Protein dose requirements to maximize skeletal muscle protein synthesis after repeated bouts of resistance exercise in young trained women.

Studies examining the effect of protein (PRO) feeding on post resistance exercise (RE) muscle protein synthesis (MPS) have primarily been performed in men, and little evidence is available regarding the quantity of PRO required to maximally stimulate MPS in trained women following repeated bouts of RE. We therefore quantified acute (4 h and 8 h) and extended (24 h) effects of two bouts of resistance exercise, alongside protein-feeding, in women, and the PRO requirement to maximize MPS. Twenty-four RE trained women (26.6 ± 0.7 years, mean ± SEM) performed two bouts of whole-body RE (3 × 8 repetitions/maneuver at 75% 1-repetition maximum) 4 h apart, with post-exercise ingestion of 15 g, 30 g, or 60 g whey PRO (n = 8/group). Saliva, venous blood, and a vastus lateralis muscle biopsy were taken at 0 h, 4 h, 8 h, and 24 h post-exercise. Plasma leucine and branched chain amino acids were quantified using gas chromatography mass spectrometry (GC-MS) after ingestion of D2 O. Fifteen grams PRO did not alter plasma leucine concentration or myofibrillar synthetic rate (MyoFSR). Thirty and sixty grams PRO increased plasma leucine concentration above baseline (105.5 ± 5.3 µM; 120.2 ± 7.4 µM, respectively) at 4 h (151.5 ± 8.2 µM, p < 0.01; 224.8 ± 16.0 µM, p < 0.001, respectively) and 8 h (176.0 ± 7.3 µM, p < 0.001; 281.7 ± 21.6 µM, p < 0.001, respectively). Ingestion of 30 g PRO increased MyoFSR above baseline (0.068 ± 0.005%/h) from 0 to 4 h (0.140 ± 0.021%/h, p < 0.05), 0 to 8 h (0.121 ± 0.012%/h, p < 0.001), and 0 to 24 h (0.099 ± 0.011%/h, p < 0.01). Ingestion of 60 g PRO increased MyoFSR above baseline (0.063 ± 0.003%/h) from 0 to 4 h (0.109 ± 0.011%/h, p < 0.01), 0 to 8 h (0.093 ± 0.008%/h, p < 0.01), and 0 to 24 h (0.086 ± 0.006%/h, p < 0.01). Post-exercise ingestion of 30 g or 60 g PRO, but not 15 g, acutely increased MyoFSR following two consecutive bouts of RE and extended the anabolic window over 24 h. There was no difference between the 30 g and 60 g responses.

Validation of dried blood spot sampling for detecting SARS-CoV-2 antibodies and total immunoglobulins in a large cohort of asymptomatic young adults.

BACKGROUND: Detecting antibody responses following infection with SARS-CoV-2 is necessary for sero-epidemiological studies and assessing the role of specific antibodies in disease, but serum or plasma sampling is not always viable due to logistical challenges. Dried blood spot sampling (DBS) is a cheaper, simpler alternative and samples can be self-collected and returned by post, reducing risk for SARS-CoV-2 exposure from direct patient contact. The value of large-scale DBS sampling for the assessment of serological responses to SARS-CoV-2 has not been assessed in depth and provides a model for examining the logistics of using this approach to other infectious diseases. The ability to measure specific antigens is attractive for remote outbreak situations where testing may be limited or for patients who require sampling after remote consultation. METHODS: We compared the performance of SARS-CoV-2 anti-spike and anti-nucleocapsid antibody detection from DBS samples with matched serum collected by venepuncture in a large population of asymptomatic young adults (N = 1070) living and working in congregate settings (military recruits, N = 625); university students, N = 445). We also compared the effect of self-sampling (ssDBS) with investigator-collected samples (labDBS) on assay performance, and the quantitative measurement of total IgA, IgG and IgM between DBS eluates and serum. RESULTS: Baseline seropositivity for anti-spike IgGAM antibody was significantly higher among university students than military recruits. Strong correlations were observed between matched DBS and serum samples in both university students and recruits for the anti-spike IgGAM assay. Minimal differences were found in results by ssDBS and labDBS and serum by Bland Altman and Cohen kappa analyses. LabDBS achieved 82.0% sensitivity and 98.2% specificity and ssDBS samples 86.1% sensitivity and 96.7% specificity for detecting anti-spike IgGAM antibodies relative to serum samples. For anti-SARS-CoV-2 nucleocapsid IgG there was qualitatively 100% agreement between serum and DBS samples and weak correlation in ratio measurements. Strong correlations were observed between serum and DBS-derived total IgG, IgA, and IgM. CONCLUSIONS: This is the largest validation of DBS against paired serum for SARS-CoV-2 specific antibody measurement and we have shown that DBS retains performance from prior smaller studies. There were no significant differences regarding DBS collection methods, suggesting that self-collected samples are a viable sampling collection method. These data offer confidence that DBS can be employed more widely as an alternative to classical serology.

Changes in physical performance during British Army Junior Entry, British Army Standard Entry and Royal Air Force Basic Training.

INTRODUCTION: The purpose was to quantify physical performance in men and women during British Army Junior Entry (Army-JE), British Army Standard Entry (Army-SE) and Royal Air Force (RAF) basic training (BT). DESIGN: Prospective longitudinal study. METHODS: 381 participants ((339 men and 42 women) n=141 Army-JE, n=132 Army-SE, n=108 RAF) completed a 2 km run, medicine ball throw (MBT) and isometric mid-thigh pull (MTP), pre-BT and post-BT. To examine changes in pre-BT to post-BT physical test performance, for each course, paired Student t-test and Wilcoxon test were applied to normally and non-normally distributed data, respectively, with effect sizes reported as Cohen's D and with rank biserial correlations, respectively. A one-way between-subjects analysis of variance (ANOVA) (or Welch ANOVA for non-normally distributed data) compared performance between quartiles based on test performance pre-BT. Where the main tests statistic, p value and effect sizes identified likely effect of quartile, post hoc comparisons were made using Games-Howell tests with Tukey's p value. Data are presented as mean±SD, with statistical significance set at p<0.05. RESULTS: During BT, 2 km run time improved by 13±46 s (-2.1%±8.1%), 30±64 s (-4.8%±12.3%) and 24±27 s (-4.5%±5.1%) for Army-JE, Army-SE and RAF, respectively (all p<0.005). MBT distance increased by 0.27±0.28 m (6.8%±7.0%) for Army-JE (p<0.001) and 0.07±0.46 m (2.3%±10.9%) for Army-SE (p=0.040), but decreased by 0.08±0.27 m (-1.4%±6.0%) for RAF (p=0.002). MTP force increased by 80±281 n (10.8%±27.6%) for Army-JE (p<0.001) and did not change for Army-SE (-36±295 n, -0.7%±20.6%, p=0.144) or RAF (-9±208 n, 1.0±17.0, p=0.603). For all tests and cohorts, participants in the lowest quartile of pre-BT performance scores demonstrated greater improvements, compared with participants in the highest quartile (except Army-JE MBT, ∆% change similar between all quartiles). CONCLUSIONS: Changes in physical performance were observed for the three fitness tests following the different BT courses, and recruits with the lowest strength and aerobic fitness experienced greatest improvements.

Effect of sex and combat employment on musculoskeletal injuries and medical downgrading in trained military personnel: an observational cohort study.

INTRODUCTION: Following the opening of all combat roles to women across the UK Armed Forces, there is a requirement to understand the risk of injury to these female personnel. Women injure at a higher rate than men during basic military training, but fewer data are published from individuals who have passed military training. METHODS: A bespoke survey was designed to investigate differences in injury prevalence and medical downgrading between sexes and career employment groups (ie, job roles) in the UK Armed Forces. RESULTS: Questionnaire data were evaluated from 847 service personnel (87% men) employed in combat roles (Royal Marines, Infantry, Royal Armoured Corps, Royal Air Force Regiment (all men)) and non-combat roles (Royal Regiment of Artillery, Corps of Royal Engineers, Royal Logistic Corps and Combat Service Support Corps who were attached to one of the participating units (men and women)). Women reported more total (OR 1.64 (95% CI: 1.03 to 2.59), p=0.035), lower limb (OR 1.92 (95% CI: 1.23 to 2.98), p=0.004) and hip (OR 2.99 (95% CI: 1.59 to 5.62), p<0.001) musculoskeletal injuries in the previous 12 months than men, but there were no sex differences in the prevalence of current or career medical downgrading due to musculoskeletal injury (both p>0.05). There were no differences in 12-month musculoskeletal injury prevalence between men in combat roles and men in non-combat roles (all p>0.05), but men in non-combat roles were more likely to be currently medically downgraded (OR 1.88 (95% CI: 1.27 to 2.78), p=0.001) and medically downgraded during their career (OR 1.49 (95% CI: 1.11 to 2.00), p=0.008) due to musculoskeletal injury than men in combat roles. More time in service and quicker 1.5-mile run times were associated with increased prevalence of total musculoskeletal injuries, and female sex was a predictor of hip injury. CONCLUSIONS: Although women are at greater risk of injury than men, we have no evidence that combat employment is more injurious than non-combat employment. The prevention of hip injuries should form a specific focus of mitigation efforts for women.

Gender data gap in military research: a review of the participation of men and women in military musculoskeletal injury studies.

Servicewomen are at increased risk of musculoskeletal injuries compared with their male counterparts, but women are under-represented in sports medicine research. The aim of this review was to assess the representation of women in military musculoskeletal injury studies. PubMed was searched for human original research studies using the terms Military OR Army OR Navy OR 'Air Force' AND 'musculoskeletal injury' Each study was categorised as epidemiology (basic training), epidemiology (trained personnel), risk factors, interventions and other. The number of male and female participants was retrieved from each study. A total of 262 studies were included: 98 (37%) studies only included men, 17 (6%) studies only included women and 147 (56%) studies included both men and women. A total of 8 051 778 participants were included in these studies (men: 6 711 082, 83%; women: 1 340 696, 17%). The study theme with the greatest proportion of women was musculoskeletal injury epidemiology studies in a basic training population (20% of participants) with the lowest proportion of women in intervention trials (6% of participants). These data suggest women are not under-represented in military musculoskeletal injury studies when considering the gender representation of most militaries. Our data are, however, biased by large epidemiological trials and women were under-represented in intervention trials. The under-representation of women in intervention trials could be due to difficulties in controlling for the effects of female sex steroids on musculoskeletal outcomes, or a focus on interventions in the most arduous military roles where injury risk is highest and women have been previously excluded.

Understanding the musculoskeletal injury risk of women in combat: the effect of infantry training and sex on musculoskeletal injury incidence during British Army basic training.

INTRODUCTION: Until recently, women were excluded from British combat roles. Their risk for musculoskeletal injury during basic training is two to three times higher than men. To better understand the musculoskeletal injury risk of women in British Army infantry basic training, we compared injury incidence between (1) men in standard entry training and men in infantry training, to assess the risk of infantry training; and (2) men and women in both standard entry and officer basic training, to assess the risk in women compared with men. METHODS: The incidence of musculoskeletal injury was determined from defence medical records for all men entering infantry training, and for all men and women entering standard entry and officer training, between April 2015 and March 2016. RESULTS: 7390 men (standard entry, n=4229; infantry, n=2683; officer, n=478) and 696 women (standard entry, n=626; officer, n=70) entered basic training. Men in infantry training had a lower incidence of musculoskeletal injury (391 vs 417 per 1000 personnel, OR 0.90 (95% CI 0.81 to 0.99), p=0.028) and a higher incidence of stress fracture (14 vs 5 per 1000 personnel, OR 2.80 (95% CI 1.64 to 4.80), p<0.001) than men in standard entry training. Women had a higher incidence of musculoskeletal injury than men in standard entry training (522 vs 417 per 1000 personnel, OR 1.53 (95% CI 1.29 to 1.81), p<0.001) and a higher incidence of stress fracture than men in officer training (114 vs 19 per 1000 personnel, OR 6.72 (95% CI 2.50 to 18.07), p<0.001). CONCLUSION: Women in infantry training may be at similar risk for musculoskeletal injury, but at higher risk for stress fracture, compared with their non-infantry counterparts. Women in infantry training may be at higher risk for musculoskeletal injury and stress fracture compared with men in infantry training.

Female UK Army Service personnel are at greater risk of work-related morbidity on return to duty postpartum.

INTRODUCTION: The 2016 Interim Report on the Health Risks to Women in Ground Close Combat Roles highlighted an increased risk of skeletal injury and significant physiological changes, including increased ligament laxity and decreased bone mineral content, during the postpartum period. The report called for further research and a re-evaluation of postpartum policy to optimise the return of female Service personnel to arduous employment. The purpose of this study was to determine whether returning to duty is at greater risk of injury and illness in the first year postpartum than they were prepregnancy. METHODS: Fifty-five female UK Army Service personnel aged 18-41 years, who had given birth in the previous 4 years, completed a lifestyle questionnaire and gave written consent for a review of their medical records. The number of working days lost (WDL) due to illness, injury and combined illness and injury was obtained from medical records, for 1 year prepregnancy and 1 year postpartum. Female Service personnel returned to duty at different time-points postpartum, so data were expressed as WDL/week. RESULTS: WDL/week due to illness and combined illness and injury were higher postpartum compared with prepregnancy (p<0.05). WDL/week due to combined illness and injury was significantly lower prepregnancy (p<0.05) and at 0-26 weeks postpartum (p<0.05), compared with 26-52 weeks postpartum. CONCLUSIONS: Postpartum female UK Army Service personnel are at greater risk of illness and a combination of illness and injury in the year after giving birth, compared with prepregnancy. The study suggests female Service personnel are unprepared for the demands of full active duty in the first year postpartum.

Influence of smoking status on acute biomarker responses to successive days of arduous military training.

INTRODUCTION: Habitual smoking is highly prevalent in military populations despite its association with poorer training outcomes. Smoking imposes challenges on the immune and endocrine systems which could alter how smokers acutely respond to, and recover from, intensive exercise particularly over multiple days of training. METHODS: Over a two-day period, 35 male British Army recruits (age 22±3 years; mass 76.9±8.0 kg; height 1.78±0.06 m; 15 smokers) completed a 16.1 km loaded march (19.1 kg additional mass) on the first morning and a best-effort 3.2 km 'log race' (carrying a 60 kg log between six and eight people) on the subsequent morning. Blood samples were obtained on waking and immediately postexercise on both days and analysed for C reactive protein (CRP), interleukin 6 (IL-6), testosterone to cortisol ratio and insulin-like growth factor 1 (IGF-1). RESULTS: Independent of smoking group, the exercise bouts on both days evoked significant increases in IL-6 (p<0.001) and decreases in testosterone to cortisol ratio (p<0.05). CRP concentrations on day 2 were significantly higher than both time points on day 1 (p<0.001), and a 9% decline in IGF-1 occurred over the two-day period, but was not significant (p=0.063). No significant differences were observed between smokers and non-smokers (p>0.05). CONCLUSIONS: Military-specific tasks elicited inflammatory and endocrine responses, with systemic CRP and IGF-1 indicating that the physiological stress generated during the first training day was still evident on the second day. Despite the well-established impacts of smoking on resting levels of the markers examined, responses to two days of arduous military-specific training did not differ by smoking status.

Hormonal contraceptive prescriptions in the UK Armed Forces.

INTRODUCTION: Thirty four per cent of women use hormonal contraceptives in the UK and the contraceptive pill is the most common method. There are no comparable data in the UK Armed Forces, but servicewomen are often required to complete physically arduous job roles in combat zones and may be more likely to take contraceptives to control or stop menstrual bleeding than the general population. We explored the prevalence of hormonal contraceptive prescriptions in the UK Armed Forces. METHODS: The study used defence medical records (Defence Medical Information Capability Programme) to identify hormonal contraceptive prescriptions for all serving regular UK servicewomen (n=15 738) as of 1 September 2017. RESULTS: Thirty one per cent of servicewomen (Royal Navy, 28%; British Army, 30%; Royal Air Force, 34%) had a current prescription for a hormonal contraceptive. Non-officer ranks were more likely to have a prescription for a hormonal contraceptive (32%) than officers (27%) (p<0.01). The contraceptive pill was more commonly prescribed (68%) than long-acting reversible contraceptive methods (32%) (contraceptive injection, 11%; contraceptive implant, 11%; intrauterine device, 10%). CONCLUSION: Prescription data suggest that the prevalence of hormonal contraceptive use in UK servicewomen is comparable with the general UK population. These findings suggest that military service does not influence prevalence or choice of hormonal contraceptives.

Role of sex and stature on the biomechanics of normal and loaded walking: implications for injury risk in the military.

Load carriage and marching 'in-step' are routine military activities associated with lower limb injury risk in service personnel. The fixed pace and stride length of marching typically vary from the preferred walking gait and may result in overstriding. Overstriding increases ground reaction forces and muscle forces. Women are more likely to overstride than men due to their shorter stature. These biomechanical responses to overstriding may be most pronounced when marching close to the preferred walk-to-run transition speed. Load carriage also affects walking gait and increases ground reaction forces, joint moments and the demands on the muscles. Few studies have examined the effects of sex and stature on the biomechanics of marching and load carriage; this evidence is required to inform injury prevention strategies, particularly with the full integration of women in some defence forces. This narrative review explores the effects of sex and stature on the biomechanics of unloaded and loaded marching at a fixed pace and evaluates the implications for injury risk. The knowledge gaps in the literature, and distinct lack of studies on women, are highlighted, and areas that need more research to support evidence-based injury prevention measures, especially for women in arduous military roles, are identified.

Hormonal contraceptive use, bone density and biochemical markers of bone metabolism in British Army recruits.

INTRODUCTION: Hormonal contraceptive use might impair bone health and increase the risk of stress fracture by decreasing endogenous oestrogen production, a central regulator of bone metabolism. This cross-sectional study investigated bone density and biochemical markers of bone metabolism in women taking hormonal contraceptives on entry to basic military training. METHODS: Forty-five female British Army recruits had biochemical markers of bone metabolism, areal bone mineral density (aBMD) and tibial speed of sound (tSOS) measured at the start of basic military training. Participants were compared by their method of hormonal contraception: no hormonal contraception (NONE), combined contraceptive pill (CP) or depot-medroxyprogesterone acetate (DMPA) (20±2.8 years, 1.64±0.63 m, 61.7±6.2 kg). RESULTS: aBMD was not different between groups (p≥0.204), but tSOS was higher in NONE (3%, p=0.014) when compared with DMPA users. Beta C-terminal telopeptide was higher in NONE (45%, p=0.037) and DMPA users (90%, p=0.003) compared with CP users. Procollagen type 1 N-terminal propeptide was higher in DMPA users compared with NONE (43%, p=0.045) and CP users (127%, p=0.001), and higher in NONE compared with CP users (59%, p=0.014). Bone alkaline phosphatase was higher in DMPA users compared with CP users (56%, p=0.044). CONCLUSIONS: DMPA use was associated with increased bone turnover and decreased cortical bone integrity of the tibia. Lower cortical bone integrity in DMPA users was possibly mediated by increased intracortical remodelling, but trabecular bone was not affected by contraceptive use.

Cognitive performance of military men and women during prolonged load carriage.

BACKGROUND: This study evaluated cognitive workload in soldiers undertaking a long duration march wearing different loads. METHODS: Military participants (n=12 men and n=10 women) performed four 3-hour loaded marches (12.25 km at 4.9 km/hour) wearing either 21 kg, 26 kg, 33 kg or 43 kg. During the march, accuracy and response time were measured using the verbal working memory n-back test (0, 1, 2 and 3) and two bespoke Go/No Go tests (visual/auditory) to assess inhibition of a pre-potent response. RESULTS: The physical demands of the march increased with load and march duration but remained at moderate intensity. N-back test accuracy ranged from 74% to 98% in men and 62% to 98% in women. Reduced accuracy was observed as load and time increased. Accuracy during the visual Go/No Go test also reduced with load, accuracy ranged from 69% to 89% in men and 65% to 90% in women. No differences due to load or time were observed during completion of the auditory Go/No Go task; accuracy ranged from 93% to 97% in men and 77% to 95% in women. A number of participants were unable to complete the march due to discomfort. Reports of discomfort were more frequent in women, which may have contributed to the greater reductions in accuracy observed. CONCLUSION: These data provide further evidence that cognitive performance of military personnel can be affected during long duration loaded marching. Women reported discomfort from equipment more frequently than men, which may make them more susceptible to declines in cognitive performance. These findings highlight important considerations for equipment procurement.

Effectiveness of parathyroid hormone (PTH) analogues on fracture healing: a meta-analysis.

This meta-analysis evaluated the evidence for the use of parathyroid hormone (PTH) analogues to improve fracture healing. Eligible studies were prospective randomised controlled trials of adults with acute fractures treated with a PTH analogue. PTH improved functional outcomes but did not affect fracture healing rate or reduce pain. PURPOSE: This meta-analysis evaluated the evidence of parathyroid hormone (PTH) analogues in fracture healing. The use of PTH analogues to prevent osteoporotic fractures is well investigated, and studies are emerging on extended indications. One such indication receiving increasing attention is the effect of PTH in fracture healing; however, the overall degree of efficacy remains inconclusive. METHODS: A systematic electronic database search of MEDLINE, EMBASE and the Cochrane Library was conducted for relevant articles in August 2019 with no date restrictions. Randomised controlled trials of adults with acute fractures treated with a PTH analogue were included. PTH was compared with a comparator intervention, placebo or no treatment. RESULTS: PTH analogue treatment improved functional outcomes in a range of fracture types but did not affect the fracture healing rate or reduce pain. Most trials included in this review were in elderly patients with osteoporosis. There was no evidence that PTH treatment caused harm or impeded fracture healing. CONCLUSIONS: Meta-analysis of published data supports the use of PTH analogues to improve functional outcomes but not fracture healing rate or pain for different fracture types. The evidence for PTH analogue use in fracture healing is less clear in younger, non-osteoporotic patient populations. Trial design was heterogeneous and of limited quality, justifying further original trials.

The effects of short-term low energy availability, achieved through diet or exercise, on cognitive function in oral contraceptive users and eumenorrheic women.

To date, no research has explored the effects of low energy availability on cognitive performance using dietary and exercise regimens relevant to athletes. Twenty female participants (10 eumenorrheic, 10 oral contraceptive [OC] users) completed three 3-day conditions: 1) controlled-balanced energy availability without exercise (BAL; 45 kcal·kg lean body mass [LBM]-1·day-1); 2) diet-induced low energy availability without exercise (DIET; 15 kcal·kg LBM-1·day-1); and 3) exercise-induced low energy availability (EX; 15 kcal·kg LBM-1·day-1, including 30 kcal·kg LBM-1·day-1 treadmill running at 70% maximal oxygen uptake). A cognitive test battery was completed before and after each 3-day condition. Mental rotation test accuracy improved in the BAL condition, but there was a decline in accuracy in the EX condition (BAL, +2.5%; EX, -1.4%; P = 0.042, d = 0.85). DIET (+1.3%) was not different to BAL or EX (P > 0.05). All other measures of cognitive performance were not affected by condition (P > 0.05) and OC use did not affect cognitive responses (P > 0.05). Accuracy in the mental rotation test was impaired when low energy availability was induced through increased exercise energy expenditure. All other aspects of cognition were unaffected by 3 days of low energy availability through diet or exercise. OC use did not mediate the effect of low energy availability on cognition. Novelty: Cognitive function was not affected by 3 days of diet-induced low energy availability. Only spatial awareness was impaired during 3 days of exercise-induced low energy availability. Reproductive hormones affected spatial awareness independent of energy availability.

Experience from the selection and nutritional preparation for Expedition ICE MAIDEN: the first successful all-female unassisted Antarctic traverse.

INTRODUCTION: Expedition ICE MAIDEN (Ex IM) was the first all-female unsupported crossing of Antarctica. We describe the prerequisite selection and training, comparing those who formed the final team with other participants, and discuss how the expedition diet was established. METHODS: All women serving in the British Army were invited to participate. Following initial assessments, successful women completed three training/selection ski expeditions. Between expeditions 1 and 2, participants completed 6 months rigorous UK-based training. Weight was measured before and after the 6 months UK-based training, expeditions 2 and 3, and body composition by skinfold before and after expedition 2. Participant feedback, body composition and weight changes were applied to modify the expedition diet and provide weight gain targets prior to Ex IM. RESULTS: Following 250 applications, 50 women were assessed and 22, 12 and seven women attended training expeditions 1, 2 and 3, respectively. The final team of six women lost more weight than other participants during UK-based training (mean (SD) change -1.3 (1.5) kg vs -0.5 (1.6) kg, respectively, p=0.046) and during training expedition 2 (-2.8 (0.8) kg vs -1.7 (0.4) kg, respectively, p=0.048), when they also gained more lean mass (+2.1 (0.8) kg vs +0.4 (0.7) kg, respectively, p=0.004). The Ex IM diet provided 5000 kCal/day, comprising approximately 45% carbohydrate, 45% fat and 10% protein. Median (range) weight change between expedition 3 and Ex IM was +8.7 (-1.9 to +14.3) kg. CONCLUSIONS: The selected Ex IM team demonstrated favourable training-associated body composition changes. Training-associated weight loss informed the expeditionary diet design.

Positive adaptation of HPA axis function in women during 44 weeks of infantry-based military training.

BACKGROUND: Basic military training (BMT) is a useful model of prolonged exposure to multiple stressors. 8-12 week BMT is associated with perturbations in the hypothalamic-pituitary-adrenal (HPA) axis which could predispose recruits to injury and psychological strain. However, characterisations of HPA axis adaptations during BMT have not been comprehensive and most studies included few if any women. METHODS: We studied women undertaking an arduous, 44-week BMT programme in the UK. Anxiety, depression and resilience questionnaires, average hair cortisol concentration (HCC), morning and evening saliva cortisol and morning plasma cortisol were assessed at regular intervals throughout. A 1-h dynamic cortisol response to 1 µg adrenocorticotrophic hormone-1-24 was performed during weeks 1 and 29. RESULTS: Fifty-three women (aged 24 ± 2.5 years) completed the study. Questionnaires demonstrated increased depression and reduced resilience during training (F 6.93 and F 7.24, respectively, both p < 0.001). HCC increased from 3 months before training to the final 3 months of training (median (IQR) 9.63 (5.38, 16.26) versus 11.56 (6.2, 22.45) pg/mg, p = 0.003). Morning saliva cortisol increased during the first 7 weeks of training (0.44 ± 0.23 versus 0.59 ± 0.24 µg/dl p < 0.001) and decreased thereafter, with no difference between the first and final weeks (0.44 ± 0.23 versus 0.38 ± 0.21 µg/dl, p = 0.2). Evening saliva cortisol did not change. Fasting cortisol decreased during training (beginning, mid and end-training concentrations: 701 ± 134, 671 ± 158 and 561 ± 177 nmol/l, respectively, p < 0.001). Afternoon basal cortisol increased during training while there was a trend towards increased peak stimulated cortisol (177 ± 92 versus 259 ± 13 nmol/l, p = 0.003, and 589 ± 164 versus 656 ± 135, p = 0.058, respectively). DISCUSSION: These results suggest a normal stress response in early training was followed quickly by habituation, despite psychological and physical stress evidenced by questionnaire scores and HCC, respectively. There was no evidence of HPA axis maladaptation. These observations are reassuring for women undertaking arduous employment.

1.5mile run time and body mass predict 8mile loaded march performance, irrespective of sex.

OBJECTIVES: To develop a statistical model to predict 8mile Loaded March (LM) performance and quantify differences in physical characteristics for men and women British Army Personnel. DESIGN: 135 trained soldiers (87 men; 48 women) completed two sessions, seven days apart. METHODS: Session 1: Participants' stature, body mass, Fat Free Mass (FFM) [by dual-energy X-ray absorptiometry], Single Lift (SL), Water Can Carry (WCC), and 1.5mile run performance were measured. Session 2: Participants completed an 8mile LM, carrying 25kg (4miles paced and 4miles individual best effort). Sex differences were compared using independent samples t-tests and 8mile LM performance time was predicted using various multiple linear regression analysis: hierarchical forced entry multiple ordinary least squares, principal component and ordinary least products. RESULTS: A combination of 1.5mile run time and body mass were the strongest predictors of 8mile LM time (R2=0.71; SEE=4.17min; p<0.001). Including stature, FFM, sex, SL score, or WCC score did not further improve predictions (p>0.05). Compared to women, men had faster mean 1.5mile run and LM times, greater body mass and total FFM and higher SL and WCC scores (p<0.001), however some women outperformed men. CONCLUSION: 1.5mile run time and body mass predict 8mile LM performance with no further improvement gained in the model by including sex as a variable.