Heat Tolerance Testing and the Return to Duty Decision: A Two-Year Case Cohort Analysis.

BACKGROUND: Among individuals with prior exertional heat illness (EHI), heat tolerance testing (HTT) may inform risk and return to duty/activity. However, little is known about HTT's predictive validity, particularly for EHI recurrence. Our project sought to demonstrate the predictive validity of HTT in EHI recurrence and HTT's utility as a diagnostic tool in exertional heat stroke (EHS). METHODS: Participants with prior EHS were recruited for the study by a physician's referral and were classified as heat tolerant or intolerant after completing demographics and an HTT. Participants were further categorized as single/simple (SS) EHI or recurrent/complex (RC) EHI by conducting a retrospective record review of the following two years. We calculated the positive (PPV) and negative predictive values (NPV) of HTT. RESULTS: The retrospective review of HTT records was used to categorize 44% of Servicemembers as RC, with 77% classified as heat tolerant, 14% as heat intolerant, and 9% as borderline. When borderline cases were classified as heat intolerant, HTT had a high NPV, indicating a high probability that heat-tolerant individuals did not have recurrent EHI. When borderline cases were classified as heat tolerant, NPV and sensitivity decreased while specificity increased. CONCLUSION: We demonstrated that the HTT had a 100% NPV for future EHI over two years of follow-up for Servicemembers with a history of recurrent heat injury and negative HTT results. An HTT can provide critical data points to inform return to duty decisions and timelines by predicting the risk of EHI recurrence.

Leading indicators of readiness among the general Army and Special Operations Forces: Predictive and psychometric analysis of the Global Assessment Tool.

Self-assessments are commonly used to track Army readiness in specialized communities, but they are rarely analyzed for reliability and predictive validity. Before introducing new assessments, existing ones should be reevaluated. We examined the Global Assessment Tool (GAT), an annual Army-required self-assessment with multiple psychosocial and health behavior short scales. Psychometric analyses on nine scales included item response theory (IRT) and measurement invariance models across total Army (n = 743,057) and special operations forces (SOF; n = 3,478) cohorts. Predictive analyses examined demographic-adjusted associations between GAT scales and one-year incident medical non-readiness (MNR). Most scales had adequate reliability, although some exhibited highly skewed distributions, which likely increased measurement error. Most scales exhibited metric and scalar measurement equivalence across total Army and SOF groups. Scores from scales measuring positive characteristics were associated with lower odds of MNR (good coping, flexibility, optimism, positive affect, work engagement, friendship, organization trust; adjusted odds ratios ≤ 0.75); scores from scales measuring negative characteristics were associated with increased odds of MNR (poor sleep, depression, negative affect, loneliness; adjusted odds ratios ≥ 1.4). Associations were similar across Army and SOF cohorts. In conclusion, self-report data can potentially contribute to command surveillance, but iterative quality-checks are necessary after deployment.

The combined effects of coping and pain interference on army readiness.

Introduction: Chronic pain and associated interference with daily activities are common in the military and impact Force readiness. Chronic pain affects one-third of service members and is a leading cause of medical non-readiness (MNR) in the military. Research suggests that underlying psychological mechanisms related to trait coping styles and pain interference (PI) affect functional outcomes, but little research exists examining this relationship within an Army population. The purpose of this study was to examine the combined effects of PI and coping on U.S. Army soldier readiness by using annual well-being data from the Global Assessment Tool (GAT) and medical non-readiness (MNR) based on duty restriction records. Methods: The sample comprised 866,379 soldiers who completed the GAT between 2014 and 2017 with no duty restrictions at the time of baseline GAT completion; subjects were observed through 2018 for duty restrictions. Parametric survival regression models with a Weibull distribution predicted demographic-adjusted hazards of MNR by dichotomized PI (no PI/PI) and beneficial/non-beneficial use of GAT coping components (good coping, bad coping, catastrophizing-flexibility, and catastrophizing-hopelessness). Incident MNR was evaluated for all duty restrictions, and stratified by selected body systems (upper extremity, lower extremity, psychiatric). Results: Among soldiers with PI, hazards were higher in those reporting non-beneficial coping styles (bad coping, hopelessness) and lower in those reporting beneficial coping styles (good coping, flexibility). Across all coping styles, PI/coping interactions were particularly strong for catastrophizing-hopelessness and when examining MNR from psychiatric conditions. Discussion: These findings suggest some synergistic associations between pain and coping that may impact pain-related occupational disability. Coping skills may be an effective interventional target for chronic pain reduction/prevention within military programs, such as the Master Resilience Training Course offered to soldiers in the Army. Further research should assess whether early coping style interventions can reduce pain-related outcomes.

Who sees the chaplain? Characteristics and correlates of behavioral health care-seeking in the military.

Chaplains have a critical role in the military organization and health care. Using the 2015 Health-Related Behavior Survey, we compared Service Members' (SM) use of chaplaincy services to their use of other behavioral health (BH) services: 26.2% used any BH service and 8.0% met with a chaplain/clergyperson for BH. Among the 36.5% of SM who self-identified needing counseling, percentages of SMs receiving counseling were lower among those perceiving stigma associated with BH services (51.0%) than those not perceiving stigma (66.7%). Of SM who sought counseling: many used multiple counseling sources (48.0%), with the most common sources being a BH professional (71.6%), a medical doctor (37.5%), and a chaplain or clergyperson (30.2%). SM who met with a chaplain or clergyperson had more severe histories of abuse, were more likely to have a mental health diagnosis, and had fewer positive health behaviors than SM who sought other sources of counseling.

Effects of training service dogs on service members with PTSD: A pilot-feasibility randomized study with mixed methods.

This pilot-feasibility randomized control trial examined effects of an adjunctive short-term service dog training program (SDTP) for service members in out-patient treatment for PTSD. Twenty-nine volunteer participants were randomly assigned to either the SDTP (n = 12) or waitlist (n = 17); 20 participants were available for post-treatment evaluation. SDTP protocol consisted of six structured one-hour sessions with a dog-trainer conducted over two weeks, intended to train a service dog to help a fellow Veteran. SMs completed symptom questionnaires (PTSD, insomnia, stress, depression, anxiety), and the SDTP group completed a post-intervention quantitative interview. Most effect sizes demonstrated moderate symptom reductions, both between-groups and within the SDTP group. Between-group effects were strongest for intrusive thoughts (Hedge's g = -0.66; 95%CI: -1.72, 0.23) and overall PTSD symptoms (g = -0.45; 95%CI: -1.47, 0.45); within-SDTP group effects were strongest for stress (d = -1.31, 95%CI: -2.17, -0.42), intrusive thoughts (d = -0.78, 95%CI: -1.55, 0.01) and hypervigilance (d = -0.77, 95%CI: -1.48, -0.04). Qualitative analyses indicated participants found SDTP in some ways challenging yet beneficial in multiple aspects of personal and social lives. Future work should examine optimal treatment parameters (e.g., duration, "dosing") when training dogs as an adjunct to other PTSD treatment.

Self-Reported Health Indicators in the US Army: Longitudinal Analysis From a Population Surveillance System, 2014‒2018.

Objectives. To describe health-related behaviors or indicators associated with overall health and well-being using the Global Assessment Tool (GAT), a health behavior and psychosocial questionnaire completed annually by US Army personnel. Methods. We analyzed GAT responses from 2014 to 2018, consisting of 367 000 to 449 000 respondents per year. We used generalized estimating equations to predict the presence of each health behavior or indicator, aggregated by year and stratified on various demographics. Results. Key findings included decreases from 2014 to 2018 in risky health behaviors such as hazardous drinking (7.5% decrease) and tobacco use (7.9% decrease), dietary supplement use (5.0% to 10.6% decrease, depending on type), self-reported musculoskeletal injury (5.1% decrease), and pain interference (3.6% decrease). Physical activity, sleep, and nutritional habits largely remained consistent over time. Conclusions. In the Army, tobacco, alcohol, and risky dietary supplement usage appears to be declining, whereas lifestyle health behaviors have been stable. Whether these trends reflect responses to health education is unknown. The GAT provides useful insights into the health of the Army, which can be leveraged when developing health-related educational programs and policies. Public Health Implications. Health behaviors that have changed less over time (e.g., nutrition, sleep) may require novel approaches compared with those that changed more (e.g., dietary supplement use, drinking). (Am J Public Health. 2021;111(11):2064-2074. https://doi.org/10.2105/AJPH.2021.306456).

Perceptual strain in a compensable hot environment: Accuracy and clinical correlates.

Heat strain monitoring indexes are important to prevent exertional heat illness (EHI) and uncover risk factors. Two indexes are the Physiological Strain Index (PSI) and a subjective PSI analogue, the Perceptual Strain Index (PeSI). The PeSI is a feasible alternative to PSI in field conditions, although the validity has been variable in previous research. However, the PeSI has been rarely examined at a low heat strain with compensable heat stress, such as during a heat tolerance test (HTT). This study evaluated the discrepancy between the maximal PeSI and maximal PSI achieved during a HTT and determined their association with EHI risk factors, including history of EHI, percent body fat (%BF), relative VO2max, fatigue and sleep status (n = 121; 47 without prior EHI, 74 with prior EHI). The PSI was calculated using the change in rectal temperature (Tre) and heart rate (HR) and PeSI was calculated based on the formula containing thermal sensation (TS), a Tre analogue, and rate of perceived exertion (RPE), a HR analogue. Significant associations were identified between PSI and PeSI and between PSIHR and PeSIHR in the total sample and between PSI and PeSI in the EHI group. Bland-Altman analyses indicated PeSI underestimated PSI in the total sample, PSIHR was greater than PeSIHR, and that PSIcore and PeSIcore were not significantly different, but values varied widely at different heat strains. This indicates the use of RPE underestimates HR and that the accuracy of TS to predict Tre may be subpar. This study also demonstrated that participants with higher %BF have a decreased perception of heat strain and that post-fatigue, sleep status and a prior EHI may increase the perception of heat strain. Overall, these results suggest that PeSI is a poor surrogate for PSI in a compensable heat stress environment at low heat strain.

A 3-D virtual human thermoregulatory model to predict whole-body and organ-specific heat-stress responses.

OBJECTIVE: This study aimed at assessing the risks associated with human exposure to heat-stress conditions by predicting organ- and tissue-level heat-stress responses under different exertional activities, environmental conditions, and clothing. METHODS: In this study, we developed an anatomically detailed three-dimensional thermoregulatory finite element model of a 50th percentile U.S. male, to predict the spatiotemporal temperature distribution throughout the body. The model accounts for the major heat transfer and thermoregulatory mechanisms, and circadian-rhythm effects. We validated our model by comparing its temperature predictions of various organs (brain, liver, stomach, bladder, and esophagus), and muscles (vastus medialis and triceps brachii) under normal resting conditions (errors between 0.0 and 0.5 °C), and of rectum under different heat-stress conditions (errors between 0.1 and 0.3 °C), with experimental measurements from multiple studies. RESULTS: Our simulations showed that the rise in the rectal temperature was primarily driven by the activity level (~ 94%) and, to a much lesser extent, environmental conditions or clothing considered in our study. The peak temperature in the heart, liver, and kidney were consistently higher than in the rectum (by ~ 0.6 °C), and the entire heart and liver recorded higher temperatures than in the rectum, indicating that these organs may be more susceptible to heat injury. CONCLUSION: Our model can help assess the impact of exertional and environmental heat stressors at the organ level and, in the future, evaluate the efficacy of different whole-body or localized cooling strategies in preserving organ integrity.

A nature-based health intervention at a military healthcare center: a randomized, controlled, cross-over study.

We describe a mixed qualitative and quantitative research study in a military facility regarding the role of nature in well-being. Study intervention included two 20-minute walks. One walk was in an intentionally designed woodland environment (Green Road) and the other was on a busy campus road in a medical treatment facility (Urban Road). Twelve volunteers from a military facility participated in both walks in a cross-over experimental design. The two walking sessions were randomly ordered and preceded by pre-walk instructions appropriate to each road's characteristics and incorporated focused attention and present moment orientation. A semi-structured post-walk interview, the primary outcome, was conducted after the conclusion of each walk. Qualitative data analyses consisted of sentiments and themes by using NVivo 12 software. The Green Road was unanimously rated as positive (100%). Responses to Urban Road were evenly distributed among positive (33.3%), negative (33.3%), and neutral/mixed (33.3%) sentiments. The Green Road yielded predominantly positive themes such as enjoyment of nature, relaxation, and feelings of privacy and safety. Urban Road produced significantly more negative themes such as concerns for safety, dislike of noise and other noxious experiences. Quantitative assessment of distress and mindfulness with Distress Thermometer (DT) and Mindful Attention Awareness Scale-state version (MAAS) demonstrated that a walk on the Green Road significantly decreased distress and increased mindfulness compared to a walk on the Urban Road. We also observed that pre-walk instructions could direct attention to both obvious and subtle elements of experience and enhance awareness. Results support the notion that an intentional nature-based environment may produce significantly more positive experiences and result in health-promoting benefits in a military health-care setting compared to an urban environment. Future studies with clinical populations could advance our understanding of the healing value of nature-based interventions. The impact of intentional green environments may be enhanced by well-designed instructions for both recreational and therapeutic use.

Healthy lifestyles among military active duty service members, and associations with body-building and weight-loss supplement use.

PURPOSE: The purpose of this study was to characterize health behavior profiles among active duty service members and associate these profiles with body-building and weight-loss dietary supplement (DS) use. METHODS: Based on U.S. active duty service members who completed the 2011 Health-Related Behavior Survey (n = 39,877), we used latent class analysis to place respondents into latent classes (using healthy/unhealthy food consumption, aerobic activity, strength training, and sleep) and examined associations between latent class and DS use. RESULTS: We identified seven health behavior classes that could be classified by physical activity and diet. Three classes with high activity were further characterized by healthy diet (24%); few unhealthy foods (18%); and unrestricted diet (9%). Three classes with low activity were further characterized by restricted diet (15%), healthy diet (15%), and unhealthy diet (6%). The last class (13%) reported moderate levels of all behaviors. The classes did not vary by sleep. Participant characteristics across most classes were relatively homogenous along demographics and military branch. The active classes had relatively higher usage of body-building and weight-loss DSs. CONCLUSIONS: Latent classes from health behavior indicators might be considered "market segments", which can be targeted with distinct messaging. Service members appear to consume DSs as part of an otherwise healthy lifestyle.

Caffeine and heat have additive but not interactive effects on physiologic strain: A factorial experiment.

This study tested the interactive effects of heat and caffeine on exercise-induced physiological strain by using a 2x2 within-subjects factorial design. Thirty-five physically fit Caucasians underwent a bout of exercise under four conditions wherein ambient conditions (heat vs no heat) and caffeine (placebo vs caffeine; double-blinded) were manipulated. Exercise consisted of a 60-min walk and 5-min step/squat test while wearing weighted backpack. Primary outcomes include measures of physiologic strain (Core temperature [Tr] and heart rate [HR]). Secondary measures included blood pressure, markers of sweat loss, and creatine kinase (CK). Repeated measures models were created to evaluate the individual and combined effects of heat and caffeine. Key results indicated that heat and caffeine significantly increased Tr and HR after walking and stair-stepping. No significant heat by caffeine interactions were detected, and caffeine's main effects were relatively low (≤0.17 °C for Tr and ≤6.6 bpm for HR). Of note, heat and caffeine exhibited opposite effects on blood pressure: caffeine increased both systolic and diastolic blood pressure (by 6-7 mmHg) and heat decreased them (by 4-6 mm Hg; ps < 0.05). In summary, heat and caffeine affected physiologic strain during exercise but exhibited no synergistic effects. In contrast, neither factor affected muscle damage. Clinical implications for heat illness risk in the military are discussed.

Health Behaviors and Psychosocial Attributes of US Soldiers.

BACKGROUND: Health trends, which promote performance enhancement and maintaining or increasing muscle strength, may appeal to soldiers looking to maintain health standards set by the US Army, but often these trends require further investigation to assess safety and efficacy. High-intensity interval training (HIIT) and use of weight loss and/or performance-enhancing/body-building dietary supplements (WL/PES DS) are two such trends that, if implemented inappropriately, can negatively impact soldier health and readiness. OBJECTIVE: Our aim was to establish health/psychosocial profiles of US Army soldiers who participate in HIIT and/or use WL/PES DS. DESIGN: This cross-sectional observational study used data from the 2016 US Army Global Assessment Tool. PARTICIPANTS: Data were analyzed from respondents to the 2016 US Army Global Assessment Tool (n=299,996) who consented to have their data used for research purposes. RESULTS: Soldiers were classified into four groups based on HIIT and/or WL/PES DS use. Thirty-five percent of soldiers participated in HIIT and 10% took WL/PES DS at least once per month in the last year. HIIT participation was associated with higher reported odds of healthy behaviors and higher emotional and social fitness. In contrast to HIIT, WL/PES DS use was associated with higher reported odds of risky behaviors (hazardous drinking and tobacco use) and lower psychosocial fitness. The group participating in HIIT but not using WL/PES DS reported fewer unhealthy behaviors compared to the HIIT+WL/PES DS and WL/PES DS-only groups. CONCLUSIONS: Engaging in HIIT is associated with higher reported odds of healthy behaviors and increased psychosocial fitness. However, soldiers who engaged in HIIT also have increased odds of WL/PES DS use, which is associated with greater reported risky behaviors and reduced fitness. Although HIIT and WL/PES DS use are related, they are associated with different reported health/risky behaviors and different psychosocial attributes.

Gene expression profiling of humans under exertional heat stress: Comparisons between persons with and without exertional heat stroke.

Exertional heat stroke (EHS) is a leading cause of preventable morbidity and mortality among both athletes and warfighters. Therefore, it is important to find blood biomarkers to predict susceptibility to EHS. We compared gene expression profiling from blood cells between two groups of participants - those with and those without a history EHS - by using genome-wide microarray analysis. Subjects with a history of EHS (n = 6) and non-EHS controls without a history of EHS (n = 18) underwent a heat tolerance test and a thermoneutral exercise challenge on separate days. The heat tolerance test comprised of 2-h of walking, at 5 km/h and 2% incline, with ambient conditions set at 40 °C, 40% relative humidity; the thermoneutral test was similar, but had ambient conditions set at 22 °C. Next, we examined gene expression profiles, quantified based on arithmetic differences (post minus pre) during the heat test minus changes during the thermoneutral test. Genes related to interleukins and cellular stress were significantly down-regulated in participants with a history of EHS compared to their non-EHS counterparts. Suppression of these genes may be associated with susceptibility to exertional heat injury. Prospective research is required to determine whether similar gene expression profiling can be potentially used as blood biomarkers to predict susceptibility to EHS.

Effects of vitamin D supplementation on salivary immune responses during Marine Corps basic training.

Vitamin D's role in regulating immune responses may increase during periods of elevated psychological and physiological stress. Due to the high demands placed on US Marine Corps recruits undergoing 12 weeks of basic military training, we hypothesized that vitamin D status would be related to markers of innate mucosal immunity, and daily vitamin D supplementation would augment immune responses during training. Males (n = 75) and females (n = 74) entering recruit basic training during the summer and winter volunteered to participate in a randomized, double-blind, placebo-controlled study. Subjects received either 1000 IU vitamin D3  + 2000 mg calcium/d (n = 73) or placebo (n = 76) for 12 weeks. Saliva samples were collected pre-training, during (weeks 4 and 8), and post-training (week 12) in order to determine salivary SIgA and cathelicidin (indices of mucosal immunity) and α-amylase (indicator of stress). Initial (baseline) and post-training serum 25(OH)D levels were measured. Results were as follows: serum 25(OH)D levels were 37% higher in recruits entering training in summer compared with winter. A positive relationship was observed between baseline 25(OH)D levels and SIgA secretion rates (-SR). When stress levels were high during summer training, baseline 25(OH)D levels contributed to an increase in salivary secretory immunoglobulin A secretion rates (SIgA-SR) and cathelicidin-SR, the latter only in males. Vitamin D supplementation contributed to the changes in SIgA-SR and cathelicidin-SR, specifically SIgA-SR was higher in the treatment group. These data highlight the importance of vitamin D and mucosal immune responses during arduous basic military training when stress levels are increased.

Activity modification in heat: critical assessment of guidelines across athletic, occupational, and military settings in the USA.

Exertional heat illness (EHI) risk is a serious concern among athletes, laborers, and warfighters. US Governing organizations have established various activity modification guidelines (AMGs) and other risk mitigation plans to help ensure the health and safety of their workers. The extent of metabolic heat production and heat gain that ensue from their work are the core reasons for EHI in the aforementioned population. Therefore, the major focus of AMGs in all settings is to modulate the work intensity and duration with additional modification in adjustable extrinsic risk factors (e.g., clothing, equipment) and intrinsic risk factors (e.g., heat acclimatization, fitness, hydration status). Future studies should continue to integrate more physiological (e.g., valid body fluid balance, internal body temperature) and biometeorological factors (e.g., cumulative heat stress) to the existing heat risk assessment models to reduce the assumptions and limitations in them. Future interagency collaboration to advance heat mitigation plans among physically active population is desired to maximize the existing resources and data to facilitate advancement in AMGs for environmental heat.

Individualized estimation of human core body temperature using noninvasive measurements.

A rising core body temperature (Tc) during strenuous physical activity is a leading indicator of heat-injury risk. Hence, a system that can estimate Tc in real time and provide early warning of an impending temperature rise may enable proactive interventions to reduce the risk of heat injuries. However, real-time field assessment of Tc requires impractical invasive technologies. To address this problem, we developed a mathematical model that describes the relationships between Tc and noninvasive measurements of an individual's physical activity, heart rate, and skin temperature, and two environmental variables (ambient temperature and relative humidity). A Kalman filter adapts the model parameters to each individual and provides real-time personalized Tc estimates. Using data from three distinct studies, comprising 166 subjects who performed treadmill and cycle ergometer tasks under different experimental conditions, we assessed model performance via the root mean squared error (RMSE). The individualized model yielded an overall average RMSE of 0.33 (SD = 0.18)°C, allowing us to reach the same conclusions in each study as those obtained using the Tc measurements. Furthermore, for 22 unique subjects whose Tc exceeded 38.5°C, a potential lower Tc limit of clinical relevance, the average RMSE decreased to 0.25 (SD = 0.20)°C. Importantly, these results remained robust in the presence of simulated real-world operational conditions, yielding no more than 16% worse RMSEs when measurements were missing (40%) or laden with added noise. Hence, the individualized model provides a practical means to develop an early warning system for reducing heat-injury risk. NEW & NOTEWORTHY A model that uses an individual's noninvasive measurements and environmental variables can continually "learn" the individual's heat-stress response by automatically adapting the model parameters on the fly to provide real-time individualized core body temperature estimates. This individualized model can replace impractical invasive sensors, serving as a practical and effective surrogate for core temperature monitoring.

Role of plasma adiponectin /C-reactive protein ratio in obesity and type 2 diabetes among African Americans.

BACKGROUND: Obesity is a modifiable risk factor for hypertension and T2D. Objective(s): We examined relations between fasting plasma adiponectin (ADIP), C-reactive protein (CRP) concentrations and markers of T2D in African Americans (AA). METHODS: Fasting plasma ADIP, CRP, Insulin (IN), HOMA-IR, lipid profiles, body fat percent (%BF), waist circumference (WC), body mass index (BMI) and blood pressure measures were determined in AA women (W: n=77) and men (M: n=34). Participants were classified into: 1) Normal fasting glucose (FG) and Normal %BF; 2) Normal FG and High %BF; and 3) High FG. RESULTS: Compared to men, women had significantly higher mean ADIP (W: 31.4±2.9 vs. M: 18.0±4.4 ng/L), CRP (W: 3.2±0.3 vs. M: 2.0±0.5 mg/L), %BF (W: 41.2±0.9 vs. M: 27.2±1.3), and BMI (W: 32.3±0.7 vs. M: 29.2±1.1 kg/m2). Women with normal FG and %BF had significantly higher ADIP (64.0±6.0) and lower CRP (1.3±0.6) concentrations than normal FG/ high %BF (ADIP: 37.0±5.0 and CRP: 3.1 ±0.5) and high FG (ADIP: 15.1±4.1 and CRP: 4.0 ± 0.5) groups. Women with high ADIP to CRP ratio had favorable metabolic and anthropometric profiles. CONCLUSION: Low ADIP and high CRP are associated with excessive %BF and FG in AA women. ADIP/CRP, may be useful for detecting metabolic dysregulation.

Using item response theory to address vulnerabilities in FFQ.

The limitations for self-reporting of dietary patterns are widely recognised as a major vulnerability of FFQ and the dietary screeners/scales derived from FFQ. Such instruments can yield inconsistent results to produce questionable interpretations. The present article discusses the value of psychometric approaches and standards in addressing these drawbacks for instruments used to estimate dietary habits and nutrient intake. We argue that a FFQ or screener that treats diet as a 'latent construct' can be optimised for both internal consistency and the value of the research results. Latent constructs, a foundation for item response theory (IRT)-based scales (e.g. Patient Reported Outcomes Measurement Information System) are typically introduced in the design stage of an instrument to elicit critical factors that cannot be observed or measured directly. We propose an iterative approach that uses such modelling to refine FFQ and similar instruments. To that end, we illustrate the benefits of psychometric modelling by using items and data from a sample of 12 370 Soldiers who completed the 2012 US Army Global Assessment Tool (GAT). We used factor analysis to build the scale incorporating five out of eleven survey items. An IRT-driven assessment of response category properties indicates likely problems in the ordering or wording of several response categories. Group comparisons, examined with differential item functioning (DIF), provided evidence of scale validity across each Army sub-population (sex, service component and officer status). Such an approach holds promise for future FFQ.

Blood Hemostatic Changes During an Ultraendurance Road Cycling Event in a Hot Environment.

OBJECTIVE: This study aims to examine blood hemostatic responses to completing a 164-km road cycling event in a hot environment. METHODS: Thirty-seven subjects (28 men and 9 women; 51.8±9.5 [mean±SD] y) completed the ride in 6.6±1.1 hours. Anthropometrics (height, body mass [taken also during morning of the ride], percent body fat [%]) were collected the day before the ride. Blood samples were collected on the morning of the ride (PRE) and immediately after (IP) the subject completed the ride. Concentrations of platelet, platelet activation, coagulation, and fibrinolytic markers (platelet factor 4, ß-thromboglobulin, von Willebrand factor antigen, thrombin-antithrombin complex, thrombomodulin, and D-Dimer) were measured. Associations between changes from PRE- to IP-ride were examined as a function of event completion time and subject characteristics (demographics and anthropometrics). RESULTS: All blood hemostatic markers increased significantly (P < .001) from PRE to IP. After controlling for PRE values, finishing time was negatively correlated with platelet factor 4 (r = 0.40; P = .017), while percent body fat (%BF) was negatively correlated with thrombin-antithrombin complex (r = -0.35; P = .038) and to thrombomodulin (r = -0.36; P = .036). In addition, male subjects had greater concentrations of thrombin-antithrombin complex (d = 0.63; P < .05) and natural logarithm thrombomodulin (d = 6.42; P < .05) than female subjects. CONCLUSION: Completing the 164-km road cycling event in hot conditions resulted in increased concentrations of platelet, platelet activation, coagulation, and fibrinolytic markers in both men and women. Although platelet activation and coagulation occurred, the fibrinolytic system markers also increased, which appears to balance blood hemostasis and may prevent clot formation during exercise in a hot environment.

Domestic Civil Support Missions Can Aggravate Negative Mental Health Outcomes Among National Guardsmen: The Moderating Role of Economic Difficulties.

Little research has addressed potentially negative health outcomes associated with domestic civil-oriented operations, but has focused instead on traditional military operations (e.g., combat). This study, conducted following a United States Defense Support to Civilian Authorities mission undertaken by National Guard forces (N = 330), showed that responding to such missions was linked to more negative mental health outcomes, including posttraumatic stress disorder (ß = 0.23) and depression (ß = 0.23), but only among those who reported difficulty meeting their basic socioeconomic needs and not among those who did not have difficulty meeting their basic needs. The study offers suggestions for identifying individuals who may be especially vulnerable to stressors.