Biomarkers of oxidative stress, diet and exercise distinguish soldiers selected and non-selected for special forces training.

INTRODUCTION: The metabolomic profiles of Soldiers entering the U.S. Special Forces Assessment and Selection course (SFAS) have not been evaluated. OBJECTIVES: To compare pre-SFAS blood metabolomes of Soldiers selected during SFAS versus those not selected, and explore the relationships between the metabolome, physical performance, and diet quality. METHODS: Fasted blood samples and food frequency questionnaires were collected from 761 Soldiers prior to entering SFAS to assess metabolomic profiles and diet quality, respectively. Physical performance was assessed throughout SFAS. RESULTS: Between-group differences (False Discovery Rate < 0.05) in 108 metabolites were detected. Selected candidates had higher levels of compounds within xenobiotic, pentose phosphate, and corticosteroid metabolic pathways, while non-selected candidates had higher levels of compounds potentially indicative of oxidative stress (i.e., sphingomyelins, acylcarnitines, glutathione, amino acids). Multiple compounds higher in non-selected versus selected candidates included: 1-carboxyethylphenylalanine; 4-hydroxy-nonenal-glutathione; α-hydroxyisocaproate; hexanoylcarnitine; sphingomyelin and were associated with lower diet quality and worse physical performance.  CONCLUSION: Candidates selected during SFAS had higher pre-SFAS levels of circulating metabolites that were associated with resistance to oxidative stress, higher physical performance and higher diet quality. In contrast, non-selected candidates had higher levels of metabolites potentially indicating elevated oxidative stress. These findings indicate that Soldiers who were selected for continued Special Forces training enter the SFAS course with metabolites associated with healthier diets and better physical performance. Additionally, the non-selected candidates had higher levels of metabolites that may indicate elevated oxidative stress, which could result from poor nutrition, non-functional overreaching/overtraining, or incomplete recovery from previous physical activity.

A Survey Instrument to Assess Intake of Dietary Supplements, Related Products, and Caffeine in High-Use Populations.

Substantial data on the use of dietary supplements by the general adult population are available, but many population subgroups have not been extensively studied. Because military service members and young people consume large amounts of dietary supplements, including for enhancement of physical performance, weight control, and bodybuilding, which can be dangerous, we developed a comprehensive questionnaire to characterize patterns of supplement use in these and other populations. The questionnaire has been used to study >7000 military service members and 1000 college students. This supplement article presents a detailed description of the questionnaire, which contains comprehensive questions on demographic characteristics, exercise habits, attitudes with regard to dietary supplements, and amount of money spent on supplements. Intakes of specific dietary supplements and caffeine, frequency of use, and reasons for use are assessed. The questionnaire was designed for studying dietary supplement and caffeine intake patterns with the use of paper-and-pencil administration to military populations and was modified for use with college students and for computer and Web administration. It is available online at https://go.usa.gov/xn9FP and in the Supplemental File for this publication. It can be used to study other populations if minor modifications are made. The online version of the questionnairewill be updated periodically as newversions become available. In conclusion, a validated, detailed, noncopyrighted questionnaire designed to assess the use of dietary supplements, energy drinks (and related products), and caffeine is available for use in diverse populations. The format of the questionnaire is adaptable to computer administration and scoring, and it can be customized for specific subpopulations, locations, and product categories including updates that reflect changes in the availability of supplements or availability of new products.

To close or not to close? Wound management in emergent colorectal surgery, an EAST multicenter prospective cohort study.

BACKGROUND: This study aimed to determine the clinical impact of wound management technique on surgical site infection (SSI), hospital length of stay (LOS), and mortality in emergent colorectal surgery. METHODS: A prospective observational study (2021-2023) of urgent or emergent colorectal surgery patients at 15 institutions was conducted. Pediatric patients and traumatic colorectal injuries were excluded. Patients were classified by wound closure technique: skin closed (SC), skin loosely closed (SLC), or skin open (SO). Primary outcomes were SSI, hospital LOS, and in-hospital mortality rates. Multivariable regression was used to assess the effect of wound closure on outcomes after controlling for demographics, patient characteristics, intensive care unit admission, vasopressor use, procedure details, and wound class. A priori power analysis indicated that 138 patients per group were required to detect a 10% difference in mortality rates. RESULTS: In total, 557 patients were included (SC, n = 262; SLC, n = 124; SO, n = 171). Statistically significant differences in body mass index, race/ethnicity, American Society of Anesthesiologist scores, EBL, intensive care unit admission, vasopressor therapy, procedure details, and wound class were observed across groups. Overall, average LOS was 16.9 ± 16.4 days, and rates of in-hospital mortality and SSI were 7.9% and 18.5%, respectively, with the lowest rates observed in the SC group. After risk adjustment, SO was associated with increased risk of mortality (OR, 3.003; p = 0.028) in comparison with the SC group. Skin loosely closed was associated with increased risk of superficial SSI (OR, 3.439; p = 0.014), after risk adjustment. CONCLUSION: When compared with the SC group, the SO group was associated with mortality but comparable when considering all other outcomes, while the SLC was associated with increased superficial SSI. Complete skin closure may be a viable wound management technique in emergent colorectal surgery. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level III.

Effects of energy balance on cognitive performance, risk-taking, ambulatory vigilance and mood during simulated military sustained operations (SUSOPS).

Sustained operations (SUSOPS) require military personnel to conduct combat and training operations while experiencing physical and cognitive stress and limited sleep. These operations are often conducted in a state of negative energy balance and are associated with degraded cognitive performance and mood. Whether maintaining energy balance can mitigate these declines is unclear. This randomized crossover study assessed the effects of energy balance on cognitive performance, risk-taking propensity, ambulatory vigilance, and mood during a simulated 72-h SUSOPS. METHODS: Ten male Soldiers (mean ± SE; 22.4 ± 1.7 y; body weight 87.3 ± 1.1 kg) completed two, 72-h simulated SUSOPS in random order, separated by 7 days of recovery. Each SUSOPS elicited ∼4500 kcal/d total energy expenditure and restricted sleep to 4 h/night. During SUSOPS, participants consumed either an energy-balanced or restricted diet that induced a 43 ± 3% energy deficit. A cognitive test battery was administered each morning and evening to assess: vigilance, working memory, grammatical reasoning, risk-taking propensity, and mood. Real-time ambulatory vigilance was assessed each morning, evening, and night via a wrist-worn monitoring device. RESULTS: Participants exhibited heightened risk-taking propensity (p = 0.047) with lower self-reported self-control (p = 0.021) and fatigue (p = 0.013) during energy deficit compared to during energy balance. Vigilance accuracy (p < 0.001) and working memory (p = 0.040) performance decreased, and vigilance lapses increased (p < 0.001) during SUSOPS, but did not differ by diet. Percentage of correct responses to ambulatory vigilance stimuli varied during SUSOPS (p = 0.019) independent of diet, with generally poorer performance during the morning and night. Total mood disturbance (p = 0.001), fatigue (p < 0.001), tension (p = 0.003), and confusion (p = 0.036) increased whereas vigor decreased (p < 0.001) during SUSOPS, independent of diet. CONCLUSION: Prolonged physical activity combined with sleep restriction is associated with impaired vigilance, memory, and mood state. Under such conditions, maintaining energy balance prevents increased risk-taking and improves self-control, but does not improve other aspects of cognitive function or mood. Given the small sample in the present study, replication in a larger cohort is warranted.

Anthropometrics and Body Composition Predict Physical Performance and Selection to Attend Special Forces Training in United States Army Soldiers.

INTRODUCTION: Anthropometrics and body composition characteristics differentiate many types of athletes and are related to performance on fitness tests and tasks in military personnel. Soldiers competing to enter elite units must demonstrate physical fitness and operational competence across multiple events. Therefore, this study determined whether anthropometrics and body composition predicted physical performance and selection for special forces training among soldiers attending the rigorous Special Forces Assessment and Selection (SFAS) course. MATERIALS AND METHODS: Soldiers attending the SFAS course between May 2015 and March 2017 were enrolled in a longitudinal, observational study. Anthropometrics (height, body mass, and body mass index [BMI]; n = 795) and body composition measured by dual-energy X-ray absorptiometry (percentage body fat, fat mass, lean mass, bone mineral content [BMC], and bone mineral density [BMD]; n = 117) were assessed before the course start. Associations with physical performance were determined with correlation coefficients. Associations with selection were determined with analyses of variance and t-tests; effect sizes were calculated as Cohen's d. The U.S. Army Research Institute of Environmental Medicine Institutional Review Board (IRB) initially approved this study, and the U.S. Army Medical Research and Development Command IRB approved the continuing review. RESULTS: Lower percentage body fat and fat mass predicted better performance on all assessments: Army Physical Fitness Test (APFT), pull-ups, SFAS run, loaded road march, obstacle course, and land navigation (P ≤ .05). Higher lean mass predicted better performance on the loaded road march (P ≤ .05). Lower body mass and BMI predicted better performance on APFT, pull-ups, run, and obstacle course; higher body mass and BMI predicted better performance on the loaded road march (P ≤ .05). Shorter stature predicted better performance on push-ups (APFT) and pull-ups; taller stature predicted better performance on SFAS run and loaded road march (P ≤ .05). On average, the selected soldiers were taller (179.0 ± 6.6 vs. 176.7 ± 6.7 cm), had higher body mass (85.8 ± 8.8 vs. 82.1 ± 9.6 kg), BMI (26.8 ± 2.2 vs. 26.3 ± 2.6 kg/m2), lean mass (67.2 ± 7.3 vs. 61.9 ± 7.6 kg), BMC (3.47 ± 0.40 vs. 3.29 ± 0.56 kg), and BMD (1.34 ± 0.10 vs. 1.28 ± 0.10 g/cm2), and lower percentage body fat (17.3 ± 3.4 vs. 20.1 ± 4.5%) and fat mass (14.2 ± 3.7 vs. 15.8 ± 4.4 kg) (P ≤ .05). Effect sizes were largest for lean mass (Cohen's d = 0.71) and percentage body fat (d = 0.70), followed by BMD (d = 0.60), body mass (d = 0.40), fat mass (d = 0.39), BMC (d = 0.37), height (d = 0.35), and BMI (d = 0.21). Body mass adjustment attenuated associations between height and selection. CONCLUSIONS: Anthropometrics and body composition are predictors of physical performance and SFAS success. Since these measures are modifiable (excluding height), they may be the focus of intervention studies aiming to improve performance in arduous military training courses, sports that require competition in multiple events, and occupations that have varied physical demands, such as firefighting, law enforcement, and construction.

Dietary Supplement Use in US Army Personnel: A Mixed-Methods, Survey and Focus-Group Study Examining Decision Making and Factors Associated With Use.

BACKGROUND: Dietary supplement (DS) use by Army personnel is high and is a safety and readiness issue. OBJECTIVE: Our aim was to examine factors motivating use of DSs among US Army personnel and preferred safety education strategies. DESIGN: This mixed-method study used a validated DS questionnaire and subsequent focus groups that were formed based on questionnaire-identified demographic characteristics. An embedded qualitative dominant design was used. PARTICIPANTS/SETTING: Data were collected from April to July 2015 from active duty soldiers at 3 military installations in the United States. MAIN OUTCOME MEASURES: A self-report questionnaire (n = 289) provided data on demographic characteristics, health, exercise, detailed use, and attitudes regarding DS safety and efficacy. Fourteen focus-group sessions (n = 129) examined factors motivating DS use, education strategies, and identified themes and DS-related behaviors. STATISTICAL ANALYSIS PERFORMED: Descriptive statistics and χ2 analyses were conducted. RESULTS: Of the soldiers who completed questionnaires, 83% were male, 60% were enlisted, and 40% were officers; mean age ± standard deviation was 27.6 ± 0.36 years and 75% used at least 1 type of DS per week: 52% used protein/amino acids, 47% used multivitamins/minerals, and 35% used a combination of products. Focus groups indicated reasons for use included physical appearance, fitness, peer endorsement, ease of access, limited availability of healthy food, occupational demands, and health. Participants requested education from an expert on safe use that was not focused on dangerous products. CONCLUSIONS: Soldiers are high DS users, especially products marked for purported performance enhancement. Motivating factors for DS use are fitness/appearance and occupational demands, but soldiers lack knowledge of DS regulatory requirements and safety/efficacy. Soldiers wished to receive education on DSs from trusted health care professionals, such as registered dietitian nutritionists, that was not focused on dangerous products. Study findings suggest guidance and education should occur before periods of high DS use, such as deployment.

Diet Quality Is Associated with Physical Performance and Special Forces Selection.

PURPOSE: This study determined associations between diet quality measured by the Healthy Eating Index (HEI)-2015, physical performance, and successful selection following a U.S. Army Special Forces Assessment and Selection course characterized by arduous cognitive and physical demands. METHODS: The HEI-2015 scores were calculated from usual diet assessed with a Block food frequency questionnaire among 782 soldiers attending Special Forces Assessment and Selection. Differences in HEI-2015 scores according to demographics and physical performance were determined with analysis of variance. Differences in likelihood of selection according to HEI-2015 scores were determined with logistic regression. Models were adjusted for potential confounders: age, education, body mass index (BMI), duration and type of resistance training, and smoking. RESULTS: The HEI-2015 total score was higher among older soldiers (≥25 yr), those with more education (≥some college), higher body mass index (≥25), longer duration of resistance training (≥400 min·wk), those that reported use of free weights, suspension training, Olympic lifting, and nonsmokers (P < 0.05). The HEI-2015 total score was higher among those with higher Army Physical Fitness Test (APFT) total scores, APFT sit-up score, APFT run score, and faster loaded road march times (P < 0.05). Those with higher HEI-2015 total scores were 75% (quartile 3 vs quartile 1: odds ratio, 1.75; 95% confidence interval, 1.09-2.81) and 65% (quartile 4 vs quartile 1: odds ratio, 1.65, 95% confidence interval, 1.03-2.65) more likely to be selected. Higher scores for total vegetables, greens and beans, seafood and plant protein, and refined grains, but lower sodium scores (indicating more sodium consumed), were associated with better physical performance (P < 0.05). CONCLUSIONS: Dietary patterns that conform to federal dietary guidelines (except sodium) are associated with physical performance and Special Forces selection.

Fatigue and its management in the workplace.

Fatigue and workplace sleepiness are consequences of modern industrial society. Fatigue is a complex biological phenomenon that occurs as a function of time awake, time-of-day, workload, health, and off-duty lifestyle. Fatigue is a function of two major biological factors - the homeostatic drive for sleep and circadian rhythm of sleepiness. The greatest cause of fatigue is insufficient or disrupted sleep. Excessive sleepiness in the workplace and on highways is a serious safety hazard, and insufficient or disrupted sleep results in numerous accidents and adverse mental and physical health outcomes. Evidence-based strategies that promote better sleep and optimize work/rest schedules can mitigate the impact of fatigue and sleep loss. Proper nap and sleep scheduling, work breaks, modeling and monitoring tools, fatigue detection technologies, and pharmacological countermeasures can be implemented at home and/or in the workplace to reduce performance and safety hazards. Education about obtaining adequate sleep, the dangers of fatigue in terms of both health and cognitive consequences, and the availability of scientifically-proven sleep-enhancement and alertness-management strategies is essential.

Physical performance, demographic, psychological, and physiological predictors of success in the U.S. Army Special Forces Assessment and Selection course.

This study assessed predictors of successful selection in the very challenging and stressful United States Army Special Forces Assessment and Selection (SFAS) course among 800 Soldiers. A battery of measures were collected during the course and their ability to predict selection were assessed using logistic regression and chi-square tests. Physical performance measures were most predictive, including road march times, land navigation coordinates found, run times, fitness test score, obstacle course score, and pull-ups (p < .05). Soldiers that were officers or 18× enlisted (fast-tracked to SFAS), had <1 year of active duty, ≥ bachelor degree, no children, were not married, and were Ranger school graduates were more likely to be selected (p < .05). Several psychological measures were predictive, including intelligence quotient, grade level equivalents, resilience score, military aptitude score, and grit (p < .05). Basal serum physiological markers weakly predicted selection and were weakly associated with behavioral assessments. Lower C-reactive protein (< 9.5 nmol/L) and higher cortisol and sex-hormone binding globulin (SHBG) predicted selection (p < .05). Higher C-reactive protein (≥ 9.5 nmol/L) was associated with lower fitness test scores and slower road march time (p < .05). Cortisol was correlated with higher grit and resilience scores (p < .05). SHBG correlated with higher grade level equivalents and better performance on pull-ups, land navigation, obstacle course, and the fitness test (p < .05). Testosterone was correlated with faster run and road march times (p < .05). Dehydroepiandrosterone-sulfate (DHEA-S) correlated with lower resilience scores, and DHEA-S, epinephrine, and norepinephrine correlated with worse performance on several physical events (p < .05). These findings suggest measures that could be targeted in interventions to monitor and enhance performance and resilience.

Cognitive function, stress hormones, heart rate and nutritional status during simulated captivity in military survival training.

Stress influences numerous psychological and physiological processes, and its effects have practical implications in a variety of professions and real-world activities. However, few studies have concurrently assessed multiple behavioral, hormonal, nutritional and heart-rate responses of humans to acute, severe stress. This investigation simultaneously assessed cognitive, affective, hormonal, and heart-rate responses induced by an intensely stressful real-world environment designed to simulate wartime captivity. Sixty males were evaluated during and immediately following participation in U.S. Army Survival, Evasion, Resistance, and Escape (SERE) school, three weeks of intense but standardized training for Soldiers at risk of capture. Simulated captivity and intense mock interrogations degraded grammatical reasoning (p<0.005), sustained-attention (p<0.001), working memory (p<0.05) and all aspects of mood assessed by the Profile of Mood States (POMS) questionnaire: Tension/Anxiety, Depression/Dejection, Anger/Hostility, Vigor/Activity, Fatigue/Inertia; Confusion/Bewilderment, and Total Mood Disturbance (p<0.001) It also elevated heart rate (p<0.001); increased serum and salivary cortisol and dehydroepiandrosterone-sulfate (DHEA-s) (p<0.01); elevated serum epinephrine, norepinephrine, and soluble transferrin receptors (sTfR) (p<0.01); increased salivary neuropeptide-Y (NPY) (p<0.001); and decreased serum prolactin and serum and salivary testosterone (p<0.001). Partial recovery was observed immediately after training, but stress-induced changes, particularly in body weight and several of the biomarkers, persisted. This study demonstrates that when individuals were exposed to realistic and controlled simulated captivity, cognition, mood, stress hormones, nutritional status and heart rate are simultaneously altered, and each of these subsequently recovers at different rates.

The catecholamine neurotransmitter precursor tyrosine increases anger during exposure to severe psychological stress.

RATIONALE: Acute stress produces behavioral and physiological changes modulated by central catecholamines (CA). Stress increases CA activity, and depletion of CA stores reduces responses to stress. Increasing CA activity by administration of the dietary amino acid CA precursor tyrosine may increase responsiveness to stress. This study determined whether tyrosine enhances the ability of humans to respond to severe stress. METHODS: Severe psychological stress was generated during training at Survival, Evasion, Resistance, and Escape (SERE) School. The acute stressor consisted of two mock interrogations conducted during several days of simulated captivity. Seventy-eight healthy male and female military personnel participated in this double-blind, between-subjects study, in which they received either tyrosine (300 mg/kg, N = 36) or placebo (N = 36). Tyrosine (or placebo) was administered in food bars in two doses of 150 mg/kg each approximately 60 min before each mock interrogation. Mood (Profile of Mood States), saliva cortisol, and heart rate (HR) were assessed prior to stress exposure during a week of academic training preceding mock captivity and immediately following the mock interrogations. RESULTS: The severe stress produced robust effects on mood (i.e., increased tension, depression, anger, fatigue, vigor, and confusion; p < .001), cortisol, and HR (p < .001). Tyrosine increased anger (p = .002, ANOVA treatment condition by test session interaction) during stress but had no other effects. CONCLUSION: Tyrosine did not alter most subjective or physiological responses to severe acute stress, but it increased ratings of anger. The modest increase in anger may be an adaptive emotional response in stressful environments.

Transient decrements in mood during energy deficit are independent of dietary protein-to-carbohydrate ratio.

Energy deficit and dietary macronutrient intake are thought to independently modulate cognition, mood and sleep. To what extent manipulating the dietary ratio of protein-to-carbohydrate affects mood, cognition and sleep during short-term energy deficit is undetermined. Using a randomized, block design, 39 non-obese young adults (21±1 years, BMI 25±1 kg/m(2)) consumed diets containing 0.8 g, 1.6 g or 2.4 g protein per kg body weight per day for 31 days. Carbohydrate intake was reduced to accommodate higher protein intakes while dietary fat was maintained at 30% of total energy intake. Cognitive performance, mood, self-reported sleep quality, and plasma amino acid concentrations were periodically assessed during a 10-day energy balance period and a subsequent 21-day, 40% energy deficit period. Anger, tension and total mood disturbance increased during the initial ten days of energy deficit (P<0.05), but by the end of the energy deficit returned to levels not different from those measured during energy balance. No effects of dietary protein-to-carbohydrate ratio on cognitive performance, mood or self-reported sleep quality were observed during energy balance or energy deficit. Thus, high-protein, low-carbohydrate, moderate-fat diets do not appear to benefit or impair cognition, mood or sleep in non-obese adults during energy deficit. These findings suggest that energy deficit may initially be psychologically difficult for non-obese individuals attempting to lose weight, but that these changes are transient. Employing strategies that alleviate decrements in mood during this initial period of adaptation may help sustain weight loss efforts.

Anticoagulant activity of select dietary supplements.

This review considers the potential of certain dietary supplements, including garlic, Ginkgo biloba, ginger, ginseng, fish oil, and vitamin E, to interfere with hemostasis. Dietary supplements are common components of the diet in the United States, with about half the US adult population taking some type of dietary supplement regularly. It has been suggested that some supplements could adversely affect coagulation when taken alone or in combination with antiplatelet medications. Supplements could alter hemostasis by a variety of mechanisms, such as reducing platelet aggregation or inhibiting arachidonic acid, a cellular signaling messenger and inflammatory intermediate. To conduct this review, multiple databases were searched using a variety of search terms to ensure relevant papers were located. Moderate to severe adverse events, such as spinal epidural hematoma, spontaneous intracerebral hemorrhage, retrobulbar hemorrhage, subarachnoid hemorrhage, spontaneous hyphema, and postoperative bleeding, have occasionally been anecdotally associated with consumption of dietary supplements. However, the number of controlled studies in the literature is too limited to demonstrate consistent anticoagulant effects of dietary supplements alone or in combination with drug therapy.