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A user trial was undertaken to determine whether a shock-absorbing insole is suitable for military use. Two thicknesses of insole (3 mm and 6 mm) were studied and were issued to 38 Royal Marine recruits to wear in their military boots for weeks 12 to 30 of training. Biomechanical measurements showed that both thicknesses of insole significantly (p < 0.05) attenuated the peak pressures generated at heel strike and during forefoot loading when new (relative to a no-insole condition) and that this was well maintained after wear. This was supported by mechanical tests conducted on the insoles. It was concluded that the insoles are sufficiently durable for military use. The main user complaint was that water retention reduced the comfort of the insoles; however, insulation tests conducted with a foot manikin indicated that switching from the current-issue Saran insoles to the trial insoles would not increase the risk of recruits sustaining nonfreezing cold injuries to their feet. [ABSTRACT FROM AUTHOR]

Background: The current in-service Royal Naval Fitness Test has two elements to test the aerobic endurance and muscular strength of Service Personnel through generic field-based tests and a short job task simulation. However, in 2017 the Royal Navy (RN) identified a requirement to update their in-service fitness test to align with international best practice., Objective: The purpose of this study was to conduct an Objective Job Task Analysis on critical, physically demanding tasks that could be undertaken by RN sailors during sea deployments., Methods: Twenty-one training exercises were observed across a range of contexts; Type 23 Frigates, Type 45 Destroyers and at shore-based training facilities. A total of 203 RN personnel (age 27.8±7.1 years) were observed undertaking 36 job related tasks (e.g., 'firefighting', 'damage control', 'abandon ship' and 'casualty handling'). Tasks were evaluated by cardiovascular response, primary functional movements and contextual factors to aid a Military Judgement Panel in task list down-selection., Results: 14 Criterion Tasks (e.g., 'firefighting', 'two-person magazine stowage' and 'casualty handling') were selected to progress to the next stage of the process. Five tasks were selected based on cardiovascular responses and a further nine tasks selected based on task ergonomics and other factors., Conclusion: This research has identified and quantified the most physically demanding, critical roles undertaken by RN sailors on sea deployments and will inform the development of the RN Physical Employment Standard.

Background: The Ministry of Defence Police recognised the requirement to develop a Physical Employment Standard (PES) for the Authorised Firearms Officer -Counter Terrorism (AFO-CT) role profile., Objective: The purpose of this study was to conduct a job task analysis to identify the most critical and physically demanding tasks performed by AFO-CT personnel., Methods: A focus group and online survey were undertaken to identify a list of job tasks. The down-selected job tasks were objectively monitored during training events to determine the most physically demanding tasks. Tasks were ranked by physical demand and additional factors (e.g., operational load, primary physical actions). Down-selected tasks were then included in a Subject Matter Experts (SME) task scenario generation workshop. The physiological demands of the resulting standardised scenarios were determined., Results: The focus group (n = 11) identified 13 physically demanding and critical role-related tasks. The subsequent survey (n = 907) down-selected eight tasks with a 'moderate' demand or greater. Thirty AFO-CT personnel completed the eight tasks as part of routine training events. From the observed tasks, four tasks were down-selected and combined into two operationally relevant, reasonable worst-case standardised scenarios during a SME workshop. The two scenarios, 'Conduct Armed Search in the Open for an Active Shooter' and 'Victim Focussed Emergency Search' were used in subsequent phases of the research to form the basis of the AFO-CT PES., Conclusion: This research elucidated the most physically demanding job tasks within the AFO-CT role profile to inform the development of a MOD armed policing PES.

Stress fractures are common amongst healthy military recruits and athletes. Reduced vitamin D availability, measured by serum 25-hydroxyvitamin D (25OHD) status, has been associated with stress fracture risk during the 32-week Royal Marines (RM) training programme. A gene-environment interaction study was undertaken to explore this relationship to inform specific injury risk mitigation strategies. Fifty-one males who developed a stress fracture during RM training (n = 9 in weeks 1-15; n = 42 in weeks 16-32) and 141 uninjured controls were genotyped for the vitamin D receptor (VDR) FokI polymorphism. Serum 25OHD was measured at the start, middle and end (weeks 1, 15 and 32) of training. Serum 25OHD concentration increased in controls between weeks 1-15 (61.8±29.1 to 72.6±28.8 nmol/L, p = 0.01). Recruits who fractured did not show this rise and had lower week-15 25OHD concentration (p = 0.01). Higher week-15 25OHD concentration was associated with reduced stress fracture risk (adjusted OR 0.55[0.32-0.96] per 1SD increase, p = 0.04): the greater the increase in 25OHD, the greater the protective effect (p = 0.01). The f-allele was over-represented in fracture cases compared with controls (p<0.05). Baseline 25OHD status interacted with VDR genotype: a higher level was associated with reduced fracture risk in f-allele carriers (adjusted OR 0.39[0.17-0.91], p = 0.01). Improved 25OHD status between weeks 1-15 had a greater protective effect in FF genotype individuals (adjusted OR 0.31[0.12-0.81] vs. 1.78[0.90-3.49], p<0.01). Stress fracture risk in RM recruits is impacted by the interaction of VDR genotype with vitamin D status. This further supports the role of low serum vitamin D concentrations in causing stress fractures, and hence prophylactic vitamin D supplementation as an injury risk mitigation strategy., Competing Interests: The authors have declared that no competing interests exist.

Introduction: Musculoskeletal injuries are common during military and other occupational physical training programs. Employers have a duty of care to reduce employees' injury risk, where females tend to be at greater risk than males. However, quantification of principle co-factors influencing the sex-injury association, and their relative importance, remain poorly defined. Injury risk co-factors were investigated during Royal Air Force (RAF) recruit training to inform the strategic prioritization of mitigation strategies., Material and Methods: A cohort of 1,193 (males n = 990 (83%); females n = 203 (17%)) recruits, undertaking Phase-1 military training, were prospectively monitored for injury occurrence. The primary independent variable was sex, and potential confounders (fitness, smoking, anthropometric measures, education attainment) were assessed pre-training. Generalized linear models were used to assess associations between sex and injury., Results: In total, 31% of recruits (28% males; 49% females) presented at least one injury during training. Females had a two-fold greater unadjusted risk of injury during training than males (RR = 1.77; 95% CI 1.49-2.10). After anthropometric, lifestyle and education measures were included in the model, the excess risk decreased by 34%, but the associations continued to be statistically significant. In contrast, when aerobic fitness was adjusted, an inverse association was identified; the injury risk was 40% lower in females compared with males (RR = 0.59; 95% CI: 0.42-0.83)., Conclusions: Physical fitness was the most important confounder with respect to differences in males' and females' injury risk, rather than sex alone. Mitigation to reduce this risk should, therefore, focus upon physical training, complemented by healthy lifestyle interventions., (Ministry of Defence © Crown Copyright 2018. If such material is available under the OGL, then a further acknowledgment will be required as follows: “Reproduced under the terms of the Open Government Licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/.)

Objectives: To investigate changes in renal status from exercise in the heat with acclimatisation and to evaluate surrogates markers of Acute Kidney Injury., Design: Prospective observational cohort study., Methods: 20 male volunteers performed 60 min standardised exercise in the heat, at baseline and on four subsequent occasions during a 23-day acclimatisation regimen. Blood was sampled before and after exercise for serum creatinine, copeptin, interleukin-6, normetanephrine and cortisol. Fractional excretion of sodium was calculated for corresponding urine samples. Ratings of Perceived Exertion were reported every 5 min during exercise. Acute Kidney Injury was defined as serum creatinine rise ≥26.5 μmol L -1 or fall in estimated glomerular filtration rate >25%. Predictive values of each candidate marker for developing Acute Kidney Injury were determined by ROC analysis., Results: From baseline to Day 23, serum creatinine did not vary at rest, but showed a significant (P<0.05) reduction post-exercise (120 [102, 139] versus 102 [91, 112] μmol L -1 ). Acute Kidney Injury was common (26/100 exposures) and occurred most frequently in the unacclimatised state. Log-normalised fractional excretion of sodium showed a significant interaction (exercise by acclimatization day), with post-exercise values tending to rise with acclimatisation. Ratings of Perceived Exertion predicted AKI (AUC 0.76, 95% confidence interval 0.65-0.88), performing at least as well as biochemical markers., Conclusions: Heat acclimatization is associated with reduced markers of renal stress and AKI incidence, perhaps due to improved regional perfusion. Acclimatisation and monitoring Ratings of Perceived Exertion are practical, non-invasive measures that could help to reduce renal injury from exercise in the heat., (Crown Copyright © 2019. Published by Elsevier Ltd. All rights reserved.)

Objective: The present review evaluated the effectiveness of environmental-based interventions aimed at improving the dietary and physical activity behaviours and body composition indices of adults in institutions., Design: A systematic review was conducted. Electronic databases (MEDLINE, Embase, PsycINFO, CINAHL, The Cochrane Library, Web of Science, ProQuest Dissertation and Theses, Scopus and Athena) were searched for relevant articles published between database inception and October 2017. Searching, selecting and reporting were undertaken according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement., Setting: Military establishments and maritime workplaces.ParticipantsAdults in institutions, aged 18-45 years., Results: A total of 27842 articles were screened for eligibility, nine studies (reported in eleven articles) were included in the review. Five studies used multilevel strategies and four used environmental strategies only. Duration of follow-up ranged from 3 weeks to 10 years. Eight of the studies reported significant positive effects on dietary behaviours, but effect sizes varied. The study that targeted physical activity had no effect on activity levels but did have a significant positive effect on physical fitness. No evidence was identified that the studies resulted in improvements in body composition indices., Conclusions: The evidence base appears to be in favour of implementing environmental interventions in institutions to improve the dietary behaviours of adults. However, due to the small number of studies included in the review, and the variable methodological quality of the studies and intervention reporting, further well-designed evaluation studies are required.

Soldier operational performance is determined by their fitness, nutritional status, quality of rest/recovery, and remaining injury/illness free. Understanding large fluctuations in nutritional status during operations is critical to safeguarding health and well-being. There are limited data world-wide describing the effect of extreme climate change on nutrient profiles. This study investigated the effect of hot-dry deployments on vitamin D status (assessed from 25-hydroxyvitamin D (25(OH)D) concentration) of young, male, military volunteers. Two data sets are presented (pilot study, n 37; main study, n 98), examining serum 25(OH)D concentrations before and during 6-month summer operational deployments to Afghanistan (March to October/November). Body mass, percentage of body fat, dietary intake and serum 25(OH)D concentrations were measured. In addition, parathyroid hormone (PTH), adjusted Ca and albumin concentrations were measured in the main study to better understand 25(OH)D fluctuations. Body mass and fat mass (FM) losses were greater for early (pre- to mid-) deployment compared with late (mid- to post-) deployment (P&lt;0·05). Dietary intake was well-maintained despite high rates of energy expenditure. A pronounced increase in 25(OH)D was observed between pre- (March) and mid-deployment (June) (pilot study: 51 (sd 20) v. 212 (sd 85) nmol/l, P&lt;0·05; main study: 55 (sd 22) v. 167 (sd 71) nmol/l, P&lt;0·05) and remained elevated post-deployment (October/November). In contrast, PTH was highest pre-deployment, decreasing thereafter (main study: 4·45 (sd 2·20) v. 3·79 (sd 1·50) pmol/l, P&lt;0·05). The typical seasonal cycling of vitamin D appeared exaggerated in this active male population undertaking an arduous summer deployment. Further research is warranted, where such large seasonal vitamin D fluctuations may be detrimental to bone health in the longer-term.

Acclimatization favors greater extracellular tonicity from lower sweat sodium, yet hyperosmolality may impair thermoregulation during heat stress. Enhanced secretion or action of vasopressin could mitigate this through increased free water retention. Aims were to determine responses of the vasopressin surrogate copeptin to dehydrating exercise and investigate its relationships with tonicity during short and long-term acclimatization. Twenty-three participants completed a structured exercise programme following arrival from a temperate to a hot climate. A Heat Tolerance Test (HTT) was conducted on Day-2, 6, 9 and 23, consisting of 60-min block-stepping at 50% VO 2 peak, with no fluid intake. Resting sweat [Na + ] was measured by iontophoresis. Changes in body mass (sweat loss), core temperature, heart rate, osmolality (serum and urine) and copeptin and aldosterone (plasma) were measured with each Test. From Day 2 to Day 23, sweat [Na + ] decreased significantly (adjusted P < 0.05) and core temperature and heart rate fell. Over the same interval, HTT-associated excursions were increased for serum osmolality (5 [-1, 9] vs. 9 [5, 12] mosm·kg -1 ), did not differ for copeptin (9.6 [6.0, 15.0] vs. 7.9 [4.3, 14.7] pmol·L -1 ) and were reduced for aldosterone (602 [415, 946] vs. 347 [263, 537] pmol·L -1 ). Urine osmolality was unchanging and related consistently to copeptin at end-exercise, whereas the association between copeptin and serum osmolality was right-shifted (P = 0.0109) with acclimatization. Unchanging urine:serum osmolality argued against increased renal action of vasopressin. In conclusion, where exercise in the heat is performed without fluid replacement, heat acclimatization does not appear to enhance AVP-mediated free water retention in humans., (© 2018 Crown copyright. Physiological Reports © 2018 published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.)

Purpose: Heat adaptation (HA) is critical to performance and health in a hot environment. Transition from short-term heat acclimatisation (STHA) to long-term heat acclimatisation (LTHA) is characterised by decreased autonomic disturbance and increased protection from thermal injury. A standard heat tolerance test (HTT) is recommended for validating exercise performance status, but any role in distinguishing STHA from LTHA is unreported. The aims of this study were to (1) define performance status by serial HTT during structured natural HA, (2) evaluate surrogate markers of autonomic activation, including heart rate variability (HRV), in relation to HA status., Methods: Participants (n = 13) were assessed by HTT (60-min block-stepping, 50% VO 2 peak) during STHA (Day 2, 6 and 9) and LTHA (Day 23). Core temperature (Tc) and heart rate (HR) were measured every 5 min. Sampling for HRV indices (RMSSD, LF:HF) and sympathoadrenal blood measures (cortisol, nephrines) was undertaken before and after (POST) each HTT., Results: Significant (P < 0.05) interactions existed for Tc, logLF:HF, cortisol and nephrines (two-way ANOVA; HTT by Day). Relative to LTHA, POST results differed significantly for Tc (Day 2, 6 and 9), HR (Day 2), logRMSSD (Day 2 and Day 6), logLF:HF (Day 2 and Day 6), cortisol (Day 2) and nephrines (Day 2 and Day 9). POST differences in HRV (Day 6 vs. 23) were + 9.9% (logRMSSD) and - 18.6% (logLF:HF)., Conclusions: Early reductions in HR and cortisol characterised STHA, whereas LTHA showed diminished excitability by Tc, HRV and nephrine measures. Measurement of HRV may have potential to aid real-time assessment of readiness for activity in the heat.

Purpose: To prevent heat-related illnesses, guidelines recommend limiting core body temperature (T c ) ≤ 38 °C during thermal stress. Copeptin, a surrogate for arginine vasopressin secretion, could provide useful information about fluid balance, thermal strain and health risks. It was hypothesised that plasma copeptin would rise with dehydration from occupational heat stress, concurrent with sympathoadrenal activation and reduced glomerular filtration, and that these changes would reflect T c responses., Methods: Volunteers (n = 15) were recruited from a British Army unit deployed to East Africa. During a simulated combat assault (3.5 h, final ambient temperature 27 °C), T c was recorded by radiotelemetry to differentiate volunteers with maximum T c  > 38 °C versus ≤ 38 °C. Blood was sampled beforehand and afterwards, for measurement of copeptin, cortisol, free normetanephrine, osmolality and creatinine., Results: There was a significant (P < 0.05) rise in copeptin from pre- to post-assault (10.0 ± 6.3 vs. 16.7 ± 9.6 pmol L -1 , P < 0.001). Although osmolality did not increase, copeptin correlated strongly with osmolality after the exposure (r = 0.70, P = 0.004). In volunteers with maximum T c  > 38 °C (n = 8) vs ≤ 38 °C (n = 7) there were significantly greater elevations in copeptin (10.4 vs. 2.4 pmol L -1 ) and creatinine (10 vs. 2 μmol L -1 ), but no differences in cortisol, free normetanephrine or osmolality., Conclusions: Changes in copeptin reflected T c response more closely than sympathoadrenal markers or osmolality. Dynamic relationships with tonicity and kidney function may help to explain this finding. As a surrogate for integrated physiological strain during work in a field environment, copeptin assay could inform future measures to prevent heat-related illnesses.

Background: Stress fractures (SFs) are one of the more severe overuse injuries in military training, and therefore, knowledge of potential risk factors is needed to assist in developing mitigating strategies., Purpose: To develop a prediction model for risk of SF in Royal Marines (RM) recruits during an arduous military training program., Study Design: Case-control study; Level of evidence, 3., Methods: RM recruits (N = 1082; age range, 16-33 years) who enrolled between September 2009 and July 2010 were prospectively followed through the 32-week RM training program. SF diagnosis was confirmed from a positive radiograph or magnetic resonance imaging scan. Potential risk factors assessed at week 1 included recruit characteristics, anthropometric assessment, dietary supplement use, lifestyle habits, fitness assessment, blood samples, 25(OH)D, bone strength as measured by heel broadband ultrasound attention, history of physical activity, and previous and current food intake. A logistic least absolute shrinkage and selection operator (LASSO) regression with 10-fold cross-validation was used to select potential predictors among 47 candidate variables. Model performance was assessed using measures of discrimination (c-index) and calibration. Bootstrapping was used for internal validation of the developed model and to quantify optimism., Results: A total of 86 (8%) volunteer recruits presented at least 1 SF during training. Twelve variables were identified as the most important risk factors of SF. Variables strongly associated with SF were age, body weight, pretraining weightbearing exercise, pretraining cycling, and childhood intake of milk and milk products. The c-index for the prediction model, which represents the model performance in future volunteers, was 0.73 (optimism-corrected c-index, 0.68). Although 25(OH)D and VO 2 max had only a borderline statistically significant association with SF, the inclusion of these factors improved the performance of the model., Conclusion: These findings will assist in identifying recruits at greater risk of SF during training and will support interventions to mitigate this injury risk. However, external validation of the model is still required., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: This work was supported by UK Ministry of Defence and the Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis (Grant reference 20194). A.J. is a consultant for Servier, UK Renal Registry, Oxford Craniofacial Unit, and Freshfields Bruckhaus Deringer, has grants/grants pending from Roche-Chugai, and receives honoraria from the Blood journal. N.K.A. is a paid consultant for Merck, Smith & Nephew, Nicox, Flexion, Bioventus, and Freshfields and has received grants from Roche, Bioiberica, and Novartis.

Aims: A prospective observational study was conducted in Royal Marines (RM) recruits to investigate throat carriage of group A Streptococcus (GAS) and incidence of soft tissue infections., Methods: 1012 RM recruits were followed through a 32-week training programme, with throat swabs being obtained in weeks 1, 6, 15, and 32. Alongside a separate cohort of 46 RM Young Officers (YO) undergoing training were sampled in parallel., Results: Carriage of group A Streptococcus was detected in only 5/1012 (0.49%) recruits at the beginning of training and remained low throughout training. There was no association between GAS carriage and development of soft tissue infection. There was no carriage of GAS in the smaller YO cohort at the start of training, (0/46). At week 6, a surge in GAS carriage was detected in 8/46 (17%) YO, that could be ascribed to a cluster of GAS genotype emm83., Conclusions: Asymptomatic GAS carriage is very infrequent among young adults in England and this should be borne in mind when considering the relevance of a positive throat swab result in symptomatic patients or outbreaks. Despite low prevalence, there is however potential for GAS to rapidly and transiently disseminate among adults during outbreaks., (Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.)

Unlabelled: The aim of this study was to investigate vitamin D status and stress fracture risk during Royal Marine military training. Poor vitamin D status was associated with an increased risk of stress fracture. Vitamin D supplementation may help to reduce stress fracture risk in male military recruits with low vitamin D status., Introduction: Stress fracture is a common overuse injury in military recruits, including Royal Marine (RM) training in the UK. RM training is recognised as one of the most arduous basic training programmes in the world. Associations have been reported between serum 25-hydroxyvitamin D (25(OH)D) and risk of stress fracture, but the threshold of 25(OH)D for this effect remains unclear. We aimed to determine if serum 25(OH)D concentrations were associated with stress fracture risk during RM training., Methods: We prospectively followed 1082 RM recruits (males aged 16-32 years) through the 32-week RM training programme. Troops started training between September and July. Height, body weight and aerobic fitness were assessed at week 1. Venous blood samples were drawn at weeks 1, 15 and 32. Serum samples were analysed for 25(OH)D and parathyroid hormone (PTH)., Results: Seventy-eight recruits (7.2 %) suffered a total of 92 stress fractures. Recruits with a baseline serum 25(OH)D concentration below 50 nmol L(-1) had a higher incidence of stress fracture than recruits with 25(OH)D concentration above this threshold (χ(2) (1) = 3.564, p = 0.042; odds ratio 1.6 (95 % confidence interval (CI) 1.0-2.6)). Baseline serum 25(OH)D varied from 47.0 ± 23.7 nmol L(-1) in February, to 97.3 ± 24.6 nmol L(-1) in July (overall mean 69.2 ± 29.2 nmol L(-1), n = 1016). There were weak inverse correlations between serum 25(OH)D and PTH concentrations at week 15 (r = -0.209, p < 0.001) and week 32 (r = -0.214, p < 0.001), but not at baseline., Conclusion: Baseline serum 25(OH)D concentration below 50 nmol L(-1) was associated with an increased risk of stress fracture. Further studies into the effects of vitamin D supplementation on stress fracture risk are certainly warranted.

Stress fracture is a common overuse injury within military training, resulting in significant economic losses to the military worldwide. Studies to date have failed to fully identify the bone density and bone structural differences between stress fractured personnel and controls due to inadequate adjustment for key confounding factors; namely age, body size and physical fitness; and poor sample size. The aim of this study was to investigate bone differences between male Royal Marine recruits who suffered a stress fracture during the 32 weeks of training and uninjured control recruits, matched for age, body weight, height and aerobic fitness. A total of 1090 recruits were followed through training and 78 recruits suffered at least one stress fracture. Bone mineral density (BMD) was measured at the lumbar spine (LS), femoral neck (FN) and whole body (WB) using Dual X-ray Absorptiometry in 62 matched pairs; tibial bone parameters were measured using peripheral Quantitative Computer Tomography in 51 matched pairs. Serum C-terminal peptide concentration was measured as a marker of bone resorption at baseline, week-15 and week-32. ANCOVA was used to determine differences between stress fractured recruits and controls. BMD at the LS, WB and FN sites was consistently lower in the stress fracture group (P<0.001). Structural differences between the stress fracture recruits and controls were evident in all slices of the tibia, with the most prominent differences seen at the 38% tibial slice. There was a negative correlation between the bone cross-sectional area and BMD at the 38% tibial slice. There was no difference in serum CTx concentration between stress fracture recruits and matched controls at any stage of training. These results show evidence of fundamental differences in bone mass and structure in stress fracture recruits, and provide useful data on bone risk factor profiles for stress fracture within a healthy military population., (Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.)

The ability to listen to commands in noisy environments and understand acoustic signals, while maintaining situational awareness, is an important skill for military personnel and can be critical for mission success. Seventeen auditory tasks carried out by British infantry and combat-support personnel were identified through a series of focus groups conducted by Bevis et al. For military personnel, these auditory tasks are termed mission-critical auditory tasks (MCATs) if they are carried in out in a military-specific environment and have a negative consequence when performed below a specified level. A questionnaire study was conducted to find out which of the auditory tasks identified by Bevis et al. satisfy the characteristics of an MCAT. Seventy-nine British infantry and combat-support personnel from four regiments across the South of England participated. For each auditory task participants indicated: 1) the consequences of poor performance on the task, 2) who performs the task, and 3) how frequently the task is carried out. The data were analysed to determine which tasks are carried out by which personnel, which have the most negative consequences when performed poorly, and which are performed the most frequently. This resulted in a list of 9 MCATs (7 speech communication tasks, 1 sound localization task, and 1 sound detection task) that should be prioritised for representation in a measure of auditory fitness for duty (AFFD) for these personnel. Incorporating MCATs in AFFD measures will help to ensure that personnel have the necessary auditory skills for safe and effective deployment on operational duties.

Military training has been associated with changes in the hypothalamic-pituitary-gonadal axis consistent with central hypogonadism. Often such changes have been associated with body mass loss, though sleep deprivation and other psychological stress may also contribute. The effects of deployment in a combat zone on the hypothalamic-pituitary-gonadal axis in military personnel are not known. The objective was to investigate the hypothalamic-pituitary-gonadal axis in male military personnel deployed in Afghanistan. Eighty-nine Royal Marines were investigated pre-deployment, following 3 months in Afghanistan and following 2 weeks mid-tour leave. Testosterone, sex hormone-binding globulin (SHBG), follicle-stimulating hormone (FSH), luteinising hormone (LH), 17-hydroxyprogesterone, androstenedione (AD) and insulin were assayed and body mass recorded. The results showed that body mass (kg) dropped from 83.2 ± 9.2 to 79.2 ± 8.2 kg during the first 3 months of deployment (p < 0.001). Total testosterone did not change, but SHBG increased (30.7 ± 9.7 vs. 42.3 ± 14.1 nmol/L, p < 0.001), resulting in a significant (p < 0.001) fall in calculated free testosterone (435.2 ± 138 vs. 375.1 ± 98 pmol/L). Luteinising hormone and FSH increased by 14.3% (p < 0.001) and 4.9% (p = 0.003) respectively. Free testosterone, SHBG, LH and FSH returned to baseline following 2 weeks of mid-tour leave. Androstenedione (AD) decreased by 14.5% (p = 0.024), and insulin decreased by 26% (p = 0.039), over the course of deployment. In this study of lean Royal Marines, free testosterone decreased during operational deployment to Afghanistan. There was no evidence to suggest major stress-induced central hypogonadism. We postulate that reduced body mass, accompanied by a decrease in insulin and AD synthesis, may have contributed to an elevated SHBG, leading to a decrease in free testosterone., (© 2015 Crown copyright. Andrology © 2015 American Society of Andrology and European Academy of Andrology. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.)

Understanding the nutritional demands on serving military personnel is critical to inform training schedules and dietary provision. Troops deployed to Afghanistan face austere living and working environments. Observations from the military and those reported in the British and US media indicated possible physical degradation of personnel deployed to Afghanistan. Therefore, the present study aimed to investigate the changes in body composition and nutritional status of military personnel deployed to Afghanistan and how these were related to physical fitness. In a cohort of British Royal Marines (n 249) deployed to Afghanistan for 6 months, body size and body composition were estimated from body mass, height, girth and skinfold measurements. Energy intake (EI) was estimated from food diaries and energy expenditure measured using the doubly labelled water method in a representative subgroup. Strength and aerobic fitness were assessed. The mean body mass of volunteers decreased over the first half of the deployment ( - 4·6 (sd 3·7) %), predominately reflecting fat loss. Body mass partially recovered (mean +2·2 (sd 2·9) %) between the mid- and post-deployment periods (P< 0·05). Daily EI (mean 10 590 (sd 3339) kJ) was significantly lower than the estimated daily energy expenditure (mean 15 167 (sd 1883) kJ) measured in a subgroup of volunteers. However, despite the body mass loss, aerobic fitness and strength were well maintained. Nutritional provision for British military personnel in Afghanistan appeared sufficient to maintain physical capability and micronutrient status, but providing appropriate nutrition in harsh operational environments must remain a priority.

In order to preserve their operational effectiveness and ultimately their survival, military personnel must be able to detect important acoustic signals and maintain situational awareness. The possession of sufficient hearing ability to perform job-specific auditory tasks is defined as auditory fitness for duty (AFFD). Pure tone audiometry (PTA) is used to assess AFFD in the UK military; however, it is unclear whether PTA is able to accurately predict performance on job-specific auditory tasks. The aim of the current study was to gather information about auditory tasks carried out by infantry personnel on the frontline and the environment these tasks are performed in. The study consisted of 16 focus group interviews with an average of five participants per group. Eighty British army personnel were recruited from five infantry regiments. The focus group guideline included seven open-ended questions designed to elicit information about the auditory tasks performed on operational duty. Content analysis of the data resulted in two main themes: (1) the auditory tasks personnel are expected to perform and (2) situations where personnel felt their hearing ability was reduced. Auditory tasks were divided into subthemes of sound detection, speech communication and sound localization. Reasons for reduced performance included background noise, hearing protection and attention difficulties. The current study provided an important and novel insight to the complex auditory environment experienced by British infantry personnel and identified 17 auditory tasks carried out by personnel on operational duties. These auditory tasks will be used to inform the development of a functional AFFD test for infantry personnel.

Objectives: To quantify changes in vitamin D and matrix metalloproteinase-9 (MMP9) in submariners over a single long patrol and compare the data to a group of non-deploying servicemen from their base port., Methods: A prospective time-series analysis was performed. Blood samples were taken from 49 submariners deploying on patrol and 43 shore-side controls from the base port (naval officers from base or non-deploying submariners), following a winter ashore at latitude 56° north. Samples were drawn immediately before the submarine sailed, in January, and again in the final week of patrol 85 days later. Paired pre-patrol and late samples from each individual were assayed together and changes in vitamin D and MMP9 were assessed., Results: Mean pre-patrol vitamin D concentrations were 58 and 49 nmol/L for the controls and submariners, respectively. Mean vitamin D concentrations increased in controls as expected (mean increase 12.6 nmol/L), but not in the submariners (mean decrease 1.6 nmol/L). MMP9 levels were significantly higher in submariners pre-patrol, and increased significantly during the patrol. There was a significant inverse correlation between MMP9 and vitamin D levels (r=-0.41, p=0.01)., Conclusions: This is the first study to quantify vitamin D and MMP levels in submariners. Circulating vitamin D concentrations on board were insufficient to prevent a rise in MMP. This has potential for adverse health effects and requires further study.

Background: For Royal Marine recruits in training, the third metatarsal is the most common site for stress fracture. Previous evidence regarding biomechanical factors contributing to metatarsal stress fracture development is conflicting, possibly due to the lack of differentiation between the metatarsals. The present retrospective study compares static anatomical characteristics and dynamic biomechanical variables for Royal Marine recruits with and without a history of third metatarsal stress fracture., Methods: Ten Royal Marine recruits with a history of third metatarsal stress fracture were compared with control subjects with no previous stress fracture occurrence. Selected static anatomical variables were measured to describe the ankle and subtalar joints. Peak ankle dorsi-flexion and rearfoot eversion were measured during running. In addition, peak vertical and horizontal ground reaction force variables were compared for the two study groups., Findings: No significant differences in static anatomical variables were identified between study groups. During running, peak rearfoot eversion was found to occur significantly earlier for the stress fracture group than for their matched controls, suggesting an increase in time spent loading the forefoot. The peak applied resultant horizontal force during the braking phase was directed significantly more laterally for the stress fracture group. In addition, the peak magnitude of resultant horizontal force applied during the propulsion phase was significantly lower for the stress fracture subjects., Interpretation: The findings of this study highlight the importance of including dynamic biomechanical data when exploring variables associated with the development of third metatarsal stress fracture and indicate that successful interventions to reduce the incidence of this injury are likely to focus on forefoot function during braking and propulsion.

Candidates who wish to undertake Royal Marine recruit training, a physically strenuous course which now extends 32 weeks, must first of all successfully complete a Personal Qualities Assessment (PQA) and four psychomotor tests (Naval Recruiting Tests or RTs) before attending a three-day selection course at the Commando Training Centre, Lympstone, where their physical capabilities are tested to the full. The effectiveness of these procedures was untested until the Institute of Naval Medicine conducted a retrospective study during 1999-2000 from which the present study is taken. Data from 1232 recruits were examined to explore the relationship between the outcome of Commando training (pass or fail) with these various selection measures. Estimated aerobic power, time to complete the assault course and age were associated with outcome, as were PQA, RTs 1, 3, 4 and total RT score. A regression equation comprising aerobic fitness, assault course time, RT4 and age gave the best overall prediction of outcome (64%). It is suggested that this mathematical approach provides a scientifically valid and objective assessment tool for future selection strategies.

The Royal Navy introduced a pre-joining fitness test to the selection procedures for RN Ratings from Summer 2003. The scientific basis for the test came from the present study to investigate if anthropometric and physical fitness measures predicted training failure. Fitness and anthropometric data from 1641 trainees were collected, together with their training outcome (i.e. pass or fail), during the period from September 2001 to March 2002. In addition, a retrospective interrogation of medical records identified those who reported any lower limb injuries. The overall rate of training attrition was 22%. Success in training was associated with: gender; age; physical fitness; and, in the case of females, Body Mass Index (BMI). The reported incidence of lower limb injury (LLI) was associated with: gender; physical fitness; and, for female trainees, BMI. The reported incidence of LLI was approximately 50% in the 'least-fit' female group compared to 10% in the 'most-fit' male group. 16% of females and 2% of males were considered 'unfit' (i.e. did not attain the prescribed run standards of 13 min 15 s and 11 min 13 s respectively). 3% of trainees were considered 'obese' (a BMI > 30 kg.m-2) whereas more than 25% were overweight (BMI > 25 kg.m-2). As a result of this work, selection candidates must now demonstrate a minimum standard of aerobic fitness prior to arrival at HMS Raleigh. The future impact of this selection measure on the reported incidence of lower limb injury and financial costs of training requires further investigation.

Mechanical degradation of three types of shock absorbing insoles equivalent to 100-130 km of running did not reduce their ability to attenuate the peak pressures generated during running when wearing military boots. Pressure measurements at the heel and forefoot were recorded with pressure measuring insoles placed in the boots of nine subjects. Two of the three insoles tested reduced the peak pressures (P<0.05) generated at the heel and forefoot relative to the no-insole (control) condition. The most effective insole reduced the peak pressures at the heel by 37% and at the forefoot by 24%.

Physical tests and selection criteria have historically been used by many military organizations. However, the standards associated with them have come under increasing scrutiny in recent years. This paper describes a series of experiments that were conducted to establish task-related occupational tests and standards (TBTs) for Royal Naval (RN) personnel. A total of 172 (106 male and 66 female) RN personnel volunteered for these experiments, which were designed to: identify the anthropometric requirements for operating various safety hatches and doors on board a RN Frigate (TBT1); quantify the metabolic demands of shipboard firefighting tasks and establish an aerobic fitness standard (TBT2); and identify a battery of tests to predict performance of shipboard casualty-carrying tasks (TBT3). Whilst all subjects completed the criterion tasks during TBT1, performance of the bulkhead door (BD) escape task was related to height (r = 0.50- 0.62, P < 0.05) and vertical reach (r = 0.42-0.54, P < 0.05), with shorter subjects struggling to perform the task. During TBT2, the mean metabolic demand of representative firefighting tasks was 38 ml/min/kg, which must be sustained for 20-30 min. Finally, a battery of tests incorporating measures of lean body mass, fat mass, standing broad jump, 20 m sprint, press-ups, sit-ups and grip strength produced a high correlation (r = 0.89, P < 0.01) with casualty-carrying task performance. From the results of these experiments, it is recommended that RN personnel perform the BD simulation task at the recruitment stage (TBT1), to prove that they possess the anthropometric characteristics commensurate with survival at sea. Secondly, personnel should be frequently screened to ascertain whether they have the maximal aerobic power (41 ml/min/kg) commensurate with shipboard firefighting for 20-30 min (TBT2). Finally, they should perform the battery of proposed tests and score at least 34 points, in order to establish whether they have the anaerobic and strength capacity commensurate with shipboard casualty-carrying tasks (TBT3).

Carbohydrate (CHO) ingestion during short-term recovery from prolonged running has been shown to increase the capacity for subsequent exercise in a warm environment. The aim of this study was to examine the effects of the amount of glucose given during recovery on substrate storage and utilisation during recovery and subsequent exercise in a warm environment. A group of 11 healthy male volunteers took part in two experiments in a controlled warm environment (35 degrees C, 40% relative humidity), 1 week apart. On each occasion the subjects completed two treadmill runs (T1 and T2) at a speed equivalent to 60% of maximal oxygen uptake, for 90 min, until they were fatigued, or until aural temperature (T(aur)) reached 39 degrees C. The two runs were separated by a 4 h recovery period (REC), during which subjects consumed 55 g of naturally enriched [U-(13)C]-glucose in the form of a 7.5% carbohydrate-electrolyte solution (CES, mass of solution 667 g) immediately after T1. The subjects then consumed either: the same quantity of CES, or an equivalent volume of an electrolyte placebo, at 60, 120 and 180 min during REC, providing a total of 220 g (C220) or 55 g (C55) of [U-(13)C]-glucose, respectively. Expired gases were collected at 15 min intervals during exercise and 60 min intervals during REC, for determination of total CHO and fat oxidation by indirect respiratory calorimetry, and orally ingested [U-(13)C]-glucose oxidation, estimated from the (13)C:(12)C ratio of expired CO(2). Substrate metabolism did not differ between conditions during T1. Despite the fact that total CHO (P < 0.05) and ingested glucose oxidation (P < 0.01) were greater during REC of the C220 condition, glycogen synthesis was estimated to be approximately fivefold greater (P < 0.01) than in the C55 condition. During T2 the rate of total CHO oxidation was higher (P < 0.01) and total fat oxidation lower (P < 0.01) at all times during the C220 compared to the C55 condition. The greater CHO oxidation during C220 appeared to be met from ingested sources, as the rate of [U-(13)C]-glucose oxidation was greater (P < 0.01) at all times during T2, compared to C55. Whilst more of the ingested substrate remained unoxidised on completion of T2 during C220, exercise duration was similar in the two experimental conditions, and was limited by thermoregulatory incapacity (T(aur) > 39 degrees C) rather than substrate availability per se.

There is increasing anecdotal evidence that simple occupational tests of aerobic fitness impose a systematic bias against heavier personnel when predicting fitness for load-carrying tasks. This study tested the hypothesis that simple field tests of aerobic fitness are not good predictors of load-carrying performance and that personnel with greater body mass are more able to perform occupationally relevant load-carrying tasks. Twelve healthy male volunteers ran on a level treadmill at 9.5 km/h for 4 min, with (T18) and without (T0) an external backpack load of 18 kg. During each exercise period, steady-state oxygen uptake (VO(2)) was assessed. On a subsequent occasion (at least 7 days later), 11 of the subjects ran to exhaustion at 9.5 km/h whilst carrying the 18 kg external load (ETT18). There was a strong inverse linear relationship between relative VO(2) and body mass (r = -0.87, P < 0.01) and between VO(2) and lean body mass (r = -0.74, P < 0.01) during the T18 trials. Furthermore, there was a moderately strong relationship between exercise time (ETT18) and body mass (r = 0.69, P < 0.05) and between exercise time and lean body mass (r = 0.71, P < 0.05). There was no relationship between exercise tolerance time and VO(2) (r = 0.12). The results show that fitness tests that determine aerobic power in units relative to body mass (e.g. timed distance run) incur a systematic bias against heavier personnel. Such tests are therefore inappropriate when predicting the ability of personnel to work in occupations that encompass load-carrying tasks.

Recovery from prolonged exercise involves both rehydration and replenishment of endogenous carbohydrate stores. This study examined the influence of drinking a carbohydrate-electrolyte solution on short-term recovery and subsequent exercise capacity in a warm environment. Thirteen healthy male volunteers completed two trials, at least 7 days apart. On each occasion subjects performed an initial treadmill run at 60% of maximal oxygen uptake (VO2max), for 90 min or until volitional fatigue (T1), in a warm environment (35 degrees C, 40% relative humidity, RH). Volitional ingestion of water was permitted during each of the exercise trials. During a subsequent 4-h recovery period (REC) subjects consumed either a 6.9% carbohydrate-electrolyte solution (CES) or a sweetened placebo (P), in a volume equivalent to 140% of body mass loss. Following REC, subjects ran to exhaustion at the same % VO2max in order to assess their endurance capacity (T2). Mean (SEM) run times during T1 did not differ between the CES [74.8 (4.6) min] and P [72.5 (5.2) min] trials. Body mass was reduced (P < 0.01) by 1.9 (0.2)% (CES) and 1.7 (0.2)% (P), and plasma volume (P < 0.01) by 6.0 (0.9)% (CES) and 5.4 (1.0)% (P) during the T1 trials. During REC 2006 (176) ml and 1830 (165) ml of fluid was ingested, providing 138 (12) g and 0 g of carbohydrate in the CES and P trials, respectively. Prior to T2, plasma volume and net fluid balance were similarly restored [CES +58 (26) g; P -4 (68) g] in both trials. During T2 the exercise duration was longer (P < 0.01) in the CES compared to the P trial [CES 60.9 (5.5) min; P 44.9 (3.0) min]. Thus, provided that an adequate hydration status is maintained, inclusion of carbohydrate within an oral rehydration solution will delay the onset of fatigue during a subsequent bout of prolonged submaximal running in a warm environment.

The effect of manipulating sodium intake upon sweat sodium secretion was investigated during heat acclimation. Twenty-five male subjects were confined to an environmental chamber at a temperature of 25 degrees C for 3 days, and then acclimated to heat by a further 5 days at 40 degrees C. The subjects' daily sodium intake was controlled throughout as follows: high (HNa), 348.4 (0.8) mmol x day(-1), n=7; moderate (MNa), 174.1 (0.6) mmol x day(-1), n=9; or low (LNa), 66.3 mmol x day(-1), n=9. Sodium losses were estimated from urinary, faecal and sweat collections using a whole-body washdown method. Plasma aldosterone concentration was also measured from venous blood sampled each morning. Measurements of body temperature and heart rate during the heat exposure phase indicated a degree of heat acclimation. During this heat phase there was a reduction (P < 0.01) in sweat sodium secretion for all three conditions which was greatest for the LNa condition, although this finding was not significant (P < 0.1). In the LNa condition, plasma aldosterone concentration increased (P < 0.05) prior to heat exposure, and the secretion of aldosterone was potentiated (P < 0.01) during the heat exposure in comparison with the MNa condition. In contrast, the HNa diet produced a fall (P < 0.05) in plasma aldosterone concentration prior to heat exposure and an attenuation of aldosterone secretion thereafter. These findings are inconsistent with the hypothesis that retention of sweat sodium is dependent upon a net body sodium deficit, but demonstrate that aldosterone secretion is potentiated under such conditions.

The effectiveness of hand immersion in water at 10 degrees C, 20 degrees C and 30 degrees C as a technique for reducing heat strain in Royal Navy (RN) personnel has been investigated at the Institute of Naval Medicine (INM). Four subjects exercised at a moderate work rate, whilst wearing fire fighting clothing in an environmental chamber at 40 degrees C. The subjects reached heat strain safety limits within 45 minutes of commencing work at which point they rested in the heat for 30 minutes whilst they underwent one of four experimental conditions: without intervention (control); or with their hands immersed in water at 10 degrees C, 20 degrees C or 30 degrees C. The experiment was repeated on a further three days so that the subjects undertook each experimental condition in a balanced randomised order. During the control condition without hand immersion the subjects were unable to cool. Immersion of the hands in water (at 10 degrees C, 20 degrees C or 30 degrees C) significantly (P < 0.05) lowered body core (auditory canal) temperature within ten minutes. Assessing the effectiveness of this technique by the initial rates of core temperature reduction, revealed that immersion of the hands was more effective the colder the water. Following 20 minutes of hand immersion mean core temperature had dropped from 38.5C to: 36.9(standard deviation 0.19) degrees C, 37.3(0.18) degrees C, and 37.8(0.10) degrees C, in 10 degrees C, 20 degrees C and 30 degrees C water respectively. Cooling powers estimated from changes in mean body temperature were 334, 307 and 113 watts using 10 degrees C, 20 degrees C and 30 degrees C water respectively. These results indicate that hand immersion in water at a temperature of between 10 degrees C and 30 degrees C is an efficient means of cooling heat stressed personnel who have been exercising. This simple and effective technique may be applied to many industrial and military tasks to reduce heat strain, lower the risk of heat injury, and increase safe total work times in the heat. For the RN, hand immersion could be used in fire fighting, damage control and NBC operations where personnel alternately work and rest.

The effects of 16 weeks at sea upon selected parameters of health and physical fitness were investigated in 30 male volunteers (from a total crew of 48 men) prior to, and immediately following deployment. The 30 subjects were assigned to either an exercise group, 'Ex' (n = 12), or a non-exercising group, 'Nilex' (n = 18), according to their reported participation in vigorous training or sports. Body mass index (BMI), calculated from height and weight, revealed that prior to deployment 13 of the 30 subjects (two in the Ex group) had a BMI over 25 kg.m-2 (i.e. overweight), and a further three subjects (all 'non-exercisers') had values of 30 kg.m-2 or more (obese). In addition, the diastolic blood pressure of two subjects was in excess of 95 mmHg and five subjects had resting heart rates above 89 beats per minute. Retrospective comparisons between the Ex and Nilex groups revealed a significantly lower percentage body fat (P < 0.01) and a faster rate of cardiac recovery (P < 0.05) following a standardised bout of exercise in the Ex group, albeit that these individuals were significantly younger (mean age of 24 years) than those in the Nilex group (32 years). Following deployment, in the Nilex group, comparison of pre- and post values showed that resting heart rate was elevated (P < 0.01) on return from sea. Similarly, in the Nilex group heart rate while performing the standardised exercise bout was also elevated (P < 0.05) on the second test occasion.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of hand immersion on body temperature have been investigated in men wearing impermeable NBC clothing. Six men worked continuously at a rate of approximately 490 J. sec-1 in an environmental temperature of 30 degrees C. Each subject was permitted to rest for a period of 20 minutes when their aural temperature reached 37.5 degrees C, and again on reaching 38 degrees C, and for a third time on reaching 38.5 degrees C (three rest periods in total). Each subject completed three experimental conditions whereby, during the rest periods they either: a. Did not immerse their hands (control). b. Immersed both hands in a water bath set at 25 degrees C. c. Immersed both hands in water at 10 degrees C. Physiological measures of core temperature, skin temperature and heart rate were recorded at intervals throughout the experiment. Measures of mean aural temperature and mean skin temperature were significantly (P less than 0.05) reduced if hands were immersed during these rest periods, compared to non immersion. As a result, the total work time of subjects was extended when in the immersed conditions by some 10-20 minutes within the confines of the protocol. It is concluded that this technique of simple hand immersion may be effective in reducing heat stress where normal routes to heat loss are compromised.