The Medical Burden of Obesity and Overweight in the US Military: Association of BMI with Clinically Diagnosed Medical Conditions in United States Military Service Members

BACKGROUND

A high BMI is associated with various medical conditions, notably type 2 diabetes, cardiovascular disease, and mental health disorders. In the US military, BMI increased linearly between 1975 and 2015.

OBJECTIVE

This cross-sectional study investigated the associations between BMI and a comprehensive range of clinically diagnosed medical conditions (CDMCs) in US military service members (SMs).

METHODS

A stratified random sample of SMs (n=26,177) completed an online questionnaire reporting their height, weight, and demographic/lifestyle characteristics. Medical conditions for 6 mo before questionnaire completion were obtained from a comprehensive military electronic medical surveillance system and grouped into 39 CDMCs covering both broad (largely systemic) and specific medical conditions. BMI was calculated as weight/height2 (kg/m2). The prevalence of CDMCs was compared among normal weight (<25.0 kg/m2), overweight (25.0-29.9 kg/m2), and obese (≥30 kg/m2) SMs.

RESULTS

After multivariable adjustment for demographic/lifestyle characteristics, higher BMI was associated with higher odds of a diagnosed medical condition in 30 of 39 CDMCs, with all 30 displaying dose-response relationships. The 5 major CDMCs with the largest odds ratios comparing obese to normal weight were endocrine/nutritional/metabolic diseases (OR=2.67, 95%CI=2.24-3.15), nervous system diseases (odds ratio [OR]=2.59, 95%CI=2.32-2.90), circulatory system diseases (OR=2.56, 95%CI=2.15-3.06), musculoskeletal system diseases (OR=1.92, 95%CI=1.76-2.09), and mental/behavioral disorders (OR=1.69, 95%CI=1.51-1.90). Compared with normal weight SMs, overweight or obese SMs had a higher number of CDMCs (1.8±1.9 vs. 2.0±2.0 and 2.5±2.3, mean ± standard deviation, respectively, P<0.01).

CONCLUSIONS

In a young, physically active population, higher BMI was associated with a host of medical conditions, even after adjustment for demographic/lifestyle characteristics. The US Department of Defense should improve nutrition education and modify other factors that contribute to overweight and obesity. This study demonstrates that the medical burden of obesity is substantial in overweight and obese SMs.

Total Force Fitness: Making Holistic, Integrated Whole-Person Research a DoD Priority

Total Force Fitness (TFF) was conceived as a holistic framework for building and sustaining Human Performance Optimization for Warfighters and their families. As such, TFF research must also be holistic in nature. During the research breakout, group barriers and challenges to TFF research were discussed, and critical research focus areas were prioritized. The top approaches discussed were (1) using big data to identify best practices and health trajectories; (2) applying community-based participatory research principles to military units; (3) focusing on "Whole-Person," integrative research (physical, behavioral, spiritual, and biological) across the Department of Defense; and, finally, (4) prioritizing key opportunities to advance TFF across the active duty and Reserve/Guard enterprises and their families. The research group noted that coordinated action would be needed to move the prioritized agenda forward. Finally, translating research into action is essential because TFF is a way of honoring our service members as whole persons with careers, goals, and families.

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.

Under Pressure: The Chronic Effects of Lower-Body Compression Garment Use during a 6-Week Military Training Course

Background: Previous studies have shown that compression garments may aid recovery in acute settings; however, less is known about the long-term use of compression garments (CG) for recovery. This study aimed to assess the influence of wearing CG on changes in physical performance, subjective soreness, and sleep quality over 6 weeks of military training. Methods: Fifty-five officer-trainees aged 24 ± 6 y from the New Zealand Defence Force participated in the current study. Twenty-seven participants wore CG every evening for 4−6 h, and twenty-eight wore standard military attire (CON) over a 6-week period. Subjective questionnaires (soreness and sleep quality) were completed weekly, and 2.4 km run time-trial, maximum press-ups, and curl-ups were tested before and after the 6 weeks of military training. Results: Repeated measures ANOVA indicated no significant group × time interactions for performance measures (p > 0.05). However, there were small effects in favour of CG over CON for improvements in 2.4 km run times (d = −0.24) and press-ups (d = 0.36), respectively. Subjective soreness also resulted in no significant group × time interaction but displayed small to moderate effects for reduced soreness in favour of CG. Conclusions: Though not statistically significant, CG provided small to moderate benefits to muscle-soreness and small benefits to aspects of physical-performance over a 6-week military training regime.

Cluster size prediction for military clothing using 3D body scan data

AIM

To determine how anthropometric characteristics cluster in the New Zealand Defence Force, and to describe the characteristics of each cluster. This information can inform the development of new uniform sizing systems for the New Zealand Defence Force.

METHODS

Anthropometric data (n = 84 variables) from 1,003 participants (212 females; 791 males) in the New Zealand Defence Force Anthropometry Survey (NZDFAS) were used. The dataset was stratified by gender and variables isolated based on their relevance to shirt and trouser sizing. Principal Component Analysis was used to identify the most important variables for clustering. A combination of two-step and k-means clustering was used to derive cluster characteristics.

RESULTS

The PCA identified optimal clothing (shirt = body height and waist girth; and trouser = inseam length and hip girth for females; inseam length and waist girth for males) variables. Two-step and k-means clustering identified optimal cluster numbers of 6 and 10 for female and male clothing, respectively. The female clothing clusters were more variable (intra-cluster) and further apart (inter-cluster) compared to males.

CONCLUSIONS

Anthropometric measurements in combination with clustering techniques show promise for partitioning individuals into distinct groups. The anthropometry dimensions associated with each cluster can be used by the garment industry to develop specific sizing systems for the New Zealand Defence Force population.

Prediction of military combat clothing size using decision trees and 3D body scan data

AIM

To determine how well decision tree models can predict tailor-assigned uniform sizes using anthropometry data from the New Zealand Defence Force Anthropometry Survey (NZDFAS). This information may inform automatic sizing systems for military personnel.

METHODS

Anthropometric data from two separate samples of the New Zealand Defence Force military were used. Data on Army personnel from the NZDFAS (n = 583) were used to develop a series of shirt- and trouser-size prediction models based on decision trees. Different combinations of physical, automatic, and post-processed measurements (the latter two derived from a 3D body scan) were trialled, and the models with the highest cross-validation accuracy were retained. The accuracy of these models were then tested on an independent sample of Army recruits (n = 154).

RESULTS

The automated measurement method (measurements derived automatically by the body scanner software) were the best predictors of shirt size (58.1% accuracy) and trouser size (61.7%), with body weight and waist girth being the strongest predictors. Clothing sizes that were incorrectly predicted by the model where generally one size above or below the tailor-predicted size.

CONCLUSIONS

Anthropometry measurements, when used with decision tree models, show promise for classifying clothing size. Methodological changes such as fitting gender-specific models, using additional anthropometry variables, and testing other data mining techniques are avenues for future work. More research is required before fully automated body scanning is a viable option for obtaining fast and accurate clothing sizes for military clothing and logistics departments.

Effects of modern military backpack loads on walking speed and cardiometabolic responses of US Army Soldiers

INTRODUCTION

Military leaders must understand how modern military equipment loads affect trade-offs between movement speed and physiological strain to optimize pacing strategies.

PURPOSE

To evaluate the effects of load carried in a recently developed military backpack on the walking speed and cardiometabolic responses of dismounted warfighters.

METHODS

Fifteen soldiers (1 woman, 14 men; age, 22 ± 2 years; height, 173 ± 7 cm; body mass (BM), 73 ± 10 kg) completed incremental walking tests with four external load conditions (0, 22, 44, or 66% BM) using the US Army's newest backpack: the Modular Lightweight Load-Carrying Equipment 4000 (MOLLE 4000). Oxygen uptake (V̇O₂) and heart rate (HR) were evaluated relative to maximal values (V̇O_2max and HR_max respectively). Testing ceased when participants completed the highest tested speed (1.97 m s^-1), exceeded a respiratory exchange ratio (RER) of 1.00, or reached volitional exhaustion.

RESULTS

Peak speed significantly decreased (p < 0.03) with successively heavier loads (0% BM, 1.95 ± 0.06 m s^-1; 22% BM, 1.87 ± 0.10 m s^-1; 44% BM, 1.69 ± 0.13 m s^-1; 66% BM, 1.48 ± 0.13 m s^-1). Peak V̇O₂ was significantly lower (p < 0.01) with 0% BM (47 ± 5% V̇O_2max) than each load (22% BM, 58 ± 8% V̇O_2max; 44% BM, 63 ± 10% V̇O_2max; 66% BM, 61 ± 11% V̇O_2max). Peak HR was significantly lower (p < 0.01) with 0% BM (71 ± 5% HR_max) versus each load (22% BM, 83 ± 6% HR_max; 44% BM, 87 ± 6% HR_max; 66% BM, 88 ± 6% HR_max).

CONCLUSION

Overburdened warfighters suffer severe impairments in walking speed even when carrying recently developed military load carriage equipment. Our results suggest that the relative work intensity of heavy load carriage may be better described when expressed relative to HR_max versus V̇O_2max.

Trends in cardiorespiratory fitness among apparently healthy adults from the Ball State Adult Fitness Longitudinal Lifestyle STudy (BALL ST) cohort from 1970-2019

Introduction

Cardiorespiratory fitness (CRF) is a strong independent predictor of cardiovascular disease (CVD) and CVD mortality. However, little is known in regards to how CRF has trended in apparently healthy adults over the past several decades.

Purpose

To analyze trends in CRF and CVD risk factors over the last 50 years in a population of apparently healthy adult men and women.

Methods

Participants were 4,214 apparently healthy adults (2,390 men and 1,824 women) from the Ball State Adult Fitness Longitudinal Lifestyle STudy (BALL ST) that performed maximal cardiopulmonary exercise testing between 1970–2019 for the assessment of CRF defined as VO_2max (ml/kg/min). Participants were self-referred either to a community-based exercise program, fitness testing, or were research subjects in exercise related studies and were placed into groups by decade based on testing date.

Results

CRF showed a general trend to decline (P<0.05) from the 1970s to the 2000s with an increase (P<0.05) from the 2000s to the 2010s for both men and women. This pattern persisted for age and sex-adjusted CRF level, determined by Fitness Registry and the Importance of Exercise: A National Data Base (FRIEND). For both women and men, CRF across the decades was associated (P<0.05) with the prevalence of physical inactivity, smoking, obesity, dyslipidemia and hypertension, and with diabetes in men only.

Conclusion

CRF declined from 1970 through the 2000s in a cohort of apparently healthy men and women which was associated with worsening CVD risk profiles. However, the decline in CRF was attenuated over the past decade which may have a positive impact on future CVD in the population. Promoting physical activity to increase CRF should be a primary aspect of CVD prevention programs.

Effects of Task-Specific and Strength Training on Simulated Military Task Performance in Soldiers

A soldier’s occupational physical task requirements are diverse and varied. However, the type of physical training that most effectively improves soldiers’ occupational task requirements has not been studied previously. The purpose of this study was to determine the important strength characteristics for soldiers during a repeated simulated military task course, and the type of training that may be effective to improve these abilities during a specialized military training period. Forty-two (n = 42) soldiers participated in the study. They were divided into three training groups; a soldier task-specific training group (TSG, n = 17), a strength training group (STG, n = 15), and a control group (CON, n = 10). Participants were measured before (PRE), middle (MID) and after (POST) the 12-week training intervention for strength performance and simulated military task test. Simulated military task performance improved significantly in TSG and STG between the PRE and MID measurements (from 9.4 to 15.7%). TSG and STG improved in various spilt times, especially in strength tasks; casualty drag (from 8.3 to 13.6%) and kettlebell carry (from 13.2 to 22.4%) between the PRE and MID measurements. The present study showed that both the training of TSG and STG were more effective than the training of CON (control group) in terms of improving the performance in the repeated simulated military task course. The present study showed that training of TSG was as effective as STG to improve repeated simulated military task course time. Therefore, an optimal training combination should include high-intensity simulated military task field training and strength training programmed with consideration of the military training phase and environmental possibilities.

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.

Dietary Intake, Hydration Status, and Body Composition of Three Belgian Military Groups

Introduction

Malnutrition, suboptimal hydration, and inadequate body composition can have negative consequences on soldiers’ performance and health. A recent consensus statement concerning “soldiers’ physical performance” points to the scarcity of data in specific military populations. Therefore, the aim of the present study was to assess and compare dietary intake, hydration status, and body composition of three military groups during their specific military training.

Materials and Methods

Eighty-five soldiers (ie, 21 in a qualification course to join the Special Forces [SF], 22 Infantrymen [Chasseurs Ardennais, CA], and 42 Recruits [REs]) participated in this 3- to 4-day study. Body mass was assessed before and after each study period. All soldiers self-reported their dietary intakes, from which energy and macronutrient intakes were calculated. In addition, their morning urine samples were collected daily to assess urine specific gravity (USG) as a measure of hydration status. Fat mass was estimated at the end of the study using bioelectrical impedance analysis.

Results

All groups lost significant amounts of body mass (ie, mean losses ranging between 1.3 and 1.7 kg). Macronutrient intakes were not fully met in respect to the recommendations. Most notably, REs’ fat intake was high (ie, 42.3 [±1.6] energy percent [E%]), while their carbohydrate intake was low (ie, 44.5 [±2.1] E%). Furthermore, saturated fat intakes were high among all groups (ie, group means ranging between 13.6 and 21.4 E%). USG values indicated suboptimal hydration status was prevalent in all groups. Most noteworthy, for SF, only 5.4% of the USG values indicated optimal hydration. The average fat mass (%) for SF, CA, and RE was 11.2 (±3.1), 18.8 (±5.1), and 19.4 (±5.0), respectively.

Conclusion

The present study showed that military men are not always adequately fed nor hydrated. These issues should be resolved by creating nutritional packages, and individual dietary and hydration strategies, all in function of military planning and weather conditions.