Utility of preinduction tests as predictors of attrition in infantry recruits: a prospective study.

INTRODUCTION: Infantry recruit attrition wastes resources and can affect combat readiness. The purpose of this study was to examine the utility of preinduction tests as a predictor of attrition among conscripts in the first year of infantry training. METHODS: 303 infantry conscripted recruits participated in a prospective study. Before their service, recruits received health profile and Quality Group Scores (QGSs). Recruits were screened at induction using questionnaires, by functional movement screening (FMS) and by upper and lower quarter Y-balance, dynamic and anthropometric tests. They were followed for musculoskeletal injuries and attrition during the first year of training. RESULTS: 165/303 (54.5%) recruits were diagnosed with musculoskeletal injury or pain during the first year of their training. 15.2% did not complete their first year of service as combatants and 5.9% were discharged. On multivariable binary stepwise logistic regression analysis for attrition, protective factors were higher QGSs (OR 0.78, 95% CI 0.69 to 0.89) and recruits diagnosed with musculoskeletal injuries or pain (OR 0.20, 95% CI 0.09 to 0.48). Pain in the balance test performed at the beginning of training was a risk factor (OR 3.31, 95% CI 1.44 to 7.61). These factors explained only 15.4% of the variance in attrition. CONCLUSIONS: FMS was not a significant predictor of infantry attrition. Measuring the three variables found to be associated with infantry attrition would seem to be valuable when the number of infantry candidates greatly exceeds the number of infantry positions. Transferring infantry attriters to non-combatant roles and not discharging them is a way to manage the problem of attrition.

Musculoskeletal injuries in military personnel-Descriptive epidemiology, risk factor identification, and prevention.

OBJECTIVES: To provide an overall perspective on musculoskeletal injury (MSI) epidemiology, risk factors, and preventive strategies in military personnel. DESIGN: Narrative review. METHODS: The thematic session on MSIs in military personnel at the 5th International Congress on Soldiers' Physical Performance (ICSPP) included eight presentations on the descriptive epidemiology, risk factor identification, and prevention of MSIs in military personnel. Additional topics presented were bone anabolism, machine learning analysis, and the effects of non-steroidal anti-inflammatory drugs (NSAIDs) on MSIs. This narrative review focuses on the thematic session topics and includes identification of gaps in existing literature, as well as areas for future study. RESULTS: MSIs cause significant morbidity among military personnel. Physical training and occupational tasks are leading causes of MSI limited duty days (LDDs) for the U.S. Army. Recent studies have shown that MSIs are associated with the use of NSAIDs. Bone MSIs are very common in training; new imaging technology such as high resolution peripheral quantitative computed tomography allows visualization of bone microarchitecture and has been used to assess new bone formation during military training. Physical activity monitoring and machine learning have important applications in monitoring and informing evidence-based solutions to prevent MSIs. CONCLUSIONS: Despite many years of research, MSIs continue to have a high incidence among military personnel. Areas for future research include quantifying exposure when determining MSI risk; understanding associations between health-related components of physical fitness and MSI occurrence; and application of innovative imaging, physical activity monitoring and data analysis techniques for MSI prevention and return to duty.

Medial tibial stress fracture diagnosis and treatment guidelines.

OBJECTIVES: To validate and make evidence based changes to the Israel Defense Forces medial tibial stress fracture diagnosis and treatment protocol. DESIGN: Prospective cohort study. METHODS: 429 Elite infantry recruits were reviewed for signs and symptoms of medial tibial stress fracture during 14 weeks of basic training. Suspicion of medial tibial stress fracture was based on the presence of pain, tenderness <1/3 the length of the tibia and a positive fulcrum and/or hop test. Recruits with suspected medial tibial stress fractures were initially treated with 10-14 days of rest. Bone scan was performed only when recruits failed to respond to the rest regimen or required immediate diagnosis. RESULTS: 31 Out of 49 recruits with a suspicion of medial tibial stress fracture underwent bone scan, including 8/26 recruits whose symptoms did not resolve after being treated clinically as stress fractures. There was a significantly greater incidence of medial tibial stress fractures when a positive hop test was present in addition to tibial pain and tenderness (p=0.0001), odds ratio 52.04 (95% CL, 2.80-967.74). Medial tibial stress fracture was found to occur when the band of tibial tenderness was ≤10cm in length. Tibial pain scores were not predictive of stress fracture. CONCLUSIONS: This validation study provides the clinician with evidence based guidelines for the clinical diagnosis and treatment of medial stress fractures and their differentiation from shin splints. An initial treatment protocol without the use of imaging was found to be effective in more than two-thirds of the cases.

Cognitive Effects of Astaxanthin Pretreatment on Recovery From Traumatic Brain Injury.

Traumatic brain injury (TBI), caused by mechanical impact to the brain, is a leading cause of death and disability among young adults, with slow and often incomplete recovery. Preemptive treatment strategies may increase the injury resilience of high-risk populations such as soldiers and athletes. In this work, the xanthophyll carotenoid Astaxanthin was examined as a potential nutritional preconditioning method in mice (sabra strain) to increase their resilience prior to TBI in a closed head injury (CHI) model. The effect of Astaxanthin pretreatment on heat shock protein (HSP) dynamics and functional outcome after CHI was explored by gavage or free eating (in pellet form) for 2 weeks before CHI. Assessment of neuromotor function by the neurological severity score (NSS) revealed significant improvement in the Astaxanthin gavage-treated group (100 mg/kg, ATX) during recovery compared to the gavage-treated olive oil group (OIL), beginning at 24 h post-CHI and lasting throughout 28 days (p < 0.007). Astaxanthin pretreatment in pellet form produced a smaller improvement in NSS vs. posttreatment at 7 days post-CHI (p < 0.05). Cognitive and behavioral evaluation using the novel object recognition test (ORT) and the Y Maze test revealed an advantage for Astaxanthin administration via free eating vs. standard chow during recovery post-CHI (ORT at 3 days, p < 0.035; improvement in Y Maze score from 2 to 29 days, p < 0.02). HSP profile and anxiety (open field test) were not significantly affected by Astaxanthin. In conclusion, astaxanthin pretreatment may contribute to improved recovery post-TBI in mice and is influenced by the form of administration.

Correction to: Astaxanthin supplementation impacts the cellular HSP expression profile during passive heating.

Due to an unfortunate misunderstanding, the top part of Figures 2 and 3 are not correctly displayed. The original article has been corrected and the proper version of Figures 2 and 3 is also published here.

Astaxanthin supplementation impacts the cellular HSP expression profile during passive heating.

Astaxanthin is a powerful carotenoid antioxidant prevalent in marine organisms and approved as a food supplement. Recent studies have demonstrated Astaxanthin's beneficial attributes in various health states. Following initial reports of potential heat protective properties in Astaxanthin supplemented rats, we present here results of a novel study examining the effect of Astaxanthin supplementation on the heat shock response in rats in relation to core temperature (Tc) and the ensuing physiological strain. Two hours of heat stress at 41 °C during which rats developed their thermoregulatory hyperthermic plateau resulted in progressive increases in HSP72 and HSP27 in the Astaxanthin (Oleoresin)-treated group but not in the control (Olive oil) group. Enhanced elevation in HSPs suggests that Astaxanthin supplementation may augment the cellular stress protective response to heat stress.

Physiological Differences Between Heat Tolerant and Heat Intolerant Young Healthy Women.

Purpose: Heat intolerance (HI) is determined in the Israel Defense Force according to a heat tolerance test (HTT) before returning to duty after an exertional heat stroke (EHS) event. Recently, increased numbers of female combatants resulted in an increased number of EHS cases among women and a higher percentage of heat intolerance (HI) individuals. We aimed to evaluate the differences between tolerance to heat among women performing an HTT in relation to their menstrual cycle phase. Method: Thirty-three female participants were sorted into two groups: HI and heat tolerant (HT) according to two HTTs performed during both the luteal and follicular phases of the menstrual cycle or while consuming and during a break from consuming contraceptives. Results: HT women had an 18% higher maximal oxygen uptake (p < .005, 95% CI [2.6,9.8]) and 1.2% lower skin temperature in the HTT at the during and follicular phases (p < .01, 95% CI [0.12,0.77]) and 1.7% lower at the off and luteal phases (p < .001, 95% CI [0.34,0.92]). The mean sweat rate was 14% lower among the HI group only at the HTT at the during and follicular phases (p < .05, 95% CI (3,88)]). Conclusion: We found that HT can be predicted using aerobic capacity and core body temperature. Moreover, during the luteal phase, women presented altered thermoregulation that decreased the probability of being HT. This emphasizes the importance of considering the HT/HI criteria in the HTT for women, according to their aerobic ability and menstrual-cycle phase.

Asthaxanthin Improves Aerobic Exercise Recovery Without Affecting Heat Tolerance in Humans.

Objectives: To examine the supplementation effects of the xanthophyll carotenoid Astaxanthin on physical performance and exertional heat strain in humans. Design: A randomized double blind placebo controlled trial. Methods: Twenty two male participants (Age: 23.14 ± 3.5 y, height: 175 ± 6 cm, body mass: 69.6 ± 8.7 kg, % body fat: 16.8 ± 3.8) received placebo (PLA, n = 10) or Astaxanthin (ATX, n = 12) 12 mg/day Per os (P.O), for 30 days, and were tested pre and post-supplementation with a maximal oxygen uptake (VO2 Max) test and the heat tolerance test (HTT) (2 h walk at 40°C, 40% relative humidity (RH), 5 kph, 2% incline). NIH database registration no. NCT02088242. Gas exchange, Heart rate (HR), Relative perceived exertion (RPE), and blood lactate were measured during the VO2 Max test. Heart rate (HR), rectal (Trec), and skin (Tskin) temperatures, RPE, and sweat rate (SR) were monitored in the HTT. Serum heat shock protein 72 (HSP72), Creatine phospho-kinase (CPK), C-reactive protein (CRP), and lipid profile were measured before and after the test. Results: The rise in blood lactate caused by the VO2 Max test was significantly diminished in the ATX group (9.4 ± 3.1 and 13.0 ± 3.1 mmole*l-1 in the ATX and PLA groups, respectively P < 0.02), as was the change in oxygen uptake during recovery (-2.02 ± 0.64 and 0.83 ± 0.79% of VO2 Max in the ATX and PLA group, respectively, p = 0.001). No significant differences were observed in the anaerobic threshold or VO2 Max. In the HTT, no significant physiological or biochemical differences were observed (HR <120 bpm, Trec rose by ~1°C to <38°C, no difference in SR). Conclusions: Astaxanthin supplementation improved exercise recovery. No benefit was observed for ATX over PLA in response to heat stress. Further examination of Astaxanthin in higher exertional heat strain is required.

The validity of the heat tolerance test in prediction of recurrent exertional heat illness events.

OBJECTIVES: Heat-tolerance-testing (HTT) protocol is used as a screening test for secondary prevention of exertional heat illness (EHI) in the military. Subjects whose test results are positive (heat-intolerant, HI) are presumed to be at higher risk of repeated EHI events than heat-tolerant subjects (HT) and are therefore prevented from return to combat duty, but may return to unsupervised recreational activity. Our aim was to determine, whether HTT results predict the risk of repeated episodes of exertional heat illness (EHI). DESIGN: Retrospective cohort. METHODS: One-hundred-forty-five subjects (110 HT, 35 HI) who were diagnosed with an EHI event by a physician and underwent HTT during 2008-2015 were contacted and asked about recurrence of EHI. Incidence of recurrent events was reported as number of cases per 1000 person-years. Ratio of events among HI and HT individuals was presented as rate ratio (RR) and its 95% confidence interval. RESULTS: Of the 145 patients, six (4.1%) had experienced recurrent EHI events (10.63 per 1000PY): four HI subjects (11.4%, 26.6 per 1000PY) and two HT (1.8%, 4.8 per 1000PY) (RR=5.504, CI 95%=1.01-30, p=0.027). Only one of the six recurrent events was a heat stroke (HT individual), other five were heat exhaustions. Sensitivity, specificity and diagnostic accuracy of HTT were 66.7%, 77.7% and 77.2%, respectively. CONCLUSIONS: The risk of EHI recurrence is measurable and can be discussed with patients before they return to sports. A referral to HTT can be considered, as negative HTT result is associated with substantial and significant EHI risk reduction.

Adherence to acne treatment guidelines in the military environment - a descriptive, serial cross-sectional study.

BACKGROUND: Acne vulgaris, a common skin disease, affects up to 80 % of the population. Moderate to severe acne requires treatment with a combination of topical and oral drugs such as antibiotics, hormones and retinoids. Retinoids have many contraindications and adverse effects requiring close monitoring. The study's objectives were to describe prescribing trends in acne medication over time in a military setting, and assess physician adherence to guidelines for acne treatment, including drug precautions, clinical monitoring, and treatment progression. METHODS: We conducted a descriptive, serial cross-sectional study of acne drugs prescribed in the Israel Defense Forces (IDF) in the years 2002-2007, analyzing the classes of drugs prescribed and patient characteristics. In addition, the clinical quality of the medical encounter was assessed by examining physician adherence to IDF guidelines. RESULTS: Between 2002 and 2007, 64,281 patients were treated for acne. Treatment courses generally persisted for 1-2 months. Over 70 % of female patients receiving oral retinoids were not concomitantly receiving oral contraceptives. CONCLUSION: This study provides a unique perspective of acne treatment in a military setting, overall displaying good adherence to general guidelines. The common prescription of oral retinoids to young females without concomitant contraception is alarming.

Physiological and Medical Aspects That Put Women Soldiers at Increased Risk for Overuse Injuries.

Anthropometric and physiological factors place female soldiers at a disadvantage relative to male soldiers in most aspects of physical performance. Average aerobic and anaerobic fitness levels are lower in women than in men. Thus, women have a lower overall work capacity and must exert themselves more than men to achieve the same output. The lower weight and fat-free mass and the higher body fat of women are associated with lower muscle strength and endurance, placing them at a disadvantage compared with men in performing military tasks such as lifting and carrying weights, or marching with a load. Working at a higher percentage of their maximal capacity to achieve the same performance levels as men, women tire earlier. Their smaller size, skeletal anatomy, and different bone geometry also predispose women to a higher incidence of exercise-related injuries. Consequently, the attrition rate of female soldiers in combat units is higher than that of their male counterparts. This review summarizes the literature on gender-related physiological and anatomical differences that put female soldiers at an increased risk of exercise-related injuries.

Cytokines and their role in hyperthermia and heat stroke.

Cytokines are intracellular peptides that serve as immune mediators. The levels of both pro- and anti-inflammatory cytokines have been demonstrated to rise in the event of heat stroke in both human and animal models. Different hyperthermic states, including both normal exercise-induced hyperthermia and classical and exertional heat stroke, result in unique characteristic profiles of plasma cytokines. The complexity of the interaction between pro- and anti-inflammatory cytokines is outlined in the vast number of experimental studies and clinical observations reported in the literature. However, there is no unanimous logic in studying the changes in cytokine levels, and therefore, it is difficult to compare the effects seen in the different reports. The strong inflammatory response to heat stroke increases after the cessation of heat stress and is intricately involved both in damage-generating processes and in repair mechanisms that are put into action during the recovery phase. In surviving individuals, this response diminishes in magnitude as time progresses and eventually subsides to allow return-to-normal homeostasis. A greater magnitude of the inflammatory response is often associated with poor prognosis and even fatalities, suggesting an imbalance of the immune system, which causes an unregulated inflammatory response. This review describes the common known processes relating to the predominant cytokines altered in the event of heat injury. The role of cytokines, specifically in the pathophysiology of heat stroke, is elaborated and depicted as part of a biaxial model pertaining to the physiological and cellular/biochemical aspects of heat stroke.