Occupational Experience Effects on Physiological and Perceptual Responses of Common Soldiering Tasks.

ABSTRACT: Cohen BS, Redmond JE, Haven CC, Foulis SA, Canino MC, Frykman PN, Sharp MA. Occupational Experience Effects on Physiological and Perceptual Responses of Common Soldiering Tasks. J Strength Cond Res 37(4): 894-901, 2023-This study measured the impact of occupational experience (i.e., time spent deployed, in military service, and in job and task performance frequency in training, deployment, and study practice) on the physiological (heart rate [HR] and oxygen consumption [VO 2 ]) and perceptual (rate of perceived exertion [RPE]) responses to performance of critical physically demanding tasks (CPDTs). Five CPDTs (road march, build a fighting position, move under fire, evacuate a casualty, and drag a casualty to safety), common to all soldiers, were performed by 237 active duty soldiers. Linear regression models examined the association between measures of experience and physiological and perceptual performance responses to task demands. The level of significance was adjusted for multiple comparisons and set at ρ ≤ 0.0125 for this study. Significant and notable effect sizes included the impact of time spent deployed on the physiological measures of the road march (PostHR F = 24.84, p < 0.0001, ß=-9.65), sandbag fill (PostHR F = 8.26, p = 0.005, ß = -2.83), and sandbag carry (MeanHR F = 7.51, p = 0.007, ß = -1.12; PostHR F = 7.35, p = 0.007, ß = -0.87). For the road march task, there was a nearly 10 bpm decrease in postperformance HR for every year spent deployed. Road march, sandbag fill, and sandbag carry tasks PostHRs were also notably negatively associated with the experience measures of time in their MOS (job and time in military service but not for other physiological and perceptual responses, including VO 2 and RPE. Frequency of task performance in training, deployment, and study practice was not meaningfully associated with experience. The results suggest that increasing task familiarization through on-the-job occupational operational experience may result in greater proficiency and reduced physiological effort.

Revalidating U.S. Army soldiers' perceptions of combat arms job tasks: Frequencies, importance and expectations of performance.

BACKGROUND: In 2013 the U.S. Army began developing physical tests to predict a recruit's ability to perform the critical physically demanding tasks (CPDTs) of combat arms jobs not previously open to women. OBJECTIVE: To revalidate 15 CPDTs chosen by subject matter experts (SMEs) and researchers through questionnaires pertaining to task performance frequency, perceived importance, and performance expectations. METHOD: Web-administered job analysis questionnaires were completed by 2,090 soldiers. Seventy-three percent ranged between 25-38 years of age, 66%were staff sergeants or above, and 73%were in service for 7 + years. RESULTS: Overall, the nine SME-endorsed CPDTs were conducted more frequently and rated as more important than the six tasks identified by researchers. Foot march, dragging a casualty to safety, and connecting a tow bar (vehicle transport) were identified as the combined most important, most frequently performed and highly expected CPDTs to be performed. The canonical correlation between task performance frequencies and ratings of task importance across all 15 CPDTs was 0.82 (p < 0.001). Expectations of task completion were strongly associated with more frequent task performance (Cramer's Vs ranged 0.22 to 0.71; all p's < 0.001), but not task importance (only four CPDTs at p < 0.05). CONCLUSION: This study revalidates the value of CPDTs chosen by SMEs and researchers. Soldier readiness should reflect tasks identified by incumbents as important to success (e.g., evacuating a casualty) be trained more often, whereas others classified as frequently performed, but less important (e.g., filling sandbags), be deemphasized while ensuring that standards are met.

Maintaining Physical Performance: The Minimal Dose of Exercise Needed to Preserve Endurance and Strength Over Time.

ABSTRACT: Maintaining physical performance: the minimal dose of exercise needed to preserve endurance and strength over time, Spiering, BA, Mujika, I, Sharp, MA, and Foulis, SA. J Strength Cond Res 35(5): 1449-1458, 2021-Nearly every physically active person encounters periods in which the time available for exercise is limited (e.g., personal, family, or business conflicts). During such periods, the goal of physical training may be to simply maintain (rather than improve) physical performance. Similarly, certain special populations may desire to maintain performance for prolonged periods, namely athletes (during the competitive season and off-season) and military personnel (during deployment). The primary purpose of this brief, narrative review is to identify the minimal dose of exercise (i.e., frequency, volume, and intensity) needed to maintain physical performance over time. In general populations, endurance performance can be maintained for up to 15 weeks when training frequency is reduced to as little as 2 sessions per week or when exercise volume is reduced by 33-66% (as low as 13-26 minutes per session), as long as exercise intensity (exercising heart rate) is maintained. Strength and muscle size (at least in younger populations) can be maintained for up to 32 weeks with as little as 1 session of strength training per week and 1 set per exercise, as long as exercise intensity (relative load) is maintained; whereas, in older populations, maintaining muscle size may require up to 2 sessions per week and 2-3 sets per exercise, while maintaining exercise intensity. Insufficient data exists to make specific recommendations for athletes or military personnel. Our primary conclusion is that exercise intensity seems to be the key variable for maintaining physical performance over time, despite relatively large reductions in exercise frequency and volume.

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

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

Relationship of Anthropometric Measures on Female Trainees' and Active Duty Soldiers' Performance of Common Soldiering Tasks.

INTRODUCTION: This study compared the relationship between height (HT), body mass (BM), and body mass index (BMI) of female trainees and active duty female soldiers and their performance on simulated common soldiering tasks (CSTs) with high physical demands. METHODS: Female trainees (n = 133) and soldiers (n = 229) completed the following CSTs: sandbag carry, move under fire, casualty drag, casualty evacuation, and road march. Quartiles were created among HT, BM, and BMI by which task performance was compared using ANOVAs with Tukey post hoc comparisons. RESULTS: For both trainees and soldiers, HT, BM, and BMI were positively associated with improved road march, casualty drag, casualty evacuation, and sandbag carry performance. On the move under fire task, only soldier HT was positively associated with improved performance. CONCLUSION: Female trainees and soldiers who are taller and heavier with a higher BMI may demonstrate better performance on CSTs required of all soldiers. In addition to task-specific training, performance of CSTs may be enhanced in tasks requiring strength and power by recruiting and retaining taller and heavier females with a higher BMIs. Allowances should be considered for soldiers and trainees who can successfully perform soldiering tasks with high physical demands despite less desirable anthropometric measurements.

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

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

A database of predictor test sex bias for development of military physical employment standards.

BACKGROUND: Hesitation to employ females for physically demanding jobs is often due to sex related physical abilities. A physical employment standard (PES) identifies individuals who are physically capable for work. OBJECTIVE: A database containing 300 + sources of physical performance tests (PFTs) will inform potential sex bias for PES development. METHODS: Weighted means and probability density curves illustrate the percentage overlap between male and female performance on PFT data from the armed forces of 11 countries and the open literature. Where female training data were available, the change in percentage overlap illustrates the potential for reduction in sex-related differences. RESULTS: PFTs demonstrating the extremes of sex disparity were bench press (11 sources) and sit-ups (14 sources) with 9% and 93% overlap in performance, respectively. Training for bench press; pull ups; VO2max; and upright pull improved female performance by 12%, 22%, 35%, and 23% respectively. This translated into narrowing the gap between male and female mean performance by 1%, 4%, 5%, and 10% respectively. CONCLUSIONS: The ability of PFT to predict performance is essential; however, PFTs with more overlap will facilitate development of PES with reduced sex bias. PFTs with the greatest potential for improvement in females are identified here.

U.S. Army physical demands study: Accuracy of occupational physical assessment test classifications for combat arms soldiers.

BACKGROUND: Beginning in 2017, successfully passing the four-part pre-enlistment Occupational Physical Assessment Test (OPAT) became a requirement for all U.S. Army recruits. To ensure the test accurately identifies individuals who are qualified for their job, it was necessary to examine classification errors. OBJECTIVE: The objectives were to 1) determine the accuracy of OPAT cut-scores for combat arms Soldiers, and 2) determine which events contribute to the individuals that are misclassified as passing or failing the OPATMETHODS:A total of 741 trainees were tested on the OPAT within two weeks of entering their initial entry training. At the end of their training, trainees were tested on simulations of the most physically demanding tasks of their job. RESULTS: There was a high classification concordance (76.5%) between success on the OPAT and job task simulations. False positives (6.7%) were misclassified because they did not perform as well on the strength-dominant task simulations. While the interval aerobic run was the greatest contributor to false negatives (16.8%), previous studies indicated high performance on this event as a potential key indicator of injury and attrition risk. CONCLUSIONS: The findings provide insight on how the accuracy of the OPAT, and similar pre-employment tests, could be improved.

Effectiveness of Mouthguards for the Prevention of Orofacial Injuries and Concussions in Sports: Systematic Review and Meta-Analysis.

BACKGROUND: Sport activities can account for up to one-third of all orofacial injuries. Mouthguards (MGs) have been proposed as a way to reduce these injuries. OBJECTIVES: To present a systematic review and meta-analysis of the effectiveness of MGs for the prevention of sports-related orofacial injuries and concussions. METHODS: Using specific search terms, PubMed, Ovid Embase, and the Cumulative Index to Nursing and Allied Health Literature were searched to find studies that (1) contained original quantitative data on MGs and orofacial injuries and/or concussions, (2) included groups involved in sports or exercise activities, (3) included MG users and non-MG users, and (4) provided either risk ratios (RRs) and 95% confidence intervals (95% CIs) comparing injuries among MG users and non-MG users, or data that could be used to calculate RRs and 95% CIs. RESULTS: Twenty-six studies met the review criteria. Investigations employed a variety of study designs, utilized different types of MGs, used widely varying injury case definitions, and had multiple methodological weaknesses. Despite these limitations, meta-analyses indicated that the use of MGs reduced the overall risk of orofacial injuries in 12 cohort trials (summary RR [nonusers/users] = 2.33, 95% CI 1.59-3.44), and 11 trials involving self-report questionnaires (summary RR [nonusers/users] = 2.32, 95% CI 1.04-5.13). The influence of MGs on concussion incidence in five cohort studies was modest (summary RR [nonusers/users] = 1.25, 95% CI 0.90-1.74). CONCLUSION: These data indicate that MGs should be used in sports activities where there is significant orofacial injury risk.

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

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

Surveyed Reasons for Not Seeking Medical Care Regarding Musculoskeletal Injury Symptoms in US Army Trainees.

INTRODUCTION: Musculoskeletal injuries (MSKIs) pose a significant threat to military readiness and are difficult to monitor due to Soldiers' reluctance to seek medical treatment. There is high risk of developing MSKIs while going through initial entry training (IET), many of which go unreported. The purposes of this study were to identify the contributing factors that influence US Army trainees to not seek medical care for self-reported symptoms of musculoskeletal injury (SMSKI) and establish how those factors may differ by sex, training school, and installation site. MATERIALS AND METHODS: Data were collected from 739 trainees (607 males, 132 females) completing IET at either Fort Benning, GA, Fort Sill, OK or Fort Leonard-Wood, MO, USA. Male trainees were in combat arms jobs while female trainees were from both combat arms and other physically demanding jobs. All surveys were completed within 5 weeks of graduation from Advanced Individual Training and One Station Unit Training. Trainees answered a series of questions about SMSKIs sustained during IET that lasted seven or more days. Using a Likert-type scale (1-strongly disagree through 5-strongly agree), trainees rated the influence that each of the following seven statements contributed to their decision not to seek medical care: "graduating on time," "avoiding negative perceptions associated with injuries," "avoiding profile," "inconvenience in seeing a provider," "self-managing the injury based on past experience," "severity of the injury," and "prior negative experiences seeking medical care in the military." Pearson's Chi-square test was used to assess significant relationships among SMSKI reporting across sex, training school and training installation. RESULTS: Overall, SMSKI incidence was 36.1% and 58.3% among IET male and female trainees, respectively (40% overall). Nearly two-thirds (64%) of all trainees injured during IET had a SMSKI that they did not report to leadership or a medical provider. Across sex, female trainees were more likely to report SMSKIs than male trainees (p < 0.01), but there was no difference in SMSKI reporting rates by sex (p = 0.48). There was a difference in SMSKI rates by training school (p < 0.01), where infantry had higher SMSKI rates than field artillery (p < 0.01). There were no differences across training schools in how often trainees sought medical care (p = 0.58). The most common reasons selected for not reporting SMSKIs (i.e., not seeking medical care) included "I wanted to graduate on time" and "I wanted to avoid a profile." "I had prior negative experiences seeking medical care in the military" was consistently rated as the least important reason. Female trainees were more likely to not report SMSKIs in order "to avoid a profile" than male trainees (p < 0.05). CONCLUSION: Over 64% of trainees' did not seek medical care for their SMSKI during IET. As early detection, better reporting and timely treatment may result in reductions in SMSKI severity, reduced IET attrition, and lower medical expenses, trainees should be encouraged to report SMSKIs for proper early stage treatment. These study findings could be used to assist military leadership to create a positive environment for reporting and seeking care for SMSKIs.

U.S. Army Physical Demands Study: Differences in Physical Fitness and Occupational Task Performance Between Trainees and Active Duty Soldiers.

Canino, MC, Foulis, SA, Zambraski, EJ, Cohen, BS, Redmond, JE, Hauret, KG, Frykman, PN, and Sharp, MA. U.S. Army Physical Demands Study: Differences in physical fitness and occupational task performance between trainees and active duty soldiers. J Strength Cond Res 33(7): 1864-1870, 2019-U.S. Army initial entry training (IET) is designed to prepare trainees for the military environment and subsequent training, including specific programs to increase physical fitness to perform job-specific tasks to the minimal acceptable performance standard (MAPS). The aim of this study was to compare physical fitness and occupational task performance of trainees at the end of IET to that of active duty soldiers. One hundred seventy-nine male combat arms trainees at the end of IET and 337 male combat arms active duty soldiers performed a sandbag carry (SBC), casualty drag (CD), and move under direct fire (MUF). Physical fitness was assessed using Army Physical Fitness Test scores. A questionnaire was administered to determine frequency of task performance. Active duty soldiers compared with trainees were older (p < 0.01) and performed more push-ups (p < 0.01) and sit-ups (p < 0.01). Trainees performed the 2-mile run faster (p < 0.01). Ninety-four percent of trainees and 99% of active duty soldiers performed the 3 tasks to the MAPSs. Active duty soldiers performed significantly faster on both the SBC (p < 0.01) and CD (p < 0.01) and reported a higher task frequency on the SBC (p = 0.03) and CD (p < 0.01). No difference in MUF performance (p = 0.16) and task frequency (p = 0.13) was detected. Initial entry training seems to provide sufficient physical training as most trainees were able to meet the MAPSs; however, performance differences were still apparent between trainees and active duty soldiers. Additional practice performing the physically demanding tasks may help maximize performance on the physically demanding job requirements.

Characterization of growth hormone disulfide-linked molecular isoforms during post-exercise release vs nocturnal pulsatile release reveals similar milieu composition.

OBJECTIVE: To characterize the influence of mode (aerobic/resistance) and volume of exercise (moderate/high) on circulating GH immediately post-exercise as well as following the onset of sleep. DESIGN: This study used repeated measures in which subjects randomly completed 5 separate conditions: control (no exercise), moderate volume resistance exercise (MR), high-volume resistance exercise (HR), moderate volume aerobic exercise (MA), and high volume aerobic exercise (HA). METHODS: Subjects had two overnight stays on each of the 5 iterations. Serial blood draws began as soon as possible after the completion of the exercise session. Blood was obtained every 20 min for 24-h. GH was measured using a chemiluminescent immunoassay. Pooled samples representing post exercise (PE) and first nocturnal pulse (NP) were divided into two aliquots. One of these aliquots was chemically reduced by adding 10 mM glutathione (GSH) to break down disulfide-linked aggregates. RESULTS: No differences were observed when pooling GH response at post-exercise (2.02 ±â€¯0.21) and nocturnal pulse (2.63 ±â€¯0.51; p = .32). Pairwise comparisons revealed main effect differences between controls (1.19 ±â€¯0.29) and both MA (2.86 ±â€¯0.31; p = .009) and HA (3.73 ±â€¯0.71; p = .001). Both MA (p = .049) and HA (p = .035) responses were significantly larger than the MR stimulus (1.96 ±â€¯0.28). With GSH reduction, controls significantly differed from MA (p = .018) and HA (p = .003) during PE, but only differed from HA (p = .003) during NP. CONCLUSIONS: This study demonstrated similar GH responses to exercise and nocturnal pulse, indicating that mode and intensity of exercise does not proportionately affect GH dimeric isoform concentration.

International consensus on military research priorities and gaps - Survey results from the 4th International Congress on Soldiers' Physical Performance.

OBJECTIVES: The objectives of this study were to identify perceived priorities related to military personnel's health and physical performance, among attendees at the 4th International Congress on Soldiers' Physical Performance (ICSPP), and to determine if perceived priorities had changed between the 3rd ICSPP survey held in 2014 and the 4th ICSPP survey held in 2017. DESIGN: Electronic survey. METHODS: Respondents were asked to grade priority areas on a Likert scale, and average ratings were used to rank priority areas. Responses to free text questions were analyzed qualitatively. Responses to the 4th ICSPP survey were described and compared to responses to the 3rd ICSPP survey. RESULTS: The 4th ICSPP survey respondents were a diverse group (40.6% military, 58.9% civilian). The two most important priority areas identified were physical demands in operational environments (mean score=4.41/5) and measuring physical performance/fitness (4.38/5), which were also the top two areas in the 3rd ICSPP survey. There was remarkable overlap in the rankings of priority areas between the two surveys. Sleep and nutrition were emerging priority areas and were perceived as relatively more important in the 4th ICSPP survey compared to the 3rd ICSPP survey. The greatest perceived emerging threat was resilience/psychological fitness of recruits (4.16/5). Physiological status monitoring (2.79/4) was identified as the most important technology. CONCLUSIONS: Despite the diverse backgrounds of the respondents, there was a clear continuing consensus about perceived important priority areas influencing military personnel's health and physical performance. Soldier resiliency and assessment of physiological status were research topics identified as top priorities.

Association between stress fracture incidence and predicted body fat in United States Army Basic Combat Training recruits.

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

Secular Trends in the Physical Fitness of United States Army Infantry Units and Infantry Soldiers, 1976-2015.

Introduction: The purpose of this investigation was to examine changes over time in the physical fitness of the United States (US) Army infantry. A systematic review was conducted to identify and analyze articles and databases that reported on physical characteristics (height, weight, and body mass index) and/or Army Physical Fitness Test (APFT) scores of male infantrymen or men in infantry units. Materials and Methods: The National Library of Medicine's PubMed and the Defense Technical Information Center were searched using specific keywords. Reference lists of obtained articles, specific author searches, contact with authors, and secondary analysis of available databases enhanced the search. Studies and databases were selected if they involved infantry soldiers or soldiers in infantry units and provided a quantitative assessment of at least one physical characteristic or APFT measure. Average values for each measure were obtained, plotted by the year of data collection, and fitted to linear regression models. Results: Thirty-one articles and five available databases met the review criteria encompassing years 1976-2015. Regression analysis suggested a small temporal increase in height for infantry soldiers (2%) and soldiers in infantry units (1%). Body weight and body mass index increased over the period (9-15%) in both groups. APFT performance of infantry soldiers was generally higher than that of infantry units. There was little change in APFT performance over the period for infantry soldiers. For soldiers in infantry units, push-up performance changed little over time, whereas sit-up performance increased (8%) and two-mile run performance decreased (8%). Conclusion: Over the surveyed period, body weight and body mass index increased in US Army infantry soldiers and soldier in infantry units. Infantry soldier performance on the APFT appears to have been maintained over the period. For soldiers in infantry units, there has been a small improvement in sit-up performance, but lower two-mile run performance.

The Relationship Between Soldier Performance on the Two-Mile Run and the 20-m Shuttle Run Test.

Background: The 20-m shuttle run test (MSRT) is a common field test used to measure aerobic fitness in controlled environments. The U.S. Army currently assesses aerobic fitness with the two-mile run (TMR), but external factors may impact test performance. The aim of this study is to examine the relationship between the Army Physical Fitness Test TMR performance and the MSRT in military personnel. Methods: A group of 531 (403 males and 128 females) active duty soldiers (age: 24.0 ± 4.1 years) performed the MSRT in an indoor facility. Heart rate was monitored for the duration of the test. Post-heart rate and age-predicted maximal heart rate were utilized to determine near-maximal performance on the MSRT. The soldiers provided their most recent Army Physical Fitness Test TMR time (min). A Pearson correlation and multiple linear regression analyses were performed to examine the relationship between TMR time (min) and MSRT score (total number of shuttles completed). The study was approved by the Human Use Review Committee at the U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts. Findings: A significant, negative correlation exists between TMR time and MSRT score (r = -0.75, p < 0.001). Sex and MSRT score significantly predicted TMR time (adjusted R2 = 0.65, standard error of estimate = 0.97, p < 0.001) with a 95% ratio limits of agreement of ±12.6%. The resulting equation is: TMR = 17.736-2.464 × (sex) - 0.050 × (MSRT) - 0.026 × (MSRT × sex) for predicted TMR time. Males equal zero, females equal one, and MSRT score is the total number of shuttles completed. Discussion: The MSRT is a strong predictor of the TMR and should be considered as a diagnostic tool when assessing aerobic fitness in active duty soldiers.

U.S. Army physical demands study: Identification and validation of the physically demanding tasks of combat arms occupations.

OBJECTIVES: In 2013, the U.S. Army began developing physical tests to predict a recruit's ability to perform the critical, physically demanding tasks (CPDTs) of combat arms jobs previously not open to women. The purpose of this paper is to describe the methodology and results of analyses of the accuracy and inclusiveness of the critical physically demanding task list. While the job analysis included seven combat arms jobs, only data from the 19D Cavalry Scout occupation are presented as the process was similar for all seven jobs. DESIGN: Job analysis METHODS: As the foundation, senior subject matter experts from each job reviewed materials and reached consensus on the CPDTs and performance standards for each job. The list was reviewed by Army leadership and provided to the researchers. The job analysis consisted of reviewing job and task related documents and field manuals, observing >900 soldiers performing the 32 CPDTs, conducting two focus groups for each job, and analyzing responses to widely distributed job analysis questionnaires. RESULTS: Of the 32 CPDTs identified for seven combat jobs, nine were relevant to 19D soldiers. Focus group discussions and job analysis questionnaire results supported the tasks and standards identified by subject matter experts while also identifying additional tasks. CONCLUSIONS: The tasks identified by subject matter experts were representative of the physically demanding aspects of the 19D occupation.

U.S. Army physical demands study: Prevalence and frequency of performing physically demanding tasks in deployed and non-deployed settings.

OBJECTIVES: To compare percentages of on-duty time spent performing physically demanding soldier tasks in non-deployed and deployed settings, and secondarily examine the number of physically demanding tasks performed among five Army combat arms occupational specialties. DESIGN: Job task analysis. METHODS: Soldiers (n=1295; over 99% serving on active duty) across five Army jobs completed one of three questionnaires developed using reviews of job and task related documents, input from subject matter experts, observation of task performance, and conduct of focus groups. Soldiers reported estimates of the total on-duty time spent performing physically demanding tasks in both deployed and non-deployed settings. One-way analyses of variance and Duncan post-hoc tests were used to compare percentage time differences by job. Two-tailed t-tests were used to evaluate differences by setting. Frequency analyses were used to present supplementary findings. RESULTS: Soldiers reported performing physically demanding job-specific tasks 17.7% of the time while non-deployed and 19.6% of the time while deployed. There were significant differences in time spent on job-specific tasks across settings (p<0.05) for three of five occupational specialties. When categories of physically demanding tasks were grouped, all soldiers reported spending more time on physically demanding tasks when deployed (p<0.001). Twenty-five percent reported performing less than half the physically demanding tasks represented on the questionnaire in the last two years. CONCLUSION: Soldiers spent more time performing physically demanding tasks while deployed compared to non-deployed but spent similar amounts of time performing job-specific tasks.

U.S. Army Physical Demands Study: Development of the Occupational Physical Assessment Test for Combat Arms soldiers.

OBJECTIVES: The United States Army sought to create a legally defensible, scientifically validated physical pre-employment screening test. The purpose of this study was to identify a single combination of predictor tests that would predict physical performance on all of the criterion measure task simulations relevant to the Combat Arms military occupational specialties. DESIGN: Concurrent validation. METHODS: Data from 838 (608 males, 230 females) soldiers who completed both the criterion measure task simulations of a military occupational specialty and up to 14 predictor tests were used in the development of the test batteries. Stepwise regressions were used to identify test batteries that significantly predicted performance on the criterion measure task simulations of the military occupational specialties. RESULTS: Three test batteries were developed based on different subsets of the predictor tests: Test Battery 1 consisted of the medicine ball put, squat lift, beep test, standing long jump, and arm ergometer (adjusted R2=0.80-0.85, p<0.01); Test Battery 2 consisted of the medicine ball put, squat lift, beep test, and standing long jump (adjusted R2=0.79-0.80, p<0.01); and Test Battery 3 consisted of the standing long jump, 1-minute push-ups, 1-minute sit-ups, 300m sprint, and Illinois agility test (adjusted R2=0.55-0.71, p<0.01). CONCLUSIONS: Test Battery 2 was selected as the Army's Occupational Physical Assessment Test. It was highly predictive of performance of the Combat Arms military occupational specialties, required no complex equipment, and covered a range of physical fitness domains.