Sex Does Not Affect Changes in Body Composition and Insulin-Like Growth Factor-I During US Army Basic Combat Training.

ABSTRACT: Roberts, BM, Staab, JS, Caldwell, AR, Sczuroski, CE, Staab, JE, Lutz, LJ, Reynoso, M, Geddis, AV, Taylor, KM, Guerriere, KI, Walker, LA, Hughes, JM, and Foulis, SA. Sex does not affect changes in body composition and insulin-like growth factor-I during US army basic combat training. J Strength Cond Res XX(X): 000-000, 2023-Insulin-like growth factor 1 (IGF-I) has been implicated as a biomarker of health and body composition. However, whether changes in body composition are associated with changes in IGF-I is unclear. Therefore, we examined the relationship between body composition changes (i.e., fat mass and lean mass) and total serum IGF-I levels in a large cohort of young men (n = 809) and women (n = 397) attending US Army basic combat training (BCT). We measured body composition using dual energy x-ray absorptiometry and total serum IGF-I levels during week 1 and week 9 of BCT. We found that pre-BCT lean mass (r = 0.0504, p = 0.082) and fat mass (r = 0.0458, p = 0.082) were not associated with pre-BCT IGF-I. Body mass, body mass index, body fat percentage, and fat mass decreased, and lean mass increased during BCT (all p < 0.001). Mean (±SD) IGF-I increased from pre-BCT (176 ± 50 ng·ml-1) to post-BCT (200 ± 50 ng·ml-1, p < 0.001). Inspection of the partial correlations indicated that even when considering the unique contributions of other variables, increases in IGF-I during BCT were associated with both increased lean mass (r = 0.0769, p = 0.023) and increased fat mass (r = 0.1055, p < 0.001) with no sex differences. Taken together, our data suggest that although changes in IGF-I weakly correlated with changes in body composition, IGF-I, in isolation, is not an adequate biomarker for predicting changes in body composition during BCT in US Army trainees.

Body composition changes during 8 weeks of military training are not accurately captured by circumference-based assessments.

In 1981, the US military adopted body fat standards to promote physical readiness and prevent obesity. Separate circumference-based equations were developed for women and men. Both predictive equations were known to underestimate %BF. However, it was not known how well these abdominal circumference-based methods tracked changes in %BF. This study examined the validity of the circumference-based %BF equations for assessing changes in %BF in young adult recruits during Army Basic Combat Training (BCT). Dual-energy X-ray absorptiometry (DXA) and circumference-based measures of %BF were obtained in women (n = 481) and men (n = 926) at the start (pre-BCT) and end (post-BCT) of 8 weeks of BCT. Repeated-measure ANOVAs were used to assess differences between DXA and circumference pre-BCT and for the change during BCT. Pre-BCT, circumferences underestimated %BF relative to DXA, with mean errors of -6.0% ± 4.4% for women and -6.0% ± 3.5% for men (both p < 0.01), and no difference between sexes was observed (p = 0.77). DXA detected a -4.0% ± 2.4% and -3.3% ± 2.8% change in %BF for women and men in response to BCT, respectively (both p < 0.01), whereas circumference estimates of %BF indicated a 0.0% ± 3.3% (p = 0.86) change in women and a -2.2% ± 3.3% (p < 0.01) change in men (sex difference by technique p < 0.01). In conclusion, circumference-based measures underestimated %BF at the start of BCT in both sexes as compared to DXA. Circumference measures underestimated changes in %BF during BCT in men and did not detect changes in women. These findings suggest that circumference-based %BF metrics may not be an appropriate tool to track changes in body composition during short duration training.

Changes in Distal Tibial Microarchitecture During Eight Weeks of U.S. Army Basic Combat Training Differ by Sex and Race.

Basic combat training (BCT) is a physically rigorous period at the beginning of a soldier's career that induces bone formation in the tibia. Race and sex are determinants of bone properties in young adults but their influences on changes in bone microarchitecture during BCT are unknown. The purpose of this work was to determine the influence of sex and race on changes in bone microarchitecture during BCT. Bone microarchitecture was assessed at the distal tibia via high-resolution peripheral quantitative computed tomography at the beginning and end of 8 weeks of BCT in a multiracial cohort of trainees (552 female, 1053 male; mean ± standard deviation [SD] age = 20.7 ± 3.7 years) of which 25.4% self-identified as black, 19.5% as race other than black or white (other races combined), and 55.1% as white. We used linear regression models to determine whether changes in bone microarchitecture due to BCT differed by race or sex, after adjusting for age, height, weight, physical activity, and tobacco use. We found that trabecular bone density (Tb.BMD), thickness (Tb.Th), and volume (Tb.BV/TV), as well as cortical BMD (Ct.BMD) and thickness (Ct.Th) increased following BCT in both sexes and across racial groups (+0.32% to +1.87%, all p < 0.01). Compared to males, females had greater increases in Tb.BMD (+1.87% versus +1.40%; p = 0.01) and Tb.Th (+0.87% versus +0.58%; p = 0.02), but smaller increases in Ct.BMD (+0.35% versus +0.61%; p < 0.01). Compared to black trainees, white trainees had greater increases in Tb.Th (+0.82% versus +0.61%; p = 0.03). Other races combined and white trainees had greater increases in Ct.BMD than black trainees (+0.56% and + 0.55% versus +0.32%; both p ≤ 0.01). Changes in distal tibial microarchitecture, consistent with adaptive bone formation, occur in trainees of all races and sexes, with modest differences by sex and race. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

The Risk of Menstrual Dysfunction Increases for Women during U.S. Army Basic Combat Training.

PURPOSE: To determine whether changes in menstruation develop in female trainees during BCT and whether changes in body mass, body composition and/or physical activity are associated with menstrual interruption during BCT. METHODS: Female trainees grouped according to self-reported menstrual status in the 12 months before BCT as having regular cycles (RC; n = 352) or MD ( n = 97) completed height, body mass, and body composition assessments and questionnaires before and after BCT. Fisher's exact test and Mann-Whitney U test were used to compare between-group differences in categorical and continuous variables, respectively. Among RC trainees, odds ratios were calculated to examine the influence of changes in body mass, lean mass, and fat mass on a trainee's likelihood to miss a period during BCT. RESULTS: There were no differences in race, height, body mass, body mass index, or physical activity history at pre-BCT between RC and MD ( P > 0.05). Overall, 86% of trainees experienced changes to menstruation during BCT. RC were more likely than MD to have at least one period during BCT (81% vs 69%, respectively, P = 0.01). Among RC, gaining more body mass and lean mass and losing less fat mass were associated with increased odds of missing a period during BCT. CONCLUSIONS: These findings demonstrate that most female trainees experience menstrual changes during BCT. Menstrual cycle interruptions do not appear to align with loss of body or fat mass.

Using a Contemporary Portable Metabolic Gas Exchange System for Assessing Energy Expenditure: A Validity and Reliability Study.

There are several methods available to assess energy expenditure, all associated with inherent pros and cons that must be adequately considered for use in specific environments and populations. A requirement of all methods is that they must be valid and reliable in their capability to accurately measure oxygen consumption (VO2) and carbon dioxide production (VCO2). The purpose of this study was to evaluate the reliability and validity of the mobile CO2/O2 Breath and Respiration Analyzer (COBRA) relative to a criterion system (Parvomedics TrueOne 2400®, PARVO) with additional measurements to compare the COBRA to a portable system (Vyaire Medical, Oxycon Mobile®, OXY). Fourteen volunteers with a mean of 24 years old, body weight of 76 kg, and a VO2peak of 3.8 L∙min-1 performed four repeated trials of progressive exercises. Simultaneous steady-state measurements of VO2, VCO2, and minute ventilation (VE) by the COBRA/PARVO and OXY systems were conducted at rest, while walking (23-36% VO2peak), jogging (49-67% VO2peak), and running (60-76% VO2peak). Data collection was randomized by the order of system tested (COBRA/PARVO and OXY) and was standardized to maintain work intensity (rest to run) progression across study trials and days (two trials/day over two days). Systematic bias was examined to assess the accuracy of the COBRA to PARVO and OXY to PARVO across work intensities. Intra- and inter-unit variability were assessed with interclass correlation coefficients (ICC) and a 95% limit of agreement intervals. The COBRA and PARVO produced similar measures for VO2 (Bias ± SD, 0.01 ± 0.13 L·min-1; 95% LoA, (-0.24, 0.27 L·min-1); R2 = 0.982), VCO2 (0.06 ± 0.13 L·min-1; (-0.19, 0.31 L·min-1); R2 = 0.982), VE (2.07 ± 2.76 L·min-1; (-3.35, 7.49 L·min-1); R2 = 0.991) across work intensities. There was a linear bias across both the COBRA and OXY with increased work intensity. The coefficient of variation for the COBRA ranged from 7 to 9% across measures for VO2, VCO2, and VE. COBRA was reliable across measurements for VO2 (ICC = 0.825; 0.951), VCO2 (ICC = 0.785; 0.876), and VE (ICC = 0.857; 0.945) for intra-unit reliability, respectively. The COBRA is an accurate and reliable mobile system for measuring gas exchange at rest and across a range of work intensities.

Physical and Physiological Characterization of Female Elite Warfighters.

INTRODUCTION: This study characterized a sample of the first women to complete elite United States (US) military training. METHODS: Twelve female graduates of the US Army Ranger Course and one of the first Marine Corps Infantry Officers Course graduates participated in 3 d of laboratory testing including serum endocrine profiles, aerobic capacity, standing broad jump, common soldiering tasks, Army Combat Fitness Test, and body composition (dual-energy x-ray absorptiometry, three-dimensional body surface scans, and anthropometry). RESULTS: The women were 6 months to 4 yr postcourse graduation, 30 ± 6 yr (mean ± SD); height, 1.67 ± 0.07 m; body mass, 69.4 ± 8.2 kg; body mass index, 25.0 ± 2.3 kg·m -2 . Dual-energy x-ray absorptiometry relative fat was 20.0% ± 2.0%; fat-free mass, 53.0 ± 5.9 kg; fat-free mass index, 20.0 ± 1.7 kg·m -2 ; bone mineral content, 2.75 ± 0.28 kg; bone mineral density, 1.24 ± 0.07 g·cm -2 ; aerobic capacity, 48.2 ± 4.8 mL·kg -1 ·min -1 ; total Army Combat Fitness Test score 505 ± 27; standing broad jump 2.0 ± 0.2 m; 123 kg casualty drag 0.70 ± 0.20 m·s -1 , and 4 mile 47 kg ruck march 64 ± 6 min. All women were within normal healthy female range for circulating androgens. Physique from three-dimensional scan demonstrated greater circumferences at eight of the 11 sites compared with the standard military female. CONCLUSIONS: These pioneering women possessed high strength and aerobic capacity, low %BF; high fat-free mass, fat-free mass index, and bone mass and density; and they were not virilized based on endocrine measures as compared with other reference groups. This group is larger in body size and leaner than the average Army woman. These elite physical performers seem most comparable to female competitive strength athletes.

Comparison of Different Variants of the U.S. Army Occupational Physical Assessment Test.

INTRODUCTION: The U.S. Army Occupational Physical Assessment Test (OPAT) is a pre-enlistment physical employment screening assessment developed to place recruits and soldiers into Military Occupational Specialties (MOSs) based on their physical capabilities in order to optimize performance and limit injury. The OPAT consists of the seated power throw (SPT), strength deadlift (SDL), standing long jump, and interval aerobic run. During the scientific validation of the OPAT, two variants of the SPT and two variants of the SDL were used. Although the OPAT was validated using both variants for each test, U.S. Army scientists and policymakers have received queries regarding how these variants compare to each other. Therefore, the purpose of this study was to compare different variants of the SPT and SDL. MATERIALS AND METHODS: Thirty-two participants (14 male and 18 female) between the ages of 18 and 42 years visited the laboratory on one occasion and performed two variants of the SPT (seated on the ground [the current OPAT standard] versus seated in a chair with a 35 cm seat height) and two variants of the SDL (using a hex-bar [the current OPAT standard] versus using paired dumbbells). Testing order for the different variants was randomized. The protocol was approved by the U.S. Army Medical Research and Development Command Institutional Review Board. RESULTS: Performing the SPT from a chair significantly (P < .05) increased performance when compared to performing the SPT from the ground (5.4 ± 1.3 m versus 5.0 ± 1.4 m, respectively). Values for the two SPT variants were correlated (tau = 0.90). Performing the SDL using the hex-bar significantly increased the maximal weight lifted when compared to performing the SDL using paired dumbbells (86.9 ± 18.4 kg versus 83.1 ± 18.0 kg, respectively). Values for the two SDL variants were correlated (tau = 0.83). CONCLUSIONS: Performing different variants of the SPT and SDL influenced the resulting score. Although these findings do not alter the administration or scoring of the OPAT, they do provide a valuable reference in the event of future inquiries regarding the development of the OPAT.

Body mass does not reflect the body composition changes in response to similar physical training in young women and men.

INTRODUCTION: U.S. Army Basic Combat Training (BCT) prepares new recruits to meet soldier physical demands. It also serves as a model of physical changes in healthy young nonobese women and men during an intensive 10-week training program without diet restriction. In this prospective observational study, we quantified the changes in lean mass and body fat induced by BCT in a large sample of men and women undergoing the same physical training program. METHODS: Young women (n = 573) and men (n = 1071) meeting Army health and fitness recruitment standards volunteered to provide DXA-derived body composition data at the beginning and end of BCT. RESULTS: During BCT, there was no change in body mass in women and a 1.7-kg loss in men. Relative body fat (%BF) declined by an average of 4.0 ± 2.4 and 3.4 ± 2.8 percentage points (±SD) for women and men, respectively. The greatest predictor of change in %BF during BCT for both sexes was %BF at the beginning of training. Women and men gained an average 2.7 ± 1.6 kg and 1.7 ± 2.0 kg of lean mass during BCT. CONCLUSIONS: Army BCT produced significant effects on body composition despite minimal changes in total body mass. These findings demonstrate the ability of a 10-week sex-integrated physical training program to positively alter body composition profiles of young adults.

Predicting Soldier Task Performance From Physical Fitness Tests: Reliability and Construct Validity of a Soldier Task Test Battery.

ABSTRACT: Spiering, BA, Walker, LA, Larcom, K, Frykman, PN, Allison, SC, and Sharp, MA. Predicting soldier task performance from physical fitness tests: reliability and construct validity of a soldier task test battery. J Strength Cond Res 35(10): 2749-2755, 2021-The purpose of this study was to determine the reliability and construct validity of a battery of tests designed to assess soldier task performance. In the first part of the study (designed to assess test-retest reliability), 33 enlisted soldiers (31 men, 2 women; 23 ± 3 years; 1.75 ± 0.08 m; and 81.4 ± 12.8 kg) completed a 4-event "soldier task test battery" (STTB) on 4 occasions, each separated by at least 1 week. The STTB consisted of the following tests, in order: (a) 30-m grenade throw for accuracy; (b) running long jump while wearing a 20.5-kg load; (c) 1 repetition maximum box lift; and (d) 3.2-km load carriage time trial while wearing a 33-kg load. In the second part of the study (designed to assess construct validity), 41 male soldiers (22 ± 3 years; 1.75 ± 0.08 m; and 81.4 ± 12.9 kg) completed the STTB and a series of physical fitness tests. The physical fitness tests included measurements of body composition, muscular strength, muscular power, muscular endurance, and cardiovascular endurance. Overall performance on the STTB (reflected by the sum of z-scores across individual tests) demonstrated an intraclass correlation coefficient of 0.95 and was correlated to lean mass, V˙o2peak, and measures of muscular strength and power. Lean body mass and standing long jump predicted performance on the STTB (R2 = 0.41). In conclusion, this STTB can reliably assess performance of soldiering tasks. The relationships between the STTB and physical fitness tests can be used to develop training programs to prepare soldiers to perform physically demanding tasks.

Quantifying Training Load During Physically Demanding Tasks in U.S. Army Soldiers: A Comparison of Physiological and Psychological Measurements.

INTRODUCTION: There are many ways to quantify the training loads required to perform soldiering tasks. Although indirect calorimetry may provide the most accurate measures, the equipment can be burdensome and expensive. Simpler measures may provide sufficient data, while being more practical for measuring soldiers in the field. The purpose of this study was to examine the relationship between total relative oxygen uptake (TotalRelVO2) measured by indirect calorimetry during three soldiering tasks, with two field-expedient measures of training load: summated heart rate zone (sumHR) and session rate of perceived exertion (sRPE). MATERIALS AND METHODS: 33 male and 28 female soldiers performed three soldiering tasks while wearing a 32.3-kg fighting load: sandbag fill, sandbag carry, and ammunition can carry. Metabolic measurements were monitored and completion times were recorded (min). TotalRelVO2 (average relative VO2*time) and age-predicted maximal heart rate (220-age) were calculated. SumHR was calculated by multiplying time spent in each of the five heart rate zones by a multiplier factor for each zone (50-59% = 1, 60-69% = 2, 70-79% = 3, 80-89% = 4, and ≥90% = 5). RPE (Borg 6-20 scale) was collected at the end of each task, then sRPE was calculated (RPE*time). Pearson and Spearman correlations were performed to examine the relationship between TotalRelVO2, sumHR and sRPE. Wilcoxon signed rank tests were conducted to determine if there was a difference in median rankings between the three variables for each task. Linear regressions were performed to determine predictability of TotalRelVO2 from sumHR and sRPE. The study was approved by the U.S. Army Research Institute of Environmental Medicine Institutional Review Board. RESULTS: Significant, positive correlations were revealed for all three tasks between TotalRelVO2, sumHR and sRPE (r ≥ 0.67, p ≤ 0.01; rho≥0.74, p ≤ 0.01). Wilcoxon signed rank tests revealed no significant differences in rankings between TotalRelVO2, sumHR and sRPE for all three tasks (p ≥ 0.43). Both sumHR and sRPE are significant predictors of TotalRelVO2 (p ≤ 0.01). CONCLUSIONS: SumHR and sRPE are acceptable alternatives to TotalRelVO2 when attempting to quantify and/or monitor training load during soldiering tasks.

A prospective field study of U.S. Army trainees to identify the physiological bases and key factors influencing musculoskeletal injuries: a study protocol.

BACKGROUND: Musculoskeletal injuries (MSKIs) are common in military trainees and present a considerable threat to occupational fitness, deployability, and overall military readiness. Despite the negative effects of MSKIs on military readiness, comprehensive evaluations of the key known and possible risk factors for MSKIs are lacking. The U.S. Army Research Institute of Environmental Medicine (ARIEM) is initiating a large-scale research effort, the ARIEM Reduction in Musculoskeletal Injury (ARMI) Study, to better understand the interrelationships among a wide range of potential MSKI risk factors in U.S. Army trainees in order to identify those risk factors that most contribute to MSKI and may be best targeted for effective mitigation strategies. METHODS: This prospective study aims to enroll approximately 4000 (2000 male and 2000 female) U.S. Army trainees undergoing Basic Combat Training (BCT). Comprehensive in-person assessments will be completed at both the beginning and end of BCT. Participants will be asked to complete surveys of personal background information, medical history, physical activity, sleep behaviors, and personality traits. Physical measurements will be performed to assess anthropometrics, tibial microarchitecture and whole body bone mineral density, muscle cross-sectional area, body composition, and muscle function. Blood sampling will be also be conducted to assess musculoskeletal, genetic, and nutritional biomarkers of risk. In addition, participants will complete weekly surveys during BCT that examine MSKI events, lost training time, and discrete risk factors for injury. Participants' medical records will be tracked for the 2 years following graduation from training to identify MSKI events and related information. Research hypotheses focus on the development of a multivariate prediction model for MSKI. DISCUSSION: Results from this study are expected to inform current understanding of known and potential risk factors for MSKIs that can be incorporated into solutions that optimize Soldier health and enhance military readiness.

Calcium and vitamin D supplementation and bone health in Marine recruits: Effect of season.

Stress fractures are common overuse injuries caused by repetitive bone loading. These fractures are of particular concern for military recruits and athletes resulting in attrition in up to 60% of recruits that sustain a fracture. Army and Navy recruits supplemented with daily calcium and vitamin D (Ca + D) demonstrated improved bone strength and reduced stress fractures. The aim of the current study was to evaluate whether Ca + D supplementation improves measures of bone health in recruits undergoing United States Marine Corps initial military training (IMT), and whether the effect of supplementation on indices of bone health varied by season. One-hundred ninety-seven Marine recruits (n = 107 males, n = 90 females, mean age = 18.9 ±â€¯1.6 y) were randomized to receive either Ca + D fortified snack bars (2000 mg Ca and 1000 IU vitamin D per day) or placebo divided into twice daily doses during 12 weeks of IMT. Anthropometrics, fasted blood samples, and peripheral quantitative computed tomography (pQCT) scans of the tibial metaphysis and diaphysis were collected upon entrance to- and post-training (12 weeks later). Half of the volunteers entered training in July and the other half started in February. Time-by-group interactions were observed for vitamin D status (25OHD) and the bone turnover markers, BAP, TRAP and OCN. 25OHD increased and BAP, TRAP and OCN all decreased in the Ca + D group (p < .05). Training increased distal tibia volumetric BMD (+1.9 ±â€¯2.8%), BMC (+2.0 ±â€¯3.1%), and bone strength index (BSI; +4.0 ±â€¯4.0%) and diaphyseal BMC (+1.0 ±â€¯2.2%) and polar stress strain index (SSIp; +0.7 ±â€¯2.1%) independent of Ca + D supplementation (p < .05 for all). When analyzed by season, change in BSI was greater in the Ca + D group as compared to placebo in the summer iteration only (T*G; p < .05). No other effects of supplementation on bone tissue were observed. When categorized by tertile of percent change in BSI, recruits demonstrating the greatest changes in BSI and 25OHD entered training with the lowest levels of 25OHD (p < .05). Over all, these results suggest that Ca + D supplementation reduced some markers of bone formation and resorption and the decline in 25OHD over training in volunteers that started training in the summer was prevented by supplementation. Baseline 25OHD and trajectory may impact bone responses to IMT, but little effect of Ca + D supplementation was observed at the investigated doses.

Widespread Use of Prescription Nonsteroidal Anti-Inflammatory Drugs Among U.S. Army Active Duty Soldiers.

INTRODUCTION: Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to treat pain and inflammation by inhibiting prostaglandin synthesis. There is a high incidence of musculoskeletal injuries in the military, which would validate the widespread use of NSAIDs. This study determined the amount and specific types of NSAIDs being prescribed to U.S. Army active duty soldiers. METHODS AND MATERIALS: This study was a quantitative study which utilized an existing database of de-identified data; therefore, institutional review board approval was not required. Data pertaining to NSAID prescriptions issued to active duty soldiers for fiscal years 2006, 2011, and 2014 were obtained from the Department of Defense Pharmacy Data Transactions Service data warehouse, which contains all outpatient prescriptions. The data include the number of soldiers receiving NSAID prescriptions (i.e., utilizers) as well as the number of prescriptions given for each specific NSAID. RESULTS: In 2006, 2011, and 2014, the numbers of active duty utilizers were 348,031, 435,364, and 418,579, respectively. For the entire active duty Army, the percentage of soldiers who were receiving NSAID prescriptions was approximately 69% in 2006, 77% in 2011, and 82% in 2014. The number of NSAIDs prescribed was 740,090 in 2006; 898,291 in 2011; and 857,964 in 2014. Celecoxib, the only cyclooxygenase-2 inhibitor prescribed in the United States accounted for 2.4% of these NSAID prescriptions in 2006, 6.3% in 2011, and 7.1% in 2014. During all 3 years, the number of prescriptions filled was almost twice the number of utilizers, indicating that many individuals were receiving more than one prescription. Female soldiers received almost twice the number of prescriptions per individual as male soldiers. The use of over-the-counter NSAIDs, which are widely available, was not accounted for in this study; therefore, total NSAID use is likely higher than reported. CONCLUSION: The vast majority of U.S. Army active duty soldiers are being prescribed NSAIDs. These data raise concerns because of the potential adverse effects that NSAIDs have on gastrointestinal, renal, and cardiovascular function, as well as bone health. Additional studies are warranted to determine the actual amounts of NSAIDs being used and the specific conditions for which they are being prescribed.

Effect of specific short-term physical training on fitness measures in conditioned men.

Physical training programs that enhance battlefield-related fitness needs have been increasingly advocated as operational demands on the US military have increased, but few studies have evaluated program effectiveness. The purpose of this study was to compare a novel 7-week physical training program with traditional army physical fitness training in improving the selected measures of physical fitness and military task performance. One hundred and eighty subjects performed a 30-m rush wearing a fighting load, a simulated casualty recovery wearing a fighting load, a 1-repetition maximum bench press, a maximum repetition pull-up test, a medicine ball put, a vertical jump, and a T-test agility drill to establish test-retest reliability and normative reference values. One hundred thirty-three subjects were assigned by block randomization to either traditional Army physical training (TT) of calisthenics and running or a novel program (NT) of calisthenics, resistance, aerobic, speed, power, and agility training. The results indicated that between-day reliability was high (intraclass correlation coefficients [ICCs] 3,1; 0.87-0.98) for all measures except for the casualty recovery (ICC 3,1; 0.67). Reliability improved for all the measures that were averaged over 3 trials (ICC 3,3; 0.93-0.95). The NT was superior to TT in improving bench press (8 vs. 3%; p < 0.01), medicine ball put (7 vs. 1%; p < 0.01), 30-m rush times (5 vs. 1%; p < 0.01), and casualty recovery times (17 vs. -15%; p < 0.01). These findings suggest that a short-term physical training program is effective in improving strength, power, and speed among previously conditioned men. Future studies should determine if similar training programs mitigate the injury risk in this population.

Effects of modified foodservice practices in military dining facilities on ad libitum nutritional intake of US army soldiers.

BACKGROUND: Modifying foodservice practices in military dining facilities could influence ad libitum nutritional intake patterns of soldiers. OBJECTIVE: We aimed to determine how changes in foodservice operations consistent with 2005 Dietary Guidelines for Americans affected soldiers' ad libitum nutritional intake in military dining facilities (DFACs). DESIGN: Ten DFACs participated, and the intervention was implemented in five DFACs in an independently sampled, partial crossover design. Nutrient intake of diners was assessed during a test meal using digital photography, and customer satisfaction with foodservice was assessed via surveys at baseline (n=602), and again at 6 months (n=519) and 12 months (n=458) after the intervention was implemented. PARTICIPANTS: Volunteers were US Army active duty soldiers recruited from among diners at 10 DFACs on Fort Bragg, NC. MAIN OUTCOME MEASURES: Primary outcomes were intakes of energy and total fat, and percent energy from fat and saturated fat. Differences between diners' intakes in control and intervention DFACs were assessed using independent samples t tests. RESULTS: At 6 months after implementing the intervention, diners at intervention DFACs had significantly lower lunchtime intakes of energy (945±338 kcal vs 1,061±380 kcal), total fat (38±19 g vs 47±25 g), percent energy from fat (35%±10% vs 39%±11%) and saturated fat (4.7%±1.7% vs 5.6%±2.3%), discretionary fat (30±18 g vs 39±24 g), and refined grains (2.3±1.7 oz equivalents vs 2.8±2.4 oz equivalents) compared with diners at control DFACs. Further, diners at intervention DFACs rated customer satisfaction higher than diners at control DFACs. CONCLUSIONS: These findings suggest that modest changes in military DFAC serving practices to promote healthy eating and food selection can facilitate positive changes in soldiers' nutritional intake.

Reliability of military-relevant tests designed to assess soldier readiness for occupational and combat-related duties.

The purpose of this study was to determine the reliability of military-relevant tests designed to assess soldier readiness. Forty-seven soldiers (46 men, 1 woman; 22 +/- 3 years; 80.4 +/- 11.7 kg) performed each of seven soldier readiness tests on four different occasions over the course of 8 weeks. The soldier readiness tests were: (1) 3.2-km load carriage (LC) time-trial, (2) running long jump (RLJ), (3) one-repetition maximum box lift (1RMBL), (4) 10-minute repetitive box lift and carry (RBLC), (5) simulated victim rescue (VR), (6) mock grenade throw (GT) for accuracy, and (7) simulated combat rushes (CR). Repeated measures analysis of variance revealed significant learning effects for 1RMBL, RBLC, and GT; these tests required two (1RMBL and RBLC) or three (GT) trials to obtain statistically stable values. The intraclass correlation coefficient was 0.78 to 0.89 for all tests. LC, 1RMBL, RBLC, CR, and RLJ all demonstrated standard error of measurement values that were 3% to 5%, whereas VR and GT were 9% and 36%, respectively. In conclusion, the 1RMBL, RBLC, and GT tests required familiarization before a stable value was obtained. The LC, 1RMBL, RBLC, CR, and RLJ tests (and, to a lesser degree, the VR test) demonstrated reasonably acceptable levels of reliability and measurement error, whereas the GT test did not.

Combined resistance and endurance training improves physical capacity and performance on tactical occupational tasks.

The purpose of this study is to evaluate the effectiveness of aerobic endurance (E), strength (R), and combined endurance and strength (CB) training for improving performance of tactical occupational tasks and determine if combined training interferes with performance enhancements of E or R alone. A total of 56 recreationally active women were randomly placed into four groups: R (n = 18), E (n = 13), CB (n = 15), Control (n = 10). Subjects trained three non-consecutive days per week for 8 weeks. Performance was measured pre-, mid-, and post-training for bench press one-repetition maximum (1-RM), squat 1-RM, bench press throw and squat jump peak power, VO2peak, 3.2 km load carriage (LC), 3.2 km run (run), and repetitive lift and carry (RLC). R and E demonstrated improvements which were generally specific to their training. R improved squat (48.3%) and bench press 1-RM (23.8%), bench press throw (41.9%), RLC (31.3%), and LC (11.5%). E improved run (14.7%), VO2peak (6.2%), squat 1-RM (15.3%), LC (12.9%), and RLC (22.5%). CB improved squat (37.6%) and bench press 1-RM (20.9%), bench press throw (39.6%), VO2peak (7.6%), run (10.4%), LC (13.1%), and RLC (45.5%). Post-training 1-RM squat was greater in R and CB than E, while E completed the 3.2 km load carriage task faster than C. In conclusion, 8 weeks of combined training improved performance in all tactical occupational tasks measured and did not interfere with improvements in strength, power and endurance measures compared to R or E alone.

Physical fitness and body composition after a 9-month deployment to Afghanistan.

PURPOSE: To examine change in physical fitness and body composition after a military deployment to Afghanistan. METHODS: One hundred and ten infantry soldiers were measured before and after a 9-month deployment to Afghanistan for Operation Enduring Freedom. Measurements included treadmill peak oxygen uptake (peak VO2), lifting strength, medicine ball put, vertical jump, and body composition estimated via dual-energy x-ray absorptiometry (percent body fat, absolute body fat, fat-free mass, bone mineral content, and bone mineral density). RESULTS: There were significant decreases (P < 0.01) in peak VO2 (-4.5%), medicine ball put (-4.9%), body mass (-1.9%), and fat-free mass (-3.5%), whereas percent body fat increased from 17.7% to 19.6%. Lifting strength and vertical jump performance did not change predeployment to postdeployment. CONCLUSIONS: Nine months deployment to Afghanistan negatively affected aerobic capacity, upper body power, and body composition. The predeployment to postdeployment changes were not large and unlikely to present a major health or fitness concern. If deployments continue to be extended and time between deployments decreased, the effects may be magnified and further study warranted.