Temporal changes in the physical fitness of US Army recruits

Development and preliminary evaluation of the Comprehensive Health Self-Assessment Questionnaire (CHSAQ) for individuals in the Chinese People Liberation Army

OBJECTIVE

There is currently no widely accepted multidimensional health assessment questionnaire for individuals in the Chinese People Liberation Army (PLA). This study developed a multidimensional health survey questionnaire (Comprehensive Health Self-Assessment Questionnaire, CHSAQ) suitable for personnel in the PLA and conducted a preliminary examination of its reliability, validity, and discriminative ability.

METHODS

After 183 items from 32 dimensions were selected to form the initial version of the CHSAQ, three groups of soldiers were selected from May 2022 to April 2023 and completed three survey rounds (with 183, 131, and 55 valid items). The items were screened based on classic test theory. After screening, the final questionnaire entries were formed, the structure of the questionnaire was explored through exploratory factor analysis and confirmatory factor analysis, and its reliability, structural validity, and discriminative ability were evaluated.

RESULTS

The final questionnaire consisted of 8 dimensions and 55 items on job satisfaction, anxiety and depression, daily activities, physical function, the otolaryngology system, the integumentary system, sleep disorders, and the visual system. The total cumulative variance contribution rate was 64.648% according to exploratory factor analysis. According to the confirmatory factor analysis, the normed fit index (NFI) was 0.880, and the comparison fit index (CFI) was 0.893 (close to 0.90). The Cronbach's α coefficient of the total questionnaire was 0.970, the split half reliability coefficient was 0.937, and the retest reliability coefficient was 0.902. The results are presented as different pairwise comparisons.

CONCLUSION

Our study developed a self-report questionnaire for evaluating the comprehensive health status of personnel in the PLA in accordance with the standard procedure for questionnaire development. Our findings also showed that the CHSAQ for individuals in the PLA has good reliability and structural validity.

Possible toxicity of chronic carbon dioxide exposure associated with face mask use, particularly in pregnant women, children and adolescents - A scoping review

Introduction

During the SARS-CoV-2-pandemic, face masks have become one of the most important ubiquitous factors affecting human breathing. It increases the resistance and dead space volume leading to a re-breathing of CO2. So far, this phenomenon and possible implications on early life has not been evaluated in depth.

Method

As part of a scoping review, literature was systematically reviewed regarding CO2 exposure and facemask use.

Results

Fresh air has around 0.04% CO2, while wearing masks more than 5 min bears a possible chronic exposure to carbon dioxide of 1.41% to 3.2% of the inhaled air. Although the buildup is usually within the short-term exposure limits, long-term exceedances and consequences must be considered due to experimental data. US Navy toxicity experts set the exposure limits for submarines carrying a female crew to 0.8% CO2 based on animal studies which indicated an increased risk for stillbirths. Additionally, mammals who were chronically exposed to 0.3% CO2 the experimental data demonstrate a teratogenicity with irreversible neuron damage in the offspring, reduced spatial learning caused by brainstem neuron apoptosis and reduced circulating levels of the insulin-like growth factor-1. With significant impact on three readout parameters (morphological, functional, marker) this chronic 0.3% CO2 exposure has to be defined as being toxic. Additional data exists on the exposure of chronic 0.3% CO2 in adolescent mammals causing neuron destruction, which includes less activity, increased anxiety and impaired learning and memory. There is also data indicating testicular toxicity in adolescents at CO2 inhalation concentrations above 0.5%.

Discussion

There is a possible negative impact risk by imposing extended mask mandates especially for vulnerable subgroups. Circumstantial evidence exists that extended mask use may be related to current observations of stillbirths and to reduced verbal motor and overall cognitive performance in children born during the pandemic. A need exists to reconsider mask mandates.

Characterization of Female US Marine Recruits: Workload, Caloric Expenditure, Fitness, Injury Rates, and Menstrual Cycle Disruption during Bootcamp

Basic training is centered on developing the physical and tactical skills essential to train a recruit into a Marine. The abrupt increase in activity and energy expenditure in young recruits may contribute to high rates of musculoskeletal injuries, to which females are more susceptible. To date, the total workload of United State Marine Corps (USMC) bootcamp is unknown and should include movement around the military base (e.g., to and from dining facilities, training locations, and classrooms). Thus, the purpose of this effort was to quantify workload and caloric expenditure, as well as qualitatively assess the impact of female reproductive health and injury rates in female recruits. Female recruits (n = 79; age: 19.1 ± 0.2 years, weight: 59.6 ± 0.8 kg, height: 161.6 ± 0.7 cm) wore physiological monitors daily throughout 10 weeks of USMC bootcamp. Physical fitness test scores, physiological metrics from wearables, injury data, and menstrual cycle information were obtained. Female recruits on average expended 3096 ± 9 kcal per day, walked 11.0 ± 0.1 miles per day, and slept 5:43 ± 1:06 h:min per night throughout the 10 weeks of bootcamp. About one-third (35%) of female recruits sustained an injury. In a subset of females that were not taking birth control and had previously been menstruating, 85% experienced cycle dysfunction during boot camp. High levels of physical activity and caloric expenditure, coupled with the stress of a new environment and insufficient sleep, may lead to alterations in female reproductive cycles and musculoskeletal injuries in young USMC recruits.

Temporal changes in physical fitness in Norwegian male and female military conscripts between 2006 and 2020

Reduced physical fitness has been documented in Western children and adults over the past five decades. The same trend has been observed among soldiers, but the number of studies is scarce. Thus, the aim of the present study was to investigate temporal changes in physical fitness in Norwegian conscripts. All conscripts who performed entry fitness tests between 2006 and 2020 were included in the study (n = 105 100; 17% females). Endurance was measured with the 3000 m run, while push-ups, sit-ups, and pull-ups (2006-2016) and medicine ball throw, standing long jump, and pull-ups (2017-2020) were used to measure muscle strength. Mean (95% confidence intervals) 3000 m run time was reduced by 52 (47, 57) seconds in men, 90 (76, 105) seconds in women, and 16 (11, 20) seconds in both sexes combined. Muscle strength increased statistically significantly in four out of five tests in men, three out of six tests in women, and two out of five tests for both sexes combined. Effect sizes for statistically significant changes ranged from 0.06 to 0.82. In conclusion, Norwegian conscripts improved their cardiorespiratory endurance between 2006 and 2020, with improvements observed for most muscle strength tests. When analyzing both sexes combined, the improvements diminished. The latter is attributed to a sevenfold increase in relative number of female conscripts over the 15-year period. The present findings should not be generalized to all young Norwegian men and women since conscripts are selected based on fitness, and only ~15% of the population end up serving.

Verification of Maximal Oxygen Uptake in Active Military Personnel During Treadmill Running

ABSTRACT

Figueiredo, PS, Looney, DP, Pryor, JL, Doughty, EM, McClung, HL, Vangala, SV, Santee, WR, Beidleman, BA, and Potter, AW. Verification of maximal oxygen uptake in active military personnel during treadmill running. J Strength Cond Res 36(4): 1053-1058, 2022-It is unclear whether verification tests are required to confirm "true" maximal oxygen uptake (V̇o2max) in modern warfighter populations. Our study investigated the prevalence of V̇o2max attainment in U.S. Army soldiers performing a traditional incremental running test. In addition, we examined the utility of supramaximal verification testing as well as repeated trials for familiarization for accurate V̇o2max assessment. Sixteen U.S. Army soldiers (1 woman, 15 men; age, 21 ± 2 years; height, 1.73 ± 0.06 m; body mass, 71.6 ± 10.1 kg) completed 2 laboratory visits, each with an incremental running test (modified Astrand protocol) and a verification test (110% maximal incremental test speed) on a motorized treadmill. We evaluated V̇o2max attainment during incremental testing by testing for the definitive V̇O2 plateau using a linear least-squares regression approach. Peak oxygen uptake (V̇o2peak) was considered statistically equivalent between tests if the 90% confidence interval around the mean difference was within ±2.1 ml·kg-1·min-1. Oxygen uptake plateaus were identified in 14 of 16 volunteers for visit 1 (87.5%) and all 16 volunteers for visit 2 (100%). Peak oxygen uptake was not statistically equivalent, apparent from the mean difference in V̇o2peak measures between the incremental test and verification test on visit 1 (2.3 ml·kg-1·min-1, [1.3-3.2]) or visit 2 (1.1 ml·kg-1·min-1 [0.2-2.1]). Interestingly, V̇o2peak was equivalent, apparent from the mean difference in V̇o2peak measures between visits for the incremental tests (0.0 ml·kg-1·min-1 [-0.8 to 0.9]) but not the verification tests (-1.2 ml·kg-1·min-1 [-2.2 to -0.2]). Modern U.S. Army soldiers can attain V̇o2max by performing a modified Astrand treadmill running test. Additional familiarization and verification tests for confirming V̇o2max in healthy active military personnel may be unnecessary.

Association between preventable risk factors and metabolic syndrome

The risk factors associated with metabolic syndrome (Met-S) including hypertension, hyperglycemia, central obesity, and dyslipidemia are preventable, particularly at their early stage. There are limited data available on the association between Met-S and preventable risk factors in young adults. We randomly selected 2,010 Saudis aged 18-30 years, who applied to be recruited in military colleges. All the procedures followed the guidelines of International Diabetes Federation. The results showed that out of 2,010 subjects, 4088 were affected with Met-S. The commonest risk factors were high blood sugar (63.6%), high systolic and diastolic blood pressures (63.3 and 37.3%), and high body mass index (57.5%). The prevalence of prediabetes and diabetes were 55.2 and 8.4%, respectively. Obesity, diabetes, hypertension, and hypertriglyceridemia were significantly associated with Met-S. The frequency of smoking was significantly linked with the development of Met-S. The prevalence of Met-S was found to be significantly higher in individuals with sedentary lifestyle. In conclusion, the results of this study clearly indicate that military recruits, who represent healthy young adults, are also prone to Met-S. The findings of this study will help in designing preventive measures as well as public awareness programs for controlling the high prevalence of Met-S in young adults.

Recent Trends of Metabolic Syndrome and Its Components in Military Recruits from Saudi Arabia

Metabolic syndrome (Met-S) constitutes the risk factors and abnormalities that markedly increase the probability of developing diabetes and coronary heart disease. An early detection of Met-S, its components and risk factors can be of great help in preventing or controlling its adverse consequences. The aim of the study was to determine the prevalence of cardio-metabolic risk factors in young army recruits from Saudi Arabia. A total of 2010 Saudis aged 18-30 years were randomly selected from groups who had applied to military colleges. In addition to designed questionnaire, anthropometric measurements and blood samples were collected to measure Met-S components according to the International Diabetes Federation (IDF) criteria. Met-S prevalence was 24.3% and it was higher in older subjects than the younger ones. There were significant associations between Met-S and age, education level and marital status. The most common Met-S components were high fasting blood sugar (63.6%) followed by high blood pressure (systolic and diastolic, 63.3% and 37.3% respectively) and high body mass index (57.5%). The prevalence of pre-diabetes and diabetes were found to be 55.2% and 8.4%, respectively. Hypertriglyceridemia was found in 19.3% and low levels of high-density lipoproteins (HDL) in 11.7% of subjects. In conclusion, there is a high prevalence of Met-S in young adults of Saudi Arabia. There is a need for regular monitoring of Met-S in young populations to keep them healthy and fit for nation building. It is also important to design and launch community-based programs for educating people about the importance of physical activity, cessation of smoking and eating healthy diet in prevention of chronic diseases.

Change in Anthropometrics and Physical Fitness in Norwegian Cadets During 3 Years of Military Academy Education

INTRODUCTION

High physical fitness is associated with increased occupational performance, better health, and reduced risk of injuries in military personnel. Thus, the military emphasizes physical training to maintain or develop physical fitness in their soldiers. It is important to monitor the effect of the physical training regime, but such information is lacking for Norwegian military cadets. Hence, the primary aim of this study was to investigate changes in anthropometrics and physical fitness among male and female army, navy and air force cadets during 3 years of military academy education.

MATERIALS AND METHODS

260 male and 29 female Norwegian cadets from the army, navy, and air force academies volunteered to participate. Anthropometrics, muscular power, muscular endurance, and maximal oxygen uptake were measured at entry (T0) and end of each year (T1, T2, and T3). Linear mixed models were used to examine the development in anthropometrics and physical fitness. We applied to the Regional Committee for Medical and Health Research Ethics to review the study before start-up, but the study was considered exempted from notification. The study was reviewed and approved by the Norwegian Social Science Data Services.

RESULTS

Male and female cadets significantly increased their body weight, fat-free mass, body mass index, and percent body fat by 1 to 5% from T0 to T3. Skeletal muscle mass was unchanged. Muscular power (medicine ball throw and vertical jump) and muscular endurance (pull-ups and push-ups) increased by 3 to 20% in male cadets, while female cadets only increased results significantly for the medicine ball throw (10%). Relative maximal oxygen uptake decreased by 4% in both sexes, while absolute maximal oxygen uptake only decreased significantly (by 2%) in male cadets. Most of the observed changes were classified as trivial or small, according to calculated effect sizes. The observed changes were generally of similar magnitude for male and female cadets, and similar among the three academies.

CONCLUSIONS

Anthropometrics and physical fitness were relatively stable in Norwegian male and female army, navy, and air force cadets during 3 years of military academy education. Observed changes were typically classified as trivial or small. The initial gap in physical fitness between male and female cadets did not narrow during the education years. Norwegian male and female cadets displayed relatively good physical fitness profiles, compared to sex-matched cadets and soldiers from previously studied military populations.

Markers of Bone Health and Impact of Whey Protein Supplementation in Army Initial Entry Training Soldiers: A Double-Blind Placebo-Controlled Study

Training civilians to be soldiers is a challenging task often resulting in musculoskeletal injuries, especially bone stress injuries. This study evaluated bone health biomarkers (P1NP/CTX) and whey protein or carbohydrate supplementations before and after Army initial entry training (IET). Ninety male IET soldiers participated in this placebo-controlled, double-blind study assessing carbohydrate and whey protein supplementations. Age and fat mass predicted bone formation when controlling for ethnicity, explaining 44% (p < 0.01) of bone formation variations. Age was the only significant predictor of bone resorption (p = 0.02) when controlling for run, fat, and ethnicity, and these factors together explained 32% of the variance in bone resorption during week one (p < 0.01). Vitamin D increased across training (p < 0.01). There was no group by time interaction for supplementation and bone formation (p = 0.75), resorption (p = 0.73), Vitamin D (p = 0.36), or calcium (p = 0.64), indicating no influence of a supplementation on bone biomarkers across training. Age, fitness, fat mass, and ethnicity were important predictors of bone metabolism. The bone resorption/formation ratio suggests IET soldiers are at risk of stress injuries. Male IET soldiers are mildly to moderately deficient in vitamin D and slightly deficient in calcium throughout training. Whey protein or carbohydrate supplementations did not affect the markers of bone metabolism.

Association Between Performance in Muscle Fitness Field Tests and Skeletal Muscle Mass in Soldiers

INTRODUCTION

Muscle strength and muscle endurance are important fitness components related to safe and efficient execution of physically demanding military work. In soldiers, these components are traditionally measured from simple field tests like push-ups, sit-ups, and pull-ups. However, the validity of such muscle fitness field tests is questioned due to reports of low association between test performance and the ability to conduct strength demanding military work (eg, lift and carry tasks). It is therefore necessary to study, develop, and implement more valid field tests, which are still feasible for mass testing in the military. Skeletal muscle mass (SMM) is an important physiological component related to maximal muscle force generation (strength). Thus, an alternative way of validating muscle fitness field tests is by comparisons against SMM. The purpose of the present study was to investigate the association between SMM and performance in five muscle fitness field tests.

MATERIALS AND METHODS

A total of 275 military cadets (including 27 women) participated in this method comparison study. The field tests included push-ups, sit-ups, pull-ups (vertical for men, horizontal for women), standing medicine ball throw, and Sargent jump (peak power and jump height). SMM was estimated from bioelectrical impedance analysis and expressed in absolute values (kg) or relative to body mass. Pearson correlation coefficients (r) were calculated to investigate associations between SMM and performance in the five field tests. The study was submitted to the Regional Committee for Medical and Health Research Ethics prior to startup, and the Committee considered the study to be exempted from notification. The study was reviewed and approved by the Norwegian Social Science Data Services.

RESULTS

In men, the highest correlation against absolute SMM was found for the Sargent jump (peak power) and the medicine ball throw (r = 0.71 and 0.54, respectively). The same trend was evident for women (r = 0.85 and 0.61, respectively) and for the two genders combined (r = 0.85 and 0.79, respectively). All these r-values were significant (P < 0.001). In men, the highest r against relative SMM was found for pull-ups (r = 0.50, P < 0.001). The same pattern was found in women, but the association was not significant (r = 0.36, P = 0.07). The sit-ups test demonstrated low or nonsignificant associations with both absolute and relative SMM.

CONCLUSIONS

Among the five muscle fitness field tests investigated, the Sargent jump (peak power) and the medicine ball throw demonstrated the strongest correlation coefficients against absolute SMM. Thus, these two tests should be better alternatives for assessing relevant upper and lower body strength and power in soldiers compared with push-ups, pull-ups, and sit-ups. Pull-ups generally demonstrated the strongest correlation against relative SMM. Sit-ups demonstrated low or nonsignificant associations with both absolute and relative SMM. Consequently, the test should be considered for removal from military fitness test batteries or replaced by alternative abdominal tests that are more valid.

Reliability and Validity of a Maximal Treadmill Test for Predicting Aerobic Fitness in Norwegian Prospective Soldiers

INTRODUCTION

The Norwegian armed forces reintroduced physical fitness testing of prospective conscript soldiers in 2011. Since then, a customized maximal treadmill test (MILMAX) has been used to screen aerobic fitness in 15-20,000 young Norwegian men and women annually. The aim of the current study was to investigate reliability and validity of the MILMAX test.

MATERIALS AND METHODS

Sixty-seven young Army recruits (including 11 women) participated in this method comparison study. The subjects completed the MILMAX test twice (test-retest), consisting of walking and running at increasing speed and inclination until voluntarily exhaustion. Performance was registered as exercise tolerance time (ETT). Later, the subjects performed a treadmill test of direct maximal oxygen uptake (V̇O2max). All tests were conducted within 15 days. The study protocol was submitted to the Regional Committee for Medical and Health Research Ethics for review, prior to study initiation. The Committee considered the study to be exempted from notification. The study was carried out according to the guidelines in the Declaration of Helsinki.

RESULTS

There was no significant mean difference in MILMAX ETT between test and retest. Test-retest intraclass correlation coefficient was 0.95 (0.91, 0.97), while 95% limits of agreement was ± 60 seconds. Regression analyses showed that MILMAX ETT and gender explained 78% of the variance in directly measured V̇O2max, and a prediction equation with these two independent variables was generated. The Pearson correlation coefficient between predicted and directly measured V̇O2max was 0.89 (0.83, 0.93), while limits of agreement was ± 5.6 mL·kg-1·min-1.

CONCLUSIONS

The MILMAX is equally reliable and valid compared with well-known maximal indirect tests like the 2-mile run and the 20-m shuttle run test, and may serve as an alternative indoor test of aerobic fitness in the military, in other potentially physically strenuous occupations, or in healthy civilians.

A longitudinal analysis of the U.S. Air Force reserve officers' training corps physical fitness assessment

BACKGROUND

The U.S. Air Force physical fitness assessment (PFA) is used to determine the overall fitness of their personnel. It is currently unknown to what extent the PFA scores of Reserve Officers' Training Corps (ROTC) cadets are affected by mandatory physical training. The purpose of this investigation was to longitudinally examine the PFAs of ROTC cadets over a four-year period, evaluate the results across class ranks, and evaluate the sensitivity of the classification of the tests.

METHODS

Air Force ROTC cadets performed the PFAs (abdominal circumference, 1-min pushups, 1-min sit-ups, and a 1.5-mile run) in both the spring (n = 26) and fall (n = 22) semesters. PFAs were compiled over a four-year period (Spring 2014 - Fall 2017) and were performed in accordance with Air Force Instruction 36-2905. A one-way repeated measures ANOVA was performed separately for the fall and spring groups for each dependent variable across the 4 years. Additionally, a one-way between groups ANOVA was performed for each dependent variable during the time point (fall 2015; N = 46) with the most recorded cadets for each class rank.

RESULTS

Longitudinal assessments revealed a main effect of time (P = 0.010) on abdominal circumference; cadets had a smaller abdominal circumference in their freshman year than in their senior year. A main effect of time (P = 0.006) was also observed on sit-up quantity; cadets performed more sit-ups in their junior year than in their freshman year. Examining between class ranks during the same year (between-subjects ANOVA) revealed a main effect of class rank on sit-up quantity (P = 0.003); the freshmen completed fewer repetitions than the sophomores (P = 0.018) and the juniors did (P = 0.001).

CONCLUSION

The results indicated that only the sit-up component showed differences between class ranks. These findings suggest that the Air Force PFA may not be sensitive enough to detect changes in physical fitness or distinguish between class ranks regarding physical performance, even after years of training. This limitation may be in part due to the limited duration of training incorporated by the ROTC program (2 h per week), which provided a maintenance effect rather than improvement in physical performance. We recommend that more attention be directed to the efficacy of physical training, the sensitivity of measures included in the PFA, or both.

Analysis to Improve the Strength of Beds Due to the Excess Weight of Users in Slovakia

Good quality sleep is a prerequisite for regenerating the human body, hence, beds should be optimized for specific group of users, taking into consideration their size or age. Current research studies show similar trends in adult populations around the world, where increases in height as well as in weight can be observed. Not only the ergonomics but also the safety of beds, which is determined by the quality and dimensions of structural elements, must be taken into account in bed design. Designing the structural elements for users with a high body weight is presented in the paper. The properties of a bed’s structural elements, which ensure comfort as well as the safety of a bed are affected by the excess weight of users. New requirements for cross sections, suitable materials and construction of structural elements were set in accordance with the standard EN 1725:1998 [1]. Also, an analysis of stresses was done using the finite element method (FEM) and the calculation of allowable stresses related to a user weighing 150 kg. The results of our research provide complete standards and regulations associated with the safety requirements of bedroom furniture for users with a weight more than 110 kg to ensure that the manusfacture of quality products in Slovakia.

Physical Fitness in Young Men between 1975 and 2015 with a Focus on the Years 2005-2015

PURPOSE

The purpose of the present study was to investigate changes in physical fitness and anthropometry of young men entering the military service in Finland during the years 1975-2015.

METHODS

The study included the fitness test results of 627,142 healthy young male conscripts (age 19.1 ± 0.4 yr). Data included results of aerobic capacity, muscle fitness tests, and anthropometric characteristics.

RESULTS

The results show that the increase in mean body mass of young men has slowed down during the last 10 yr. However, the total increase in body mass was 6.8 kg (8.8%, P ≤ 0.001) between 1993 and 2015. The mean distance achieved in the 12-min running test decreased by 337 m (12.2%, P ≤ 0.001) between the peak in 1980 and 2015. The relative number of conscripts who ran less than 2200 m increased from 3.6% to 25.9% (P ≤ 0.001) between 1980 and 2015, and the proportion who ran more than 3000 m decreased from 25.1% to 6.5% (P ≤ 0.001). The relative number of conscripts who achieved an excellent or good muscle fitness index decreased from 66.8% to 40.1% (P ≤ 0.001) between 1992 and 2000, and remained unchanged between 2000 and 2010. However, the proportion who achieved a poor muscle fitness index increased from 8.1% to 31.4% (P ≤ 0.001) between 1992 and 2010.

DISCUSSION

The present study shows that the increase in mean body mass of young male conscripts has slowed down during the last 10 yr. However, their aerobic capacity has still decreased during recent decades. In addition, the proportion of conscripts with poor muscle fitness has increased. From the national defense and health perspective, more initiatives are needed to encourage young men to increase their level of daily physical activity to be fit and ready for operations.

Kinetic analysis of push-up exercises: a systematic review with practical recommendations

Push-ups represent one of the simplest and most popular strengthening exercise. The aim of this study was to systematically review and critically appraise the literature on the kinetics-related characteristics of different types of push-ups, with the objective of optimising training prescription and exercise-related load. A systematic search was conducted in the electronic databases PubMed, Google Scholar and Science Direct up to April 2018. Studies that reported kinetic data (e.g. initial and peak-force supported by the upper-limbs, impact-force, peak-flexion-moment of the elbow-joint, rate of propulsive- and impact-, and vertebral-joint compressive-forces) related to push-ups and included trained, recreational and untrained participants, were considered. The risk of bias in the included studies was assessed using the Critical Appraisal Skills Programme scale. From 5290 articles retrieved in the initial search, only 26 studies were included in this review. Kinetic data for 46 push-up variants were assessed. A limitation of the current review is that the relationship between our findings and actual clinical or practical consequences is not statistically proven but can only be inferred from our critical descriptive approach. Overall, this review provides detailed data on specific characteristics and intensities of push-up variations, in order to optimise exercise prescription for training and rehabilitation purposes.

Positive Secular Trend in Slovak Population Urges on Updates of Functional Dimensions of Furniture

The presented study is focused on the evaluation of the changes in weight and height of the adult population in Slovakia to provide updated information on the secular growth trend. The main objective was to identify and quantify the pace of gradual changes in the dimensions of the Slovak adult population, which is key ergonomic information for multiple disciplines. The measurements of weights, heights and body mass indices of the current adult population of Slovakia ranging from 26 to 94 years of age that were obtained in period 1993–2017 were compared with a sample of students studying at four Slovak universities during the same years (aged 18 to 25). The increase of mean heights was app. 0.104–0.203 cm per one year (or app. 1–2 cm per decade) for males and app. 0.031–0.178 cm per one year (or app. 0.3–1.8 cm per decade) for females was statistically confirmed at different age classes covering the age structure of the whole adult population. The positive secular height trends were manifested in weight and BMI increases too. The changes in means and variation of distributions of selected variables also cause changes in quantile values. For example, the 95% quantiles of heights derived for the period 1993–2003 only cover 92–93% of the heights in the current population. This fact could have a major impact on proposals for optimal and safe arrangement of work, residential and non-residential space, including the furniture production.

Associations of Physical Fitness and Body Composition Characteristics With Simulated Military Task Performance

Pihlainen, K, Santtila, M, Häkkinen, K, and Kyröläinen, H. Associations of physical fitness and body composition characteristics with simulated military task performance. J Strength Cond Res 32(4): 1089-1098, 2018-The purpose of this study was to evaluate the associations of physical fitness and body composition characteristics with anaerobic endurance performance, tested in the combat load using the occupationally relevant military simulation test (MST). Eighty-one male soldiers, deployed to a crisis management operation in the Middle East, volunteered for the study and participated in a test battery consisting measurements of muscle strength, body composition characteristics, endurance capacity, and MST. A Spearman correlational analysis revealed that the strongest variable, correlated with MST time, was the countermovement jump performed with the combat load (CMJ2) (rs = -0.66, p < 0.001). Among the individual body composition variables, the MST time had the strongest relationship with fat percentage (rs = 0.53, p < 0.001) and skeletal muscle mass (SMM) (rs = -0.47, p < 0.001). The use of the dead mass ratio, which was calculated dividing body mass by fat mass accompanied with the weight of the combat load, increased body composition-based associations significantly, and this variable turned out to be the best single predictor for the MST performance (rs = -0.67, p < 0.001). Significant predictors of the MST time in the stepwise multivariate regression analysis included CMJ2, 3000 m, SMM, and push-ups. Together, these variables explained 66% ((Equation is included in full-text article.), model p < 0.001) of the variance in the MST time. In conclusion, the novel MST is a promising military specific assessment method of muscle power of the lower extremities and endurance capacity, which are crucial performance components in anaerobic combat situations.

Secular Trends in the Physical Fitness of United States Army Recruits on Entry to Service, 1975-2013

Knapik, JJ, Sharp, MA, and Steelman, RA. Secular trends in the physical fitness of United States Army recruits on entry to service, 1975-2013. J Strength Cond Res 31(7): 2030-2052, 2017-A systematic literature search was conducted to identify and analyze articles that reported on physical fitness of new US Army recruits. The National Library of Medicine's PubMed and the Defense Technical Information Center were searched using the keywords (military personnel OR trainee OR recruit OR soldier) AND (physical fitness OR strength OR endurance OR flexibility OR balance OR coordination OR muscle contraction OR running OR exercise OR physical conditioning). Reference lists of obtained articles and contact with authors enhanced the search. Studies were selected if they involved recruits in Basic Combat Training or One-Station Unit Training, provided a quantitative assessment of at least one fitness measure, and the fitness measure(s) were obtained early in training. Average values for each fitness measure were obtained, plotted by the year of data collection, and fitted to linear regression models (fitness measure × year). Fifty-three articles met the review criteria. Regression analysis indicated little temporal change in height, but body weight, body mass index, body fat, and fat-free mass increased over time. Limited V[Combining Dot Above]O2max data suggested no temporal change in male recruits, but those in female recruits V[Combining Dot Above]O2max seem to have slightly improved. Apparently contradicting the V[Combining Dot Above]O2max findings, performance on endurance runs (1- and 2-mile) declined, possibly because of the increase in body weight. Muscular endurance (push-ups, sit-ups) demonstrated little systematic change over time. Limited but multiple measures of muscular strength suggest a temporal increase in strength. Specific components of US Army recruit fitness seem to have changed over time.

Association Between Single Gene Polymorphisms and Bone Biomarkers and Response to Calcium and Vitamin D Supplementation in Young Adults Undergoing Military Training

Initial military training (IMT) is associated with increased stress fracture risk. In prior studies, supplemental calcium (Ca) and vitamin D provided daily throughout IMT reduced stress fracture incidence, suppressed parathyroid hormone (PTH), and improved measures of bone health compared with placebo. Data were analyzed from a randomized, double-blind, placebo-controlled trial to determine whether single-nucleotide polymorphisms (SNPs) in Ca and vitamin D-related genes were associated with circulating biomarkers of bone metabolism in young adults entering IMT, and whether responses to Ca and vitamin D supplementation were modulated by genotype. Associations between SNPs, including vitamin D receptor (VDR), vitamin D binding protein (DBP), and 1-alpha-hydroxylase (CYP27B1), and circulating biomarkers were measured in fasting blood samples from volunteers (n = 748) starting IMT. Volunteers were block randomized by race and sex to receive Ca (2000 mg) and vitamin D (1000 IU) or placebo daily throughout Army or Air Force IMT (7 to 9 weeks). Total Ca and vitamin D intakes were calculated as the sum of supplemental intake based on intervention compliance and dietary intake. Relationships between SNPs, Ca, and vitamin D intake tertile and change in biomarkers were evaluated in trial completers (n = 391). At baseline, the minor allele of a DBP SNP (rs7041) was positively associated with both 25OHD (B = 4.46, p = 1.97E-10) and 1,25(OH)₂ D₃ (B = 9.63, p < 0.001). Combined genetic risk score (GRS) for this SNP and a second SNP in the VDR gene (rs1544410) was inversely associated with baseline 25OHD (r = -0.28, p < 0.001) and response to Ca and vitamin D intake differed by GRS (p < 0.05). In addition, presence of the minor allele of a second VDR SNP (rs2228570) was associated with lower P1NP (B = -4.83, p = 0.04) and osteocalcin (B = -0.59, p = 0.03). These data suggest that VDR and DBP SNPs are associated with 25OHD status and bone turnover and those with the highest GRS require the greatest vitamin D intake to improve 25OHD during IMT. © 2016 American Society for Bone and Mineral Research.

Excess Stress Fractures, Musculoskeletal Injuries, and Health Care Utilization Among Unfit and Overweight Female Army Trainees

BACKGROUND

Musculoskeletal injuries are prevalent among military trainees and certain occupations. Fitness and body mass index (BMI) have been associated with musculoskeletal conditions, including stress fractures.

HYPOTHESIS

The incidence of, and excess health care utilization for, stress fracture and non-stress fracture overuse musculoskeletal injuries during the first 6 months of service is higher among unfit female recruits. Those who exceeded body fat limits are at a greater risk of incident stress fractures, injuries, or health care utilization compared with weight-qualified recruits.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All applicants to the United States Army were required to take a preaccession fitness test during the study period (February 2005-September 2006). The test included a 5-minute step test scored as pass or fail. BMI was recorded at application. There were 2 distinct comparisons made in this study: (1) between weight-qualified physically fit and unfit women and (2) between weight-qualified physically fit women and those who exceeded body fat limits. We compared the incidence of, and excess health care utilization for, musculoskeletal injuries, including stress fractures and physical therapy visits, during the first 183 days of military service.

RESULTS

Among the weight-qualified women, unfit participants had a higher non-stress fracture injury incidence and related excess health care utilization rate compared with fit women, with rate ratios of 1.32 (95% CI, 1.14-1.53) and 1.18 (95% CI, 1.10-1.27), respectively. Among fit women, compared with the weight-qualified participants, those exceeding body fat limits had higher rate ratios for non-stress fracture injury incidence and related excess health care utilization of 1.27 (95% CI, 1.07-1.50) and 1.20 (95% CI, 1.11-1.31), respectively. Weight-qualified women who were unfit had a higher incidence of stress fractures and related excess health care utilization compared with fit women, with rate ratios of 1.62 (95% CI, 1.19-2.21) and 1.22 (95% CI, 1.10-1.36), respectively. Among fit women exceeding body fat limits, the stress fracture incidence and related excess health care utilization rate ratios were 0.79 (95% CI, 0.49-1.28) and 1.44 (95% CI, 1.20-1.72), respectively, compared with those who were weight qualified.

CONCLUSION

The results indicate a significantly increased risk of musculoskeletal injuries, including stress fractures, among unfit recruits and an increased risk of non-stress fracture musculoskeletal injuries among recruits who exceeded body fat limits. Once injured, female recruits who were weight qualified but unfit and those who were fit but exceeded body fat limits had increased health care utilization. These findings may have implications for military accession and training policies as downsizing of military services will make it more important than ever to optimize the health and performance of individual service members.

Time changes in the body dimensions of male Australian Army personnel between 1977 and 2012

The aim of this study was to quantify time changes in the body dimensions of male Australian Army personnel. Following a systematic review, two studies were identified and matched for occupation and age (n = 669) with time changes in 12 absolute and 11 proportional body dimensions assessed between 1977 and 2010-12. Changes in means were expressed as absolute, percent and standardised changes, with changes in variability assessed visually and as the ratio of coefficients of variation (CVs). Time changes in absolute dimensions were typically positive (increases) and moderate in magnitude (median standardised change ± 95%CI: 0.53 ± 0.23), and while changes in proportional dimensions were typically negligible (median standardised change ± 95%CI: 0.16 ± 0.33), substantial changes (standardised changes ≥0.2 or ≤-0.2) were observed in several dimensions. Variability in body dimensions has also typically increased (median ratio of CVs ± 95%CI: 1.10 ± 0.07) and become more right-skewed. These findings have important implications for the design and acquisition of new military vehicles, body equipment and clothing.

Optimal Physical Training During Military Basic Training Period

The goal for military basic training (BT) is to create a foundation for physical fitness and military skills of soldiers. Thereafter, more advanced military training can safely take place. Large differences in the initial physical performance of conscripts or recruits have led military units to develop more safe and effective training programs. The purpose of this review article was to describe the limiting factors of optimal physical training during the BT period. This review revealed that the high volume of low-intensity physical activity combined with endurance-type military training (like combat training, prolonged physical activity, and field shooting) during BT interferes with optimal development of maximal oxygen uptake and muscle strength of the soldiers. Therefore, more progressive, periodized, and individualized training programs are needed. In conclusion, optimal training programs lead to higher training responses and lower risks for injuries and overloading.

Consumption of a calcium and vitamin D-fortified food product does not affect iron status during initial military training: a randomised, double-blind, placebo-controlled trial

Ca/vitamin D supplementation maintains bone health and decreases stress fracture risk during initial military training (IMT); however, there is evidence that Ca may negatively affect the absorption of other critical micronutrients, particularly Fe. The objective of this randomised, double-blind, placebo-controlled trial was to determine whether providing 2000 mg/d Ca and 25µg/d vitamin D in a fortified food product during 9 weeks of military training affects Fe status in young adults. Male (n98) and female (n54) volunteers enrolled in US Army basic combat training (BCT) were randomised to receive a snack bar with Ca/vitamin D (n75) or placebo (snack bar without Ca/vitamin D;n77) and were instructed to consume 2 snack bars/d between meals throughout the training course. Circulating ionised Ca was higher (P<0·05) following BCT among those consuming the Ca/vitamin D bars compared with placebo. Fe status declined in both groups over the course of BCT. Transferrin saturation, serum ferritin and Hb were reduced (P<0·05) and soluble transferrin receptor increased (P<0·05) following BCT. There were no differences (P>0·05) in markers of Fe status between placebo and Ca/vitamin D groups. Collectively, these data indicate that Ca/vitamin D supplementation through the use of a fortified food product consumed between meals does not affect Fe status during IMT.

Calcium and vitamin D supplementation maintains parathyroid hormone and improves bone density during initial military training: a randomized, double-blind, placebo controlled trial

Calcium and vitamin D are essential nutrients for bone health. Periods of activity with repetitive mechanical loading, such as military training, may result in increases in parathyroid hormone (PTH), a key regulator of Ca metabolism, and may be linked to the development of stress fractures. Previous studies indicate that consumption of a Ca and vitamin D supplement may reduce stress fracture risk in female military personnel during initial military training, but circulating markers of Ca and bone metabolism and measures of bone density and strength have not been determined. This randomized, double-blind, placebo-controlled trial sought to determine the effects of providing supplemental Ca and vitamin D (Ca+Vit D, 2000mg and 1000IU/d, respectively), delivered as 2 snack bars per day throughout 9weeks of Army initial military training (or basic combat training, BCT) on PTH, vitamin D status, and measures of bone density and strength in personnel undergoing BCT, as well as independent effects of BCT on bone parameters. A total of 156 men and 87 women enrolled in Army BCT (Fort Sill, OK; 34.7°N latitude) volunteered for this study. Anthropometric, biochemical, and dietary intake data were collected pre- and post-BCT. In addition, peripheral quantitative computed tomography was utilized to assess tibia bone density and strength in a subset of volunteers (n=46). Consumption of supplemental Ca+Vit D increased circulating ionized Ca (group-by-time, P=0.022), maintained PTH (group-by-time, P=0.032), and increased the osteoprotegerin:RANKL ratio (group-by-time, P=0.006). Consistent with the biochemical markers, Ca+Vit D improved vBMD (group-by-time, P=0.024) at the 4% site and cortical BMC (group-by-time, P=0.028) and thickness (group-by-time, P=0.013) at the 14% site compared to placebo. These data demonstrate the benefit of supplemental Ca and vitamin D for maintaining bone health during periods of elevated bone turnover, such as initial military training. This trial was registered with ClincialTrials.gov, NCT01617109.

Lesões musculoesqueléticas em policiais militares

INTRODUÇÃO: As qualidades físicas precisam ser analisadas e estão associadas como fatores de risco a desenvolver lesões musculoesqueléticas durante o treinamento esportivo militar. OBJETIVO: Levantar a epidemiologia das lesões musculoesqueléticas ocorridas em tornozelo e pé de policiais militares. MATERIAIS E MÉTODOS: Foram coletados todos os prontuários de policiais militares que sofreram lesões prévias no tornozelo e pé durante o período de setembro de 2005 a agosto de 2011, as informações foram obtidas através da ficha de avaliação fisioterapêutica constatada nos prontuários, posteriormente os dados obtidos foram tabulados e analisados. RESULTADOS: Após a coleta de dados dos prontuários foi observado que houve 29% de lesões ósseas, 32% de ligamentares e 35% de musculares. CONCLUSÃO: A entorse de tornozelo demonstra um risco à saúde pública como descrita pela classificação estatística internacional de doenças e problemas relacionados à saúde, sendo no meio militar também descrita como um risco durante a prática esportiva.

A prospective study of physical fitness, obesity, and the subsequent risk of mental disorders among healthy young adults in army training

OBJECTIVE

Mental health disorders contribute substantially to medical and occupational morbidity. The role of fitness and physical activity in the prevention of mental health disorders is not well established, but epidemiologic data suggest that physical activity can protect against anxiety and depression.

METHOD

The analyses presented in this report, from a prospective cohort study, evaluate the association between fitness (as measured by a 5-minute step test), and being overweight (defined as exceeding weight and body fat allowances) at military entrance, with subsequent onset of mental disorder diagnosis in the first year of service. The association between risk factors and mental disorder diagnosis was analyzed using multivariate Poisson regression with the adjusted incidence rate ratio (aIRR) as the measure of association.

RESULTS

Among weight-qualified participants, factors associated with increased incidence of mental disorder included failing the physical fitness test (aIRR: 1.36, p<0.0001), female sex (aIRR: 2.17, p<0.0001), and smoking (aIRR: 1.49, p<0.0001). Among fit participants, being overweight was not significantly associated with mental disorder (aIRR: 1.11, p=0.1540).

CONCLUSIONS

This test has potential military utility as an adjunct part of the medical examination process. Additional research is needed among civilians to determine if similar associations exist. If so, intervention studies should be conducted to determine if improving physical fitness reduces subsequent psychiatric disorder risk, particularly among young adults entering into stressful situations.

Self-control is associated with physical activity and fitness among young males

The personality trait self-control has been associated with various adaptive outcomes. The objective of this cross-sectional study was to explore whether self-control is associated with self-reported leisure time physical activity (LTPA), Body Mass Index (BMI), muscle-fitness and aerobic fitness among young men. Participants (482 male conscripts; age M = 20) completed a questionnaire and participated in anthropometric measurements in the DefenceNutri Study, and took standard aerobic fitness and muscle fitness tests as part of their military training. Self-control was found to have a positive association with LTPA, aerobic fitness, and muscle fitness, and a negative association with BMI. Self-control predicted aerobic and muscular fitness regardless of BMI, and remained a significant and independent predictor of aerobic fitness (R² (adj.) = .28, β = .10, p < .05), but not muscle fitness, when LTPA and BMI were controlled for.

Differential effects of military training on fat-free mass and plasma amino acid adaptations in men and women

Fat-free mass (FFM) adaptations to physical training may differ between sexes based on disparities in fitness level, dietary intake, and levels of plasma amino acids (AA). This investigation aimed to determine FFM and plasma AA responses to military training, examine whether adaptations differ between male and female recruits, and explore potential associations between FFM and AA responses to training. Body composition and plasma AA levels were assessed in US Army recruits (n = 209, 118 males, 91 females) before (baseline) and every three weeks during basic combat training (BCT), a 10-week military training course. Body weight decreased in men but remained stable in women during BCT (sex-by-time interaction, P < 0.05). Fifty-eight percent of recruits gained FFM during BCT, with more (P < 0.05) females (88%) gaining FFM than males (36%). Total plasma AA increased (P < 0.05) during BCT, with greater (P < 0.05) increases observed in females (17%) then in males (4%). Essential amino acids (EAA) and branched-chain amino acids (BCAA) were increased (P < 0.05) in females but did not change in males (sex-by-time interaction, P < 0.05). Independent of sex, changes in EAA (r = 0.34) and BCAA (r = 0.27) from baseline were associated with changes in FFM (P < 0.05); greater (P < 0.05) increases in AA concentrations were observed for those who gained FFM. Increases in FFM and plasma AA suggest that BCT elicits a more pronounced anabolic response in women compared to men, which may reflect sex-specific differences in the relative intensity of the combined training and physiological stimulus associated with BCT.

Teste de força/resistência de membros superiores: análise metodológica e dados normativos

INTRODUÇÃO: A força e a resistência muscular são componentes da aptidão física importantes para a saúde e alto rendimento. Os testes de flexão de braços, puxada em suspensão na barra e puxada em suspensão na barra modificada, utilizam o próprio peso corporal e avaliam as capacidades motoras relacionadas à aptidão física, saúde e ao desempenho atlético, no sentido de mensurar a força e resistência muscular dos membros superiores em ambos os sexos e ampla faixa etária. OBJETIVOS: O objetivo deste estudo foi buscar na literatura os aspectos metodológicos relacionados à validade, fidedignidade, objetividade e procedimentos específicos utilizados nos testes: flexão de braços, puxada suspensão na barra e puxada em suspensão na barra modificada, fazendo, dessa forma, um levantamento dos indicadores de rendimento desses testes em atletas de alto nível de diferentes modalidades. CONCLUSÃO: Os testes de flexão de braços, puxada em suspensão na barra e puxada em suspensão na barra modificada são eficientes, confiáveis, de fácil aplicação e são ferramentas que empregam baixo custo, além de requererem pouco treinamento do avaliador. Entretanto, devemos chamar a atenção quanto à padronização e as recomendações metodológicas para suas aplicações, para que possam ser utilizados com segurança na reabilitação e no desempenho atlético.

Cardiometabolic risk in US Army recruits and the effects of basic combat training

BACKGROUND

Cardiometabolic disease risk in US military recruits and the effects of military training have not been determined. This study examined lifestyle factors and biomarkers associated with cardiometabolic risk in US Army recruits (209; 118 male, 91 female, 23 ± 5 yr) before, during, and after basic combat training (BCT).

METHODOLOGY/PRINCIPAL FINDINGS

Anthropometrics; fasting total (TC), high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol; triglycerides (TG); glucose; and insulin were measured at baseline and every 3 wks during the 10 wk BCT course. At baseline, 14% of recruits were obese (BMI>30 kg/m(2)), 27% were cigarette smokers, 37% were sedentary, and 34% reported a family history of cardiometabolic disease. TC was above recommended levels in 8%, LDL in 39%, TG in 5%, and glucose in 8% of recruits, and HDL was below recommended levels in 33% of recruits at baseline. By week 9, TC decreased 8%, LDL 10%, TG 13%, glucose 6% and homeostasis model assessment of insulin resistance (HOMA-IR) 40% in men (P<0.05). In women, TC, LDL, glucose and HOMA-IR were decreased from baseline at weeks 3 and 6 (P<0.05), but were not different from baseline levels at week 9. During BCT, body weight declined in men but not women, while body fat percentage declined in both men and women (P<0.05).

CONCLUSIONS/SIGNIFICANCE

At the start of military service, the prevalence of cardiometabolic risk in US military recruits is comparable to that reported in similar, college-aged populations. Military training appears to be an effective strategy that may mitigate risk in young people through improvements in lipid profiles and glycemic control.

Retrospective examination of injuries and physical fitness during Federal Bureau of Investigation new agent training

Background

A retrospective examination was conducted of injuries, physical fitness, and their association among Federal Bureau of Investigation (FBI) new agent trainees.

Methods

Injuries and activities associated with injuries were obtained from a review of medical records in the medical clinic that served the new agents. A physical fitness test (PFT) was administered at Weeks 1, 7 and 14 of the 17-week new agent training course. The PFT consisted of push-ups, sit-ups, pull-ups, a 300-meter sprint, and a 1.5-mile run. Injury data were available from 2000 to 2008 and fitness data were available from 2004 to early 2009.

Results

During the survey period, 37% of men and 44% of women experienced one or more injuries during the new agent training course (risk ratio (women/men) = 1.18, 95% confidence interval = 1.07-1.31). The most common injury diagnoses were musculoskeletal pain (not otherwise specified) (27%), strains (11%), sprains (10%), contusions (9%), and abrasions/lacerations (9%). Activities associated with injury included defensive tactics training (48%), physical fitness training (26%), physical fitness testing (6%), and firearms training (6%). Over a 6-year period, there was little difference in performance of push-ups, sit-ups, pull-ups, or the 300-meter sprint; 1.5-mile run performance was higher in recent years. Among both men and women, higher injury incidence was associated with lower performance on any of the physical fitness measures.

Conclusion

This investigation documented injury diagnoses, activities associated with injury, and changes in physical fitness, and demonstrated that higher levels of physical fitness were associated with lower injury risk.

One in four people may develop symptomatic hip osteoarthritis in his or her lifetime

OBJECTIVE

To estimate the lifetime risk of symptomatic hip osteoarthritis (OA).

DESIGN

We analyzed data from the Johnston County Osteoarthritis Project [a longitudinal population-based study of OA in North Carolina, United States (n=3068)]. The weighted baseline sample comprised 18% blacks and 54% women, and the mean age was 63 years (range=45-93). Symptomatic hip OA was defined as a Kellgren-Lawrence (K-L) radiographic score of ≥ 2 (anterior-posterior pelvis X-rays) and pain, aching or stiffness on most days, or groin pain, in the same hip. Lifetime risk, defined as the proportion who developed symptomatic hip OA in at least one hip by age 85, among people who live to age 85, was modeled using logistic regression with repeated measures (through generalized estimating equations).

RESULTS

Lifetime risk of symptomatic hip OA was 25.3% [95% confidence interval (CI)=21.3-29.3]. Lifetime risk was similar by sex, race, highest educational attainment, and hip injury history. We studied lifetime risk by body mass index (BMI) in three forms: at age 18; at baseline and follow-up; and at age 18, baseline and follow-up and found no differences in estimates.

CONCLUSION

The burden of symptomatic hip OA is substantial with one in four people developing this condition by age 85. The similar race-specific estimates suggest that racial disparities in total hip replacements are not attributable to differences in disease occurrence. Despite increasing evidence that obesity predicts an increased risk of both hip OA and joint replacement, we found no association between BMI and lifetime risk.

Secular changes in body dimensions of Royal Australian Air Force aircrew (1971-2005)

The aim of this study was to quantify the secular changes in body dimensions of Royal Australian Air Force aircrew. Following corrections for methodological differences, two samples (matched for age and overall body size) of male aircrew measured in 1971 (n = 220) and 2005 (n = 220) were compared across 13 absolute and proportional body dimensions. Changes in means were expressed as standardised effect sizes and changes in distributional characteristics were expressed as the ratio of coefficients of variation and as changes in skew. Small secular increases (standardised effects sizes >0.2) in age-matched aircrew were observed for mass, height, BMI, sitting height, buttock-knee length, waist girth, hip girth and waist:hip ratio, with a small decline observed for head girth. Changes in body dimensions were not independent of changes in overall body size (except for head girth) and were not always uniform across the distribution. These changes in body size have implications for ensuring correct human-machine and human-equipment fit. STATEMENT OF RELEVANCE: There have been small secular changes in body dimensions of RAAF aircrew between 1971 and 2005, although these secular changes have not always been uniform across the distribution. These secular changes in body dimensions have implications for ensuring correct human-machine and human-equipment fit and underscore the need for regular anthropometric surveys.

Randomized, double-blind, placebo-controlled trial of an iron-fortified food product in female soldiers during military training: relations between iron status, serum hepcidin, and inflammation

BACKGROUND

Iron status degrades in female soldiers during military training. Inflammation-mediated up-regulation of hepcidin, a key mediator of iron homeostasis, may be a contributing factor.

OBJECTIVE

We measured the efficacy of an iron-fortified food product for maintaining iron status in female soldiers during basic combat training (BCT) and examined relations between iron status, serum hepcidin concentrations, and inflammation.

DESIGN

A randomized, double-blind, placebo-controlled trial was conducted. Volunteers received an iron-fortified food product (total dose = 56 mg Fe/d) or a placebo twice daily during the 9-wk BCT course. Iron-status indicators, serum hepcidin concentrations, and markers of inflammation were measured pre- and post-BCT.

RESULTS

BCT affected iron status; serum ferritin concentrations decreased (P < or = 0.05), and concentrations of soluble transferrin receptor (sTfR) and hemoglobin and the red cell distribution width increased (P < or = 0.05). Consumption of the iron-fortified food product attenuated declines in iron status in iron-deficient anemic soldiers; a group-by-time interaction was observed for hemoglobin and sTfR concentrations (P < or = 0.05). Serum hepcidin concentrations were not affected by BCT; however, hepcidin concentrations were lower in iron-deficient anemic soldiers than in those with normal iron status (P < or = 0.05) and were positively associated with serum ferritin (P < or = 0.05) and C-reactive protein (P < or = 0.05) concentrations pre- and post-BCT.

CONCLUSIONS

Twice-daily consumption of an iron-fortified food product improved iron status in iron-deficient anemic soldiers but not in iron-normal or iron-deficient nonanemic soldiers. Serum hepcidin concentrations were not affected by training but were associated with iron status and inflammation pre- and post-BCT. This trial was registered at clinicaltrials.gov as NCT01100905.

Outcomes of highly active antiretroviral therapy in the context of universal access to healthcare: the U.S. Military HIV Natural History Study

Background

To examine the outcomes of highly-active antiretroviral therapy (HAART) for individuals with free access to healthcare, we evaluated 2327 patients in a cohort study composed of military personnel and beneficiaries with HIV infection who initiated HAART from 1996 to the end of 2007.

Methods

Outcomes analyzed were virologic suppression (VS) and failure (VF), CD4 count changes, AIDS and death. VF was defined as never suppressing or having at least one rebound event. Multivariate (MV) analyses stratified by the HAART initiation year (before or after 2000) were performed to identify risk factors associated with these outcomes.

Results

Among patients who started HAART after 2000, 81% had VS at 1 year (N = 1,759), 85% at 5 years (N = 1,061), and 82% at 8 years (N = 735). Five years post-HAART, the median CD4 increase was 247 cells/ml and 34% experienced VF. AIDS and mortality rates at 5 years were 2% and 0.3%, respectively. In a MV model adjusted for known risk factors associated with treatment response, being on active duty (versus retired) at HAART initiation was associated with a decreased risk of AIDS (HR = 0.6, 95% CI 0.4-1.0) and mortality (0.6, 0.3-0.9), an increased probability of CD4 increase ≥ 50% (1.2, 1.0-1.4), but was not significant for VF.

Conclusions

In this observational cohort, VS rates approach those described in clinical trials. Initiating HAART on active duty was associated with even better outcomes. These findings support the notion that free access to healthcare likely improves the response to HAART thereby reducing HIV-related morbidity and mortality.

Effect on injuries of assigning shoes based on foot shape in air force basic training

BACKGROUND

This study examined whether assigning running shoes based on the shape of the bottom of the foot (plantar surface) influenced injury risk in Air Force Basic Military Training (BMT) and examined risk factors for injury in BMT.

METHODS

Data were collected from BMT recruits during 2007; analysis took place during 2008. After foot examinations, recruits were randomly consigned to either an experimental group (E, n=1042 men, 375 women) or a control group (C, n=913 men, 346 women). Experimental group recruits were assigned motion control, stability, or cushioned shoes for plantar shapes indicative of low, medium, or high arches, respectively. Control group recruits received a stability shoe regardless of plantar shape. Injuries during BMT were determined from outpatient visits provided from the Defense Medical Surveillance System. Other injury risk factors (fitness, smoking, physical activity, prior injury, menstrual history, and demographics) were obtained from a questionnaire, existing databases, or BMT units.

RESULTS

Multivariate Cox regression controlling for other risk factors showed little difference in injury risk between the groups among men (hazard ratio [E/C]=1.11, 95% CI=0.89-1.38) or women (hazard ratio [E/C]=1.20, 95% CI= 0.90-1.60). Independent injury risk factors among both men and women included low aerobic fitness and cigarette smoking.

CONCLUSIONS

This prospective study demonstrated that assigning running shoes based on the shape of the plantar surface had little influence on injury risk in BMT even after controlling for other injury risk factors.

Optimizing exercise outcomes: the efficacy of resistance training using conventional vs. novel movement arcs

The purpose of this study was to examine the effect of using multidirectional movement arcs in a resistance training program for the shoulder. It was hypothesized that multidirectional exercises performed against resistance would result in a greater positive adaptation of the muscle tissue than conventional movement patterns commonly used in strength training. Fourteen female athletes were initially assessed using a 1x repetition maximum (1xRM) test for shoulder flexion and shoulder abduction (dominant and nondominant arm). After randomization into 2 groups, subjects engaged in different strength training programs against Thera-Band resistance for 6 weeks. Follow-up testing was then completed. Group A was assigned a strength training program that used conventional curvilinear movement arcs. Group B completed resistance training that comprised multidirectional exercises. Both the conventional and novel strength training programs induced improvements in the 1x RM test (p < 0.01). There was a trend toward greater improvements in the nonconventional training group, but this was statistically insignificant. This suggests that varying the axial or torsional loading of muscle fibers during strength training may confer further benefit to conventional methods of training variation. Consequently, further studies are indicated to investigate if resistance training that incorporates multidirectional movement arcs is more effective than those used in conventional strength training programs. This may have implications on the design of future training programs that aim to optimize strength gains.

[Anthropometry and cardiorespiratory fitness of military men in active duty, Brazil]

OBJECTIVE

To analyze differences in body mass index (BMI) and waist circumference according to cardiorespiratory fitness in active military men.

METHODS

The study sample comprised 50,523 active military men of the Brazilian army. Anthropometric measures (body mass, height, and waist circumference) and maximal oxygen consumption (VO2max) information, estimated in a 12-min run, were obtained in a fitness test in 2001.

RESULTS

Subjects' age ranged between 18 and 52 years, but most were young (mean+/-SD 25.8+/-6.6 years). Cardiorespiratory fitness varied from 22.2 to 82.5 mL.O2.kg(-1).min(-1). Waist circumference mean values were significantly lower in those subjects in the highest fitness level compared to those in the lowest level (p<0.001) even after adjusting for age, BMI, and both together.

CONCLUSIONS

For the same BMI, military men with better cardiorespiratory fitness have significantly lower waist circumference measures compared to those with lower fitness. These findings suggest that military with better physical fitness have lower abdominal fat accumulation.

Assessment of male anthropometric trends and the effects on simulated heat stress responses

Assessing temporal changes in anthropometrics and body composition of US Army soldiers is important because these changes may affect fitness, performance, and safety. This study investigated differences in body dimensions (height, weight, percent body fat (%BF)) of US Army male soldiers by comparing 2004 and 1988 databases. Anthropometric somatotypes were identified and physiological responses of the different somatotypes to simulated heat stress (35 degrees C/50%rh, approximately 550 W work rate, carrying 12 kg load including battle dress uniform and body armor, rest for 30 min and walk for 70 min) using a thermal regulatory model were evaluated. A significant increase in body weight (2.4 kg) was observed between the 2004 and 1988 data (P < 0.05, after Bonferroni correction). However, changes in height and circumference measurements for %BF were insignificant, with the magnitude of the changes not exceeding inter-observer errors. Multivariate analyses demonstrated that anthropometric distributions did not differ between the two databases and identified five primary somatotypes: "tall-fat", "tall-lean", "average", "short-lean", and "short-fat." Within each database, anthropometric values differed among the somatotypes. However, simulated physiological responses to heat stress in each somatotype were similar in the 2004 and 1988 populations. In conclusion, an increase in body weight was the primary change observed in this sample of US Army male soldiers. Temporal changes in somatotypes of soldiers over a 16-year period had minimal impact on simulated physiological response to heat stress using a thermal regulatory model.

Transmissibility of swine flu at Fort Dix, 1976

The 1976 outbreak of A/New Jersey/76 influenza in Fort Dix is a rare example of an influenza virus with documented human to human transmission that failed to spread widely. Despite extensive epidemiological investigation, no attempt has been made to quantify the transmissibility of this virus. The World Health Organization and the United States Government view containment of emerging influenza strains as central to combating pandemic influenza. Computational models predict that it may be possible to contain an emergent pandemic influenza if virus transmissibility is low. The A/New Jersey/76 outbreak at the United States Army Training Center at Fort Dix, New Jersey in January 1976 caused 13 hospitalizations, 1 death and an estimated 230 cases. To characterize viral transmission in this epidemic, we estimated the basic reproductive number and serial interval using deterministic epidemic models and stochastic simulations. We estimated the basic reproductive number for this outbreak to be 1.2 (supported interval 1.1-1.4), the serial interval to be 1.9 days (supported interval 1.6-3.8 days), and that the virus had at least six serial human to human transmissions. This places the transmissibility of A/New Jersey/76 virus at the lower end of circulating flu strains, well below the threshold for control.