Gender Differences in Static and Dynamic Postural Stability of Soldiers in the Army's 101st Airborne Division (Air Assault).

CONTEXT: Postural stability is essential for injury prevention and performance. Differences between genders may affect training focus. OBJECTIVE: To examine static and dynamic postural stability in male and female soldiers. DESIGN: Descriptive laboratory study. SETTING: Biomechanics laboratory. PARTICIPANTS: 25 healthy female soldiers (26.4 ± 5.3 y) and 25 healthy male soldiers (26.4 ± 4.9 y) matched on physical demand rating and years of service from the Army's 101st Airborne Division (Air Assault). INTERVENTIONS: Each person underwent static and dynamic postural stability testing. MAIN OUTCOME MEASURES: Standard deviation of the ground reaction forces during static postural stability and the dynamic stability index for dynamic postural stability. RESULTS: Female soldiers had significantly better static postural stability than males but no differences were observed in dynamic postural stability. CONCLUSIONS: Postural stability is important for injury prevention, performance optimization, and tactical training. The differences observed in the current study may indicate the need for gender-specific training emphasis on postural stability.

The Effect of Target Position on the Accuracy of Cervical-Spine-Rotation Active Joint-Position Sense.

CONTEXT: The cervical spine can be divided into upper and lower units, each making a different contribution to the magnitude of rotation and proprioception. However, few studies have examined the effect of the cervical-rotation positions on proprioception. OBJECTIVE: To compare cervical-spine rotation active joint-position sense (AJPS) near midrange of motion (mid-ROM; 30°) and near end-ROM (60°). DESIGN: Cross-sectional study. SETTING: Human performance research laboratory. PARTICIPANTS: 53 military helicopter pilots (age 28.4 ± 6.2 y, height 175.3 ± 9.3 cm, weight 80.1 ± 11.8 kg). MAIN OUTCOME MEASURES: A motion-analysis system was used to record cervical-rotation kinematics. Subjects sat in a chair wearing a headband and blindfold. First, they actively rotated the head right or left to a target position (30°/60°), with real-time verbal cues provided by the tester. Subjects held the target position for 5 s and then returned to the start position. After this, they replicated the target position as closely as possible. Five trials were performed in both directions to both target positions (R30/R60/L30/L60). Order of direction/position was randomized. The difference between target and replicated positions was calculated and defined as absolute error (AE), and the mean of 5 trials was used for analyses. Wilcoxon signed-ranks tests were used to compare AJPS at the different target positions (P < .0125 with Bonferroni adjustments). RESULTS: End-ROM AEs were significantly more accurate than mid-ROM AEs (P = .001). CONCLUSION: Cervical-spine-rotation AJPS is more accurate near end-ROM than mid-ROM. Both target positions should be used to examine cervical-spine-rotation AJPS of both the upper and lower units.

Neck proprioception, strength, flexibility, and posture in pilots with and without neck pain history.

INTRODUCTION: Neck pain (NP) is common among military helicopter pilots. Older age and more flight-hours have been associated with pilots with a history of NP. However, modifiable neuromuscular and musculoskeletal characteristics such as neck proprioception, strength, flexibility, and posture have rarely been investigated in military helicopter pilots with a history of NP. The purpose of the study was to compare demographics, flight characteristics, physical fitness information, neck proprioception, strength, flexibility, and posture between helicopter pilots with and without a history of NP. METHODS: A total of 27 Army helicopter pilots with NP in the past 12 mo (pain group) were matched based on age with pilots without a history of NP (nonpain group). All pilots had flown at least 100 h in the past 12 mo and were cleared for flight and physical training. All pilots completed a battery of laboratory testing: neck proprioception, neck and scapular muscular strength, neck active range-of-motion (ROM), forward head and shoulder posture, and pectoralis minor length. Paired t-tests or Wilcoxon tests were used to compare differences between groups. RESULTS: The pain group had significantly less cervical extension (63.7 +/- 8.5 degrees) and rotation ROM (R rotation: 67.7 +/- 8.8 degrees; L rotation: 67.4 +/- 9.0 degrees) when compared to the nonpain group (extension: 68.3 +/- 7.4 degrees; R rotation: 73.4 +/- 7.4 degrees; L rotation: 72.9 +/- 6.8 degrees). No significant differences were found for other variables. CONCLUSION: The results demonstrate less neck active ROM in pilots with a history of NP. Operating a helicopter with limited neck ROM or NP may negatively impact flight safety and force readiness. Continued research is warranted.

Limiting Exposure to Scattered Radiation From a CT System Installed in a Two-Sided Deployable ISO-Shelter.

INTRODUCTION: Diagnostic radiology in the deployed military environment (in-theater diagnostic radiology) was greatly improved in the early 1990s with the addition of CT systems installed in military-grade one-sided expandable ISO-shelters. These shelters were provided with limited radiation shielding by several flexible lead curtains covering only a small portion of the shelter walls, necessitating placement of deployed CT systems at substantial distances from the field medical facility to limit exposures to personnel from secondary radiation. The newest generation deployable CT system is housed in a two-sided ISO-shelter with radiation shielding applied to the shelter walls. To ensure compliance with military and national standards for protection against ionizing radiation, we developed a simple method to calculate safe distances based on workload, frequencies of the various CT exams performed, and occupancy of controlled and uncontrolled areas. MATERIALS AND METHODS: Calculation of radiation air kerma rates outside a two-sided CT ISO-shelter was developed using guidance from the National Council on Radiation Protection and Measurements Report No. 147. The simplified formula included measured radiation transmission factors for the ISO-shelter wall and installed shielding, occupancy factors, fraction of all CT exams that covered the chest, abdomen, and/or pelvis, total number of CT exams per week, and shielding design goals for controlled and uncontrolled areas. The formula was modified subsequently to account for whole-body CT exams expected during armed conflict. RESULTS: Calculated safe distances revealed that the shielded two-sided CT ISO-shelter can be positioned much closer to the surgical shelters of the field medical unit than the previously unshielded one-sided CT ISO-shelter. Tables of safe distances for controlled and uncontrolled areas for the two medical support environments of disaster relief/peacekeeping and combat are provided. For example, for a controlled area at 100% occupancy when 300 CT exams per week are performed and 50% of those exams are of the chest, abdomen, and/or pelvis, the safe distance between the nearest surgical shelter and the shielded CT ISO-shelter is 2.1 m. By comparison, the safe distance for an unshielded CT ISO-shelter is 8.5 m under the same conditions. For lower occupancy factors and lower weekly workload, safe distances from the nearest surgical shelter are often negligible. CONCLUSIONS: The shielding in the new deployable CT ISO-shelter substantially reduces the distance between it and the surgical shelters of the field medical unit necessary to ensure radiation safety. Safe distances depend on several factors including workload, types and frequencies of CT exams, occupancy factors, and classification of the area around the ISO-shelter, i.e., controlled and uncontrolled.

The addition of body armor diminishes dynamic postural stability in military soldiers.

Poor postural stability has been identified as a risk factor for lower extremity musculoskeletal injury. The additional weight of body armor carried by Soldiers alters static postural stability and may predispose Soldiers to lower extremity musculoskeletal injuries. However, static postural stability tasks poorly replicate the dynamic military environment, which places considerable stress on the postural control system during tactical training and combat. Therefore, the purpose of this study was to examine the effects of body armor on dynamic postural stability during single-leg jump landings. Thirty-six 101st Airborne Division (Air Assault) Soldiers performed single-leg jump landings in the anterior direction with and without wearing body armor. The dynamic postural stability index and the individual stability indices (medial-lateral stability index, anterior-posterior stability index, and vertical stability index) were calculated for each condition. Paired sample t-tests were performed to determine differences between conditions. Significant differences existed for the medial-lateral stability index, anterior-posterior stability index, vertical stability index, and dynamic postural stability index (p < 0.05). The addition of body armor resulted in diminished dynamic postural stability, which may result in increased lower extremity injuries. Training programs should address the altered dynamic postural stability while wearing body armor in attempts to promote adaptations that will result in safer performance during dynamic tasks.

Developmental progress and creatine restoration upon long-term creatine supplementation of a patient with arginine:glycine amidinotransferase deficiency.

BACKGROUND: Arginine:glycineamidinotransferase (AGAT/GATM) deficiency has been described in 9 patients across 4 families. Here we describe the clinical outcome and response to creatine supplementation in a patient of the second family affected with AGAT deficiency-a 9-year-old girl. PATIENT AND METHODS: Delayed motor milestones were noticed from 4 months of age and at 14 months moderate hypotonia, developmental delay and failure to thrive. Laboratory studies revealed low plasma creatine as well as extremely low levels of guanidinoacetic acid in urine and plasma. Proton magnetic resonance spectroscopy (MRS) of the brain showed absence of creatine. DNA sequence analysis revealed a homozygous mutation (c.484+1G>T) in the AGAT/GATM gene. AGAT activity was not detectable in lymphoblasts and RNA analysis revealed a truncated mRNA (r.289_484del196) that is degraded via Nonsense Mediated Decay. At 16 months, Bayley's Infant Development Scale (BIDS) showed functioning at 43% of chronologic age. Oral creatine supplementation (up to 800 mg/kg/day) was begun. RESULTS: At age 9 years she demonstrated advanced academic performance. Partial recovery of cerebral creatine levels was demonstrated on MRS at 25 months of age. Brain MRS at 40 months of age revealed a creatine/NAA ratio of about 80% of that in age-matched controls. CONCLUSIONS: 8 years post initiation of oral creatine supplementation, patient demonstrates superior nonverbal and academic abilities, with average verbal skills. We emphasize that early diagnosis combined with early treatment onset of AGAT deficiency may lead to improvement of developmental outcome.

Using the capture-recapture method to estimate the incidence of musculoskeletal injuries among U.S. Army soldiers.

Musculoskeletal injury (MSI) data typically are obtained from medical chart-review (MCR) or injury self-reports (ISR). MSI incidence may be under-counted if only one source is utilized, as MCR will not capture MSI for which medical care was not sought, and ISR may be affected by issues with recall. OBJECTIVES: The purposes of this study were to determine MSI incidence from two sources (MCR, ISR) and to estimate the incidence, after accounting for the under-counting in both sources, among a sample of U.S. Army soldiers. DESIGN: Descriptive cross-sectional study. METHODS: The estimated cumulative incidence during a one-year period was calculated from the two sources of MSI data using a novel statistical analysis (capture-recapture-CRC). RESULTS: MSI data were available for 287 soldiers (age: 27.5±6.3years (mean±standard deviation)). The one-year cumulative incidence of MSI was 17.8% (MCR), 19.5% (ISR), and 54.0% (CRC). CRC analysis showed that there was under-counting from both sources of data and the percent of CRC estimated MSI observed were 32.9% (MCR), 36.1% (ISR), and 57.4% (MCR and ISR combined). When analyzed by MSI type, percent of CRC estimated MSI counted from both sources was highest (75.0%) for fracture, followed by sprain (53.8%), strain (43.8%), and pain/spasm/ache (35.8%). CONCLUSIONS: There was under-counting of MSI from both sources of data, and the under-counting varied by MSI type. There is a need for further investigation of the relative benefits of various sources of MSI data and the application of the capture-recapture analysis in military populations.

Poor anaerobic power/capability and static balance predicted prospective musculoskeletal injuries among Soldiers of the 101st Airborne (Air Assault) Division.

Musculoskeletal injuries have negatively impacted tactical readiness. The identification of prospective and modifiable risk factors of preventable musculoskeletal injuries can guide specific injury prevention strategies for Soldiers and health care providers. OBJECTIVES: To analyze physiological and neuromuscular characteristics as predictors of preventable musculoskeletal injuries. DESIGN: Prospective-cohort study. METHODS: A total of 491 Soldiers were enrolled and participated in the baseline laboratory testing, including body composition, aerobic capacity, anaerobic power/capacity, muscular strength, flexibility, static balance, and landing biomechanics. After reviewing their medical charts, 275 male Soldiers who met the criteria were divided into two groups: with injuries (INJ) and no injuries (NOI). Simple and multiple logistic regression analyses were used to calculate the odds ratio (OR) and significant predictors of musculoskeletal injuries (p<0.05). RESULTS: The final multiple logistic regression model included the static balance with eyes-closed and peak anaerobic power as predictors of future injuries (p<0.001). CONCLUSIONS: The current results highlighted the importance of anaerobic power/capacity and static balance. High intensity training and balance exercise should be incorporated in their physical training as countermeasures.

The Compensatory Reserve For Early and Accurate Prediction Of Hemodynamic Compromise: A Review of the Underlying Physiology.

Shock is deadly and unpredictable if it is not recognized and treated in early stages of hemorrhage. Unfortunately, measurements of standard vital signs that are displayed on current medical monitors fail to provide accurate or early indicators of shock because of physiological mechanisms that effectively compensate for blood loss. As a result of new insights provided by the latest research on the physiology of shock using human experimental models of controlled hemorrhage, it is now recognized that measurement of the body's reserve to compensate for reduced circulating blood volume is the single most important indicator for early and accurate assessment of shock. We have called this function the "compensatory reserve," which can be accurately assessed by real-time measurements of changes in the features of the arterial waveform. In this paper, the physiology underlying the development and evaluation of a new noninvasive technology that allows for real-time measurement of the compensatory reserve will be reviewed, with its clinical implications for earlier and more accurate prediction of shock.

Effects of Age and Military Service on Strength and Physiological Characteristics of U.S. Army Soldiers.

Soldiers must maintain tactical performance capabilities over the course of their career. Loss in physical readiness may be a function of age and the operational demands associated with increasing years of service. The purpose of this study was to assess strength and physiological characteristics in different cohorts of U.S. Army Soldiers based on years of service and age. A total of 253 Soldiers (age: 28.1 ± 6.8 years; height: 1.76 ± 0.11 m; mass: 84.1 ± 12.2 kg) participated. Individual subject cohorts were created based on years of service (1-5 years, 6-10 years, 11-15 years) and age (20-24 years, 25-29 years, 30-34 years, 35-39 years, 40-44 years). Testing included shoulder, knee, ankle, and torso strength, aerobic capacity/lactate threshold, anaerobic power/capacity, and body composition/total mass. Those with 11 to 15 years of service and between ages 30 and 34 had a higher percentage of body fat, and lower aerobic capacity and lactate threshold than younger Soldiers with fewer years of service. Physical training interventions should focus on maintenance of physiological characteristics to offset the loss of readiness at the similar time point of 11 to 15 years of service and 30 to 34 years of age.

The Eagle Tactical Athlete Program Reduces Musculoskeletal Injuries in the 101st Airborne Division (Air Assault).

UNLABELLED: The Eagle Tactical Athlete Program (ETAP) was scientifically developed for the U.S. Army's 101st Airborne Division (Air Assault) to counter unintentional musculoskeletal injuries (MSIs). PURPOSE: To determine if ETAP would reduce unintentional MSIs in a group of 101st Airborne Division (Air Assault) Soldiers. METHODS: ETAP-trained noncommissioned led physical training. 1,720 Soldiers were enrolled (N = 1,136 experimental group [EXP], N = 584 control group [CON]) with injuries tracked before and after initiation of ETAP. The International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes were analyzed and described the anatomic locations, anatomic sub-locations, onset, and injury types. McNemar tests compared the proportions of injured subjects within each group. RESULTS: There was a significant reduction in the proportion of Soldiers with preventable MSIs in the EXP (pre: 213/1,136 (18.8%), post: 180/1,136 (15.8%), p = 0.041) but not in the CON. In addition, there was a significant reduction in stress fractures in the EXP (pre: 14/1,136 (1.2%), post: 5/1,136 (0.4%), p = 0.022) but no significant differences in the CON. CONCLUSION: The current analysis demonstrated that ETAP reduces preventable MSIs in garrison. The capability of ETAP to reduce injuries confirms the vital role of a scientifically designed training program on force readiness and health.

Descriptive Epidemiology of Musculoskeletal Injuries in the Army 101st Airborne (Air Assault) Division.

The purpose of this study was to describe the epidemiology of musculoskeletal injuries among Soldiers of the 101st Airborne (Air Assault) Division. A total of 451 subjects (age: 27.6 ± 6.2 years, gender: males 395/451 = 87.6%) volunteered. Musculoskeletal injury data were extracted from subjects' medical charts and injuries that occurred during 1 year were described. Injury frequency, injury anatomic location and sublocation, injury cause, activity when injury occurred, and injury type were described. Injury frequency was 29.5 injuries per 100 subjects per year. Most injures affected the lower extremity (60.2% of injuries) and common anatomic sublocations for injuries were the ankle (17.3%) and knee (15.0%). Frequent causes of injuries were running (13.5%) and direct trauma (9.0%). Physical training was associated with 29.3% of the injuries. A majority of injuries were classified as pain/spasm/ache (29.3%), without further elucidation of pathology. Other frequent injury types were sprain (21.8%) and strain (14.3%). The descriptive epidemiology of musculoskeletal injuries in this population underscores the need to explore the modifiable risk factors of potentially preventable lower extremity injuries associated with physical training and running. There is scope for the development of an optimized and targeted physical training program for injury prevention in this population.

Evaluation of role 2 (R2) medical resources in the Afghanistan combat theater: Initial review of the joint trauma system R2 registry.

BACKGROUND: A Role 2 registry (R2R) was developed in 2008 by the US Joint Trauma System (JTS). The purpose of this project was to undertake a preliminary review of the R2R to understand combat trauma epidemiology and related interventions at these facilities to guide training and optimal use of forward surgical capability in the future. METHODS: A retrospective review of available JTS R2R records; the registry is a convenience sample entered voluntarily by members of the R2 units. Patients were classified according to basic demographics, affiliation, region where treatment was provided, mechanism of injury, type of injury, time and method of transport from point of injury (POI) to R2 facility, interventions at R2, and survival. Analysis included trauma patients aged ≥18 years or older wounded in year 2008 to 2014, and treated in Afghanistan. RESULTS: A total of 15,404 patients wounded and treated in R2 were included in the R2R from February 2008 to September 2014; 12,849 patients met inclusion criteria. The predominant patient affiliations included US Forces, 4,676 (36.4%); Afghan Forces, 4,549 (35.4%); and Afghan civilians, 2,178 (17.0%). Overall, battle injuries predominated (9,792 [76.2%]). Type of injury included penetrating, 7,665 (59.7%); blunt, 4,026 (31.3%); and other, 633 (4.9%). Primary mechanism of injury included explosion, 5,320 (41.4%); gunshot wounds, 3,082 (24.0%); and crash, 1,209 (9.4%). Of 12,849 patients who arrived at R2, 167 (1.3%) were dead; of 12,682 patients who were alive upon arrival, 342 (2.7%) died at R2. CONCLUSION: This evaluation of the R2R describes the patient profiles of and common injuries treated in a sample of R2 facilities in Afghanistan. Ongoing and detailed analysis of R2R information may provide evidence-based guidance to military planners and medical leaders to best prepare teams and allocate R2 resources in future operations. Given the limitations of the data set, conclusions must be interpreted in context of other available data and analyses, not in isolation. LEVEL OF EVIDENCE: Epidemiologic study, level IV.

Suboptimal Nutritional Characteristics in Male and Female Soldiers Compared to Sports Nutrition Guidelines.

The purpose of this study was to evaluate the nutrient intake of male and female Soldiers in the 101 st Airborne Division (Air Assault) compared to sports nutrition standards for athletes, and to identify suboptimal eating characteristics that may impair physical performance and jeopardize military readiness. Male and female Soldiers from the 101 st Airborne Division (Air Assault) completed a 24-hour dietary recall and nutrition history questionnaire before anthropometric and body composition measurements were taken. Compared to sports nutrition guidelines, Soldiers of the 101 st under consume carbohydrates (males: 3.9 ± 2.0 vs. 5.0 g/kg, p < 0.001; females: 4.0 ± 2.1 vs. 5.0 g/kg, p = 0.001), male Soldiers eat too much fat (32.4% of kcal vs. <30% of kcal, p = 0.000) and saturated fat (males: 10.5 ± 3.9% of kcal vs. 10.0% of kcal, p = 0.044), and both males and females follow a meal pattern that may not optimize energy availability throughout the day. Eating too much fat and under fueling carbohydrate may negatively impact the adaptations to physical training and compromise overall health. Although Soldiers continue to participate in arduous training programs, future research should be aimed at determining the energy and macronutrient needs to fuel and recover from specific types of military training.

Lumbar spine and hip flexibility and trunk strength in helicopter pilots with and without low back pain history.

BACKGROUND: Low back pain (LBP) is one of the most common musculoskeletal issues facing military helicopter pilots. It is clinically important to identify differences in musculoskeletal characteristics between pilots with and without a LBP history for formulating effective interventions. OBJECTIVE: To compare lumbar spine and hip flexibility and trunk strength in pilots with and without a LBP history. METHODS: A total of 30 pilots with a LBP history were matched with pilots without a LBP history. An isokinetic dynamometer and a digital inclinometer were used to evaluate trunk and hip strength and a range-of-motion (ROM), respectively. All tests were performed bilaterally, if applicable, and agonist/antagonist ratios and side-to-side (low/high) symmetries were calculated. Paired t-tests or Wilcoxon tests were used to assess group differences (p <  0.050). RESULTS: The LBP group demonstrated significantly lower trunk extension strength and trunk extension/flexion strength ratio (p <  0.008). The LBP group demonstrated significantly less lateral flexion ROM as well as greater lateral flexion and rotation side-to-side asymmetry (p <  0.009). The LBP group demonstrated significantly greater total hip rotation side-to-side asymmetry (p = 0.037). CONCLUSIONS: Given the results, specific exercises that are targeted to improve trunk strength, ROM, and side-to-side symmetries could be developed to reduce LBP in helicopter pilots.

Integration of XNAT/PACS, DICOM, and Research Software for Automated Multi-modal Image Analysis.

Traumatic brain injury (TBI) is an increasingly important public health concern. While there are several promising avenues of intervention, clinical assessments are relatively coarse and comparative quantitative analysis is an emerging field. Imaging data provide potentially useful information for evaluating TBI across functional, structural, and microstructural phenotypes. Integration and management of disparate data types are major obstacles. In a multi-institution collaboration, we are collecting electroencephalogy (EEG), structural MRI, diffusion tensor MRI (DTI), and single photon emission computed tomography (SPECT) from a large cohort of US Army service members exposed to mild or moderate TBI who are undergoing experimental treatment. We have constructed a robust informatics backbone for this project centered on the DICOM standard and eXtensible Neuroimaging Archive Toolkit (XNAT) server. Herein, we discuss (1) optimization of data transmission, validation and storage, (2) quality assurance and workflow management, and (3) integration of high performance computing with research software.