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.

Prevention of Lower Extremity Musculoskeletal Injuries in Tactical and First Responder Populations: A Systematic Review and Meta-Analysis of Randomized Trials From 1955 to 2020.

ABSTRACT: Sinnott, AM, Krajewski, KT, LaGoy, AD, Beckner, ME, Proessl, F, Canino, MC, Nindl, BC, Turner, RL, Lovalekar, MT, Connaboy, C, and Flanagan, SD. Prevention of lower extremity musculoskeletal injuries in tactical and first responder populations: A systematic review and meta-analysis of randomized trials from 1955 to 2020. J Strength Cond Res 37(1): 239-252, 2023-Lower extremity musculoskeletal injuries (LEMSIs) impose a significant burden on tactical and first responder populations. To determine the effectiveness of LEMSI prevention strategies, we performed a systematic review and meta-analysis of randomized controlled trials published in English from 1955 to 2020 (PROSPERO: CRD42018081799). MEDLINE, EMBASE, Cochrane, CINAHL, ProQuest, and DTIC databases were searched for trials that assigned military service members, police, firefighters, or paramedics to LEMSI prevention interventions with a minimum surveillance period of 12 weeks. Evidence was synthesized as odds ratios (OR) for LEMSI occurrence between individuals assigned to interventions and those assigned to standard activities. Risk of bias was assessed with the Cochrane Risk of Bias tool 2.0. Random-effects meta-analyses were conducted for (a) physical training and (b) footwear modifications to reduce LEMSI and (c) footwear modifications to reduce stress fractures specifically. Certainty in the body of evidence was determined with the GRADE approach. Of 28,499 records, 18 trials comprised of more than 11,000 subjects were synthesized. Interventions included physical training (8, N = 6,838), footwear modifications (8, N = 3,792), nutritional supplementation (1, N = 324), and training modifications (1, N = 350). Overall risk of bias was generally moderate ( N = 7 of 18) or high ( N = 9 of 18). Physical training (OR = 0.87, 95% CI [0.71, 1.08], p = 0.22, I 2 = 58.4%) and footwear modification (OR = 1.13, 95% CI [0.85, 1.49], p = 0.42, I 2 = 0.0%) did not reduce LEMSI or stress fractures (OR = 0.76, 95% CI [0.45, 1.28], p = 0.30, I 2 = 70.7%). Our results indicate that there is weak evidence to support current LEMSI prevention strategies. Future efforts will benefit from longer surveillance periods, assessment of women and nonmilitary populations, improved methodological rigor, and a greater breadth of approaches.

Differences in brain structure and theta burst stimulation-induced plasticity implicate the corticomotor system in loss of function after musculoskeletal injury.

Traumatic musculoskeletal injury (MSI) may involve changes in corticomotor structure and function, but direct evidence is needed. To determine the corticomotor basis of MSI, we examined interactions among skeletomotor function, corticospinal excitability, corticomotor structure (cortical thickness and white matter microstructure), and intermittent theta burst stimulation (iTBS)-induced plasticity. Nine women with unilateral anterior cruciate ligament rupture (ACL) 3.2 ± 1.1 yr prior to the study and 11 matched controls (CON) completed an MRI session followed by an offline plasticity-probing protocol using a randomized, sham-controlled, double-blind, cross-over study design. iTBS was applied to the injured (ACL) or nondominant (CON) motor cortex leg representation (M1LEG) with plasticity assessed based on changes in skeletomotor function and corticospinal excitability compared with sham iTBS. The results showed persistent loss of function in the injured quadriceps, compensatory adaptations in the uninjured quadriceps and both hamstrings, and injury-specific increases in corticospinal excitability. Injury was associated with lateralized reductions in paracentral lobule thickness, greater centrality of nonleg corticomotor regions, and increased primary somatosensory cortex leg area inefficiency and eccentricity. Individual responses to iTBS were consistent with the principles of homeostatic metaplasticity; corresponded to injury-related differences in skeletomotor function, corticospinal excitability, and corticomotor structure; and suggested that corticomotor adaptations involve both hemispheres. Moreover, iTBS normalized skeletomotor function and corticospinal excitability in ACL. The results of this investigation directly confirm corticomotor involvement in chronic loss of function after traumatic MSI, emphasize the sensitivity of the corticomotor system to skeletomotor events and behaviors, and raise the possibility that brain-targeted therapies could improve recovery.NEW & NOTEWORTHY Traumatic musculoskeletal injuries may involve adaptive changes in the brain that contribute to loss of function. Our combination of neuroimaging and theta burst transcranial magnetic stimulation (iTBS) revealed distinct patterns of iTBS-induced plasticity that normalized differences in muscle and brain function evident years after unilateral knee ligament rupture. Individual responses to iTBS corresponded to injury-specific differences in brain structure and physiological activity, depended on skeletomotor deficit severity, and suggested that corticomotor adaptations involve both hemispheres.

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.

Agreement and Consistency of Absolute and Relative Corticospinal Stimulus-Response Curves for Upper, Lower, and Axial Musculature in Healthy Adults.

PURPOSE: To assess the agreement and consistency of absolute and relative stimulus-response curve (SRC) parameter estimates for upper extremity, lower extremity, and axial muscles. METHODS: Thirty (15 W, age: 27.0 ± 6.3 y, height: 171.9 ± 8.9 cm, weight: 80.2 ± 19.3 kg) healthy adults completed absolute (5% to 100% stimulator output) and relative (65% to 160% motor threshold) SRCs of the first dorsal interosseous, vastus lateralis, and rectus abdominis during submaximal isometric contractions. Mean motor-evoked potential amplitudes were fit with nonlinear regression to derive MEPmax, V50, and slope. Absolute agreement and consistency were assessed with ICCs, Cronbachs alphas, and Bland-Altman plots. Independent t-tests were used to examine differences in motor threshold, physical activity, strength, and muscle activity among participants with valid and invalid SRC parameters. RESULTS: Absolute and relative SRCs displayed good agreement and consistency for MEPmax and V50 but not slope. Motor thresholds were lower among participants with valid absolute SRCs for the rectus abdominis and vastus lateralis. Motor threshold, physical activity, strength, and muscle activity did not differ among those with valid and invalid parameters for all relative SRCs and absolute SRCs for the first dorsal interosseous. CONCLUSIONS: Absolute and relative SRCs produce similar MEPmax and V50 estimates in the first dorsal interosseous, vastus lateralis, and rectus abdominis. The validity of absolute and relative SRC results may differ depending on individual characteristics and tested muscles.

Urinary Proteomic Biomarkers of Trabecular Bone Volume Change during Army Basic Combat Training.

PURPOSE: Optimize a dMS-based urinary proteomic technique and evaluate the relationship between urinary proteome content and adaptive changes in bone microarchitecture during BCT. METHODS: Urinary proteomes were analyzed with an optimized dMS technique in two groups of 13 recruits (n = 26) at the beginning (Pre) and end (Post) of BCT. Matched by age (21 ± 4 yr), sex (16 W), and baseline tibial trabecular bone volume fractions (Tb.BV/TV), these groups were distinguished by the most substantial (High) and minimal (Low) improvements in Tb.BV/TV. Differential protein expression was analyzed with mixed permutation ANOVA and false discovery proportion-based adjustment for multiple comparisons. RESULTS: Tibial Tb.BV/TV increased from pre- to post-BCT in High (3.30 ± 1.64%, p < 0.0001) but not Low (-0.35 ± 1.25%, p = 0.4707). The optimized dMS technique identified 10,431 peptides from 1,368 protein groups that represented 165 integrative biological processes. 74 urinary proteins changed from pre- to post-BCT (p = 0.0019) and neutrophil mediated immunity was the most prominent ontology. Two proteins (Immunoglobulin heavy constant gamma 4 and C-type lectin domain family 4 member G) differed from pre- to post-BCT in High and Low (p = 0.0006). CONCLUSIONS: The dMS technique can identify more than 1000 urinary proteins. At least 74 proteins are responsive to BCT, and other principally immune system-related proteins show differential expression patterns that coincide with adaptive bone formation.

Monitoring cognitive function in the fatigued warfighter: A rapid review of cognitive biomarkers.

OBJECTIVES: Decreases in cognitive function impair occupational performance, reduce occupational safety, and increase musculoskeletal injury risk. The aim of this paper was to identify measures that may be used to monitor cognitive function in the warfighter. DESIGN: A rapid review. METHODS: A rapid search of Academic Search Complete, MEDLINE, PsycINFO, and SPORTSDiscus databases was conducted. ELIGIBILITY CRITERIA: original peer reviewed research articles, written in English, published between 2002 and 2022, and using human participants with no health issues in military training environments or active service. RESULTS: Of the 248 articles screened, 58 full-text articles were assessed for eligibility and 29 included in the review. Of these, 16 papers presented data from multi-stressor military training environments, or experimental studies where simulated military tasks were being performed. Thirteen papers focused on an aspect of military work and the implications for cognitive function (i.e., physical load, periods of extended wakefulness or fatigue, and hypoxic conditions). The domains of cognitive function that were assessed (i.e. vigilance, reaction time, working memory, situational awareness, and decision-making) were somewhat consistent among studies. CONCLUSIONS: Prolonged exposure to high-stress military environments compromises multiple aspects of cognitive function. These findings highlight the need for a suite of biomarkers to monitor cognitive function and assess the ability of military personnel to attend to and process mission-critical information and make appropriate decisions on the battlefield and other high-stress environments. Our findings suggest that a suite of common tests may provide useful information about cognitive function in the warfighter.

Finding a rhythm: Relating ultra-short-term heart rate variability measures in healthy young adults during rest, exercise, and recovery.

Ultra-short-term (UST; <5 min) heart rate variability (HRV) is increasingly used to indirectly assess autonomic nervous system modulation and physical health. However, UST HRV estimates may vary with measurement technique, physiological state, and data preprocessing. The purpose of this investigation was to assess the information content of UST HRV and its sensitivity to different physiological states and preprocessing techniques. 26 time, frequency, and non-linear HRV measures were determined in 80 healthy men (age: 22.1 ± 3.7 yr) and 25 women (age: 19.4 ± 2.8 yr) from 2-min ECG recordings during seated and standing rest, low-intensity exercise, and seated recovery after maximal exercise. For men, HRV measures obtained during each condition were further analyzed with principal component analysis, k-means clustering, and one-way ANCOVAs. Backward stepwise regression was used to determine the ability of UST HRV to predict aerobic fitness. The sensitivity of UST HRV estimates to different artifact correction procedures was determined with intraclass correlation coefficients. Compared with men, women displayed HRV characteristics suggestive of greater vagal modulation. Nearly 80% of HRV information content was distilled into three principal components comprised of similar measures across conditions. K-means clusters varied in composition and HRV characteristics but not aerobic fitness, which was best predicted by HRV during standing rest. HRV estimates differed depending on artifact correction procedures but were generally similar after individualized correction. Our results indicate that UST HRV measures display redundancy but convey state-specific information and do not strongly predict aerobic fitness in healthy men. Most UST HRV measures are robust to slight differences in artifact correction procedures.

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.

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.

Constitutive and Stress-Induced Psychomotor Cortical Responses to Compound K Supplementation.

Isolated ginsenoside metabolites such as Compound K (CK) are of increasing interest to consumer and clinical populations as safe and non-pharmacological means to enhance psychomotor performance constitutively and in response to physical or cognitive stress. Nevertheless, the influence of CK on behavioral performance and EEG measures of cortical activity in humans is undetermined. In this double-blinded, placebo-controlled, counterbalanced within-group study, dose-dependent responses to CK (placebo, 160 and 960 mg) were assessed after 2 weeks of supplementation in nineteen healthy men and women (age: 39.9 ± 7.9 year, height 170.2 ± 8.6 cm, weight 79.7 ± 11.9 kg). Performance on upper- and lower-body choice reaction tests (CRTs) was tested before and after intense lower-body anaerobic exercise. Treatment- and stress-related changes in brain activity were measured with high-density EEG based on event-related potentials, oscillations, and source activity. Upper- (-12.3 ± 3.5 ms, p = 0.002) and lower-body (-12.3 ± 4.9 ms, p = 0.021) response times improved after exercise, with no difference between treatments (upper: p = 0.354; lower: p = 0.926). Analysis of cortical activity in sensor and source space revealed global increases in cortical arousal after exercise. CK increased activity in cortical regions responsible for sustained attention and mitigated exercise-induced increases in arousal. Responses to exercise varied depending on task, but CK appeared to reduce sensory interference from lower-body exercise during an upper-body CRT and improve the general maintenance of task-relevant sensory processes.

Structural Connectome Disruptions in Military Personnel with Mild Traumatic Brain Injury and Post-Traumatic Stress Disorder.

Mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD) are common in military populations and share numerous symptoms. Functional graph theory studies demonstrate altered small-world brain networks in mTBI and PTSD, but little is known about structural covariance networks or the potentially distinct topology of mTBI-PTSD comorbidity. The purpose of this study was to compare brain structural covariance networks in healthy active duty military service members (CON) to those with PTSD, mTBI, and mTBI-PTSD. Seventy-six service members (31 CON, 14 PTSD, 12 mTBI, 19 mTBI-PTSD) completed clinical questionnaires and structural magnetic resonance imaging scans. Cortical thickness-derived adjacency matrices were used to determine structural covariance network topologies. Pairwise comparisons for characteristic path length, clustering coefficient, modularity (global), closeness centrality (nodal), and local efficiency were made across a range of network densities (5-35%) using non-parametric permutation tests. All clinical groups showed greater levels of arousal, stress, anxiety, and depression compared with CON. Global network analysis revealed greater clustering and local efficiency in PTSD compared with CON, whereas nodal analysis indicated altered path lengths and closeness centrality in fronto-limbic areas with mTBI-PTSD. Global and nodal graph outcomes suggest distinct pathophysiological manifestations of mTBI, PTSD, and mTBI-PTSD in structural brain networks. Greater network segregation and nodal differences in fronto-limbic areas may be tied to emotional fluctuations.

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.

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.

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.

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: 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.

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: 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.