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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.

The US military Meal, Ready-to-Eat food ration is approved as a nutritionally adequate sole source of nutrition for ≤21 days. However, the ration continuously evolves, requiring periodic reassessment of its influence on nutritional status and health.To determine the effects of consuming the US Armed Services Meal, Ready-to-Eat ration for 21 days, relative to usual diets, on nutrient intake, and indicators of nutritional status and cardiometabolic health.Parallel-arm, randomized, controlled trial, secondary analysis.Sixty healthy, weight stable, free-living adults from the Natick, MA, area participated between June 2015 and March 2017.Participants were randomized to consume their usual diet for 31days (CON), or a strictly controlled Meal, Ready-to-Eat-only diet for 21 days followed by their usual diet for 10 days (MRE).Nutrient intake (absolute and adjusted) throughout the study period, and indicators of nutrition status (vitamins B, D, folate, homocysteine, iron, magnesium, and zinc) and cardiometabolic health (glucose, insulin, and blood lipid levels) before (Day 0), during (Day 10 through Day 21), and after (Day 31) the intervention period.Between-group differences over time were assessed using marginal models. Models for nutritional status and cardiometabolic health indicators were adjusted for age, initial body mass index, and baseline value of the dependent variable.Energy-adjusted fiber; polyunsaturated fatty acids; vitamins A, thiamin, riboflavin, B-6, C, D, and E; and magnesium and zinc intakes all increased in MRE during the intervention and were higher compared with CON (P0.05), whereas relative protein intake decreased and was lower (P0.05). Serum triglyceride concentrations averaged 19% (95% CI 0% to 41%) higher in MRE relative to CON during Days 10 to 31 (P=0.05). No statistically significant effects of diet on any other nutritional status or cardiometabolic health indicators were observed.Findings demonstrate that a Meal, Ready-to-Eat ration diet can provide a more micronutrient-dense diet than usual dietary intake aiding in maintenance of nutritional status over 21 days.

Consumption of certain berries appears to slow postprandial glucose absorption, attributable to polyphenols, which may benefit exercise and cognition, reduce appetite and/or oxidative stress. This randomised, crossover, placebo-controlled study determined whether polyphenol-rich fruits added to carbohydrate-based foods produce a dose-dependent moderation of postprandial glycaemic, glucoregulatory hormone, appetite andex vivooxidative stress responses. Twenty participants (eighteen males/two females; 24 (sd5) years; BMI: 27 (sd3) kg/m2) consumed one of five cereal bars (approximately 88 % carbohydrate) containing no fruit ingredients (reference), freeze-dried black raspberries (10 or 20 % total weight; LOW-Rasp and HIGH-Rasp, respectively) and cranberry extract (0·5 or 1 % total weight; LOW-Cran and HIGH-Cran), on trials separated by ≥5 d. Postprandial peak/nadir from baseline (Δmax) and incremental postprandial AUC over 60 and 180 min for glucose and other biochemistries were measured to examine the dose-dependent effects. Glucose AUC0–180 mintrended towards being higher (43 %) after HIGH-Raspv.LOW-Rasp (P=0·06), with no glucose differences between the raspberry and reference bars. Relative to reference, HIGH-Rasp resulted in a 17 % lower Δmaxinsulin, 3 % lower C-peptide (AUC0–60 minand 3 % lower glucose-dependent insulinotropic polypeptide (AUC0–180 min)Pex vivooxidation, appetite-mediating hormones or appetite. Fortification with freeze-dried black raspberries (approximately 25 g, containing 1·2 g of polyphenols) seems to slightly improve the glucoregulatory hormone and glycaemic responses to a high-carbohydrate food item in young adults but did not affect appetite or oxidative stress responses at doses or with methods studied herein.

Introduction Effective, standardized, and easily accessible weight management programs are urgently needed for military beneficiaries. Videoconference interventions have the potential for widespread scaling, and can provide both real time interaction and flexibility in delivery times regardless of location, but there is little information on their effectiveness and acceptability. Materials and Methods This study as part of a larger weight loss trial describes the videoconference adaption of Group Lifestyle Balance (GLB) program, a community group-based Diabetes Prevention Program intervention, and provides a comparison of weight loss and meeting attendance between in-person and videoconference delivery modes over 12 weeks in adult family members of military service members. Forty-three participants were enrolled from two military installations and received either the videoconference-adapted or an in-person GLB program in a non-randomized trial design. Differences in program attendance and percent weight lost at 12 weeks were compared by independent samples t-tests and nonparametric methods. Group differences in the percentage of weight lost over the 12-week period were analyzed using a linear mixed model. Results All GLB intervention components were successfully delivered by videoconference with minor adaptations for the different delivery mechanism. Participant retention was 70% and 96% in the in-person and videoconference groups, respectively (p = 0.04). Completing participants in both groups lost a significant percent body weight over the 12 week intervention (p < 0.001) and there was no difference in percent body weight after 12 weeks of intervention (6.2 ± 3.2% and 5.3 ± 3.4% for in-person and videoconference at 12 weeks, respectively; p = 0.60). Conclusion This study describes the first videoconference adaption of the GLB program for use in military families. Attrition was lower in the videoconference group, and there were a similar levels of weight loss in both groups regardless of delivery modality. Videoconference weight loss interventions are effective and feasible for scaling to support healthy weight management in military as well as civilian populations.

BACKGROUND Lifestyle interventions are the first-line treatment for obesity, but participant weight loss is typically low. OBJECTIVES We evaluated the efficacy of an alternative lifestyle intervention [Healthy Weight for Living (HWL)] compared with a modified Diabetes Prevention Program (m-DPP). HWL was based on a revised health behavior change model emphasizing hunger management and the development of healthy food preferences. m-DPP was a standard Diabetes Prevention Program implemented with counselor time matched to HWL. Participants were adult dependents of military personnel and had overweight or obesity. METHODS Participants were randomly assigned to HWL (n = 121) or m-DPP (n = 117), delivered primarily by group videoconference with additional midweek emails. The primary outcome was 12-mo weight change. Secondary outcomes included 6-mo changes in cardiometabolic risk factors and diet. Intention-to-treat (ITT) and complete case (CC) analyses were performed using linear mixed models. RESULTS Retention did not differ between groups (72% and 66% for HWL and m-DPP at 12 mo, respectively; P = 0.30). Mean ± SE adjusted 12-mo weight loss in the ITT cohort was 7.46 ± 0.85 kg for HWL and 7.32 ± 0.87 kg for m-DPP (P = 0.91); in the CC cohort, it was 7.83 ± 0.82 kg for HWL and 6.86 ± 0.88 kg for m-DPP (P = 0.43). Thirty-eight percent of HWL and 30% of m-DPP completers achieved ≥10% weight loss (P = 0.32). Improvements in systolic blood pressure, LDL cholesterol, triglycerides, fasting glucose, general health, sleep, and mood were similar across groups; improvements in diastolic blood pressure were greater in m-DPP. Adjusted group mean reductions in energy intake were not significantly different between groups, but HWL participants were more adherent to their dietary prescription for lower glycemic index and high fiber and protein (P = 0.05 to

Objective: Humans avoid overheating through physiological and behavioral mechanisms. However, elite athletes, industrial workers, and military personnel, driven by the tasks at hand, may choose to continue working and face an increased risk of exertional heat illness (EHI). We wanted to examine the efficacy of a new core temperature (Tcr) estimation algorithm in assessing EHI risk. Approach: Physiological responses of 21 male Royal Marines recruits (age 21±2 y, height 1.79±0.05 m, weight 80.5±7.2 kg) were collected during a physically-demanding criterion road march (14.5 km in 90 min with a 9.6 kg load; air temperature 16°C, relative humidity ≥ 84%). Measured Tcr (thermometer pill) and estimated Tcr (ECTempTM Tcr-est) were compared. Main Results: Measured Tcr either increased to an asymptote Tcr 40.0°C (HOT; n=10). In the HOT group, Tcr-est reflected measured Tcr up to Tcr = 40.0°C (Bias = −0.10 ± 0.37°C, root mean square error = 0.37 ± 0.13°C). In the WARM group, Tcr-est overestimated Tcr (Bias = 0.34 ± 0.40°C) and was higher from mid-point to end. A logistic regression (Skin temperature approximate entropy and mean heart rate) was able to predict group membership (95% accuracy) at 20 minutes, allowing a WARM group ECTemp(TM) correction factor (corrected Bias=0.00 ± 0.29°C). Significance: The Tcr-est successfully tracked Tcr in the HOT group with high risk of exertional heat illness (EHI) (40% incidence). Skin temperature complexity shows promise as a non-invasive means of insight into the state of thermoregulatory control mechanisms.

Objective To assess the impact of the Special Operations Forces Human Performance Program dining facility (DFAC) intervention on patron diet quality and meal satisfaction. Design Nonrandomized, controlled time series study using digital food photography and surveys pre-post intervention (0, 4, 8, and 12 months). Setting Two Fort Bragg, NC military installation DFACs. Participants Volunteers (n = 688 total; n = 573 complete dataset) were US Army active duty soldiers. Intervention The DFAC intervention included food choice architecture, new performance-optimizing food recipes to increase nutrient density, revised menus to offer more performance foods daily, and nutrition labeling to influence food choice. Main Outcome Measures Daily DFAC nutrient intake and Healthy Eating Index (HEI) 2010 scores. Analysis Descriptive and ANOVA statistical analyses were performed between control and intervention groups and from baseline to 4, 8, and 12 months postintervention (α = .05; 80% power). Results The intervention resulted in a higher posttest HEI score (60.1 ± 8.8 points; +3.4%; P = .005) and DFAC satisfaction compared with control (49.0 ± 10.4 points; P > .05). Improved intervention HEI scores were attributed to changes in citrus and melon fruit (+46%), red and orange vegetables (+35%), whole grains (+181%), legumes (65%), yogurt (+45%), oils (–26%), and solid fat (–18%) consumption (all P Conclusions and Implications These data illustrate that the Special Operations Forces Human Performance Program military DFAC nutrition intervention was feasible to implement and was associated with diet quality improvements. Access to high-quality ingredients and recipes may improve soldier meal quality and acceptance in other settings and warrants further investigation.

Military personnel generally under-consumen-3 fatty acids and overconsumen-6 fatty acids. In a placebo-controlled, double-blinded study, we investigated whether a diet suitable for implementation in military dining facilities and civilian cafeterias could benefitn-3/n-6 fatty acid status of consumers. Three volunteer groups were provided different diets for 10 weeks. Control (CON) participants consumed meals from the US Military’s Standard Garrison Dining Facility Menu. Experimental, moderate (EXP-Mod) and experimental-high (EXP-High) participants consumed the same meals, but highn-6 fatty acid and lown-3 fatty acid containing chicken, egg, oils and food ingredients were replaced with products having lessn-6 fatty acids and moren-3 fatty acids. The EXP-High participants also consumed smoothies containing 1000 mgn-3 fatty acids per serving, whereas other participants received placebo smoothies. Plasma and erythrocyte EPA and DHA in CON group remained unchanged throughout, whereas EPA, DHA and Omega-3 Index increased in EXP-Mod and EXP-High groups, and were higher than in CON group after 5 weeks. After 10 weeks, Omega-3 Index in EXP-High group had increased further. No participants exhibited changes in fasting plasma TAG, total cholesterol, LDL, HDL, mood or emotional reactivity. Replacing high linoleic acid (LA) containing foods in dining facility menus with similar high oleic acid/low LA and highn-3 fatty acid foods can improven-6/n-3 blood fatty acid status after 5 weeks. The diets were well accepted and suitable for implementation in group feeding settings like military dining facilities and civilian cafeterias.

BACKGROUND Adaptive responses of appetite-mediating hormones to negative energy balance are thought to contribute to a counterregulatory response that drives weight regain, but they have not been studied while controlling for reduced diet volume. OBJECTIVE In this secondary analysis, we aimed to determine the effects of short-term, severe energy deprivation (ED) on appetite and appetite-mediating hormone concentrations. METHODS Twenty-one adults with a mean ± SD age of 21 ± 3 y and body mass index of 25 ± 3 kg/m(2) consumed isovolumetric diets provided over separate 48-h periods while increasing habitual energy expenditure by 1683 ± 329 kcal/d through light- and moderate-intensity exercise. Energy intake was matched to energy expenditure to maintain energy balance (EB) (-44 ± 92 kcal/d) or was

Background A stress fracture (SF) is a highly debilitating injury commonly experienced in United States Army Basic Combat Training (BCT). Body fat (BF) may be associated with this injury but previous investigations (in athletes) have largely used SF self-reports and lacked sufficient statistical power. This investigation developed an equation to estimate %BF and used that equation to examine the relationship between %BF and SF risk in BCT recruits. Methods Data for the %BF predictive equation involved 349 recruits with BF obtained from dual-energy X-ray absorptiometry. %BF was estimated using body mass index (BMI, weight/height2), age (yr), and sex in the entire population of BCT recruits over an 11-year period (n = 583,651). Medical information was obtained on these recruits to determine SF occurrence. Recruits were separated into deciles of estimated %BF and the risk of SFs determined in each decile. Results The equation was %BF = − 7.53 + 1.43 ● BMI + 0.13 ● age − 14.73 ● sex, with sex either 1 for men or 0 for women (r = 0.88, standard error of estimate = 4.2%BF). Among the men, SF risk increased at the higher and lower %BF deciles: compared to men in the mean %BF decile, the risk of a SF for men in the first (lowest %BF) and tenth (highest %BF) decile were 1.27 (95%confidence interval (95%CI) = 1.17–1.40) and 1.15 (95%CI = 1.05–1.26) times higher, respectively. Among women, SF risk was only elevated in the first %BF decile with risk 1.20 (95%CI = 1.09–1.32) times higher compared to the mean %BF decile. Conclusions Low %BF was associated with higher SF risk in BCT; higher %BF was associated with higher SF risk among men but not women.

Skin wound healing models can be used to detect changes in immune function in response to interventions. This study used a test-retest format to assess the reliability of a skin suction blister procedure for quantitatively evaluating human immune function in repeated measures type studies. Up to eight suction blisters (~30 mm(2)) were induced via suction on each participant's left and right forearm (randomized order; blister session 1 and 2), separated by approximately one week. Fluid was sampled from each blister, and the top layer of each blister was removed to reveal up to eight skin wounds. Fluid from each wound was collected 4, 7 and 24h after blisters were induced, and proinflammatory cytokines were measured. Transepidermal water loss (TEWL), to assess skin barrier recovery, was measured daily at each wound site until values were within 90% of baseline values (i.e., unbroken skin). Sleep, stress and inflammation (i.e., factors that affect wound healing and immune function), preceding the blister induction, were assessed via activity monitors (Actical, Philips Respironics, Murrysville, Pennsylvania), the Perceived Stress Scale (PSS) and C-reactive protein (CRP), respectively. Area-under-the-curve and TEWL, between blister session 1 and 2, were compared using Pearson correlations and partial correlations (controlling for average nightly sleep, PSS scores and CRP). The suction blister method was considered reliable for assessing immune response and skin barrier recovery if correlation coefficients reached 0.7. Volunteers (n=16; 12 M; 4F) were 23 ± 5 years [mean ± SD]. Time to skin barrier restoration was 4.9 ± 0.8 and 4.8 ± 0.9 days for sessions 1 and 2, respectively. Correlation coefficients for skin barrier restoration, IL-6, IL-8 and MIP-1α were 0.9 (P

Development of n‐3 fortified, shelf‐stable foods is facilitated by encapsulated docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), since natural n‐3 food sources cannot withstand high temperature and prolonged shelf life. Organoleptic stability of n‐3 fortified, shelf‐stable foods has been demonstrated, but chemical changes in the food matrix throughout storage could conceivably impact digestibility of the protein‐based encapsulant thereby compromising n‐3 bioavailability. We assessed the effect of prolonged high‐temperature storage and variations in food matrix (proteinaceous or carbohydrate) on the time course and magnitude of blood fatty acids changes associated with ingestion of n‐3 fortified foods. Low‐protein (i.e., cake) and high‐protein (i.e., meat sticks) items were supplemented with 600 mg encapsulated DHA+EPA, and frozen either immediately after production (FRESH) or after 6 months storage at 100°F (STORED). Fourteen volunteers consumed one item per week (randomized) for 4 weeks. Blood samples obtained at baseline, 2, 4, and 6 h post‐consumption were analyzed for circulating long‐chain omega 3 fatty acids (LCn3). There was no difference in LCn3 area under the curve between items. LCn3 in response to cakes peaked at 2‐h (FRESH: 54.0 ± 16.8 μg/mL, +18%; STORED: 53.0 ± 13.2 μg/mL, +20%), while meats peaked at 4‐h (FRESH: 51.9 ± 12.5 μg/mL, +22%; STORED: 53.2 ± 16.9 μg/mL, +18%). There were no appreciable differences in time course or magnitude of n‐3 appearance in response to storage conditions for either food types. Thus, bioavailability of encapsulated DHA/EPA, within low‐ and high‐protein food items, was not affected by high‐temperature shelf‐storage. A shelf‐stable, low‐ or high‐protein food item with encapsulated DHA/EPA is suitable for use in shelf‐stable foods.

Objective The US Army recruits new soldiers from an increasingly obese civilian population. The change in weight status at entry into the Army between 1989 and 2012 and the demographic characteristics associated with overweight/obesity at entry were examined. Methods 1,741,070 unique individuals with complete sex, age, and anthropometric information contributed data to linear and logistic regressions examining time trends and associations between demographic characteristics and overweight/obesity. Results The prevalence of overweight (body mass index 25

Cardiovascular (CV) and thermal responses to metabolically demanding multi-day military operations in extreme cold-weather environments are not well described. Characterization of these operations will provide greater insights into possible performance capabilities and cold injury risk. Soldiers from two cold-weather field training exercises (FTX) were studied during 3-day (study 1, n = 18, age: 20 ± 1 year, height: 182 ± 7 cm, mass: 82 ± 9 kg) and 4-day (study 2, n = 10, age: 20 ± 1 year, height: 182 ± 6 cm, mass: 80.7 ± 8.3 kg) ski marches in the Arctic. Ambient temperature ranged from −18 to −4 °C during both studies. Total daily energy expenditure (TDEE, from doubly labeled water), heart rate (HR), deep body (T pill), and torso (T torso) skin temperature (obtained in studies 1 and 2) as well as finger (T fing), toe (T toe), wrist, and calf temperatures (study 2) were measured. TDEE was 6821 ± 578 kcal day−1 and 6394 ± 544 for study 1 and study 2, respectively. Mean HR ranged from 120 to 140 bpm and mean T pill ranged between 37.5 and 38.0 °C during skiing in both studies. At rest, mean T pill ranged from 36.0 to 36.5 °C, (lowest value recorded was 35.5 °C). Mean T fing ranged from 32 to 35 °C during exercise and dropped to 15 °C during rest, with some T fing values as low as 6–10 °C. Ttoe was above 30 °C during skiing but dropped to 15–20 °C during rest. Daily energy expenditures were among the highest observed for a military training exercise, with moderate exercise intensity levels (~65% age-predicted maximal HR) observed. The short-term cold-weather training did not elicit high CV and T pill strain. T fing and T toe were also well maintained while skiing, but decreased to values associated with thermal discomfort at rest.

Background and aims: Due to the formation of strictures and fistulas, patients with Crohn’s disease (CD) frequently need surgery. Vitamin D has been found to play a role in the degree of inflammation. We aimed to study the effect of UV exposure on the need for inpatient surgery in patients with CD. Methods: The national inpatient sample, the largest database of hospitalizations from the USA, was used to conduct a retrospective study of patients hospitalized from 2004–2011 with CD by ICD-9CM code 555. Surgery was characterized as any intestinal surgery or fistula repair. An average state UV exposure was calculated for each hospitalization. Multivariate logistic regression was used to calculate the effect of UV exposure on surgery accounting for important covariates. Results: There were 481712 hospitalizations with a primary diagnosis of CD. Of these hospitalizations, 67751 included a relevant surgical procedure code. Mean UV exposure was statistically lower in the group undergoing surgery (4.3 units versus 4.4 units, p = 0.001). The ratio of hospitalizations per UV exposure tertile for CD was statistically different compared with all hospitalizations ( p < 0.001). In univariate analysis, increased UV exposure was associated with a lower risk of inpatient surgery with an OR of 0.90 per unit (95% CI 0.84–0.96, p = 0.001). Accounting for age, gender, race/ethnicity, season, income, hospital setting, and Charlson–Deyo comorbidities, the effect of UV exposure remained protective for inpatient surgery (OR 0.91, 95% CI: 0.84–0.98, p = 0.01). Conclusions: Increased UV exposure is associated with a reduced risk of inpatient surgery among patients with CD. Further studies of vitamin D’s role in CD are necessary. * Abbreviations : CD : Crohn’s disease UV : Ultraviolet NIS : National Inpatient Sample IBD : inflammatory bowel disease UC : ulcerative colitis

Physiological consequences of winter military operations are not well described. This study examined Norwegian soldiers (n = 21 males) participating in a physically demanding winter training program to evaluate whether short-term military training alters energy and whole-body protein balance, muscle damage, soreness, and performance. Energy expenditure (D218O) and intake were measured daily, and postabsorptive whole-body protein turnover ([15N]-glycine), muscle damage, soreness, and performance (vertical jump) were assessed at baseline, following a 4-day, military task training phase (MTT) and after a 3-day, 54-km ski march (SKI). Energy intake (kcal·day−1) increased (P < 0.01) from (mean ± SD (95% confidence interval)) 3098 ± 236 (2985, 3212) during MTT to 3461 ± 586 (3178, 3743) during SKI, while protein (g·kg−1·day−1) intake remained constant (MTT, 1.59 ± 0.33 (1.51, 1.66); and SKI, 1.71 ± 0.55 (1.58, 1.85)). Energy expenditure increased (P < 0.05) during SKI (6851 ± 562 (6580, 7122)) compared with MTT (5480 ± 389 (5293, 5668)) and exceeded energy intake. Protein flux, synthesis, and breakdown were all increased (P < 0.05) 24%, 18%, and 27%, respectively, during SKI compared with baseline and MTT. Whole-body protein balance was lower (P < 0.05) during SKI (–1.41 ± 1.11 (–1.98, –0.84) g·kg−1·10 h) than MTT and baseline. Muscle damage and soreness increased and performance decreased progressively (P < 0.05). The physiological consequences observed during short-term winter military training provide the basis for future studies to evaluate nutritional strategies that attenuate protein loss and sustain performance during severe energy deficits.

Understanding the nutritional demands on serving military personnel is critical to inform training schedules and dietary provision. Troops deployed to Afghanistan face austere living and working environments. Observations from the military and those reported in the British and US media indicated possible physical degradation of personnel deployed to Afghanistan. Therefore, the present study aimed to investigate the changes in body composition and nutritional status of military personnel deployed to Afghanistan and how these were related to physical fitness. In a cohort of British Royal Marines (n249) deployed to Afghanistan for 6 months, body size and body composition were estimated from body mass, height, girth and skinfold measurements. Energy intake (EI) was estimated from food diaries and energy expenditure measured using the doubly labelled water method in a representative subgroup. Strength and aerobic fitness were assessed. The mean body mass of volunteers decreased over the first half of the deployment ( − 4·6 (sd3·7) %), predominately reflecting fat loss. Body mass partially recovered (mean +2·2 (sd2·9) %) between the mid- and post-deployment periods (Psd3339) kJ) was significantly lower than the estimated daily energy expenditure (mean 15 167 (sd1883) kJ) measured in a subgroup of volunteers. However, despite the body mass loss, aerobic fitness and strength were well maintained. Nutritional provision for British military personnel in Afghanistan appeared sufficient to maintain physical capability and micronutrient status, but providing appropriate nutrition in harsh operational environments must remain a priority.

Objective: Energy density (ED) and eating rate (ER) influence energy intake; their combined effects on intake and on postprandial pancreatic and gut hormone responses are undetermined. To determine the combined effects of ED and ER manipulation on voluntary food intake, subjective appetite, and postprandial pancreatic and gut hormone responses. Design and Methods: Twenty nonobese volunteers each consumed high (1.6 kcal g−1; HED) and low (1.2 kcal g−1; LED) ED breakfasts slowly (20 g min−1; SR) and quickly (80 g min−1; FR) ad libitum to satiation. Appetite, and pancreatic and gut hormone concentrations were measured periodically over 3 h. Ad libitum energy intake during the subsequent lunch was then measured. Results: Main effects of ED and ER on energy intake and a main effect of ER, but not ED, on mass of food consumed were observed, FR and HED being associated with increased intake (P < 0.05). Across all conditions, energy intake was highest during FR-HED (P ≤ 0.01). Area under the curve (AUC) of appetite ratings was not different between meals. Main effects of ED and ER on insulin, peptide-YY, and glucagon-like peptide-1 AUC (P < 0.05) were observed, FR and HED being associated with larger AUC. No effects on active or total ghrelin AUC were documented. Total energy intake over both meals was highest during the FR-HED trial with the greatest difference between FR-HED and SR-LED trials (P ≤ 0.01). Conclusion: Consuming an energy dense meal quickly compounds independent effects of ER and ED on energy intake. Energy compensation at the following meal may not occur despite altered gut hormone responses.

Individuals entering US Army service are generally young and healthy, but many are overweight, which may impact cardiometabolic risk despite physical activity and fitness requirements. This analysis examines the association between Soldiers' BMI at accession and incident cardiometabolic risk factors (CRF) using longitudinal data from 731,014 Soldiers (17.0% female; age: 21.6 [3.9] years; BMI: 24.7 [3.8] kg/m2) who were assessed at Army accession, 2001-2011. CRF were defined as incident diagnoses through 2011, by ICD-9 code, of metabolic syndrome, glucose/insulin disorder, hypertension, dyslipidemia, or overweight/obesity (in those not initially overweight/obese). Multivariable-adjusted proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) between BMI categories at accession and CRF. Initially underweight (BMI

Strategic translational research is designed to address research gaps that answer specific guidance questions. It provides translational value with respect to nutrition guidance and regulatory and public policy. The relevance and the quality of evidence both matter in translational research. For example, design decisions regarding population, intervention, comparator, and outcome criteria affect whether or not high-quality studies are considered relevant to specific guidance questions and are therefore included as evidence within the context of systematic review frameworks used by authoritative food and health organizations. The process used in systematic reviews, developed by the USDA for its Nutrition Evidence Library, is described. An eating pattern and cardiovascular disease (CVD) evidence review is provided as an example, and factors that differentiated the studies considered relevant and included in that evidence base from those that were excluded are noted. Case studies on ω-3 (n-3) fatty acids (FAs) and industrial trans-FAs illustrate key factors vital to relevance and translational impact, including choice of a relevant population (e.g., healthy, at risk, or diseased subjects; general population or high-performance soldiers); dose and form of the intervention (e.g., food or supplement); use of relevant comparators (e.g., technically feasible and realistic); and measures for both exposure and outcomes (e.g., inflammatory markers or CVD endpoints). Specific recommendations are provided to help increase the impact of nutrition research on future dietary guidance, policy, and regulatory issues, particularly in the area of lipids.

Load carriage (LC) exercise may exacerbate inflammation during training. Nutritional supplementation may mitigate this response by sparing endogenous carbohydrate stores, enhancing glycogen repletion, and attenuating negative energy balance. Two studies were conducted to assess inflammatory responses to acute LC and training, with or without nutritional supplementation. Study 1: 40 adults fed eucaloric diets performed 90‐min of either LC (treadmill, mean ± SD 24 ± 3 kg LC) or cycle ergometry (CE) matched for intensity (2.2 ± 0.1 VO2peak L min−1) during which combined 10 g protein/46 g carbohydrate (223 kcal) or non‐nutritive (22 kcal) control drinks were consumed. Study 2: 73 Soldiers received either combat rations alone or supplemented with 1000 kcal day−1 from 20 g protein‐ or 48 g carbohydrate‐based bars during a 4‐day, 51 km ski march (~45 kg LC, energy expenditure 6155 ± 515 kcal day−1 and intake 2866 ± 616 kcal day−1). IL‐6, hepcidin, and ferritin were measured at baseline, 3‐h post exercise (PE), 24‐h PE, 48‐h PE, and 72‐h PE in study 1, and before (PRE) and after (POST) the 4‐d ski march in study 2. Study 1: IL‐6 was higher 3‐h and 24‐h post exercise (PE) for CE only (mode × time, P

This study examined demographic and physical risk factors for stress fractures in a large cohort of basic trainees. New recruits participating in US Army BCT from 1997 through 2007 were identified, and birth year, race/ethnicity, physical characteristics, body mass index, and injuries were obtained from electronic databases. Injury cases were recruits medically diagnosed with inpatient or outpatient stress fractures. There were 475 745 men and 107 906 women. Stress fractures incidences were 19.3 and 79.9 cases/1 000 recruits for men and women, respectively. Factors that increased stress fracture risk for both men and women included older age, lower body weight, lower BMI, and race/ethnicity other than black. Compared to Asians, those of white race/ethnicity were at higher stress fractures risk. In addition, men, but not women, who were taller or heavier were at increased stress fracture risk. Stress fracture risk generally increased with age (17-35 year range) at a rate of 2.2 and 3.9 cases/1 000 recruits per year for men and women, respectively. This was the largest sample of military recruits ever examined for stress fractures and found that stress fracture risk was elevated among recruits who were female, older, had lower body weight, had lower BMI, and/or were not of black race/ethnicity.

The mechanisms by which dehydration impairs endurance performance remain unresolved but may involve alterations in afferent neural processing. The purpose of this study was to determine the effect of hypohydration on somatosensory evoked potentials (SEPs) at rest and during recovery from fatiguing exercise. Fourteen volunteers (12 men, 2 women) performed repetitive isometric thumb contractions (50% maximal voluntary contractions (MVC) and 100% MVC in a 5:1 ratio, each contraction separated by 5 s of rest) until exhaustion when euhydrated (EU) and when hypohydrated by 4% body mass (HY). SEPs were obtained from the median nerve. The results indicated that HY did not produce statistical differences in time to exhaustion (EU = 754 (SD 255); HY = 714 (SD 318) s; p = 0.66) or rate of muscle fatigue. However, HY was associated with greater subjective feelings of fatigue and loss of vigor after exhaustive exercise (p < 0.01). HY affected N20 latency with an interaction effect of hydration by fatigue state (EU-Rest: 18.5 (SD 1.6) ms; EU-Fatigue: 19.0 (SD 1.6) ms; HY-Rest: 18.3 (SD 1.3) ms; HY-Fatigue: 18.4 (SD 1.5) ms; p = 0.034), but N20 and N20-P22 amplitude responses were similar between HY and EU trials. We concluded that moderate water deficits appear to alter afferent signal processing within the cerebral cortex.

Repeated carbohydrate feedings and caffeine have been shown to increase self-paced physical activity. Whether a field ration pack that promotes snacking of these items would enhance physical activity remains unclear.Evaluate the effectiveness of a ration pack consisting of eat-on-move items to promote snacking, as well as caffeine items, as a nutritional strategy to improve performance.Twenty-eight wildland firefighters consumed both an eat-on-move ration (first strike ration (FSR): 13.2 MJ, 420 g CHO, 665 mg caffeine daily) and entrée-based ration (meals, ready-to-eat (MRE): 11.9 MJ, 373 g CHO, 100 mg caffeine daily) for 2 d separated by 1 d. Diet order was counterbalanced. Outcome measurements included self-paced physical activity determined by actimetry, reaction time, number of eating occasions using dietary recall, and dietary intake from food wrapper collection.Total eating episodes were higher with FSR compared with MRE (P = 0.013; mean +/- SD: 8.2 +/- 1.3 vs 7.6 +/- 1.1 episodes x 2 d(-1)), as were 2-d energy intake (22.0 +/- 2.4 vs 18.4 +/- 2.5 MJ; P0.01), carbohydrate intake (698 +/- 76 vs 546 +/- 82 mg; P0.01), self-reported caffeine intake (347 +/- 262 vs 55 +/- 65 mg; P0.01), and average end-shift salivary caffeine (1.6 +/- 1.9 vs 0.7 +/- 1.0 microg x mL(-1); P0.01). Total activity counts were higher (P = 0.046) when consuming FSR (507,833 +/- 129,130 counts per shift) compared with MRE (443,095 +/- 142,208 counts per shift). This was accomplished by spending a greater percentage of work shift with activity counts1000 counts x min(-1) (21 +/- 8% vs 18 +/- 6%; P = 0.01) and less percent of work shift50 counts x min(-1) (33 +/- 10% vs 38 +/- 10%; P = 0.01).Delivery of energy and caffeine in a manner that promotes snacking behavior is advantageous for increasing self-selected physical activity during arduous labor.

Protective vests worn by global security personnel, and weighted vests worn by athletes, may increase physiological strain due to added load, increased clothing insulation and vapor resistance. The impact of protective vest clothing properties on physiological strain, and the potential of a spacer garment to reduce physiological strain, was examined. Eleven men performed 3 trials of intermittent treadmill walking over 4 h in a hot, dry environment (35°C, 30% rh). Volunteers wore the US Army battledress uniform (trial B), B + protective vest (trial P), and B + P + spacer garment (trial S). Biophysical clothing properties were determined and found similar to many law enforcement, industry, and sports ensembles. Physiological measurements included core (T c), mean skin (T sk) and chest (T chest) temperatures, heart rate (HR), and sweating rate (SR). The independent impact of clothing was determined by equating metabolic rate in all trials. In trial P, HR was +7 b/min higher after 1 h of exercise and +19 b/min by the fourth hour compared to B (P S) via a lower T chest (−0.40°C) (P

The primary purpose of this review is to relate a universal strategy for replacing fluids to optimise marathon performance. A secondary purpose is to examine common 'matters of debate' that may modify fluid needs to include the importance of realistic convective air flow, metabolic water production and waters of association with glycogen. The metabolic demands of marathon running can result in substantial sweat losses and levels of dehydration consistent with compromised endurance performance. Recommendations are provided to individualise fluid intakes with the goal of preventing excessive dehydration (>2% body mass) as well as weight gain. The minor importance of 'matters of debate' to fluid replacement is also discussed.

Little data exist regarding the long-term impact of excess weight on lower extremity musculoskeletal injury/disorder (MID) in U.S. Army Soldiers. This prospective analysis examines the association between BMI of Soldiers at accession and risk of MID.A total of 736,608 Soldiers were followed from accession into the Army, 2001-2011. Data were analyzed January through March 2015. MID was categorized as any first incident lower extremity musculoskeletal injury/disorder, and secondarily, as first incident injury/disorder at a specific site (i.e., hips, upper legs/thighs, knees, lower legs/ankles, feet/toes). Multivariable-adjusted proportional hazards models estimated associations between BMI category at accession and MID risk.During 15,678,743 person-months of follow-up, 411,413 cases of any first MID were documented (70,578 hip, 77,050 upper leg, 162,041 knee, 338,080 lower leg, and 100,935 foot injuries in secondary analyses). The overall MID rate was 2.62 per 100 person-months. Relative to Soldiers with normal BMI (18.5 to25 kg/m(2)) at accession, those who were underweight (18.5); overweight (25 to30); or obese (≥30) had 7%, 11%, and 33% higher risk of MID, respectively, after adjustment. Risks were highest in Soldiers who were obese at accession, and lowest in those with a BMI of 21-23 kg/m(2).Soldier BMI at accession has important implications for MID. A BMI of 21-23 kg/m(2) in newly accessing Soldiers was associated with the lowest risk of incident MID, suggesting that accession be limited to people within this range to reduce overall incidence of MID among service personnel.

The 3rd International Exercise-Associated Hyponatremia (EAH) Consensus Development Conference convened in Carlsbad, California, in February 2015, with a panel of 17 international experts. The delegates represented four countries and nine medical and scientific subspecialties pertaining to athletic training, exercise physiology, sports medicine, water/sodium metabolism and body fluid homoeostasis. The primary goal of the panel was to review the existing data on EAH and update the 2008 Consensus Statement.1 This document serves to replace the 2nd International EAH Consensus Development Conference Statement and launch an educational campaign designed to address the morbidity and mortality associated with a preventable and treatable fluid imbalance . The following statement is a summary of the data synthesised by the 2015 EAH Consensus Panel and represents an evolution of the most current knowledge on EAH. This document will summarise the most current information on the prevalence, aetiology, diagnosis, treatment and prevention of EAH for medical personnel, athletes, athletic trainers and the greater public. The EAH Consensus Panel strove to clearly articulate what we agreed on, did not agree on and did not know, including minority viewpoints that were supported by clinical experience and experimental data. Further updates will be necessary to: (1) remain current with our understanding and (2) critically assess the effectiveness of our present recommendations. Suggestions for future research and educational strategies to reduce the incidence and prevalence of EAH are provided at the end of the document; areas of controversy that remain in this topic have also been outlined. The 3rd International EAH Consensus Development Conference utilised National Institutes of Health guidelines, amended for a more holistic approach to fit the needs of both the group and the topic. Twenty-two individuals (17 accepted) were invited to participate in the consensus conference who: (1) have made scientific and/or clinical contributions to the topic …

Background: The development of symptomatic hyponatraemia consequent on participation in marathon and ultraendurance races has led to questions about its aetiology and prevention. Objectives: To evaluate: ( a ) the assertion that sweat sodium losses cannot contribute to the development of hyponatraemia during endurance exercise; ( b ) the adequacy of fluid replacement recommendations issued by the International Marathon Medical Directors Association (IMMDA) for races of 42 km or longer; ( c ) the effectiveness of commercial sports drinks, compared with water, for attenuating plasma sodium reductions. Methods: A mathematical model was used to predict the effects of different drinking behaviours on hydration status and plasma sodium concentration when body mass, body composition, running speed, weather conditions, and sweat sodium concentration were systematically varied. Results: Fluid intake at rates that exceed sweating rate is predicted to be the primary cause of hyponatraemia. However, the model predicts that runners secreting relatively salty sweat can finish ultraendurance exercise both dehydrated and hyponatraemic. Electrolyte-containing beverages are predicted to delay the development of hyponatraemia. The predictions suggest that the IMMDA fluid intake recommendations adequately sustain hydration over the 42 km distance if qualifiers—for example, running pace, body size—are followed. Conclusions: Actions to prevent hyponatraemia should focus on minimising overdrinking relative to sweating rate and attenuating salt depletion in those who excrete salty sweat. This simulation demonstrates the complexity of defining fluid and electrolyte consumption rates during athletic competition.

This paper provides a historical summary of military nutrition research into the role of diet for sustaining soldier physical performance. Studies of underfeeding document that physical performance is preserved during several days of underfeeding provided sufficient carbohydrate and minerals are consumed to minimize the diuresis associated with semi-starvation diets and serial intake of carbohydrate is available to support metabolism during prolonged work. The Military Recommended Dietary Allowances, AR 40-25, currently recommends that when restricted rations are required, that the ration contain at least 1,100-1,500 kcal, 50-70 g of protein, and a minimum of 100 g of carbohydrate on a daily basis. This low energy diet, however, is not recommended for subsistence for longer than 10 consecutive days. Dietary carbohydrate intakes of approximately 300-400 g will more closely match the quantity of carbohydrate oxidized to meet daily energy requirements during field operations. Research into the potential advantages of dietary supplements has generally not proved advantageous when compared to eating a well balanced diet. Future investigations of the role of diet for sustaining soldier health and performance should be directed toward a better understanding of the influence of energy intake and macro-nutrient composition for preserving lean body mass, reducing susceptibility to illness and injury and enhancing recovery during and after sustained operations.

Insulin-like growth factor-I (IGF-I) is sensitive to nutritional stress and is reduced in soldiers during stressful field training. Methods have recently been developed to measure IGF-I from filter paper blood spots. Filter paper has advantages over traditional blood sampling in that neither blood separation equipment nor refrigeration is necessary after sample collection. This study determined whether filter paper blood spots collected in a field environment could measure IGF-I and subsequent changes during military operational stress. Thirty-four Marines participating in an 8-day military field exercise characterized by near-continuous physical work (total daily energy expenditure 17-25 MJ/day) and underfeeding (dietary intake 7.0 MJ/day) had blood samples taken on day 0, day 4, and day 8. IGF-I was measured by filter paper blood spot assays from fingertip blood samples and by conventional methods using serum. Correlation and measurement agreement were assessed. Blood spot (Day 0 152 +/- 6 ng mL(-1)Day 4 111 +/- 6 ng mL(-1)Day 8 74 +/- 4 ng mL(-1)) and serum IGF-I (Day 0 412 +/- 10 ng mL(-1)Day 4 258 +/- 14 ng mL(-1)Day 8 203 +/- 13 ng mL(-1)) concentrations declined (p0.05) progressively over the 8-day exercise. Overall, the two methods significantly (p0.05) correlated (r = 0.92); however, the blood spot values were on average 61% lower than serum, but could be used to predict serum values ( +/- 10%). IGF-I is a biomarker of metabolic status. The filter paper blood spot method for IGF-I detected reductions accompanying nutritional stress and may be of potential value for characterizing the IGF-I response when conventional blood sampling methods are not feasible.

This study was conducted to determine whether hypohydration (Hy) alters blood flow, skin temperature, or cold-induced vasodilation (CIVD) during peripheral cooling. Fourteen subjects sat in a thermoneutral environment (27°C) during 15-min warm-water (42°C) and 30-min cold-water (4°C) finger immersion (FI) while euhydrated (Eu) and, again, during Hy. Hy (−4% body weight) was induced before FI by exercise-heat exposure (38°C, 30% relative humidity) with no fluid replacement, whereas during Eu, fluid intake maintained body weight. Finger pad blood flow [as measured by laser-Doppler flux (LDF)] and nail bed (Tnb), pad (Tpad), and core (Tc) temperatures were measured. LDF decreased similarly during Eu and Hy (32 ± 10 and 33 ± 13% of peak during warm-water immersion). Mean Tnb and Tpad were similar between Eu (7.1 ± 1.0 and 11.5 ± 1.6°C) and Hy (7.4 ± 1.3 and 12.6 ± 2.1°C). CIVD parameters (e.g., nadir, onset time, apex) were similar between trials, except Tpad nadir was higher during Hy (10.4 ± 3.8°C) than during Eu (7.9 ± 1.6°C), which was attributed to higher Tc in six subjects during Hy (37.5 ± 0.2°C), compared with during Eu (37.1 ± 0.1°C). The results of this study provide no evidence that Hy alters finger blood flow, skin temperature, or CIVD during peripheral cooling.

This study evaluated a new test of physical persistence, a wall building task. Volunteers (n=14) built as many 10 × 10 walls as possible using brick-size wooden blocks in 25 min on six different days. Four of the six days were without treatment effects to measure test reliability. Assessment was also done twice during a simulated military sustained operation scenario (SUSOPS) at 48 and 72 hours after SUSOPS initiation. Volunteers were kept busy with military tasks 21–22 hours per day when not being tested. There was a 26% decrement ( p≤0.001) in walls built after 48 hrs of SUSOPS, with intraclass reliability of R = 0.84. The wall building test was demonstrated to be reproducible, easily administered, and is sensitive to the effects of prolonged work and sleep deprivation that occur during SUSOPS. This test would be a useful tool to measure potential interventions used to combat the effects of SUSOPS.

Physically intense military training may diminish whole-body protein retention and increase dietary protein requirements. This study characterized the effects of military training on whole-body protein turnover in 21 Soldiers participating in a 7-day winter training exercise that culminated in a 3-day, 54 km ski march. Energy expenditure was assessed during training using doubly labeled water (D218O), and protein turnover, synthesis, breakdown, and net balance were measured at baseline (BL), day 4 (PRE, prior to the ski march), and day 7 (POST, following the ski march) using 15N-glycine. Energy (kcal·d-1) intake increased (P 0.0...

This report describes a series of hyponatremia hospitalizations associated with heat-related injuries and apparent over-hydration. Data from the U.S. Army Inpatient Data System were used to identify all hospitalizations for hyposmolality/hyponatremia from 1996 and 1997. Admissions were considered as probable cases of overhydration hyponatremia if this was the only, or primary, diagnosis or if it was associated with any heat-related diagnosis. Seventeen medical records were identified, and the events leading to hospitalization were analyzed. The average serum sodium level was 122 +/- 5 mmol/L (range, 115-130 mmol/L). All 17 patients were soldiers attending training schools. Seventy-seven percent of hyponatremia cases occurred in the first 4 weeks of training. Nine patients had water intake rates equal to or exceeding 2 quarts per hour. Most patients were in good health before developing hyponatremia. The most common symptoms were mental status changes (88%), emesis (65%), nausea (53%), and seizures (31%). In 5 of 6 cases in which extensive history was known, soldiers drank excess amounts of water before developing symptoms and as part of field treatment. The authors conclude that hyponatremia resulted from too aggressive fluid replacement practices for soldiers in training status. The fluid replacement policy was revised with consideration given to both climatic heat stress and physical activity levels. Field medical policy should recognize the possibility of overhydration. Specific evacuation criteria should be established for exertional illness.

This study determined whether exercise (30 min)-rest (10 min) cycles alter physiologic tolerance to uncompensable heat stress (UCHS) when outdoors in the desert. In addition, the relationship between core temperature and exhaustion from heat strain previously established in laboratory studies was compared with field studies.Twelve men completed four trials: moderate intensity continuous exercise (MC), moderate intensity exercise with intermittent rest (MI), hard intensity continuous exercise (HC), and hard intensity exercise with intermittent rest (HI). UCHS was achieved by wearing protective clothing and exercising (estimated at 420 W or 610 W) outdoors in desert heat.Heat Stress Index values were 200%, 181%, 417%, and 283% for MC, MI, HC, and HI, respectively. Exhaustion from heat strain occurred in 36 of 48 trials. Core temperatures at exhaustion averaged 38.6 +/- 0.5 degrees, 38.9 +/- 0.6 degrees, 38.9 +/- 0.7 degrees, and 39.0 +/- 0.7 degrees C for MC, MI, HC, and HI, respectively. Core temperature at exhaustion was not altered (P0.05) by exercise intensity or exercise-rest cycles and 50% of subjects incurred exhaustion at core temperature of 39.4 degrees C. These field data were compared with laboratory and field data collected over the past 35 years. Aggregate data for 747 laboratory and 131 field trials indicated that 50% of subjects incurred exhaustion at core temperatures of 38.6 degrees and 39.5 degrees C, respectively. When heat intolerant subjects (exhaustion38.3 degrees C core temperature) were removed from the analysis, subjects from laboratory studies (who underwent short-term acclimation) still demonstrated less (0.8 degrees C) physiological tolerance than those from field studies (who underwent long-term acclimatization).Exercise-rest cycles did not alter physiologic tolerance to UCHS. In addition, subjects from field studies demonstrate greater physiologic tolerance than subjects from laboratory studies.

Five women and 3 men (29.8 ± 1.4 yr) performed dynamic knee-extension exercise inside a magnetic resonance system (means ± SE). Two trials were performed 7–14 days apart, consisting of a 4- to 5-min exhaustive exercise bout. To determine quadriceps cost of contraction, brief static and dynamic contractions were performed pre- and postexercise.31P spectra were used to determine pH and relative concentrations of Pi, phosphocreatine (PCr), and βATP. Subjects consumed 0.3 g ⋅ kg−1 ⋅ day−1of a placebo ( trial 1) or creatine ( trial 2) for 5 days before each trial. After creatine supplementation, resting ΔPCr increased from 40.7 ± 1.8 to 46.6 ± 1.1 mmol/kg ( P = 0.04) and PCr during exercise declined from −29.6 ± 2.4 to −34.1 ± 2.8 mmol/kg ( P = 0.02). Muscle static (ΔATP/N) and dynamic (ΔATP/J) costs of contraction were unaffected by creatine supplementation as well as were ATP, Pi, pH, PCr resynthesis rate, and muscle strength and endurance. ΔATP/J and ΔATP/N were greatest at the onset of the exercise protocol ( P< 0.01). In summary, creatine supplementation increased muscle PCr concentration, which did not affect muscle ATP cost of contraction.

Exercise performance can be compromised by a body water deficit, particularly when exercise is performed in hot climates. It is recommended that individuals begin exercise when adequately hydrated. This can be facilitated by drinking 400 mL to 600 mL of fluid 2 hours before beginning exercise and drinking sufficient fluid during exercise to prevent dehydration from exceeding 2% body weight. A practical recommendation is to drink small amounts of fluid (150-300 mL) every 15 to 20 minutes of exercise, varying the volume depending on sweating rate. Core temperature, heart rate, and perceived effort remain lowest when fluid replacement comes closest to matching the rate of sweat loss. During exercise lasting less than 90 minutes, water alone is sufficient for fluid replacement. During prolonged exercise lasting longer than 90 minutes, commercially available carbohydrate electrolyte beverages should be considered to provide an exogenous carbohydrate source to sustain carbohydrate oxidation and endurance performance. Electrolyte supplementation is generally not necessary because dietary intake is adequate to offset electrolytes lost in sweat and urine; however, during initial days of hot-weather training or when meals are not calorically adequate, supplemental salt intake may be indicated to sustain sodium balance.

Young [ n = 5, 30 ± 5 (SD) yr] and middle-aged ( n = 4, 58 ± 4 yr) men and women performed single-leg knee-extension exercise inside a whole body magnetic resonance system. Two trials were performed 7 days apart and consisted of two 2-min bouts and a third bout continued to exhaustion, all separated by 3 min of recovery.31P spectra were used to determine pH and relative concentrations of Pi, phosphocreatine (PCr), and β-ATP every 10 s. The subjects consumed 0.3 g ⋅ kg−1 ⋅ day−1of a placebo ( trial 1) or creatine ( trial 2) for 5 days before each trial. During the placebo trial, the middle-aged group had a lower resting PCr compared with the young group (35.0 ± 5.2 vs. 39.5 ± 5.1 mmol/kg, P < 0.05) and a lower mean initial PCr resynthesis rate (18.1 ± 3.5 vs. 23.2 ± 6.0 mmol ⋅ kg−1 ⋅ min−1, P < 0.05). After creatine supplementation, resting PCr increased 15% ( P < 0.05) in the young group and 30% ( P < 0.05) in the middle-aged group to 45.7 ± 7.5 vs. 45.7 ± 5.5 mmol/kg, respectively. Mean initial PCr resynthesis rate also increased in the middle-aged group ( P < 0.05) to a level not different from the young group (24.3 ± 3.8 vs. 24.2 ± 3.2 mmol ⋅ kg−1 ⋅ min−1). Time to exhaustion was increased in both groups combined after creatine supplementation (118 ± 34 vs. 154 ± 70 s, P < 0.05). In conclusion, creatine supplementation has a greater effect on PCr availability and resynthesis rate in middle-aged compared with younger persons.

The effect of exercise, consumption of a carbohydrate-electrolyte drink and shooting position (standing vs. prone) on marksmanship accuracy and sighting time were measured in 27 experienced marksmen. Participants ‘dry-fired’ a laser equipped rifle simulator system at a 2.3 cm circular target at a distance of 5 m. Marksmanship was assessed under the following conditions: (1) at rest; (2) after completing a 14.7 km road march (10.4 km with a 21 kg pack); and (3) after a combined timed rock climb and 700 m uphill run. The road march reduced marksmanship accuracy and sighting time (p < 0.05) while the climb and uphill run did not affect marksmanship. Consumption of a carbohydrate-electrolyte drink did not preserve marksmanship accuracy after exercise. Shooting prone was significantly more accurate and faster than shooting from the standing position (p < 0.05). The effects of drinking a carbohydrate-electrolyte drink and performing heavy work on a subsequent fine motor-visual vigilance type task was studied. Implications are for the military, but also for industries whose work involves tasks that are both physically demanding and require precision (e.g. linemen working for the telephone company climbing a pole and then cutting a small single wire).

Protein supplements (PSs) are, after multivitamins, the most frequently consumed dietary supplement by U.S. military personnel. Warfighters believe that PSs will improve health, promote muscle strength, and enhance physical performance. The estimated prevalence of regular PS use by military personnel is nearly 20% or more in active-duty personnel, which is comparable to collegiate athletes and recreationally active adults, but higher than that for average U.S. civilians. Although the acute metabolic effects of PS ingestion are well described, little is known regarding the benefits of PS use by warfighters in response to the metabolic demands of military operations. When dietary protein intake approaches 1.5 g kg 21 d 21 , and energy intake matches energy expenditure, the use of PSs by most physically active military personnel may not be necessary. However, dismounted infantry often perform operations consisting of long periods of strenuous physical activity coupled with inadequate dietary energy and protein intake. In these situations, the use of PSs may have efficacy for preserving fat-free mass. This article reviews the available literature regarding the prevalence of PS use among military personnel. Furthermore, it highlights the unique metabolic stressors affecting U.S. military personnel and discusses potential conditions during which protein supplementation might be beneficial. J. Nutr. 143: 1815S‐1819S, 2013.