US Army soldiers

INTRODUCTION

Minimising temporary and permanent disability associated with musculoskeletal conditions (MSK-D) is critical to the mission of the US Army. Prior research has identified potentially actionable risk factors for overall military disability and its MSK-D subset, including elevated body mass index, tobacco use and physical fitness. However, prior work does not appear to have addressed the impact of these factors on MSK-D when controlling for a full range of factors that may affect health behaviours, including aptitude scores that may serve as a proxy for health literacy. Identifying risk factors for MSK-D when providing control for all such factors may inform efforts to improve military readiness.

METHODS

We studied 494 757 enlisted Army soldiers from 2014 to 2017 using a combined medical and administrative database. Leveraging data from the Army's digital 'eProfile' system of duty restriction records, we defined MSK-D as the first restriction associated with musculoskeletal conditions and resulting in the inability to deploy or train. We used multivariable Cox proportional hazards regression to assess the associations between incident MSK-D and selected risk factors including aptitude scores, physical fitness test scores, body mass index and tobacco use.

RESULTS

Among the subjects, 281 278 (45.14%) experienced MSK-D. In the MSK-D hazards model, the highest effect size was for failing the physical fitness test (adjusted HR=1.63, 95% CI 1.58 to 1.67, p<0.001) compared with scoring ≥290 points.

CONCLUSIONS

The analysis revealed the strongest associations between physical fitness and MSK-D. Additional efforts are warranted to determine potential mechanisms for the observed associations between selected factors and MSK-D.

Demographic Factors and Instantaneous Lower Extremity Injury Occurrence in a National Collegiate Athletic Association Division I Population

CONTEXT

Temporal prediction of the lower extremity (LE) injury risk will benefit clinicians by allowing them to better leverage limited resources and target those athletes most at risk.

OBJECTIVE

To characterize the instantaneous risk of LE injury by demographic factors of sex, sport, body mass index (BMI), and injury history.

DESIGN

Descriptive epidemiologic study.

SETTING

National Collegiate Athletic Association Division I athletic program.

PATIENTS OR OTHER PARTICIPANTS

A total of 278 National Collegiate Athletic Association Division I varsity student-athletes (119 males, 159 females; age = 19.07 ± 1.21 years, height = 175.48 ± 11.06 cm, mass = 72.24 ± 12.87 kg).

MAIN OUTCOME MEASURE(S)

Injuries to the LE were tracked for 237 ± 235 consecutive days. Sex-stratified univariate Cox regression models were used to investigate the association between time to first LE injury and sport, BMI, and LE injury history. The instantaneous LE injury risk was defined as the injury risk at any given point in time after the baseline measurement. Relative risk ratios and Kaplan-Meier curves were generated. Variables identified in the univariate analysis were included in a multivariate Cox regression model.

RESULTS

Female athletes displayed similar instantaneous LE injury risk to male athletes (hazard ratio [HR] = 1.29; 95% CI= 0.91, 1.83; P = .16). Overweight athletes (BMI >25 kg/m2) had similar instantaneous LE injury risk compared with athletes with a BMI of <25 kg/m2 (HR = 1.23; 95% CI = 0.84, 1.82; P = .29). Athletes with previous LE injuries were not more likely to sustain subsequent LE injury than athletes with no previous injury (HR = 1.09; 95% CI = 0.76, 1.54; P = .64). Basketball (HR = 3.12; 95% CI = 1.51, 6.44; P = .002) and soccer (HR = 2.78; 95% CI = 1.46, 5.31; P = .002) athletes had a higher risk of LE injury than cross-country athletes. In the multivariate model, instantaneous LE injury risk was greater in female than in male athletes (HR = 1.55; 95% CI = 1.00, 2.39; P = .05), and it was greater in male athletes with a BMI of >25 kg/m2 than that in all other athletes (HR = 0.44; 95% CI = 0.19, 1.00; P = .05), but these findings were not significantly different.

CONCLUSIONS

In a collegiate athlete population, previous LE injury was not a contributor to the risk of future LE injury, whereas being female or being male with a BMI of >25 kg/m2 resulted in an increased risk of LE injury. Clinicians can use these data to extrapolate the LE injury risk occurrence to specific populations.

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

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

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.

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

Objective

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

Methods

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

Results

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

Conclusions

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

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.

Occupational Injuries in Musicians: A Literature Review

INTRODUCTION

The U.S. Department of Defense employs more musicians than any other organization in the USA with over 6,000 musicians employed. Musculoskeletal pathologies, behavioral health disorders, hearing loss, and dystonias account for the majority of reasons a musician seek medical care. The aim of this study is to review recent medical literature documenting occupational hazards in musicians.

MATERIALS AND METHODS

Authors performed a literature review of publications related to musician performance-related musculoskeletal disorders (PRMDs) and performance-related pain (PRP), behavioral health disorders, dystonias, and hearing loss, published from 2004 to 2019 PubMed.

RESULTS

The search returned 174 possible articles which, after review and exclusion, yielded 88 articles.

CONCLUSIONS

Medical literature suggests several risk factors for multiple disease categories. Practice time and history of PRMD/PRP were both associated with development of PRMD/PRP and focal dystonia. A history of behavioral health disorder was associated with development of focal dystonia. Clinicians should counsel their musician patients on strategies to minimize risks, and additional research is needed to identify specific causes of illnesses in musician populations.

Much work remains to reach consensus on musculoskeletal injury risk in military service members: A systematic review with meta-analysis

Musculoskeletal injuries are the most common reason military service members cannot perform their military duties. Not only are they costly and associated with long-term disability, often long after completion of military service, but injuries also adversely affect the military readiness of a nation. This can be seen as a threat to national security and part of the impetus behind many efforts to better understand, predict, and mitigate injury risk in the military. A systematic review of the literature published between 1995 and October 31, 2020 was conducted to identify significant risk factors of musculoskeletal injury in military populations across the world. 74 out of 170 eligible studies addressed comprehensive injuries, providing 994 unique risk factors. 46 of these studies provided data that could be included in a meta-analysis, which was possible for 15 predictor variables. Seven predictors were significant in meta-analysis: female sex(RR=1.46;95CI 1.30,1.64), high body mass index(RR=1.36;95CI 1.21,1.53), functional movement screen pain (RR=1.70;95CI 1.55,1.87) or scores ≤ 14(RR=1.42 95CI 1.29,1.56), prior injury(RR=1.54;95CI 1.32,1.80), slower running performance(RR=1.33;95CI 1.18,1.51), and poorer push-up performance(RR=1.15;95CI 1.04,1.27). Low BMI, height, weight, smoking, physical activity scores, and sit-up and jump performance were not significant risk factors in the meta-analysis. Most studies had a high risk of bias. Lack of raw data and large heterogeneity in definitions of predictors and injury outcomes limited comparison across many studies.Highlights Female sex, high body mass index, pain with functional movement screen or a score of ≤ 14, prior injury, slower running performance and poorer push-up performance were all significant predictors of musculoskeletal injury.Low body mass index, height, weight, smoking, physical activity scores, and sit-up and jump performance were not significant predictors of musculoskeletal injury.Many other predictors were present only in single studies, but large heterogeneity in definitions of both outcomes and predictors limited comparison across studies.Overall, studies assessing risk factors to predict musculoskeletal injuries in the military were at high risk for bias, especially in regards to statistical approaches.

Military nutrition research: Contemporary issues, state of the science and future directions

The importance of diet and nutrition to military readiness and performance has been recognized for centuries as dietary nutrients sustain health, protect against illness, and promote resilience, performance and recovery. Contemporary military nutrition research is increasingly inter-disciplinary with emphasis often placed on the broad topics of (1) determining operational nutrition requirements in all environments, (2) characterizing nutritional practices of military personnel relative to the required (role/environment) standards, and (3) developing strategies for improving nutrient delivery and individual choices. This review discusses contemporary issues shared internationally by military nutrition research programmes, and highlights emerging topics likely to influence future military nutrition research and policy. Contemporary issues include improving the diet quality of military personnel, optimizing operational rations, and increasing understanding of biological factors influencing nutrient requirements. Emerging areas include the burgeoning field of precision nutrition and its technological enablers.

Eating Behaviors Are Associated With Physical Fitness and Body Composition Among US Army Soldiers

OBJECTIVE

Examine associations between soldiers' eating behaviors, compliance with body composition and fitness standards, and physical performance.

DESIGN

Cross-sectional study.

SETTING

Eight Army installations.

PARTICIPANTS

US Army Soldiers (n = 1,591; 84% male).

MAIN OUTCOME MEASURES

Characteristics, eating behaviors, compliance with body composition and physical fitness standards, and fitness level were assessed via questionnaire.

ANALYSIS

Bivariate and multivariable logistic regression.

RESULTS

Eating mostly at a dining facility was associated with lower odds of body composition failure (odds ratio [OR], 0.44; 95% confidence interval [CI], 0.26-0.73); whereas, eating at a fast rate (OR, 1.51; 95% CI, 1.05-2.17) or often/always ignoring satiety cues (OR, 2.12; 95% CI, 1.06-4.27) was associated with higher odds of body composition failure. Eating mostly fast-food/convenience meals (OR, 1.75; 95% CI, 1.19-2.59) and eating at a fast rate (OR, 1.42; 95% CI, 1.04-1.93) was associated with higher odds of physical fitness failure. Skipping breakfast was associated with lower odds of high physical performance (OR, 0.41; 95% CI, 0.23-0.74); whereas, nutrition education was associated with higher odds of high physical performance (OR, 1.02; 95% CI, 1.01-1.04).

CONCLUSIONS AND IMPLICATIONS

As eating behaviors are modifiable, findings suggest opportunities for improving the specificity of Army health promotion and education programs.

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.

Antiretroviral Therapy Anchor-based Trends in Body Mass Index Following Treatment Initiation Among Military Personnel with HIV

INTRODUCTION

Weight gain and obesity in people living with HIV have been associated with increased risk for non-AIDS-related comorbidities, and integrase strand transfer inhibitor (INSTI)-based regimens may lead to comparatively more weight gain than other regimens. We evaluated body mass index (BMI) following antiretroviral therapy (ART) initiation among participants in the U.S. Military HIV Natural History Study (NHS).

MATERIALS AND METHODS

NHS participants with available baseline weight and height data initiating ART from 2006 to 2017 were considered for analysis. Antiretroviral therapy was categorized by anchor class to include INSTIs, non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs). Linear growth-curve modeling was used to predict BMI changes from ART initiation through 2 years of follow-up in participants stratified by baseline BMI (<25 vs ≥25 kg/m2) at ART start and anchor drug class. These models were adjusted for demographic- and HIV-related characteristics.

RESULTS

Of 961 NHS participants started on initial ART between 2006 and 2017, 491 men who had available baseline BMI data and were virally suppressed (<200 c/mL) at 1 and 2 years of follow-up were included. Overall, the predicted BMI increased at each time point over 2 years regardless of baseline BMI. There was a trend toward less weight gain for non-INSTI regimens regardless of demographic- or HIV-related factors (-0.65 kg/m2/yr, P = .070). In participants with BMI <25, all regimens were associated with BMI gains except in those with high viral load (≥100,000 copies/mL) started on PI regimens (-1.91 kg/m2/yr, P = .000; n = 13). For those participants with BMI ≥25, only INSTI- and PI-based regimens were significantly associated with increased BMI (INSTI 0.54 kg/m2/y, P = .000; PI 0.39 kg/m2/yr, P = .006). Non-nucleoside reverse transcriptase inhibitors were not associated with weight gain regardless of race- or HIV-related characteristics. African Americans with BMI ≥25 were more likely to gain weight as compared to Whites (0.99 kg/m2/yr, P = .016). Specific anchor drug-based predictions revealed that only INSTI use among African Americans was significantly associated with BMI gains (1.85 kg/m2/yr, P = .007); NNRTI- and PI-related weight change was not significant as compared to Whites.

CONCLUSIONS

In our cohort of young military members with HIV infection, those with BMI <25 experienced BMI gains across all ART classes. Among those with BMI ≥25, African Americans on INSTI regimens had the greatest BMI gains. Further studies are needed to determine whether NNRTI regimens should be considered in certain individuals at risk for INSTI-associated weight gain.

Cognitive disinhibition and infrequent moderate-to-intense physical activity linked with obesity in U.S. soldiers

PURPOSE

To explore the relationship between body weight status and neurocognitive functioning in soldiers.

METHODS

U.S. soldiers (N = 109) answered survey questions and completed neurocognitive tests including simple reaction time, code substitution, procedural reaction time, go-no-go, matching to sample, code substitution recall, and four versions of the Stroop test including congruent (color and meaning of word agreed); incongruent (color and meaning of word differed); neutral (nonsense words appeared), and emotional (combat-related words such as "I.E.D" and "convoy" appeared). Self-reported heights and weights were used to calculate BMI. A BMI ≥ 30.00 kg/m² was categorized as obese. Multivariate analysis of variance was used to analyze weight status differences (p ≤ 0.05) across neurocognitive variables. Binomial logistic regression analysis with obesity as the dependent variable was used to ascertain the contributions (p ≤ 0.05) of exercise and the neurocognitive measures that differed based on weight status.

RESULTS

Twenty-nine participants (26.6%) were obese. The obese group had significantly lower scores on code substitution, and both neutral and emotional Stroop tasks. Only Stroop emotional scores, p = 0.022, OR = 0.97, and frequency of moderate/intense physical activity, p = 0.009, OR = 0.10, were significant predictors of weight status.

CONCLUSIONS

Obesity was associated with less frequent moderate/intense physical activity and compromised executive functioning, namely decrements in response inhibition. Given the design and sample size, additional research is needed to better understand the direction of the relationship between these variables and to inform research related to the treatment and prevention of obesity within military populations.

LEVEL OF EVIDENCE

Level III, case-control analytic study.

Factors associated with musculoskeletal injuries in an infantry commanders course

OBJECTIVES

To evaluate the prevalence of injuries among young combat soldiers as assessed and reported by the military physicians, and to investigate whether parameters such as anthropometric measures, postural balance, proprioceptive ability, and chronic ankle instability are related to injuries during and following an infantry commanders course.

METHODS

In this cross-sectional study, 165 soldiers were tested for anthropometric measurements, proprioceptive ability, and dynamic postural balance (DPB), as well as for their responses to an ankle stability questionnaire (CAIT), on three occasions: pre-course, middle-course, and end-course testing. All musculoskeletal injuries were assessed and recorded in the digital medical file of each participant by specialist military physicians before and during/following the course.

RESULTS

Ninety-eight soldiers (59.4%) were injured before the course. Forty soldiers (24.2%) incurred an injury during/following the course (with 33 out of the 40 [82.5%] soldiers that were injured during/following the course having also been injured before the course). Sixty soldiers had no injury before/during/following the course. A survival curve showed that half of the soldiers who were injured during/following the course (20 soldiers) were recorded as injured in the first half of the course (during the first 46 days of the 92-day course). Logistic regression showed that the pre-course parameters that were significant among injured soldiers compared with the non-injured soldiers were: low CAIT results (OR = 2.736, 95% CI = 1.178-6.354), high BMI (OR = 1.234, 95% CI = 1.082-1.406) and reduced proprioceptive ability (OR =.858, 95% CI =.797-.924).

CONCLUSION

With a high prevalence of soldiers injured during and following a commanders course, a somatosensory intervention program should be generalized into the practical daily preparation and training routines of the soldiers for improving somatosensory abilities, optimizing military physical readiness, and for preventing future musculoskeletal injuries.

Profiling lower extremity injuries sustained in a state police population: a retrospective cohort study

Background

Tactical populations, such as military, firefighter and law enforcement populations, are known to suffer a relatively high number of musculoskeletal injuries, with the lower extremity of notable concern. The aim of this retrospective cohort study was to determine the profile of lower extremity musculoskeletal injuries within a state police agency.

Methods

Injury data were collected by an Australian state police force over a 7-year period (2009–2016) and records not meeting the definition for lower extremity musculoskeletal injury were excluded. Statistical analyses were descriptive, with frequencies, means and standard deviations calculated where applicable. Chi-square analysis was performed to compare injury profiles by gender. Ethics approval was granted by Bond University Human Research Ethics Committee (Research Protocol 15360).

Results

Of the initial 65,579 incident records, 12,452 (19%) related to lower extremity musculoskeletal injuries. The knee was the most commonly injured site (31.4%) with sprains/strains (42.3%) the most common nature of injury and arresting offenders (24.2%) the most common activity at time of injury. Slips/trips/falls (37.8%) was found to be the most common cause of injury. Variations were found between genders, most notably within the injury activity (p < .001). 27.1% of male officers were injured when arresting offenders compared to 16.5% for female officers. Walking/running contributed to 17.9% of female officer incidents compared to 9.3% for male officers. The mean number of hours worked prior to injury occurrence was 6.00 ± 3.56 h with significantly more injuries occurring in the middle third of the shift (4.34–8.67 h, p < 0.001).

Conclusions

While the proportion of injuries that affected the lower extremity was lower for police, the leading sites of injuries (knees and ankles) were similar to those of military and fire and rescue populations. Variations between genders suggest there may need to be differences in return-to-work rehabilitation.

Prevalence of Eating Disorder Risk and Body Image Dissatisfaction among ROTC Cadets

Injury risk is multifactorial including non-modifiable and modifiable factors such as nutrition and mental health. The purpose of this study was to estimate eating disorder risk and body image (BI) dissatisfaction among Reserve Officers Training Corps (ROTC) cadets. A total of 102 (male: n = 75, female: n = 27; age: 20 ± 2 years) ROTC cadets self-reported height, current and ideal weight, and completed the Eating Attitudes Test-26 (EAT-26) and self-perceived BI current and perceived sex-specific figural stimuli. The overall eating disorder risk for ROTC cadets was 32.4%. No significant differences were found when comparing sex, ethnicity, or military branch. Overall risk of pathogenic behaviors included 11.8% who reported binge eating; 8.8% who used laxatives, diuretics, or diet pills; 8.8% who exercised for >60 min to control their weight; and 8.8% who lost 9.1 kg or more within the last 6 months. We identified significant interactions (p ≤ 0.01) between sex of the solider, overall perceptions of male and female soldiers, and BI self-perceptions. The ROTC cadets in this study displayed eating disorder risk and BI dissatisfaction, which is concerning for tactical readiness, long-term behavioral health issues, and injury from pathogenic behaviors. Education and quality healthcare are necessary to mitigate the increased risk of eating and BI dissatisfaction within this population.

Extended Ketogenic Diet and Physical Training Intervention in Military Personnel

INTRODUCTION

Ketogenic diets (KDs) that elevate ketones into a range referred to as nutritional ketosis represent a possible nutrition approach to address the emerging physical readiness and obesity challenge in the military. An emerging body of evidence demonstrates broad-spectrum health benefits attributed to being in nutritional ketosis, but no studies have specifically explored the use of a KD in a military population using daily ketone monitoring to personalize the diet prescription.

MATERIALS AND METHODS

To evaluate the feasibility, metabolic, and performance responses of an extended duration KD, healthy adults (n = 29) from various military branches participated in a supervised 12-wk exercise training program. Fifteen participants self-selected to an ad libitum KD guided by daily measures of capillary blood ketones and 14 continued their normal mixed diet (MD). A battery of tests were performed before and after the intervention to assess changes in body mass, body composition, visceral fat, liver fat, insulin sensitivity, resting energy metabolism, and physical performance.

RESULTS

All KD subjects were in nutritional ketosis during the intervention as assessed by daily capillary beta-hydroxybutyrate (βHB) (mean βHB 1.2 mM reported 97% of all days) and showed higher rates of fat oxidation indicative of keto-adaptation. Despite no instruction regarding caloric intake, the KD group lost 7.7 kg body mass (range -3.5 to -13.6 kg), 5.1% whole-body percent fat (range -0.5 to -9.6%), 43.7% visceral fat (range 3.0 to -66.3%) (all p < 0.001), and had a 48% improvement in insulin sensitivity; there were no changes in the MD group. Adaptations in aerobic capacity, maximal strength, power, and military-specific obstacle course were similar between groups (p > 0.05).

CONCLUSIONS

US military personnel demonstrated high adherence to a KD and showed remarkable weight loss and improvements in body composition, including loss of visceral fat, without compromising physical performance adaptations to exercise training. Implementation of a KD represents a credible strategy to enhance overall health and readiness of military service members who could benefit from weight loss and improved body composition.

Regular strength training and baseline fitness in overweight infantry members of Slovenian Armed Forces

INTRODUCTION

The prevalence of overweight subjects in military cohorts increases despite the obligatory army physical fitness test (APFT) requirements and the negative consequences of possible test failure due to the increased body mass index (BMI). Studies that have examined the association of BMI with baseline fitness in the military are showing conflicting evidence. The primary aim of the study is to examine BMI effects on baseline fitness that was measured by APFT and additional functional performance tests (FT) (vertical countermovement jump with and without load, loaded prone plank, single-leg hamstring bridge test and pull-ups). Our secondary goal is to explore if regular strength training modifies the BMI effect on baseline fitness.

METHODS

A cross-sectional study on a sample of 118 male infantry soldiers that have performed APFT and FT was carried out. Body mass and body height measurements were used to calculate BMI, and to categorise participants into BMI ranks. Two independent categorical variables (BMI rank and strength training) were used to evaluate their influence on dependent variables of physical performance acquired from APFT and FT.

RESULTS

A significantly large size effect of BMI rank (F=1.69, p=0.037; effect size (ES)=0.15) and regular strength training (F=2.66, p=0.006; ES=0.21) on physical performance was found. It was shown that strength training had a medium ES on push-up and pull-up performance, as well as on the overall APFT score and loaded plank.

CONCLUSIONS

The importance of regular strength training and normal BMI for better overall baseline fitness in infantry members was highlighted. Most importantly, it was shown that performance is not affected in overweight soldiers who are performing regular strength training in addition to their daily physical training.

TRIAL REGISTRATION NUMBER

NCT03415464.

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.

Body weight status, perceived stress, and emotional eating among US Army Soldiers: A mediator model

BACKGROUND

In civilians, overweight and obesity are associated with emotional eating behaviors such as eating in response to stress, but this association has not been examined in Soldiers, a population with unique stressors. This cross-sectional study examined the relationship between perceived stress (PS), emotional eating (EE), and outcomes of body mass index (BMI), and failing Army body composition (BC) standards among Soldiers.

METHODS

Soldiers (N = 1460, 83% male, 23.5 ± 5.2 years old) completed validated surveys on PS, EE, and adherence with military BC standards. Conditional process models and mediation models tested gender as a moderator and EE as a mediator of associations between PS and BMI and PS and BC failure, respectively.

RESULTS

Higher PS was associated with more frequent self-reported EE behaviors (p < 0.001), higher BMI (p < 0.001), and BC failure (p < 0.001). BMI significantly increased with frequency of reported EE behaviors (p < 0.001). Gender was not a statistically significant moderator in the relationship between PS, EE, and, BMI (p = 0.83) or BC failure (p = 0.57). PS appears to affect BMI indirectly through EE behaviors (c' = 0.03, 95% CI: 0.02, 0.04). PS may affect BC failure directly (c' = 1.04, 95% CI: 1.01, 1.08) and indirectly (ab = 1.02, 95% CI: 1.01, 1.03) through EE as a mediator.

CONCLUSIONS

EE behaviors may mediate the positive association between PS, BMI, and BC failure. Prospective investigation is warranted to better understand the role of EE in health-related outcomes among Soldiers and populations in high stress professions.

Weight Gain of Service Members After Basic Military Training

INTRODUCTION

Despite weight and fitness requirements, the prevalence of overweight and obesity in the U.S. military approaches that in the general population. The purpose of this study is to assess trends in anthropometric measurements shortly after military enlistment.

METHODS

This longitudinal study evaluated the change in objectively measured body weight and waist circumference in the population of U.S. Air Force members who enlisted in 2012-2013 and graduated from Basic Military Training (n=49,466). Individuals were followed for 4 years or until they left the military, for a mean follow-up of 1,218 (SD=261) days. Data were collected in 2018 and analyzed in 2019.

RESULTS

Among Basic Military Training graduates with available and plausible baseline data (n=46,706), weight increased incrementally by a mean of 1.5-1.8 kg per year and waist circumference by 0.3-1.1 cm per year. Over the 4-year period, total mean weight gain was 6.6 (SD=7.7) kg and waist circumference increase was 3.1 (SD=6.4) cm. Male graduates gained 7.0 (SD=7.7) kg and female graduates gained 4.7 (SD=7.5) kg. Of those who stayed in the military for 4 years, 37.3% transitioned to a higher BMI category (i.e., from normal to overweight/obese or from overweight to obese), whereas 3.9% transitioned to a lower category.

CONCLUSIONS

Future research is needed to understand determinants of unhealthy weight gain and the association between weight gain and physical fitness among young adults embarking on a military career.

Cost-Effectiveness of a Weight Loss Intervention: An Adaptation of the Look AHEAD Lifestyle Intervention in the US Military

OBJECTIVE

This study aimed to assess whether a counselor-initiated (CI) adaptation of the Look AHEAD (Action for Health in Diabetes) intensive lifestyle intervention in a military setting was cost-effective relative to a self-paced (SP) adaptation.

METHODS

A cost-effectiveness analysis from a payer perspective was performed alongside a 2014-2017 randomized behavioral weight loss trial among 248 active-duty military personnel stationed at a US Air Force base in Texas. Incremental cost-effectiveness ratios were calculated for weight loss, reductions in waist circumference, and quality-adjusted life-years (QALYs).

RESULTS

After 12 months, the CI adaptation cost more per participant compared with the SP adaptation ($1,081 vs. $120) but achieved greater weight loss (1.86 kg vs. 0.06 kg), greater reductions in waist circumference (1.85 cm vs. 0.48 cm), and more QALYs (0.871 vs. 0.856). The incremental cost-effectiveness ratio for the CI adaptation relative to the SP adaptation was $61,268 per additional QALY. At willingness-to-pay thresholds of $50,000 and $100,000 per QALY, the CI adaptation was 45% and 49% likely to be cost-effective, respectively.

CONCLUSIONS

The CI delivery of the Look AHEAD Intensive Lifestyle Intervention may offer a cost-effective approach to tackle excess weight in the US military.

Creation of a predictive equation to estimate fat-free mass and the ratio of fat-free mass to skeletal size using morphometry in lean working farm dogs

AIMS To develop an equation that accurately estimates fat-free mass (FFM) and the ratio of FFM to skeletal size or mass, using morphometric measurements in lean working farm dogs, and to examine the association between FFM derived from body condition score (BCS) and FFM measured using isotope dilution. METHODS Thirteen Huntaway and seven Heading working dogs from sheep and beef farms in the Waikato region of New Zealand were recruited based on BCS (BCS < 3, 3-4, > 4) using a nine-point scale. Bodyweight, BCS, and morphometric measurements (head length and circumference, body length, thoracic girth, and fore and hind limb length) were recorded for each dog, and body composition was measured using an isotopic dilution technique. A new variable using morphometric measurements, termed skeletal size, was created using principal component analysis. Models for predicting FFM, leanST (FFM minus skeletal mass) and ratios of FFM and leanST to skeletal size or mass were generated using multiple linear regression analysis. RESULTS Mean FFM of the 20 dogs, measured by isotope dilution, was 22.1 (SD 4.4) kg and the percentage FFM of bodyweight was 87.0 (SD 5.0)%. Median BCS was 3.0 (min 1, max 6). Bodyweight, breed, age and skeletal size or mass were associated with measured FFM (p<0.001). There was a good correlation between predicted FFM and measured FFM (R²=0.96), and for the ratio of predicted FFM to skeletal size and measured values (R²=0.99). Correlation coefficients were higher for the ratio FFM and leanST to skeletal size than for ratios using skeletal mass. There was a positive correlation between BCS-derived fat mass as a percentage of bodyweight and fat mass percentage determined using isotope dilution (R²=0.65). CONCLUSIONS AND CLINICAL RELEVANCE As expected, the predictive equation was accurate in estimating FFM when tested on the same group of dogs used to develop the equation. The significance of breed, independent of skeletal size, in predicting FFM indicates that individual breed formulae may be required. Future studies that apply these equations on a greater population of working Huntaway and Heading dogs are needed to establish the utility of these equations on a large scale. Such studies could ascertain if there is a ratio for lean mass to skeletal size below which the risk of injury or disease increases. If these equations prove useful they would provide an objective and non-invasive measure to determine when welfare in individual dogs is compromised by underfeeding.

Gender differences in the associations of body mass index, physical fitness and tobacco use with lower extremity musculoskeletal injuries among new US Army soldiers

BACKGROUND

Musculoskeletal (MSK) injuries are a leading cause of morbidity among US Army soldiers, especially among women and the newly enlisted. While extremes of body mass index (BMI), low physical fitness and tobacco use have been identified as risk factors, no prior studies have determined the combined effects of these risk factors or tested for gender differences in the associations.

METHODS

We conducted a retrospective cohort study utilising the Stanford Military Data Repository to study all enlisted soldier accessions to the US Army between January 2011 and January 2014, with follow-up through December 2014 (n=238 772). We used discrete-time logistic regression to test for associations between demographic, socioeconomic and health behaviour-related predictors and incident lower extremity injuries. We included interaction terms to test for gender differences.

RESULTS

Among men, there were greater adjusted odds of injury among underweight (OR 1.27), overweight (OR 1.14) and obese soldiers (OR 1.54) (all p<0.001) relative to normal-weight soldiers. No statistically significant differences in the odds of injury on the basis of BMI were observed for female soldiers. Physical fitness was a significantly stronger predictor of injury for female as compared with male soldiers, while the association between tobacco use and injury was stronger for men (OR 1.47) than for women (OR 1.30) (p<0.001 for both).

CONCLUSION

This is the largest known study to simultaneously assess important, modifiable musculoskeletal injury risk factors and to test for gender differences in these associations. These findings provide critical gender-related nuances for clinicians and leaders seeking to reduce the risk of these problems.

Body Mass Index at Accession and Incident Cardiometabolic Risk Factors in US Army Soldiers, 2001-2011

Individuals entering US Army service are generally young and healthy, but many are overweight, which may impact cardiometabolic risk despite physical activity and fitness requirements. This analysis examines the association between Soldiers' BMI at accession and incident cardiometabolic risk factors (CRF) using longitudinal data from 731,014 Soldiers (17.0% female; age: 21.6 [3.9] years; BMI: 24.7 [3.8] kg/m2) who were assessed at Army accession, 2001-2011. CRF were defined as incident diagnoses through 2011, by ICD-9 code, of metabolic syndrome, glucose/insulin disorder, hypertension, dyslipidemia, or overweight/obesity (in those not initially overweight/obese). Multivariable-adjusted proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) between BMI categories at accession and CRF. Initially underweight (BMI<18.5 kg/m2) were 2.4% of Soldiers, 53.5% were normal weight (18.5-<25), 34.2% were overweight (25-<30), and 10.0% were obese (≥30). Mean age range at CRF diagnosis was 24-29 years old, with generally low CRF incidence: 228 with metabolic syndrome, 3,880 with a glucose/insulin disorder, 26,373 with hypertension, and 13,404 with dyslipidemia. Of the Soldiers who were not overweight or obese at accession, 5,361 were eventually diagnosed as overweight or obese. Relative to Soldiers who were normal weight at accession, those who were overweight or obese, respectively, had significantly higher risk of developing each CRF after multivariable adjustment (HR [95% CI]: metabolic syndrome: 4.13 [2.87-5.94], 13.36 [9.00-19.83]; glucose/insulin disorder: 1.39 [1.30-1.50], 2.76 [2.52-3.04]; hypertension: 1.85 [1.80-1.90], 3.31 [3.20-3.42]; dyslipidemia: 1.81 [1.75-1.89], 3.19 [3.04-3.35]). Risk of hypertension, dyslipidemia, and overweight/obesity in initially underweight Soldiers was 40%, 31%, and 79% lower, respectively, versus normal-weight Soldiers. BMI in early adulthood has important implications for cardiometabolic health, even within young, physically active populations.