Publications by authors named "Julie P Greeves"

43 Publications

Tibial Macrostructure and Microarchitecture Adaptations in Women During 44 Weeks of Arduous Military Training.

J Bone Miner Res 2021 Apr 15. Epub 2021 Apr 15.

Army Health and Performance Research, Army Headquarters, Andover, UK.

Bone adapts to unaccustomed, high-impact loading but loses mechanosensitivity quickly. Short periods of military training (≤12 weeks) increase the density and size of the tibia in women. The effect of longer periods of military training, where the incidence of stress fracture is high, on tibial macrostructure and microarchitecture in women is unknown. This observational study recruited 51 women (age 19 to 30 years) at the start of 44 weeks of British Army Officer training. Tibial volumetric bone mineral density (vBMD), geometry, and microarchitecture were measured by high-resolution peripheral quantitative computed tomography (HRpQCT). Scans of the right tibial metaphysis (4% site) and diaphysis (30% site) were performed at weeks 1, 14, 28, and 44. Measures of whole-body areal bone mineral density (aBMD) were obtained using dual-energy X-ray absorptiometry (DXA). Blood samples were taken at weeks 1, 28, and 44, and were analyzed for markers of bone formation and resorption. Trabecular vBMD increased from week 1 to 44 at the 4% site (3.0%, p < .001). Cortical vBMD decreased from week 1 to 14 at the 30% site (-0.3%, p < .001). Trabecular area decreased at the 4% site (-0.4%); trabecular bone volume fraction (3.5%), cortical area (4.8%), and cortical thickness (4.0%) increased at the 4% site; and, cortical perimeter increased at the 30% site (0.5%) from week 1 to 44 (p ≤ .005). Trabecular number (3.5%) and thickness (2.1%) increased, and trabecular separation decreased (-3.1%), at the 4% site from week 1 to 44 (p < .001). Training increased failure load at the 30% site from week 1 to 44 (2.5%, p < .001). Training had no effect on aBMD or markers of bone formation or resorption. Tibial macrostructure and microarchitecture continued to adapt across 44 weeks of military training in young women. Temporal decreases in cortical density support a role of intracortical remodeling in the pathogenesis of stress fracture. © 2021 Crown copyright. Journal of Bone and Mineral Research © 2021 American Society for Bone and Mineral Research (ASBMR). This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.
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http://dx.doi.org/10.1002/jbmr.4290DOI Listing
April 2021

SEX DIFFERENCES IN THE PHYSICAL PERFORMANCE, PHYSIOLOGICAL, AND PSYCHO-COGNITIVE RESPONSES TO MILITARY OPERATIONAL STRESS.

Eur J Sport Sci 2021 Apr 10:1-34. Epub 2021 Apr 10.

Department of Sports Medicine and Nutrition, Neuromuscular Research Laboratory & Warrior Human Performance Research Center, University of Pittsburgh, United States.

Combat roles are physically demanding and expose service personnel to operational stressors such as high levels of physical activity, restricted nutrient intake, sleep loss, psychological stress, and environmental extremes. Women have recently integrated into combat roles, but our knowledge of the physical, physiological, and psycho-cognitive responses to these operational stressors in women is limited. The aim of this narrative review was to evaluate the evidence for sex-specific physical, physiological, and psycho-cognitive responses to real, and simulated, military operational stress. Studies examining physical and cognitive performance, body composition, metabolism, hypothalamic-pituitary-gonadal axis, and psychological health outcomes were evaluated. These studies report that women expend less energy and lose less body mass and fat-free mass, but not fat mass, than men. Despite having similar physical performance decrements as men during operational stress, women experience greater physiological strain than men completing the same physical tasks, but this may be attributed to differences in fitness. From limited data, military operational stress suppresses hypothalamic-pituitary-gonadal, but not hypothalamic-pituitary-adrenal, axis function in both sexes. Men and women demonstrate different psychological and cognitive responses to operational stress, including disturbances in mood, with women having a higher risk of post-traumatic stress symptoms compared with men. Based on current evidence, separate strategies to maximize selection and combat training are not warranted until further data directly comparing men and women are available. However, targeted exercise training programs may be advisable to offset the physical performance gap between sexes and optimize performance prior to inevitable declines caused by intense military operations.
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http://dx.doi.org/10.1080/17461391.2021.1916082DOI Listing
April 2021

Biomechanical Basis of Predicting and Preventing Lower Limb Stress Fractures During Arduous Training.

Curr Osteoporos Rep 2021 Feb 26. Epub 2021 Feb 26.

Army Health and Performance Research, Army Headquarters, Andover, Hampshire, UK.

Purpose Of Review: Stress fractures at weight-bearing sites, particularly the tibia, are common in military recruits and athletes. This review presents recent findings from human imaging and biomechanics studies aimed at predicting and preventing stress fractures.

Recent Findings: Peripheral quantitative computed tomography (pQCT) provides evidence that cortical bone geometry (tibial width and area) is associated with tibial stress fracture risk during weight-bearing exercise. The contribution of bone trabecular microarchitecture, cortical porosity, and bone material properties in the pathophysiology of stress fractures is less clear, but high-resolution pQCT and new techniques such as impact microindentation may improve our understanding of the role of microarchitecture and material properties in stress fracture prediction. Military studies demonstrate osteogenic outcomes from high impact, repetitive tibial loading during training. Kinetic and kinematic characteristics may influence stress fracture risk, but there is no evidence that interventions to modify biomechanics can reduce the incidence of stress fracture. Strategies to promote adaptive bone formation, in combination with improved techniques to assess bone strength, present exciting opportunities for future research to prevent stress fractures.
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http://dx.doi.org/10.1007/s11914-021-00671-1DOI Listing
February 2021

Influence of Vitamin D Supplementation by Simulated Sunlight or Oral D3 on Respiratory Infection during Military Training.

Med Sci Sports Exerc 2021 Jan 21. Epub 2021 Jan 21.

College of Human Sciences, Bangor University, Bangor, Gwynedd, United Kingdom Faculty of Science, Liverpool John Moores University, Liverpool, United Kingdom Norwich Medical School, University of East Anglia, Norwich, Norfolk, United Kingdom Department of Nutrition and Health Care Management, Appalachian State University, Boone, NC Headquarters Army Recruiting and Initial Training Command, Upavon, Wiltshire, United Kingdom Defence Science and Technology, Porton Down, Wiltshire, United Kingdom Army Health and Physical Performance, Army HQ, Andover, Hampshire, United Kingdom Medical Physics Department, Salford Royal NHS Foundation Trust, and University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom Faculty of Biology, Medicine and Health, University of Manchester, and Dermatology Centre, Salford Royal NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom Departments of Endocrinology and Clinical Biochemistry, Norfolk and Norwich University Hospitals Trust, Norwich, United Kingdom Division of Surgery and Interventional Science, UCL, London, United Kingdom.

Purpose: To determine the relationship between vitamin D status and upper respiratory tract infection (URTI) of physically active men and women across seasons (study 1). Then, to investigate the effects on URTI and mucosal immunity of achieving vitamin D sufficiency (25(OH)D ≥50 nmol·L-1) by a unique comparison of safe, simulated-sunlight or oral D3 supplementation in winter (study 2).

Methods: In study 1, 1,644 military recruits were observed across basic military training. In study 2, a randomized controlled trial, 250 men undertaking military training received either placebo, simulated-sunlight (1.3x standard erythemal dose, three-times-per-week for 4-weeks and then once-per-week for 8-weeks) or oral vitamin D3 (1,000 IU·day-1 for 4-weeks and then 400 IU·day-1 for 8-weeks). URTI was diagnosed by physician (study 1) and Jackson common cold questionnaire (study 2). Serum 25(OH)D, salivary secretory immunoglobulin A (SIgA) and cathelicidin were assessed by LC-MS/MS and ELISA.

Results: In study 1, only 21% of recruits were vitamin D sufficient during winter. Vitamin D sufficient recruits were 40% less likely to suffer URTI than recruits with 25(OH)D <50 nmol·L-1 (OR (95% CI) = 0.6 (0.4-0.9)); an association that remained after accounting for sex and smoking. Each URTI caused on average 3 missed training days. In study 2, vitamin D supplementation strategies were similarly effective to achieve vitamin D sufficiency in almost all (≥95%). Compared to placebo, vitamin D supplementation reduced the severity of peak URTI symptoms by 15% and days with URTI by 36% (P < 0.05). These reductions were similar with both vitamin D strategies (P > 0.05). Supplementation did not affect salivary SIgA or cathelicidin.

Conclusion: Vitamin D sufficiency reduced the URTI burden during military training.
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http://dx.doi.org/10.1249/MSS.0000000000002604DOI Listing
January 2021

Measuring Protein Turnover in the Field: Implications for Military Research.

Adv Nutr 2020 Oct 20. Epub 2020 Oct 20.

Army Health and Performance Research, Army Headquarters, Andover, United Kingdom.

Protein turnover reflects the continual synthesis and breakdown of body proteins, and can be measured at a whole-body (i.e. aggregated across all body proteins) or tissue (e.g. skeletal muscle only) level using stable isotope methods. Evaluating protein turnover in free-living environments, such as military training, can help inform protein requirements. We undertook a narrative review of published literature with the aim of reviewing the suitability of, and advancements in, stable isotope methods for measuring protein turnover in field research. The 2 primary approaches for measuring protein turnover are based on precursor- and end-product methods. The precursor method is the gold-standard for measuring acute (over several hours) skeletal muscle protein turnover, whereas the end-product method measures chronic (over several weeks) skeletal muscle protein turnover and provides the opportunity to monitor free-living activities. Both methods require invasive procedures such as the infusion of amino acid tracers and muscle biopsies to assess the uptake of the tracer into tissue. However, the end-product method can also be used to measure acute (over 9-24 h) whole-body protein turnover noninvasively by ingesting 15N-glycine, or equivalent isotope tracers, and collecting urine samples. The end-product method using 15N-glycine is a practical method for measuring whole-body protein turnover in the field over short (24 h) time frames and has been used effectively in recent military field research. Application of this method may improve our understanding of protein kinetics during conditions of high physiological stress in free-living environments such as military training.
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http://dx.doi.org/10.1093/advances/nmaa123DOI Listing
October 2020

Measuring the Exercise Component of Energy Availability during Arduous Training in Women.

Med Sci Sports Exerc 2021 04;53(4):860-868

University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UNITED KINGDOM.

Introduction: Low energy availability (EA) may impede adaptation to exercise, suppressing reproductive function and bone turnover. Exercise energy expenditure (EEE) measurements lack definition and consistency. This study aimed to compare EA measured from moderate and vigorous physical activity from accelerometry (EEEmpva) with EA from total physical activity (EEEtpa) from doubly labeled water in women. The secondary aim was to determine the relationship of EA with physical fitness, body composition by dual-energy x-ray absorptiometry, heart rate variability (HRV), and eating behavior (Brief Eating Disorder in Athletes Questionnaire [BEDA-Q]).

Methods: This was a prospective, repeated-measures study, assessing EA measures and training adaptation during 11-month basic military training. Forty-seven women (23.9 ± 2.6 yr) completed three consecutive 10-d assessments of EEEmvpa, EEEtpa, and energy intake (EI). EA measures were compared using linear regression and Bland-Altman analyses; relationships of EA with fat mass, HRV, 1.5-mile run times, and BEDA-Q were evaluated using partial correlations.

Results: EA from EEEmvpa demonstrated strong agreement with EA from EEEtpa across the measurement range (R2 = 0.76, r = 0.87, P < 0.001) and was higher by 10 kcal·kg-1 FFM·d-1. However, EA was low in absolute terms because of underreported EI. Higher EA was associated with improved 1.5-mile run time (r = 0.28, P < 0.001), fat mass loss (r = 0.38, P < 0.001), and lower BEDA-Q score (r = -0.37, P < 0.001) but not HRV (all P > 0.10).

Conclusion: Accelerometry-based EEE demonstrated validity against doubly labeled water during multistressor training, the difference representing 10 kcal·kg-1 FFM·d-1 EEE from nonexercise activity. Beneficial physical but not autonomic adaptations were associated with higher EA. EAmvpa and BEDA-Q warrant consideration for low EA assessment and screening.
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http://dx.doi.org/10.1249/MSS.0000000000002527DOI Listing
April 2021

Energy Deficiency in Soldiers: The Risk of the Athlete Triad and Relative Energy Deficiency in Sport Syndromes in the Military.

Front Nutr 2020 25;7:142. Epub 2020 Aug 25.

Army Health and Performance Research, Army Headquarters, Andover, United Kingdom.

Military personnel experience energy deficit (total energy expenditure higher than energy intake), particularly during combat training and field exercises where exercising energy expenditures are high and energy intake is reduced. Low energy availability (energy intake minus exercising energy expenditure expressed relative to fat free mass) impairs endocrine function and bone health, as recognized in female athletes as the Female Athlete Triad syndrome. More recently, the Relative Energy Deficiency in Sport (RED-S) syndrome encompasses broader health outcomes, physical and cognitive performance, non-athletes, and men. This review summarizes the evidence for the effect of low energy availability and energy deficiency in military training and operations on health and performance outcomes. Energy availability is difficult to measure in free-living individuals but doubly labeled water studies demonstrate high total energy expenditures during military training; studies that have concurrently measured energy intake, or measured body composition changes with DXA, suggest severe and/or prolonged energy deficits. Military training in energy deficit disturbs endocrine and metabolic function, menstrual function, bone health, immune function, gastrointestinal health, iron status, mood, and physical and cognitive performance. There are more data for men than women, and little evidence on the chronic effects of repeated exposures to energy deficit. Military training impairs indices of health and performance, indicative of the Triad and RED-S, but the multi-stressor environment makes it difficult to isolate the independent effects of energy deficiency. Studies supplementing with energy to attenuate the energy deficit suggest an independent effect of energy deficiency in the disturbances to metabolic, endocrine and immune function, and physical performance, but randomized controlled trials are lacking.
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http://dx.doi.org/10.3389/fnut.2020.00142DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477333PMC
August 2020

Supplementary Energy Increases Bone Formation during Arduous Military Training.

Med Sci Sports Exerc 2021 02;53(2):394-403

Norwich Medical School, University of East Anglia, Norwich, UNITED KINGDOM.

Purpose: This study aimed to investigate the effect of supplementary energy on bone formation and resorption during arduous military training in energy deficit.

Methods: Thirty male soldiers completed an 8-wk military combat course (mean ± SD, age = 25 ± 3 yr, height = 1.78 ± 0.05 m, body mass = 80.9 ± 7.7 kg). Participants received either the habitual diet (control group, n = 15) or an additional 5.1 MJ·d-1 to eliminate the energy deficit (supplemented group, n = 15). Circulating markers of bone formation and resorption, and reproductive, thyroid, and metabolic status, were measured at baseline and weeks 6 and 8 of training.

Results: Bone-specific alkaline phosphatase decreased in controls (-4.4 ± 1.9 μg·L-1) and increased in the supplemented group (16.0 ± 6.6 μg·L-1), between baseline and week 8 (P < 0.001). Procollagen type 1 N-terminal propeptide increased between baseline and week 6 for both groups (5.6 ± 8.1 μg·L-1, P = 0.005). Beta carboxy-terminal cross-linking telopeptide of type 1 collagen decreased between baseline and week 8 for both groups (-0.16 ± 0.20 μg·L-1, P < 0.001). Prolactin increased from baseline to week 8 for the supplemented group (148 ± 151 IU·L-1, P = 0.041). The increase in adiponectin from baseline to week 8 was higher in controls (4.3 ± 1.8 mg·L-1, P < 0.001) than that in the supplemented group (1.4 ± 1.0 mg·L-1, P < 0.001). Insulin-like growth factor binding protein-3 was lower at week 8 than baseline for controls (-461 ± 395 ng·mL-1, P < 0.001).

Conclusion: The increase in bone-specific alkaline phosphatase, a marker of bone formation, with supplementation supports a role of energy in osteoblastic activity; the implications for skeletal adaptation and stress fracture risk are unclear. The mechanism is likely through protecting markers of metabolic, but not reproductive or thyroid, function.
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http://dx.doi.org/10.1249/MSS.0000000000002473DOI Listing
February 2021

Accuracy of Metabolic Cost Predictive Equations During Military Load Carriage.

J Strength Cond Res 2020 May 8. Epub 2020 May 8.

Occupational Performance Research Group, Institute of Sport, University of Chichester, Chichester, United Kingdom.

Vine, CA, Coakley, SL, Blacker, SD, Doherty, J, Hale, B, Walker, EF, Rue, CA, Lee, BJ, Flood, TR, Knapik, JJ, Jackson, S, Greeves, JP, and Myers, SD. Accuracy of metabolic cost predictive equations during military load carriage. J Strength Cond Res XX(X): 000-000, 2020-To quantify the accuracy of 5 equations to predict the metabolic cost of load carriage under ecologically valid military speed and load combinations. Thirty-nine male serving infantry soldiers completed thirteen 20-minute bouts of overground load carriage comprising 2 speeds (2.5 and 4.8 km·h) and 6 carried equipment load combinations (25, 30, 40, 50, 60, and 70 kg), with 22 also completing a bout at 5.5 km·h carrying 40 kg. For each speed-load combination, the metabolic cost was measured using the Douglas bag technique and compared with the metabolic cost predicted from 5 equations; Givoni and Goldman, 1971 (GG), Pandolf et al. 1997 (PAN), Santee et al. 2001 (SAN), American College of Sports Medicine 2013 (ACSM), and the Minimum-Mechanics Model (MMM) by Ludlow and Weyand, 2017. Comparisons between measured and predicted metabolic cost were made using repeated-measures analysis of variance and limits of agreement. All predictive equations, except for PAN, underpredicted the metabolic cost for all speed-load combinations (p < 0.001). The PAN equation accurately predicted metabolic cost for 40 and 50 kg at 4.8 km·h (p > 0.05), underpredicted metabolic cost for all 2.5 km·h speed-load combinations as well as 25 and 30 kg at 4.8 km·h, and overpredicted metabolic cost for 60 and 70 kg at 4.8 km·h (p < 0.001). Most equations (GG, SAN, ACSM, and MMM) underpredicted metabolic cost while one (PAN) accurately predicted at moderate loads and speeds, but overpredicted or underpredicted at other speed-load combinations. Our findings indicate that caution should be applied when using these predictive equations to model military load carriage tasks.
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http://dx.doi.org/10.1519/JSC.0000000000003644DOI Listing
May 2020

Vitamin D and the hepatitis B vaccine response: a prospective cohort study and a randomized, placebo-controlled oral vitamin D and simulated sunlight supplementation trial in healthy adults.

Eur J Nutr 2021 Feb 10;60(1):475-491. Epub 2020 May 10.

Faculty of Science, Liverpool John Moores University, Liverpool, UK.

Purpose: To determine serum 25(OH)D and 1,25(OH)D relationship with hepatitis B vaccination (study 1). Then, to investigate the effects on hepatitis B vaccination of achieving vitamin D sufficiency (serum 25(OH)D ≥ 50 nmol/L) by a unique comparison of simulated sunlight and oral vitamin D supplementation in wintertime (study 2).

Methods: Study 1 involved 447 adults. In study 2, 3 days after the initial hepatitis B vaccination, 119 men received either placebo, simulated sunlight (1.3 × standard-erythema dose, 3 × /week for 4 weeks and then 1 × /week for 8 weeks) or oral vitamin D (1000 IU/day for 4 weeks and 400 IU/day for 8 weeks). We measured hepatitis B vaccination efficacy as percentage of responders with anti-hepatitis B surface antigen immunoglobulin G ≥ 10 mIU/mL.

Results: In study 1, vaccine response was poorer in persons with low vitamin D status (25(OH)D ≤ 40 vs 41-71 nmol/L mean difference [95% confidence interval] - 15% [- 26, - 3%]; 1,25(OH)D ≤ 120 vs ≥ 157 pmol/L - 12% [- 24%, - 1%]). Vaccine response was also poorer in winter than summer (- 18% [- 31%, - 3%]), when serum 25(OH)D and 1,25(OH)D were at seasonal nadirs, and 81% of persons had serum 25(OH)D < 50 nmol/L. In study 2, vitamin D supplementation strategies were similarly effective in achieving vitamin D sufficiency from the winter vitamin D nadir in almost all (~ 95%); however, the supplementation beginning 3 days after the initial vaccination did not effect the vaccine response (vitamin D vs placebo 4% [- 21%, 14%]).

Conclusion: Low vitamin D status at initial vaccination was associated with poorer hepatitis B vaccine response (study 1); however, vitamin D supplementation commencing 3 days after vaccination (study 2) did not influence the vaccination response.

Clinical Trial Registry Number: Study 1 NCT02416895; https://clinicaltrials.gov/ct2/show/study/NCT02416895 ; Study 2 NCT03132103; https://clinicaltrials.gov/ct2/show/NCT03132103 .
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http://dx.doi.org/10.1007/s00394-020-02261-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7867563PMC
February 2021

Validity of energy expenditure estimation methods during 10 days of military training.

Scand J Med Sci Sports 2019 Sep 18;29(9):1313-1321. Epub 2019 Jun 18.

Occupational Performance Research Group, University of Chichester, Chichester, UK.

Wearable physical activity (PA) monitors have improved the ability to estimate free-living total energy expenditure (TEE) but their application during arduous military training alongside more well-established research methods has not been widely documented. This study aimed to assess the validity of two wrist-worn activity monitors and a PA log against doubly labeled water (DLW) during British Army Officer Cadet (OC) training. For 10 days of training, twenty (10 male and 10 female) OCs (mean ± SD: age 23 ± 2 years, height 1.74 ± 0.09 m, body mass 77.0 ± 9.3 kg) wore one research-grade accelerometer (GENEActiv, Cambridge, UK) on the dominant wrist, wore one commercially available monitor (Fitbit SURGE, USA) on the non-dominant wrist, and completed a self-report PA log. Immediately prior to this 10-day period, participants consumed a bolus of DLW and provided daily urine samples, which were analyzed by mass spectrometry to determine TEE. Bivariate correlations and limits of agreement (LoA) were employed to compare TEE from each estimation method to DLW. Average daily TEE from DLW was 4112 ± 652 kcal·day against which the GENEActiv showed near identical average TEE (mean bias ± LoA: -15 ± 851 kcal day ) while Fitbit tended to underestimate (-656 ± 683 kcal·day ) and the PA log substantially overestimate (+1946 ± 1637 kcal·day ). Wearable physical activity monitors provide a cheaper and more practical method for estimating free-living TEE than DLW in military settings. The GENEActiv accelerometer demonstrated good validity for assessing daily TEE and would appear suitable for use in large-scale, longitudinal military studies.
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http://dx.doi.org/10.1111/sms.13488DOI Listing
September 2019

Skeletal macro- and microstructure adaptations in men undergoing arduous military training.

Bone 2019 08 8;125:54-60. Epub 2019 May 8.

Army Personnel Research Capability, Army Headquarters, Andover, United Kingdom; Norwich Medical School, University of East Anglia, Norwich, United Kingdom. Electronic address:

Purpose: Short periods of basic military training increase the density and size of the tibia, but the adaptive response of bone microarchitecture, a key component of bone strength, is not fully understood.

Methods: Tibial volumetric bone mineral density (vBMD), geometry, microarchitecture and mechanical properties were measured using high-resolution peripheral quantitative computed tomography in 43 male British Army infantry recruits (mean ± SD, age 21 ± 3 years, height 1.76 ± 0.06 m, body mass 76.5 ± 9.4 kg). Bilateral scans were performed at the distal tibia at the start (week 1) and end (week 13) of basic military training. Concurrent measures were obtained for whole-body areal bone mineral density (aBMD) using DXA, and markers of bone metabolism (βCTX, P1NP, PTH, total 25(OH)D and ACa) from venous blood.

Results: Training increased areal BMD for total body (1.4%) and arms (5.2%) (P ≤ 0.031), but not legs and trunk (P ≥ 0.094). Training increased trabecular (1.3 to 1.9%) and cortical vBMD (0.6 to 0.9%), trabecular volume (1.3 to 1.9%), cortical thickness (3.2 to 5.2%) and cortical area (2.6 to 2.8%), and reduced trabecular area (-0.4 to -0.5%) in both legs (P < 0.001). No changes in trabecular number, thickness and separation, cortical porosity, stiffness or failure load were observed (P ≥ 0.188). βCTX decreased (-0.11 μg∙l, P < 0.001) and total 25(OH)D increased (9.4 nmol∙l, P = 0.029), but no differences in P1NP, PTH or ACa were observed between timepoints (P ≥ 0.233).

Conclusion: A short period of basic military training increased density and altered geometry of the distal tibia in male military recruits. The osteogenic effects of basic military training are likely due to an increase in unaccustomed, dynamic and high-impact loading.
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http://dx.doi.org/10.1016/j.bone.2019.05.009DOI Listing
August 2019

Skeletal responses to an all-female unassisted Antarctic traverse.

Bone 2019 04 5;121:267-276. Epub 2019 Feb 5.

Army Personnel Research Capability, Army Headquarters, Andover, UK. Electronic address:

Purpose: To investigate the skeletal effects of the first all-female trans-Antarctic traverse.

Methods: Six women (mean ± SD, age 32 ± 3 years, height 1.72 ± 0.07 m, body mass 72.8 ± 4.0 kg) hauled 80 kg sledges over 1700 km in 61 days from coast-to-coast across the Antarctic. Whole-body areal bone mineral density (aBMD) (dual-energy X-ray absorptiometry) and tibial volumetric BMD (vBMD), geometry, microarchitecture and estimated mechanical properties (high-resolution peripheral quantitative computed tomography) were assessed 39 days before (pre-expedition) and 15 days after the expedition (post-expedition). Serum and plasma markers of bone turnover were assessed pre-expedition, and 4 and 15 days after the expedition.

Results: There were reductions in trunk (-2.6%), ribs (-5.0%) and spine (-3.4%) aBMD from pre- to post-expedition (all P ≤ 0.046); arms, legs, pelvis and total body aBMD were not different (all P ≥ 0.075). Tibial vBMD, geometry, microarchitecture and estimated mechanical properties at the metaphysis (4% site) and diaphysis (30% site) were not different between pre- and post-expedition (all P ≥ 0.082). Bone-specific alkaline phosphatase was higher 15 days post- than 4 days post-expedition (1.7 μg∙l, P = 0.028). Total 25(OH)D decreased from pre- to 4 days post-expedition (-36 nmol∙l, P = 0.008). Sclerostin, procollagen 1 N-terminal propeptide, C-telopeptide cross-links of type 1 collagen and adjusted calcium were unchanged (all P ≥ 0.154).

Conclusion: A decline in aBMD of the axial skeleton may be due to indirect and direct effects of prolonged energy deficit. We propose that weight-bearing exercise was protective against the effects of energy deficit on tibial vBMD, geometry, microarchitecture and strength.
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http://dx.doi.org/10.1016/j.bone.2019.02.002DOI Listing
April 2019

Confirmation of ovulation from urinary progesterone analysis: assessment of two automated assay platforms.

Sci Rep 2018 12 4;8(1):17621. Epub 2018 Dec 4.

MRC Centre for Reproductive Health, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK.

Urinary concentrations of the major progesterone (P4) metabolite pregnanediol-3-glucuronide (PDG) are used to confirm ovulation. We aimed to determine whether automated immunoassay of urinary P4 was as efficacious as PDG to confirm ovulation. Daily urine samples from 20 cycles in 14 healthy women in whom ovulation was dated by ultrasound, and serial weekly samples from 21 women in whom ovulation was unknown were analysed. Daily samples were assayed by two automated P4 immunoassays (Roche Cobas and Abbott Architect) and PDG ELISA. Serial samples were assayed for P4 by Architect and PDG by ELISA. In women with detailed monitoring of ovulation, median (95% CI) luteal phase increase was greatest for PDG, 427% (261-661), 278% (187-354) for P4 Architect and least for P4 Cobas, 146% (130-191), p < 0.0001. Cobas P4 also showed marked inaccuracy in serial dilution. Similar ROC AUCs were observed for individual threshold values and two-sample percent rise analyses for P4 Architect and PDG (both >0.92). In serial samples classified as (an)ovulatory by PDG, P4 Architect gave ROC AUC 0.95 (95% CI 0.89 to 1.01), with sensitivity and specificity for confirmation of ovulation of 0.90 and 0.91 at a cutoff of 1.67 μmol/mol. Automated P4 may potentially be as efficacious as PDG ELISA but research from a range of clinical settings is required.
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http://dx.doi.org/10.1038/s41598-018-36051-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6279762PMC
December 2018

Seasonal Difference in Bone Characteristics and Body Composition of Elite Speed Skaters.

Int J Sports Med 2019 Jan 27;40(1):9-15. Epub 2018 Nov 27.

Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.

We investigated the changes in bone characteristics and body composition of elite speed skaters across two competitive seasons. Twelve elite speed skaters (age 23±4 years; height 1.73±0.09 m; body mass 68.5±8.8 kg; mean±1 SD) were assessed by DXA and pQCT for Bone Mineral Density (BMD), Bone Mineral Content (BMC), area, bone strength, cortical thickness and density at four points over the course of four competitive seasons. Body composition data was also collected. A main effect of time was shown for whole body BMC, right leg BMC, and trabecular area (P<0.05). Whole body BMC was higher during pre-season and end of season in comparison to mid-season (1.0%, P=0.007; 0.8%, P=0.017), right leg BMC was higher at the pre-season scan in comparison to the post pre-season scan (1.8%,P=0.020) and trabecular area was higher during the mid-season and end of season when compared to the pre-season (1.4%, P=0.012; 1.0%, P=0.003). Seasonal changes in bone characteristics and body composition are shown in elite speed skaters over a competitive season. The changes are thought to be a result of fluctuations in training load. These data may have implications for training design and injury risk management in elite sport.
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http://dx.doi.org/10.1055/a-0767-6924DOI Listing
January 2019

Female Reproductive, Adrenal, and Metabolic Changes during an Antarctic Traverse.

Med Sci Sports Exerc 2019 03;51(3):556-567

Research & Clinical Innovation, Royal Centre for Defence Medicine, Lichfield, UNITED KINGDOM.

Purpose: To explore the effects of the first all-female transantarctic expedition on hormonal axes pertinent to reproductive and metabolic function.

Methods: Six females (age, 28-36 yr; body mass index, 24.2 ± 0.97 kg·m) hauled 80-kg sledges 1700 km in 61 d. Estimated average energy intake was 20.8 ± 0.1 MJ·d (4970 ± 25 kcal·d). Whole and regional body composition was measured by dual-energy x-ray absorptiometry 1 and 2 months before and 15 d after, the expedition. Body fat was also estimated by skinfold and bioimpedance immediately before and after the expedition. Basal metabolic and endocrine blood markers and, after 0.25 mg dexamethasone suppression, 1-h 10-μg gonadorelin and 1.0 μg adrenocortiocotrophin-(1-24) tests were completed, 39-38 d preexpedition and 4 to 5 d and 15 to 16 d postexpedition. Cortisol was assessed in hair (monthly average concentrations) and saliva (five-point day curves and two-point diurnal sampling).

Results: Average body mass loss was 9.37 ± 2.31 kg (P < 0.0001), comprising fat mass only; total lean mass was maintained. Basal sex steroids, corticosteroids, and metabolic markers were largely unaffected by the expedition except leptin, which decreased during the expedition and recovered after 15 d, a proportionately greater change than body fat. Luteinizing hormone reactivity was suppressed before and during the expedition, but recovered after 15 d, whereas follicle-stimulating hormone did not change during or after the expedition. Cortisol reactivity did not change during or after the expedition. Basal (suppressed) cortisol was 73.25 ± 45.23 mmol·L before, 61.66 ± 33.11 mmol·L 5 d postexpedition and 54.43 ± 28.60 mmol·L 16 d postexpedition (P = 0.7). Hair cortisol was elevated during the expedition.

Conclusions: Maintenance of reproductive and hypothalamic-pituitary-adrenal axis function in women after an extreme physical endeavor, despite energy deficiency, suggests high female biological capacity for extreme endurance exercise.
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http://dx.doi.org/10.1249/MSS.0000000000001803DOI Listing
March 2019

Influence of Vitamin D Supplementation by Sunlight or Oral D3 on Exercise Performance.

Med Sci Sports Exerc 2018 12;50(12):2555-2564

College of Health and Behavioural Sciences, Bangor University, Bangor, Gwynedd, UNITED KINGDOM.

Purpose: To determine the relationship between vitamin D status and exercise performance in a large, prospective cohort study of young men and women across seasons (study 1). Then, in a randomized, placebo-controlled trial, to investigate the effects on exercise performance of achieving vitamin D sufficiency (serum 25(OH)D ≥ 50 nmol·L) by a unique comparison of safe, simulated-sunlight and oral vitamin D3 supplementation in wintertime (study 2).

Methods: In study 1, we determined 25(OH)D relationship with exercise performance in 967 military recruits. In study 2, 137 men received either placebo, simulated sunlight (1.3× standard erythemal dose in T-shirt and shorts, three times per week for 4 wk and then once per week for 8 wk) or oral vitamin D3 (1000 IU·d for 4 wk and then 400 IU·d for 8 wk). We measured serum 25(OH)D by high-pressure liquid chromatography tandem mass spectrometry and endurance, strength and power by 1.5-mile run, maximum dynamic lift and vertical jump, respectively.

Results: In study 1, only 9% of men and 36% of women were vitamin D sufficient during wintertime. After controlling for body composition, smoking, and season, 25(OH)D was positively associated with endurance performance (P ≤ 0.01, ΔR = 0.03-0.06, small f effect sizes): 1.5-mile run time was ~half a second faster for every 1 nmol·L increase in 25(OH)D. No significant effects on strength or power emerged (P > 0.05). In study 2, safe simulated sunlight and oral vitamin D3 supplementation were similarly effective in achieving vitamin D sufficiency in almost all (97%); however, this did not improve exercise performance (P > 0.05).

Conclusions: Vitamin D status was associated with endurance performance but not strength or power in a prospective cohort study. Achieving vitamin D sufficiency via safe, simulated summer sunlight, or oral vitamin D3 supplementation did not improve exercise performance in a randomized-controlled trial.
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http://dx.doi.org/10.1249/MSS.0000000000001721DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6282681PMC
December 2018

Bone metabolic responses to low energy availability achieved by diet or exercise in active eumenorrheic women.

Bone 2018 09 19;114:181-188. Epub 2018 Jun 19.

Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, School of Science and Technology, Nottingham Trent University, Clifton Campus, NG11 8NS, UK. Electronic address:

Purpose: We aimed to explore the effects of low energy availability (EA)[15 kcal·kg lean body mass (LBM)·d] achieved by diet or exercise on bone turnover markers in active, eumenorrheic women.

Methods: By using a crossover design, ten eumenorrheic women (VO: 48.1 ± 3.3 ml·kg·min) completed all three, 3-day conditions in a randomised order: controlled EA (CON; 45 kcal·kgLBM·d), low EA through dietary energy restriction (D-RES; 15 kcal·kgLBM·d) and low EA through increasing exercise energy expenditure (E-RES; 15 kcal·kgLBM·d), during the follicular phase of three menstrual cycles. In CON, D-RES and E-RES, participants consumed diets providing 45, 15 and 45 kcal·kgLBM·d. In E-RES only, participants completed supervised running sessions (129 ± 10 min·d) at 70% of their VO that resulted in an exercise energy expenditure of 30 kcal·kg LBM·d. Blood samples were collected at baseline (BASE) and at the end of the 3-day period (D6) and analysed for bone turnover markers (β-CTX and P1NP), markers of calcium metabolism (PTH, albumin-adjusted Ca, Mg and PO) and hormones (IGF-1, T, insulin, leptin and 17β-oestradiol).

Results: In D-RES, P1NP concentrations at D6 decreased by 17% (BASE: 54.8 ± 12.7 μg·L, D6: 45.2 ± 9.3 μg·L, P < 0.001, d = 0.91) and were lower than D6 concentrations in CON (D6: 52.5 ± 11.9 μg·L, P = 0.001). P1NP did not change significantly in E-RES (BASE: 55.3 ± 14.4 μg·L, D6: 50.9 ± 15.8 μg·L, P = 0.14). β-CTX concentrations did not change following D-RES (BASE: 0.48 ± 0.18 μg·L, D6: 0.55 ± 0.17 μg·L) or E-RES (BASE: 0.47 ± 0.24 μg·L, D6: 0.49 ± 0.18 μg·L) (condition × time interaction effect, P = 0.17). There were no significant differences in P1NP (P = 0.25) or β-CTX (P = 0.13) responses between D-RES and E-RES. Both conditions resulted in reductions in IGF-1 (-13% and - 23% from BASE in D-RES and E-RES, both P < 0.01) and leptin (-59% and - 61% from BASE in D-RES and E-RES, both P < 0.001); T decreased in D-RES only (-15% from BASE, P = 0.002) and PO concentrations decreased in E-RES only (-9%, P = 0.03).

Conclusions: Low EA achieved through dietary energy restriction resulted in a significant decrease in bone formation but no change in bone resorption, whereas low EA achieved through exercise energy expenditure did not significantly influence bone metabolism. Both low EA conditions elicited significant and similar changes in hormone concentrations.
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http://dx.doi.org/10.1016/j.bone.2018.06.016DOI Listing
September 2018

Increased Risk of Upper Respiratory Infection in Military Recruits Who Report Sleeping Less Than 6 h per night.

Mil Med 2018 11;183(11-12):e699-e704

College of Health and Behavioural Sciences, Holyhead Road, Bangor University, Bangor, Gwynedd, UK.

Introduction: Professional sleep associations recommend 7-9 h of sleep per night for young adults. Habitually sleeping less than 6 h per night has been shown to increase susceptibility to common cold in otherwise healthy, adult civilians. However, no investigations have examined the importance of sleep duration on upper respiratory tract infection (URTI) and loss of training days in military recruits. The purpose of this study was to describe self-reported sleep duration in a large cohort of military recruits and to assess the relationship between reported sleep duration and incidence of URTI's. We hypothesized that recruits who reported sleeping less than the recommended 7-9 h per night during training suffered a greater incidence of URTI and, as a consequence, lost more training days compared with recruits who met sleep recommendations.

Materials And Methods: Participants included 651 British Army recruits aged 22 ± 3 yr who completed 13 wk of basic military training (67% males, 33% females). Participants were members of 21 platoons (11 male, 10 female) who commenced training across four seasons (19% winter, 20% spring, 29% summer, and 32% autumn). At the start and completion of training, participants completed a questionnaire asking the typical time they went to sleep and awoke. Incidence of physician-diagnosed URTI and lost training days due to URTI were retrieved from medical records.

Results: Self-reported sleep duration decreased from before to during training (8.5 ± 1.6 vs. 7.0 ± 0.8 h; p < 0.01). Prior to training, 13% of participants reported sleeping less than the recommended 7 h sleep per night; however, this increased to 38% during training (X2 = 3.8; p = 0.05). Overall, 49 participants (8%) were diagnosed by a physician with at least one URTI and 3 participants (<1%) were diagnosed with two URTI's. After controlling for sex, body mass index, season of recruitment, smoking, and alcohol, participants who reported sleeping less than 6 h per night during training were four times more likely to be diagnosed with URTI compared with participants who slept 7-9 h per night in a logistic regression model (OR 4.4; 95% CI, 1.5-12.9, p < 0.01). On average, each URTI resulted in 2.9 ± 1.5 lost training days. Participants who were diagnosed with URTI had more overall lost training days for any illness compared with participants who did not report a URTI during basic military training (3.3 ± 1.9 vs. 0.4 ± 1.3; p < 0.01).

Conclusion: In a large population of British Army recruits, these findings show that more than one third of participants failed to meet sleep duration recommendations during training. Furthermore, those who reported sleeping less than 6 h per night were four times more likely to be diagnosed with an URTI and lost more training days due to URTI. Since sleep restriction is considered a necessary element of military training, future studies should examine interventions to reduce any negative effects on immunity and host defense.
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http://dx.doi.org/10.1093/milmed/usy090DOI Listing
November 2018

SNPs in the vicinity of P2X7R, RANK/RANKL/OPG and Wnt signalling pathways and their association with bone phenotypes in academy footballers.

Bone 2018 03 8;108:179-185. Epub 2018 Jan 8.

Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, UK. Electronic address:

Context: Genotype plays an important role in influencing bone phenotypes, such as bone mineral density, but the role of genotype in determining responses of bone to exercise has yet to be elucidated.

Objective: To determine whether 10 SNPs associated with genes in the vicinity of P2X7R, RANK/RANKL/OPG and Wnt Signalling Pathways are associated with bone phenotypes in elite academy footballers (Soccer players) and to determine whether these genotypes are associated with training induced changes in bone. Design, participants, and methods: 99 elite academy footballers volunteered to participate. Peripheral computed tomography of the tibia (4%, 14%, 38% and 66% sites) was performed immediately before and 12 weeks after an increase in football training volume. Genotypes were determined using proprietary fluorescence-based competitive allele-specific PCR assays.

Results: No significant genotype by time interactions were shown for any of the SNPs analysed (P > .05). A main effect of genotype was shown. SOST SNP rs1877632 (trabecular density), P2X7R SNPs rs1718119 (cortical thickness and CSA), rs3751143 (SSI, CSA, cortical CSA and periosteal circumference) RANK/RANKL/OPG SNPs rs9594738 (periosteal circumference), rs1021188 (cortical thickness and CSA) and rs9594759 (cortical density) were associated with bone phenotypes (P < .05).

Conclusions: No association was shown between P2X7R, RANK/RANKL/OPG and Wnt Signalling SNPs and a change in bone phenotypes following 12 weeks of increased training volume in elite academy footballers. However, SNPs were associated with bone phenotypes pre training. These data highlight the complexity of the interaction between SNPs in the vicinity of the RANK/RANKL/OPG, P2X7R and Wnt metabolic regulatory pathways and bone phenotypes in elite academy footballers.
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http://dx.doi.org/10.1016/j.bone.2018.01.007DOI Listing
March 2018

The association of novel polymorphisms with stress fracture injury in Elite Athletes: Further insights from the SFEA cohort.

J Sci Med Sport 2018 Jun 7;21(6):564-568. Epub 2017 Nov 7.

Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, UK. Electronic address:

Objectives: To determine, in conjunction with a wider investigation, whether 11 genetic variants in the vicinity of vitamin D, collagen and Wnt signalling pathways were associated with stress fracture injury in the Stress Fracture Elite Athlete (SFEA) cohort.

Design: Genotype-phenotype association study.

Methods: Self-reported stress fracture history and demographic data were recorded in 518 elite athletes, 449 male and 69 female (mean age 24.2±5.5 years) from the SFEA cohort. Elite athletes were assigned to two groups based on history of stress fracture injury. Data were analysed for the whole cohort and sub-stratified in to male only and multiple stress fracture cases. Genotype was determined using a proprietary fluorescence-based competitive allele-specific polymerase chain reaction assay.

Results: SOST SNP rs1877632 and VDR SNPs rs10735810 and rs731236 were associated with stress fracture (p<0.05). In the whole cohort, rs1877632 heterozygotes and homozygotes of the rare allele combined made up 59% of stress fracture sufferers in comparison to 46% in the non-stress fracture group (p=0.05). In the multiple stress fracture cohort, homozygotes of the rare allele of rs10735810 and rs731236 showed an association with stress fracture when compared to those homozygotes for the common allele combined with heterozygotes (p=0.03; p=0.01). No significant associations were shown in the other SNPs analysed (p>0.05).

Conclusions: These data suggest an important role for SOST SNP rs1877632 and VDR SNPs rs10735810 and rs731236 in the pathophysiology of stress fracture. This might be due to the role of the SNPs in the regulation of bone remodelling and adaptation to mechanical loading, with potential implications for the prevention and treatment of stress fracture injuries.
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http://dx.doi.org/10.1016/j.jsams.2017.10.038DOI Listing
June 2018

Mitigating the risk of musculoskeletal injury: A systematic review of the most effective injury prevention strategies for military personnel.

J Sci Med Sport 2017 Nov 23;20 Suppl 4:S3-S10. Epub 2017 Sep 23.

Division of Applied Human Physiology, Army Personnel Research Capability, Army Headquarters, Andover, UK.

Objectives: To update the current injury prevention strategy evidence base for making recommendations to prevent physical training-related musculoskeletal injury.

Design: We conducted a systematic review to update the evidence base on injury prevention strategies for military personnel.

Methods: Literature was systematically searched and extracted from five databases, and reported according to PRISMA guidelines. Sixty one articles meeting the inclusion criteria and published during the period 2008-2015 were selected for systematic review.

Results: The retrieved articles were broadly categorised into six injury prevention strategies; (1) conditioning, (2) footwear modifications, (3) bracing, (4) physical activity volume, (5) physical fitness, and (6) leadership/supervision/awareness. The majority of retrieved articles (n=37 (of 61) evaluated or systematically reviewed a conditioning intervention of some nature. However, the most well-supported strategies were related to reducing physical activity volume and improving leadership/supervision/awareness of injuries and injury prevention efforts.

Conclusions: Several injury prevention strategies effectively reduce musculoskeletal injury rates in both sexes, and many show promise for utility with military personnel. However, further evaluation, ideally with prospective randomised trials, is required to establish the most effective injury prevention strategies, and to understand any sex-specific differences in the response to these strategies.
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http://dx.doi.org/10.1016/j.jsams.2017.09.014DOI Listing
November 2017

Effects of reduced energy availability on bone metabolism in women and men.

Bone 2017 Dec 25;105:191-199. Epub 2017 Aug 25.

Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, School of Science and Technology, Nottingham Trent University, UK. Electronic address:

Background: The short-term effects of low energy availability (EA) on bone metabolism in physically active women and men are currently unknown.

Purpose: We evaluated the effects of low EA on bone turnover markers (BTMs) in a cohort of women and a cohort of men, and compared effects between sexes.

Methods: These studies were performed using a randomised, counterbalanced, crossover design. Eleven eumenorrheic women and eleven men completed two 5-day protocols of controlled (CON; 45kcal·kgLBM·d) and restricted (RES; 15kcal·kgLBM·d) EAs. Participants ran daily on a treadmill at 70% of their peak aerobic capacity (VO peak) resulting in an exercise energy expenditure of 15kcal·kgLBM·d and consumed diets providing 60 and 30kcal·kgLBM·d. Blood was analysed for BTMs [β-carboxyl-terminal cross-linked telopeptide of type I collagen (β-CTX) and amino-terminal propeptide of type 1 procollagen (P1NP)], markers of calcium metabolism [parathyroid hormone (PTH), albumin-adjusted calcium (ACa), magnesium (Mg) and phosphate (PO)] and regulatory hormones [sclerostin, insulin-like growth factor 1 (IGF-1), triiodothyronine (T), insulin, leptin, glucagon-like-peptide-2 (GLP-2)].

Results: In women, β-CTX AUC was significantly higher (P=0.03) and P1NP AUC was significantly lower (P=0.01) in RES compared to CON. In men, neither β-CTX (P=0.46) nor P1NP (P=0.12) AUCs were significantly different between CON and RES. There were no significant differences between sexes for any BTM AUCs (all P values>0.05). Insulin and leptin AUCs were significantly lower following RES in women only (for both P=0.01). There were no differences in any AUCs of regulatory hormones or markers of calcium metabolism between men and women following RES (all P values>0.05).

Conclusions: When comparing within groups, five days of low EA (15kcal·kgLBM·d) decreased bone formation and increased bone resorption in women, but not in men, and no sex specific differences were detected.
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http://dx.doi.org/10.1016/j.bone.2017.08.019DOI Listing
December 2017

Increased Training Volume Improves Bone Density and Cortical Area in Adolescent Football Players.

Int J Sports Med 2017 May 1;38(5):341-346. Epub 2017 Mar 1.

Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, Nottingham Trent University, Nottingham, Nottingham Trent University, United Kingdom of Great Britain and Northern Ireland.

Habitual football participation has been shown to be osteogenic, although the specific volume of football participation required to cause bone adaptations are not well established. The aim of the present study is to investigate tibial bone adaptations in response to 12 weeks of increased training volume in elite adolescents who are already accustomed to irregular impact training. 99 male adolescent elite footballers participated (age 16±0 y; height 1.76±0.66 m; body mass 70.2±8.3 kg). Tibial scans were performed using peripheral quantitative computed tomography immediately before and 12 weeks after an increase in football training volume. Scans were obtained at 4, 14, 38 and 66% of tibial length. Trabecular density (mg/cm), cortical density (mg/cm), cross-sectional area, cortical area (mm), cortical thickness (mm) and strength strain index (mm) were assessed. Trabecular (4%) and cortical density (14, 38%), cortical cross-sectional area (14, 38%), total cross-sectional area (66%), cortical thickness (14, 38%) and strength strain index (14, 38%) increased following 12 weeks of augmented volume training (P<0.05). Increased density of trabecular and cortical compartments and cortical thickening were shown following an increased volume of training. These adaptive responses may have been enhanced by the adolescent status of the cohort, supporting the role of early exercise intervention in improving bone strength.
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http://dx.doi.org/10.1055/s-0042-124510DOI Listing
May 2017

Increased density and periosteal expansion of the tibia in young adult men following short-term arduous training.

Bone 2016 07 31;88:13-19. Epub 2016 Mar 31.

HQ Army Recruiting and Training Division, Upavon, UK. Electronic address:

Purpose: Few human studies have reported early structural adaptations of bone to weight-bearing exercise, which provide a greater contribution to improved bone strength than increased density. This prospective study examined site- and regional-specific adaptations of the tibia during arduous training in a cohort of male military (infantry) recruits to better understand how bone responds in vivo to mechanical loading.

Methods: Tibial bone density and geometry were measured in 90 British Army male recruits (ages 21±3years, height: 1.78±0.06m, body mass: 73.9±9.8kg) in weeks 1 (Baseline) and 10 of initial military training. Scans were performed at the 4%, 14%, 38% and 66% sites, measured from the distal end plate, using pQCT (XCT2000L, Stratec Pforzheim, Germany). Customised software (BAMPack, L-3 ATI) was used to examine whole bone cross-section and regional sectors. T-tests determined significant differences between time points (P<0.05).

Results: Bone density of trabecular and cortical compartments increased significantly at all measured sites. Bone geometry (cortical area and thickness) and bone strength (i, MMi and BSI) at the diaphyseal sites (38 and 66%) were also significantly higher in week 10. Regional changes in density and geometry were largely observed in the anterior, medial-anterior and anterior-posterior sectors. Calf muscle density and area (66% site) increased significantly at week 10 (P<0.01).

Conclusions: In vivo mechanical loading improves bone strength of the human tibia by increased density and periosteal expansion, which varies by site and region of the bone. These changes may occur in response to the nature and distribution of forces originating from bending, torsional and shear stresses of military training. These improvements are observed early in training when the osteogenic stimulus is sufficient, which may be close to the fracture threshold in some individuals.
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http://dx.doi.org/10.1016/j.bone.2016.03.015DOI Listing
July 2016

Functional polymorphisms in the P2X7 receptor gene are associated with stress fracture injury.

Purinergic Signal 2016 Mar 29;12(1):103-13. Epub 2016 Jan 29.

Bone and Joint Research Group, Department of Musculoskeletal Biology, Institute of Ageing and Chronic Diseases, Faculty of Health and Life Sciences, University of Liverpool, Sherrington Buildings, Ashton Street, Liverpool, L69 3GE, UK.

Military recruits and elite athletes are susceptible to stress fracture injuries. Genetic predisposition has been postulated to have a role in their development. The P2X7 receptor (P2X7R) gene, a key regulator of bone remodelling, is a genetic candidate that may contribute to stress fracture predisposition. The aim of this study is to evaluate the putative contribution of P2X7R to stress fracture injury in two separate cohorts, military personnel and elite athletes. In 210 Israeli Defense Forces (IDF) military conscripts, stress fracture injury was diagnosed (n = 43) based on symptoms and a positive bone scan. In a separate cohort of 518 elite athletes, self-reported medical imaging scan-certified stress fracture injuries were recorded (n = 125). Non-stress fracture controls were identified from these cohorts who had a normal bone scan or no history or symptoms of stress fracture injury. Study participants were genotyped for functional SNPs within the P2X7R gene using proprietary fluorescence-based competitive allele-specific PCR assay. Pearson's chi-squared (χ (2)) tests, corrected for multiple comparisons, were used to assess associations in genotype frequencies. The variant allele of P2X7R SNP rs3751143 (Glu496Ala-loss of function) was associated with stress fracture injury, whilst the variant allele of rs1718119 (Ala348Thr-gain of function) was associated with a reduced occurrence of stress fracture injury in military conscripts (P < 0.05). The association of the variant allele of rs3751143 with stress fractures was replicated in elite athletes (P < 0.05), whereas the variant allele of rs1718119 was also associated with reduced multiple stress fracture cases in elite athletes (P < 0.05). The association between independent P2X7R polymorphisms with stress fracture prevalence supports the role of a genetic predisposition in the development of stress fracture injury.
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http://dx.doi.org/10.1007/s11302-016-9495-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4749527PMC
March 2016

Physiological Implications, Performance Assessment and Risk Mitigation Strategies of Women in Combat-Centric Occupations.

Authors:
Julie P Greeves

J Strength Cond Res 2015 Nov;29 Suppl 11:S94-100

Department of Occupational Medicine, HQ Army Recruiting and Training Division, Pewsey, United Kingdom.

Women have historically featured in military conflicts, but were not formally integrated into the military until the 20th century; occupations were mainly restricted to clerical or support roles. An increasing number of occupations have been opened to women and the higher physical demands of combat roles present new challenges. Inherent biological differences between sexes require women to work harder when undertaking the same tasks as men. This is reflected, in part, by the greater risk of musculoskeletal injuries of women observed notably during integrated military training. Gender "neutral" occupational standards, based on the physical requirements of the role, will ensure that women are suitably selected to cope with the demands of military tasks with a minimal risk of injury and to operational effectiveness. Initiatives such as reduced running mileage and single-sex training have contributed to a reduction in lower-limb musculoskeletal injuries, but the risk of injury remains higher in women. Nevertheless, women experience substantial gains in aerobic power and strength with appropriate and targeted training, narrowing the gap in physical performance between the sexes. Evidence-based occupational standards and optimal training programs provide short-term solutions for integrating women in support combat, and indeed direct combat roles.
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http://dx.doi.org/10.1519/JSC.0000000000001116DOI Listing
November 2015

Development and Implementation of Evidence-Based Physical Employment Standards: Key Challenges in the Military Context.

J Strength Cond Res 2015 Nov;29 Suppl 11:S28-33

1Human Performance Research and Development, Canadian Forces Morale and Welfare Services, Ottawa, Ontario, Canada; 2Human Performance Systems, Inc., Beltsville, Maryland; 3Land Division, Defence Science and Technology Organisation, Melbourne, Victoria, Australia; 4Department of Occupational Medicine, HQ Army Recruiting and Training Division, Pewsey, Wilts, UK; and 5U S Army Research Institute of Environmental Medicine, Natick, Massachusetts.

The use of evidence-based physical employment standards is critical in selecting individuals who can meet the requirements of arduous military occupations. The methods used to generate the physical assessments and standards are critical to the process and must withstand legal scrutiny. This article addresses the challenges encountered when developing, validating, and implementing physical standards and assessments. The challenges covered by the study include: (a) identification of critical job tasks and minimum requirements for performance of the tasks, (b) involvement of military personnel as subject-matter experts,
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http://dx.doi.org/10.1519/JSC.0000000000001105DOI Listing
November 2015

Force and acceleration characteristics of military foot drill: implications for injury risk in recruits.

BMJ Open Sport Exerc Med 2015 21;1(1). Epub 2015 Aug 21.

Department of Sport & Exercise Sciences , University of Chichester , Chichester , UK.

Background: Foot drill involving marching and drill manoeuvres is conducted regularly during basic military recruit training. Characterising the biomechanical loading of foot drill will improve our understanding of the contributory factors to lower limb overuse injuries in recruits.

Aim: Quantify and compare forces, loading rates and accelerations of British Army foot drill, within and between trained and untrained personnel.

Methods: 24 trained soldiers (12 men and 12 women; TRAINED) and 12 civilian men (UNTRAINED) performed marching and five drill manoeuvres on force platforms; motion capture recorded tibial position. Peak vertical impact force (PF), peak vertical loading rate (PLR), expressed as multiples of body weight (BW) and peak tibial impact acceleration (PTA) were recorded.

Results: Drill manoeuvre PF, PLR and PTA were similar, but higher in TRAINED men (PF, PLR: p<0.01; PTA: p<0.05). Peak values in TRAINED men were shown for the halt (mean (SD); PF: 6.5 (1.5) BW; PLR: 983 (333) BW/s PTA; PTA: 207 (57) m/s) and left turn (PF: 6.6 (1.7) BW; PLR: 928 (300) BW/s; 184 (62) m/s). Marching PF, PLR, PTA were similar between groups and lower than all drill manoeuvres (PF: 1.1-1.3 BW; PLR: 42-70 BW/s; p<0.01; PTA: 23-38 m/s; p<0.05).

Conclusions: Army foot drill generates higher forces, loading rates and accelerations than activities such as running and load carriage, while marching is comparable to moderate running (10.8 km/h). The large biomechanical loading of foot drill may contribute to the high rate of overuse injuries during initial military training, and strategies to regulate/reduce this loading should be explored.
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http://dx.doi.org/10.1136/bmjsem-2015-000025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5117012PMC
August 2015

Effect of carbohydrate feeding on the bone metabolic response to running.

J Appl Physiol (1985) 2015 Oct 6;119(7):824-30. Epub 2015 Aug 6.

Department of Occupational Medicine, HQ Army Recruiting and Training Division, Upavon, United Kingdom.

Bone resorption is increased after running, with no change in bone formation. Feeding during exercise might attenuate this increase, preventing associated problems for bone. This study investigated the immediate and short-term bone metabolic responses to carbohydrate (CHO) feeding during treadmill running. Ten men completed two 7-day trials, once being fed CHO (8% glucose immediately before, every 20 min during, and immediately after exercise at a rate of 0.7 g CHO · kg body mass(-1) · h(-1)) and once being fed placebo (PBO). On day 4 of each trial, participants completed a 120-min treadmill run at 70% of maximal oxygen consumption (V̇o2 max). Blood was taken at baseline (BASE), immediately after exercise (EE), after 60 (R1) and 120 (R2) min of recovery, and on three follow-up days (FU1-FU3). Markers of bone resorption [COOH-terminal telopeptide region of collagen type 1 (β-CTX)] and formation [NH2-terminal propeptides of procollagen type 1 (P1NP)] were measured, along with osteocalcin (OC), parathyroid hormone (PTH), albumin-adjusted calcium (ACa), phosphate, glucagon-like peptide-2 (GLP-2), interleukin-6 (IL-6), insulin, cortisol, leptin, and osteoprotogerin (OPG). Area under the curve was calculated in terms of the immediate (BASE, EE, R1, and R2) and short-term (BASE, FU1, FU2, and FU3) responses to exercise. β-CTX, P1NP, and IL-6 responses to exercise were significantly lower in the immediate postexercise period with CHO feeding compared with PBO (β-CTX: P = 0.028; P1NP: P = 0.021; IL-6: P = 0.036), although there was no difference in the short-term response (β-CTX: P = 0.856; P1NP: P = 0.721; IL-6: P = 0.327). No other variable was significantly affected by CHO feeding during exercise. We conclude that CHO feeding during exercise attenuated the β-CTX and P1NP responses in the hours but not days following exercise, indicating an acute effect of CHO feeding on bone turnover.
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Source
http://dx.doi.org/10.1152/japplphysiol.00241.2015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4593812PMC
October 2015