Warfighter Performance Research Articles

Military Medicine and Medical Research as a Source of Inspiration and Innovation to Solve National Security and Health Challenges in the 21st Century.

The history of military medicine and research is rife with examples of novel treatments and new approaches to heal and cure soldiers and others impacted by war's devastation. In the 21st century, new threats, like climate change, are combined with traditional threats, like geopolitical conflict, to create novel challenges for our strategic interests. Extreme and inaccessible environments provide heightened risks for warfighter exposure to dangerous bacteria, viruses, and fungi, as well as exposure to toxic substances and extremes of temperature, pressure, or both providing threats to performance and eroding resilience. Back home, caring for our veterans is also a health-care priority, and the diseases of veterans increasingly overlap with the health needs of an aging society. These trends of climate change, politics, and demographics suggest performance evaluation and resilience planning and response are critical to assuring both warfighter performance and societal health. The Cleveland ecosystem, comprising several hospitals, a leading University, and one of the nation's larger Veteran's Health Administration systems, is ideal for incubating and understanding the response to these challenges. In this review, we explore the interconnections of collaborations between Defense agencies, particularly Air Force and Army and academic medical center-based investigators to drive responses to the national health security challenges facing the United States and the world.

From the laboratory to the field: Chemical analysis of colored smoke pyrotechnic formulations via mass spectrometry techniques.

Smoke dyes are complex molecular systems that have the potential to form many molecular derivatives and fragments when deployed. The chemical analysis of smoke samples is challenging due to the adiabatic temperature of the pyrotechnic combustion and the molecular complexity of the physically dispersed reaction products. Presented here is the characterization of the reaction byproducts of a simulant Mk124 smoke signal on a multigram scale, which contain the dye disperse red 9 (1-(methylamino)anthraquinone), by ambient ionization mass spectrometry. Our previous work has examined the thermal decomposition of a simplified smoke system consisting of disperse red 9, potassium chlorate, and sucrose by anaerobic pyrolysis gas chromatography mass spectrometry performed at the laboratory milligram scale. The results from the lab scale test were compared with a fully functioned Mk124 in the field. To achieve this, Mk124 smokes were functioned in the presence of sampling swabs that collected byproduct residues from the smoke plume in the ambient environment. These swabs were then analyzed using ambient ionization mass spectrometry to identify the expended pyrotechnic residues, with particular interest in halogenated species. Previous work determined the toxicity of unforeseen byproducts identified on the laboratory scale, which were also detected in the field demonstrating the correlation of the laboratory testing to the fielded systems. By understanding the chemical composition of smokes and their reaction products, potential toxicity effects can be easily assessed, leading to safer formulations with improved performance. These results can help assess how smoke byproducts may impact Warfighter performance, personnel health, and the environment.

The Lighter Side of Aviation Medicine during World War 2: Aero Medical Training Cartoons

The air war of 1939‐1945 was the world’s first high‐speed, high‐altitude air war. The limiting factor in aerial combat was no longer the warplane’s performance, but rather, the aviator’s limited tolerances for exposure to the rarefied, anoxic, subzero atmosphere. Aviators flew unpressurized planes to altitudes of 20,000‐35,000 feet during reconnaissance and bombing missions to evade enemy interceptors and anti‐aircraft fire. At altitude, warfighter performance could be impaired by anoxia, decompression sickness, hypothermia & frostbite. Escaping from a disabled aircraft at high‐altitude also presented physiological challenges, including anoxia, frostbite, and parachute opening shock G‐forces. High‐performance fighter aircraft also subjected pilots to G‐forces during violent dogfighting maneuvers that left them temporarily blinded and unconscious from reduced brain blood flow. One of the challenges for the “medical men” was teaching young airmen, from all walks of life, the fundamentals of aviation physiology and how to use their oxygen equipment in this new physiological air war. This task fell in large part to the physiologists of the U. S. Army Air Forces (USAAF) and U. S. Navy (USN). The USAAF used training cartoons known as Thought Pictures to illustrate conceptually difficult topics in anatomy, physiology, and the physics of the atmosphere (Figs. 1 & 2). Thought Pictures, drawn by the artist/author Eric Sloane (1905‐1985), were combined with concisely written text in the popular training manual, Your Body in Flight (1943, 1944), which was published by the Aero Medical Laboratory at Wright Field, Dayton, Ohio. The USAAF also published aero medical training cartoons in Air Force Magazine.In the USN, a popular training cartoon character was the accident prone, bumbling airman, Dilbert Groundloop,drawn by satirist Robert C. Osborn (1904–1994). The USN Bureau of Medicine also highlighted important aero medical issues using comical illustrations in the widely distributed Senseseries; e.g. Oxygen Sense, High Altitude Sense, “G” Sense& Parachute Sense. Likewise, the School of Aviation Medicine, U. S. Naval Air Station, Pensacola, FL, published altitude training cartoons in CONTACTmagazine. Even Boeing and Lockheed aircraft manufacturing companies published humorous cartoons in Boeing News Magazine and Hangar Flying to reinforce the medical dangers of altitude flying to their test pilots and flight engineers. Finally, those mischievous pixies of the air, the Aero Medical Gremlins, proved to be another valuable training tool (see author's Aviation Gremlins abstract). Together, these humorous illustrations enabled America’s aviation physiologists and flight surgeons to drive home the serious nature of the physiological challenges of combat flying to aviators, while at the same time, presenting difficult material in an easily remembered format that was also amusing and entertaining for airmen soon to be facing life or death on every mission. Aero medical cartoons worked so well as a training tool that interrogation of German aviation physiologists at the end of the war revealed a professional admiration by them for the depth of understanding that American aviators had regarding the physiological effects of high‐altitude and the physiologic principles underlying their protective flight gear.

Risk Assessment In The Military: A Work/Rest Schedule-Based Tool For The Usn Surface Fleet

Long working hours, 24/7 shift work, restricted sleep opportunities, and circadian misalignment all lead to degraded human performance and impairments in decision making. After several mishaps involving U.S. Navy warships in 2017, renewed attention was devoted to optimizing warfighter performance and reducing safety risks associated with crew endurance and fatigue issues. This paper summarizes the development and initial evaluation of the Scheduling Management Aid for Risk Tracking (SMART) prototype. SMART is a human performance risk assessment tool designed to help the U.S. Navy systematically assess and mitigate risk due to crew fatigue during in port and at-sea operations. The heuristics underlying the prototype are selected to identify and quantify human performance risk based on a Sailor’s work and rest patterns. The results are designed to enable data-driven crew resource management decisions, take targeted fatigue mitigation actions, and rapidly calculate human performance risks.

A-140 Computer Based Cognitive Rehabilitation Interventions for Visual Attention Following Mild Traumatic Brain Injury

Abstract Background Service members with a history of mild traumatic brain injury (mTBI) frequently report problems paying attention. In combat and training settings, visual attention is critical given the demand to warfighter performance. Many computerized cognitive rehabilitation programs exist, however the impact of their effectiveness on improving visual attention is unknown. Methods A randomized controlled trial consisted of 22 active-duty service members with a history of mTBI. Participants were randomized to Lumosity (N = 8) which focused on multiple cognitive domains or UCR which has a specific focus on visual attention (N = 14). Cognitive assessment was completed at baseline and following treatment. The Neuropsychological Assessment Battery (NAB) Driving Scenes subtest was used as the primary assessment of visual attention. All participants passed a validity measure pre and post assessment. Results A one-way ANOVA revealed that performance on NAB Driving Scenes improved for all participants after treatment (F = 4.18, p = 0.046); however, when computer program type was analyzed there was no interaction (F = 0.32, p = 0.860). Participants who completed the UCR intervention improved from M = 41.64, SD = 11.58 to M = 46.79, SD = 14.52, Cohen’s d = 0.43. For the Lumosity condition, there was a medium effect size (Cohen’s d = 0.46) from baseline (M = 38.63, SD = 14.33) to post treatment (M = 44.75, SD = 9.47) Conclusions The results indicated that both programs proved effective at improving visual attention symptoms. These findings provide support for the use of computerized cognitive rehabilitation programs as a form of intervention for mTBI.

Developing a Model Based Systems Engineering Architecture for Defense Wearable Technology

AbstractThe rapid advancement of commercial wearable sensing technologies provides an unprecedented opportunity to gather information that improves warfighter performance during military activities and to detect the onset of illness (such as COVID‐19) through surveillance. However, the promise of improved performance and illness prevention through these technologies remains unfulfilled because of the complexity of guaranteeing that technology development outside of the standard military acquisition cycle will meet military requirements. The key to meeting this challenge is to facilitate coordination among R&D efforts, commercially developed products, and military acquisition strategies. To address this, we developed an MBSE architecture and methodology for validating independently developed wearable system designs against military end‐user needs. This methodology includes developing a conceptual framework, a model library, and a capability needs matrix that maps defense mission characteristics to physiological states and product design implementations. This architecture allows military stakeholders to determine where capability gaps or opportunities for wider application of commercial technologies exist, thus providing a bridge between externally developed wearable sensing technologies and military acquisition strategies.

Error-state Kalman filter for lower-limb kinematic estimation: Evaluation on a 3-body model

Human lower-limb kinematic measurements are critical for many applications including gait analysis, enhancing athletic performance, reducing or monitoring injury risk, augmenting warfighter performance, and monitoring elderly fall risk, among others. We present a new method to estimate lower-limb kinematics using an error-state Kalman filter that utilizes an array of body-worn inertial measurement units (IMUs) and four kinematic constraints. We evaluate the method on a simplified 3-body model of the lower limbs (pelvis and two legs) during walking using data from simulation and experiment. Evaluation on this 3-body model permits direct evaluation of the ErKF method without several confounding error sources from human subjects (e.g., soft tissue artefacts and determination of anatomical frames). RMS differences for the three estimated hip joint angles all remain below 0.2 degrees compared to simulation and 1.4 degrees compared to experimental optical motion capture (MOCAP). RMS differences for stride length and step width remain within 1% and 4%, respectively compared to simulation and 7% and 5%, respectively compared to experiment (MOCAP). The results are particularly important because they foretell future success in advancing this approach to more complex models for human movement. In particular, our future work aims to extend this approach to a 7-body model of the human lower limbs composed of the pelvis, thighs, shanks, and feet.

Quantifying warfighter performance during a bounding rush (prone-sprinting-prone) maneuver

A single sacrum mounted inertial measurement unit (IMU) was employed to analyze warfighter performance on a bounding rush (prone-sprinting-prone) task. Thirty-nine participants (23M/16F) performed a bounding rush task consisting of four bounding rush cycles. The sacrum mounted IMU recorded angular velocity and acceleration data were used to provide estimates of sacral velocity and position. Individual rush cycles were parsed into three principal movement phases; namely, the get up, sprint, and get down phases. The timing of each phase was analyzed, averaged for each participant, and compared to the overall rush cycle time using regression analysis. A cluster analysis further reveals differences between high and low performers. Get down time was most predictive of bounding rush performance (R2 = 0.75) followed by get up time (R2 = 0.58) and sprint time (R2 = 0.40). Comparing high and low performers, the get down time exhibited nearly twice the effect on mean rush cycle time compared to get up time (effect size of −2.61 to −1.46, respectively). Overall, this IMU-based method reveals key features of the bounding rush that govern performance. Consequently, this objective method may support future training regimens and performance standards for military recruits, and parallel applications for athletes.

VICTORS: A Conceptual Framework for Implementing and Measuring Military Spiritual Fitness

Spiritual Fitness is one of eight components of the Department of Defense’s Total Force Fitness (TFF) model of warfighter health, readiness, and performance. To date, the lack of a shared framework for describing the beliefs and practices that optimize human performance has hampered the identification, measurement, and operationalization of spiritual fitness within the military. To address this need, we propose a values-centered model of spiritual fitness —VICTORS—that defines military spiritual fitness in terms of Values, Integrity, Calling, Tolerance, Openness, Routine, and Selfless Service. The VICTORS framework comprises a broad set of inclusive traits and capabilities that characterize the spiritually fit warfighter within the definition of spiritual fitness as established by instruction of the Chairman of the Joint Chiefs of Staff (CJCSI). The application of this framework includes; (1) measurement, (2) training and consultation, (3) supporting chaplaincy, and (4) leadership development. We believe that VICTORS will provide a common military language for the essential components of spiritual fitness and become an actionable framework for enhancing spiritual fitness across the Armed Forces.

Biomimetic Gut Model Systems for Development of Targeted Microbial Solutions for Enhancing Warfighter Health and Performance.

The human gut microbiome plays a vital role in both health and disease states and as a mediator of cognitive and physical performance. Despite major advances in our understanding of the role of gut microbes in host physiology, mechanisms underlying human-microbiome dynamics have yet to be fully elucidated. This knowledge gap represents a major hurdle to the development of targeted gut microbiome solutions influencing human health and performance outcomes. The microbiome as it relates to warfighter health and performance is of interest to the Department of Defense (DoD) with the development of interventions impacting gut microbiome resiliency among its top research priorities. While technological advancements are enabling the development of experimental model systems that facilitate mechanistic insights underpinning human health, disease, and performance, translatability to human outcomes is still questionable. This review discusses some of the drivers influencing the DoD's interest in the warfighter gut microbiome and describes current in vitro gut model systems supporting direct microbial-host interactions.

Use of a randomized clinical trial design to study cognitive rehabilitation approaches to enhance warfighter performance

Within the military, cognitive readiness is essential to ensure the warfighter can return to highly demanding combat training and deployment operations. The warfighter must be able to make split second decisions and adapt to new tools and environments. After a traumatic brain injury, clinicians helping the warfighter must have techniques that address warfighter cognitive readiness. Current rehabilitation for cognitive complaints used in military medicine are modeled after civilian therapies which focus on remediating moderate to severe impairment through building compensatory strategies. This traditional approach to cognitive rehabilitation does not translate well to mild traumatic brain injury (mTBI) where impairments are subtle, nor does it meet the needs of our warfighters in deployed and combat training environments. Challenging our current methods is critical in adapting to the needs of this highly valued population to ensure that our warfighters are able to carry out mission critical decision making. Here we present a review of our best current practices for cognitive rehabilitation, describe the limitations our traditional approaches impose for mTBI in military personnel, and present an alternative treatment called Strategic Memory Advanced Reasoning Training (SMART) that can be adopted through a randomized clinical trial design. We propose directly comparing traditional treatment approaches with a novel cognitive rehabilitation strategy which has been well validated outside of the military setting. Procedures were developed to execute this clinical trial in a way that is most relevant to the study population by establishing ecologically valid outcome metrics.

Feasibility of Phototherapy as a Community-Based Solution for Vitamin D Deficiency

Abstract Objectives 1. Determine acceptability and feasibility of a phototherapy kiosk designed as a self-care intervention for low vitamin D; 2. Demonstrate that narrow spectrum ultraviolet (UV) B delivered by the kiosk is equivalent to recommended daily D3 supplementation to raise or maintain serum 25-hydroxyvitamin (OH)D levels at or above 30 ng/mL; and 3. Examine the relationship of demographic variables, including age, gender, body mass index, physical activity, ethnicity, skin type, season, and sun exposure to serum 25(OH)D levels in both treatment arms. Methods Participants were randomized to either the phototherapy kiosk (PK) for a treatment every other week or 600 IU D3 oral supplement (OS) daily, for 10 weeks. PK exposure was based on response to previous treatment and Fitzpatrick Skin Type category; subjects wore undergarments only and eye protection for treatments of 2–6 minutes duration. OS group received a one-time prescription of 70 capsules, dispensed by a research pharmacist. Primary outcome was serum 25(OH)D level. Results Final sample 88 adults; OS group n = 45 and PK group n = 43. Demographics: median age 35 years, mostly female (66%), no difference observed between groups for age, race/ethnicity, or marital status. No difference seen in skin type, birth location, sun exposure, or use of sunscreen. OS group had higher BMI and %body fat. Baseline 25(OH)D level were similar, P = 0.25. At 12 weeks median OS 25(OH)D 25.5 ng/mL and PK 30 ng/mL; P = .01. At 16 weeks, OS group 25(OH)D level 21 ng/mL and PK 27 ng/mL; P = .04. Adherence: OS 92% vs PK 100%. There were no reportable adverse events. Conclusions Use of PK every other week achieved higher serum levels of 25(OH)D than usual care vitamin D3 600 IU/day for 10 weeks, although both groups returned to baseline levels 30 days post-treatment. At a time when self-care measures are highly valued for health promotion, programmed UVB delivered via PK in the community appears to be a safe, efficacious alternative to oral D3 supplementation but requires recurring use. Results from this study suggest a need for early intervention in preventable health conditions impacting Warfighter performance and readiness, particularly pre-deployment when optimizing long-term wellness for duty in austere environments. Funding Sources Benesol, Inc.

Changes in strength and power performance and serum hormone concentrations during 12 weeks of task-specific or strength training in conscripts.

The purpose of this study was to investigate the effects of two different training programs on strength and power performance and serum hormone concentrations. A total of 104 male soldiers volunteered and took part in the 12‐week training period with baseline, mid‐, and post‐measurements of body composition, muscle strength, lower and upper body power, and blood samples to determine serum hormone concentrations. The mean (±SD) age of subjects was 20 ± 1 years, height 180 ± 6 cm and body mass 72.4 ± 8.8 kg. The subjects were divided into three different training groups: soldier task‐specific training (TS), strength training (ST), and control (CON). Each group had a total of 18 training sessions during the 12‐week study. In the muscle strength tests, most improvements could be observed in the TS and ST groups, especially, during the first weeks of the training period. Maximal isometric leg extension force increased significantly by 7.9 ± 12.2% (p < .05) in the TS and 7.1 ± 12.6% (p < .05) in the ST groups between the PRE and MID, as well as between the PRE and POST measurements by 8.1 ± 12.4% (p < .05) in TS and 12.3 ± 15.3% (p < .01) in ST. Serum TES concentration increased significantly in TS between the PRE and MID (16.8 ± 33.9%) and PRE and POST (11.2 ± 16.7%) measurements. Serum COR concentrations decreased in TS between the MID and POST (−7.8 ± 10.9%) and PRE and POST (−11.0 ± 14.3%) measurements. Although the differences observed were rather minor in magnitude, training in the TS and ST groups led to greater improvements in muscle strength and power performance compared to the training in the CON group. The development of strength and/or power of the lower and upper body was greater in the TS and ST groups, which is crucial for warfighter's performance. Therefore, it is important to have a structured resistance‐training program during military training to optimize the strength, power, and military‐specific performance.

Compromised Dynamic Postural Stability Under Increased Load Carriage Magnitudes.

Warfighter performance may be compromised through the impact of load carriage on dynamic postural stability. Men and women may experience this impact to differing extents due to postural stability differences. Therefore, the authors investigated the effect of load magnitude on dynamic postural stability in men and women during a landing and stabilization task. Dynamic postural stability of 32 subjects (16 women) was assessed during the unilateral landing of submaximal jumps under 3 load conditions: +0%, +20%, and +30% body weight. Dynamic postural stability was measured using the dynamic postural stability index, which is calculated from ground reaction force data sampled at 1200Hz. Two-way mixed-measures analysis of variance compared dynamic postural stability index scores between sexes and loads. Dynamic postural stability index scores were significantly affected by load (P = .001) but not by sex or by the sex by load interaction (P > .05). Dynamic postural stability index scores increased between the 0% (0.359 ± 0.041), 20% (0.396 ± 0.034), and 30% (0.420 ± 0.028) body weight conditions. Increased load negatively affects dynamic postural stability with similar performance decrements displayed by men and women. Men and women warfighters may experience similar performance decrements under load carriage conditions of similar relative magnitudes.

Effect of the firing position on aiming error and probability of hit

This is an extended abstract of a paper to be published in Defence Technology, 2019. Sources of dispersions that contribute to delivery error and reduce the soldier performance in terms of hit probability are numerous. In order to improve the warfighter performance, the source of the errors contributing to the inaccuracy and dispersion of the weapon systems must be understood. They include ammunition dispersion error, gun dispersion, aerodynamic jump and the aiming error. The aiming error or gun pointing error is defined as the angle between the gun muzzle at the instant the trigger is pulled and the line of fire that corresponds to the intendent aim point. This is a round-to-round error. In weapons systems that include the rifle, the ammunition, a sight and a gunner, the aiming error was shown to be the single most important source of dispersion for the regular infantryman. In other words, for the general purpose rifle weapon system, the weak link is often the human. In order to verify and quantify this assertion, an experimental investigation was carried out to determine the aiming error associated with general purpose rifle fired by infantryman. The aiming error was evaluated for various firing positions and scenarios using infantryman for ranges varying between 100 m and 500 m. The results show that the aiming error is the main contributor to dispersion for the general purpose rifle fired by a non-specialized infantryman. The aiming error induced dispersion for unstressed and rested gunners is shown to be at best equivalent to that of the weapon fired from a bench rest by a marksman.

5‐hydroxymethyl‐2‐furfural (5HMF) Improves Exercise Capacity During Normoxia and Preserves Cardiovascular Function During Severe Hypoxia in Exercising Swine

BACKGROUNDModern military operations at high altitudes &gt;5,000m result in reduced warfighter performance due to a lack of acclimatization. The exercise performance decrements are attributed to acute exposure to hypobaric hypoxia (HH), characterized by reduced arterial oxygen content and oxygen tissue delivery. The compound 5‐hydroxymethyl‐2‐furfural (5HMF), facilitates oxygen binding to hemoglobin (HgB) at low FiO2. Recent swine experiments in our lab demonstrated that 5HMF can increase oxygen‐HgB affinity, reduce cardiopulmonary decrements, and improve survival time during normobaric hypoxia (10% FiO2) exposure. The experiment determined if prophylactic treatment with 5HMF would mitigate hypoxia‐dependent decrements in exercise performance.METHODSCastrated Yorkshire swine (30–35kg, n=9) completed a one week treadmill familiarization protocol, followed by a baseline maximal exercise test (BET) consisting of staged increases in speed at a fixed 19% grade. Animals were randomized to receive IV infusion of either normal saline (VEH) or 5HMF (20mg/kg; 2hrs pre‐testing) and completed two additional maximal exercise tests during exposure to normoxic air (21% FiO2) (NET) and hypoxia (12% FiO2) (HET) on successive days. The same three tests (BET, NET, and HET) were completed the following week with the other IV treatment not used during the first testing week, allowing each animal to serve as its own control. Physiological parameters collected included cardiovascular and exercise performance during baseline, exercise, and recovery phases.RESULTSHET led to ~40% lower total exercise time compared to both normoxic tests [BET (p=0.001) and NET (p=0.001)] regardless of treatment. During NET, 5HMF resulted in a 7% greater peak workload (METS) than BET (p=0.02) that was not seen with VEH (p=0.07). During HET, 5HMF resulted in a similar mean workload as VEH (p=0.6), but reduced peak heart rate by 12% (p=0.04, n=4). Average heart rate during recovery from HET was 6% lower in swine administered 5HMF compared to recovery following NET (p=0.02).CONCLUSIONSThis study developed an exercise model in swine exposed to acute hypoxia that reliably reduced exercise performance. Using our model, we observed that 5HMF increased exercise capacity under normoxic conditions and preserved cardiovascular function during and immediately after exercising in severe hypoxic conditions. This work further demonstrates the utility of using an oxygen‐HgB affinity increasing compound (5HMF) to improve operational effectiveness and capabilities in high altitude environments without the need for prior acclimatization.Support or Funding InformationOffice of Naval Research, USUHS Grant, HU0001‐14‐1‐0008This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Body-worn IMU array reveals effects of load on performance in an outdoor obstacle course.

This study introduces a new method to understand how added load affects human performance across a broad range of athletic tasks (ten obstacles) embedded in an outdoor obstacle course. The method employs an array of wearable inertial measurement units (IMUs) to wirelessly record the movements of major body segments to derive obstacle-specific metrics of performance. The effects of load are demonstrated on (N = 22) participants who each complete the obstacle course under four conditions including unloaded (twice) and with loads of 15% and 30% of their body weight (a total of 88 trials across the group of participants). The IMU-derived performance metrics reveal marked degradations in performance with increasing load across eight of the ten obstacles. Overall, this study demonstrates the significant potential in using this wearable technology to evaluate human performance across multiple tasks and, simultaneously, the adverse effects of body-borne loads on performance. The study addresses a major need of military organizations worldwide that frequently employ standardized obstacle courses to understand how added loads influence warfighter performance. Importantly, the findings and conclusions drawn from IMU data would not be possible using traditional timing metrics used to evaluate task performance.

A Prospective Cohort Study of Vitamin D Supplementation in AD Soldiers: Preliminary Findings.

To explore response to vitamin D supplementation in active duty (AD) warfighters and translate findings into evidence-based health policy. Soldiers are at risk for musculoskeletal injuries and metabolic dysfunction that impact physical performance and military readiness; the link with low vitamin D status is unclear. This prospective trial enrolled 152 soldiers; baseline 25 hydroxyvitamin (OH) D level determined assignment to a no-treatment control (CG) or treatment group (TG) receiving a vitamin D3 supplement for 90 days. Symptoms, diet, sun exposure, and blood biomarkers obtained at baseline (T1) and 3 months (T2). Cohort was predominantly white (58%) with a significant difference in racial distribution for vitamin D status. Mean (SD) 25(OH)D levels were 37.8 (5.6) ng/mL, 22.2 (5.0) ng/mL, and 22.9 (4.7) ng/mL for the CG, low dose TG, and high-dose TG at T1, respectively. Following three months of treatment, one-way ANOVA indicated a statistically significant difference between groups (F5,246 = 44.37; p < 0.0001). Vitamin D intake was 44% of Recommended Dietary Allowance throughout the first phase of the trial. Patient-Reported Outcomes Measurement Information System scores improved in TG for fatigue and sleep, p < 0.01. Vitamin D deficiency is widespread in AD soldiers. Clinicians must intervene early in preventable health conditions impacting warfighter performance and readiness and recommend appropriate self-care strategies.

Human crawling performance and technique revealed by inertial measurement units

Human crawling performance and technique are of broad interest to roboticists, biomechanists, and military personnel. This study explores the variables that define crawling performance in the context of an outdoor obstacle course used by military organizations worldwide to evaluate the effects of load and personal equipment on warfighter performance. Crawling kinematics, measured from four body-worn inertial measurement units (IMUs) attached to the upper arms and thighs, are recorded for thirty-three participants. The IMU data is distilled to four metrics of crawling performance; namely, crawl speed, crawl stride time, ipsilateral limb coordination, and contralateral limb coordination. We hypothesize that higher performance (as identified by higher crawl speeds) is associated with more coordinated limbs and lower stride times. A cluster analysis groups participants into high and low performers exhibiting statistically significant differences across the four performance metrics. In particular, high performers exhibit superior limb coordination associated with a “diagonal gait” in which contralateral limbs move largely in-phase to produce faster crawl speeds and shorter crawl stride times. In contrast, low performers crawl at slower speeds with longer crawl stride times and less limb coordination. Beyond these conclusions, a major contribution of this study is a method for deploying wearable IMUs to study crawling in contextually relevant (i.e. non-laboratory) environments.

The Sensitivity and Role of Equipment Bulk on a Military Mission Oriented Obstacle Course

Standardized military mission oriented obstacle courses are being used to assess the impact of clothing and individual equipment on Warfighter performance. While the role of and sensitivity of weight has been investigated, the role and sensitivity of the course to bulk has not. Bulk was varied using lightweight foam inserts, with limited variation in weight at 0% (duty uniform), 25%, 50%, 75% and 100% (based on encumbered measurements of a body armor vest with grenadier load configuration). Bulk had minimal impact on total completion time until the largest bulk configuration was added. Individual obstacle completion time findings were similar, although the sprint and agility may have been less sensitive and the walls and windows may have been more sensitive. Chest depth was the most predictive anthropometric measure for completion time. This information will aid equipment designers in understanding how their design impacts performance.