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Background: Military aircrews' health status is critical to their mission readiness, as they perform physically and cognitively demanding tasks in nontraditional work environments. Research Objectives: Our objective is to develop a broad operational risk assessment framework and demonstrate its applicability to health risks to aircrews because of airborne chemical exposure, considering stressors such as heat and exertion.Methods: Extrapolation of generic exposure standards to military aviation-specific conditions can include computation of risk-relevant internal dosimetry estimates by incorporating changes in breathing patterns and blood flow distribution because of aspects of the in-flight environment. We provide an example of the effects of exertion on peak blood concentrations of 1,2,4-trimethylbenzene computed using a physiologically based pharmacokinetic model.Results: Existing published collections on the effects of flight-related stressors on breathing patterns and blood flow address only a limited number of stressors. Although data exist that can be used to develop operational exposure limits specific to military aircrew activities, efforts to integrate this information in specific chemical assessments have been limited.Conclusions: Efforts to develop operational exposure limits would benefit from guidance on how to make use of existing assessments and expanded databases of the impact of environmental stressors on adult human physiology. [ABSTRACT FROM AUTHOR]

Background: The prevalence of Achilles tendon (AT) pathology is common and can result in disability. Understanding normal AT properties can improve our ability to prevent AT injuries. We examined the cross-sectional area of the AT at multiple levels in an asymptomatic population of Army Rangers.Methods: This is a prospective cohort study composed of 41 voluntarily recruited United States Army Rangers deployed in a combat theater. All subjects were members of the Ranger Regiment participating in more than 20 h of intense bipedal non-sport weekly training with no history of AT pathology. While standing, each subject had bilateral AT calcaneal tuberosity insertions (0 cm) marked, along with skin markings made at 2 cm, 4 cm, and 6 cm superior to the AT insertion. AT diameter was measured at each level in the coronal and sagittal planes using ultrasound.Results: Mean sagittal diameter of the AT was 4.4 mm, 4.3 mm, 4.2 mm, and 3.9 mm at 0 cm, 2 cm, 4 cm, and 6 cm, respectively. Mean coronal diameter of the AT was 19.3 mm, 14.7 mm, 13.8 mm, and 14.5 mm at 0 cm, 2 cm, 4 cm, and 6 cm, respectively. The cross-sectional area was calculated as 0.66 cm2, 0.5 cm2, 0.46 cm2, and 0.44 cm2 at 0 cm, 2 cm, 4 cm, and 6 cm, respectively.Conclusion: Our data suggest that increased non-sport activity may not increase the cross-sectional area of the AT. Identifying the normal diameter at multiple levels throughout the most commonly injured area may improve the provider's ability to identify early disease processes and apply targeted interventions to help slow or prevent progression and possible rupture.Level of Evidence: Level III-V. [ABSTRACT FROM AUTHOR]

Objective: The high-mobility multipurpose wheeled vehicle (HMMWV) is a light military tactical vehicle. During Operation Iraqi Freedom and Operation Enduring Freedom, the U.S. Army modified the HMMWV into a combat vehicle by adding vehicle armor, which made the vehicle more difficult to control and more likely to roll over. Consequently, reports of fatal rollover accidents involving up-armored HMMWVs began to accumulate during the up-armoring period (August 2003 to April 2005). Furthermore, the lack of occupant restraint use prevalent in a predominantly young, male, and enlisted military population compounded the injuries resulting from these accidents. In this retrospective case series analysis, we describe the characteristics of U.S. Army HMMWV rollover accidents, occupants, and injuries reported worldwide from fiscal year 1992 to 2013 based on reported occupant restraint use.Methods: We conducted all analyses using Microsoft Excel 2010 and SAS version 9.1. Because this analysis does not constitute human subjects research, no institutional review board review was required. First, we obtained U.S. Army HMMWV accident records from the U.S. Army Combat Readiness Center, and selected those records indicating a HMMWV rollover had occurred. Next, we successively deduplicated the records at the accident, vehicle, occupant, and injury levels for descriptive analysis of characteristics at each level. For each occupant position, we calculated relative, attributable, and population attributable risks of nonfatal and fatal injury based on reported occupant restraint use. Finally, we analyzed body part injured and nature of injury to characterize the injury patterns that HMMWV occupants in each position sustained based on restraint use. We performed a χ2 test of homogeneity to assess differences in injury patterns between restrained and unrestrained occupants.Results: A total of 819 U.S. Army HMMWV rollover accidents worldwide were reported from October 1991 through May 2013 involving 821 HMMWVs and 1,395 occupants (828 nonfatally injured, 151 fatally injured, and 416 noninjured). Thirty-five percent of more severe (class A and B) accidents involved the M1114 up-armored variant, whereas 32% of less severe (class C and D) accidents involved the M998 nonarmored variant. Unrestrained occupants were 20% more likely to be nonfatally injured and 5.6 times more likely to be fatally injured than were restrained occupants. Among unrestrained occupants, restraint use could have potentially saved 82% of lives lost. Among all occupants involved in a HMMWV rollover, an estimated 56% of fatalities could have been prevented by restraint use. Unrestrained drivers and vehicle commanders had greater than expected torso injuries, while restrained vehicle commanders and passengers had greater than expected upper extremity injuries. Unrestrained drivers had greater than expected fractures, whereas restrained drivers and vehicle commanders had greater than expected sprains/strains.Conclusion: While reporting bias may exist, nevertheless these results show that occupant restraint use confers substantial life-saving protection to HMMWV occupants in rollover accidents. Therefore, commanders, safety officers, and peers should continue to promote and enforce restraint use consistently during all Army ground operations and training involving HMMWVs. Doing so will save Soldiers' lives in rollover accidents during the remaining years of the HMMWV program. [ABSTRACT FROM AUTHOR]

Introduction: Dietary intake of military initial entry trainees is often inadequate because of the structured food environment, lack of snacking, and limited time for meals. Inadequate intake during training increases risk for injury, poor performance, and attrition from training. A performance nutrition initiative was implemented at Joint Base San Antonio Lackland to mitigate this inadequacy in Air Force trainees and better reflect recommendations for active populations and mitigate nutritional inadequacy.Materials and Methods: Trainees (N = 867) in two squadrons either received a nutrition bar before bed (snack squadron n = 423) or did not (standard squadron n = 444). This study retrospectively compared trainees' attrition and fitness measures as recorded in the Basic Military Training (BMT) Surveillance database.Results: Both groups had similar rates of attrition and graduation at the end of 8 weeks (p = 0.23). At the start of training, only one out of four trainees in either Squadron passed the Physical Fitness Assessment (PFA). Although both squadrons' fitness measures improved as a result of the effects of training, the snack squadron had a significantly greater percent improvement in all PFA categories (p < 0.001), as represented by improved muscular fitness measures (p < 0.001), decreased median run time (p = 0.001), and greater improvement in scaled run scores (p = 0.013) as compared to the standard squadron. Those who received the snack were 1.62 (confidence interval: 1.2-2.2) times more likely to pass the PFA at 4 weeks than those who did not receive the snack.Conclusion: This study shows that military trainees' fitness improves with a modest nutritional supplement and suggests that optimizing overall nutrition benefits trainees. Attrition from BMT costs the U.S. Air Force up to $22,000 per trainee lost. In contrast, a trainee could receive one nutrition bar per day during BMT for $34. As the nutrition bar initiative improves fitness as well as costs less than recruiting and medically treating trainees whom ultimately attrite from training, the snack intervention was beneficial. Future studies of strategic nutrition interventions in military training populations can help trainees to better meet their macronutrient and micronutrient needs and further optimize training performance. [ABSTRACT FROM AUTHOR]

This study compares population mean hearing threshold levels in decibels (dB) at 4 kHz among the 2001-02 National Health and Nutrition Examination Survey (NHANES) (n = 1,872) and the 2003-05 Fort Bliss Army Active Duty (AD) (n = 9,096), National Guard (NG) (n = 3,842), and Reserve Components (RC) (n = 2,025) and by gender. Comparisons between male populations show that mean hearing thresholds are not significantly different (p < 0.05) between U.S. Army Active Duty males and NHANES males, which differ from a 1984 U.S. Army Active Duty/1971-74 NHANES study showing significantly higher hearing thresholds for the Army Active Duty population. In addition, this study shows that Active Duty males have significantly lower hearing thresholds than National Guard males at ages <40 years old. Female groups generally have significantly lower hearing thresholds than male groups at all ages, but there are not significant differences between female military and civilian populations. [ABSTRACT FROM AUTHOR]