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O'Leary TJ, Gifford RM, Knight RL, Wright J, Handford S, Venables MC, Reynolds RM, Woods D, Wardle SL, Greeves JP. Sex differences in energy balance, body composition, and metabolic and endocrine markers during prolonged arduous military training. J Appl Physiol (1985) 2024; 136:938-948. [PMID: 38385180 DOI: 10.1152/japplphysiol.00864.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/20/2024] [Accepted: 02/20/2024] [Indexed: 02/23/2024] Open
Abstract
This study investigated sex differences in energy balance, body composition, and metabolic and endocrine markers during prolonged military training. Twenty-three trainees (14 women) completed 44-wk military training (three terms of 14 wk with 2-wk adventurous training). Dietary intake and total energy expenditure were measured over 10 days during each term by weighed food and doubly labeled water. Body composition was measured by dual-energy X-ray absorptiometry (DXA) at baseline and at the end of each term. Circulating metabolic and endocrine markers were measured at baseline and at the end of terms 2 and 3. Absolute energy intake and total energy expenditure were higher, and energy balance was lower, for men than women (P ≤ 0.008). Absolute energy intake and balance were lower, and total energy expenditure was higher, during term 2 than terms 1 and 3 (P < 0.001). Lean mass did not change with training (P = 0.081). Fat mass and body fat increased from term 1 to terms 2 and 3 (P ≤ 0.045). Leptin increased from baseline to terms 2 and 3 in women (P ≤ 0.002) but not in men (P ≥ 0.251). Testosterone and free androgen index increased from baseline to term 3 (P ≤ 0.018). Free thyroxine (T4) decreased and thyroid-stimulating hormone (TSH) increased from baseline to term 2 and term 3 (P ≤ 0.031). Cortisol decreased from baseline to term 3 (P = 0.030). IGF-I and total triiodothyronine (T3) did not change with training (P ≥ 0.148). Men experienced greater energy deficits than women during military training due to higher total energy expenditure.NEW & NOTEWORTHY Energy deficits are common in military training and can result in endocrine and metabolic disturbances. This study provides first investigation of sex differences in energy balance, body composition, and endocrine and metabolic markers in response to prolonged and arduous military training. Men experienced greater energy deficits than women due to higher energy expenditure, which was not compensated for by increased energy intake. These energy deficits were not associated with decreases in fat or lean mass or metabolic or endocrine function.
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Affiliation(s)
- Thomas J O'Leary
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom
- Division of Surgery and Interventional Science, UCL, London, United Kingdom
| | - Robert M Gifford
- University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Rebecca L Knight
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom
| | - Jennifer Wright
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom
| | - Sally Handford
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom
| | - Michelle C Venables
- Medical Research Council, Elsie Widdowson Laboratory, Cambridge, United Kingdom
| | - Rebecca M Reynolds
- University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - David Woods
- Research and Clinical Innovation, Royal Centre for Defence Medicine, Birmingham, United Kingdom
- Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, United Kingdom
- Northumbria and Newcastle NHS Trusts, Wansbeck General and Royal Victoria Infirmary, Newcastle, United Kingdom
| | - Sophie L Wardle
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom
- Division of Surgery and Interventional Science, UCL, London, United Kingdom
| | - Julie P Greeves
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom
- Division of Surgery and Interventional Science, UCL, London, United Kingdom
- Norwich Medical School, University of East Anglia, Norwich, United Kingdom
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2
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Sekel NM, Hughes JM, Sterczala AJ, Mroz KH, Lovalekar M, Cauley J, Greeves JP, Nindl BC. Utility of HR-pQCT in detecting training-induced changes in healthy adult bone morphology and microstructure. Front Physiol 2023; 14:1266292. [PMID: 37929211 PMCID: PMC10623356 DOI: 10.3389/fphys.2023.1266292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/03/2023] [Indexed: 11/07/2023] Open
Abstract
Healthy bone adjusts its traits in an exceptionally coordinated, compensatory process. Recent advancements in skeletal imaging via High-Resolution Peripheral Quantitative Computed Tomography (HR-pQCT) allows for the in vivo 3-dimensional and longitudinal quantification of bone density, microarchitecture, geometry, and parameters of mechanical strength in response to varying strain stimuli including those resulting from exercise or military training. Further, the voxel size of 61 microns has the potential to capture subtle changes in human bone in as little as 8 weeks. Given the typical time course of bone remodeling, short-term detection of skeletal changes in bone microstructure and morphology is indicative of adaptive bone formation, the deposition of new bone formation, uncoupled from prior resorption, that can occur at mechanistically advantageous regions. This review aims to synthesize existing training-induced HR-pQCT data in three distinct populations of healthy adults excluding disease states, pharmacological intervention and nutritional supplementation. Those included are: 1) military basic or officer training 2) general population and 3) non-osteoporotic aging. This review aims to further identify similarities and contrasts with prior modalities and cumulatively interpret results within the scope of bone functional adaptation.
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Affiliation(s)
- Nicole M. Sekel
- Neuromuscular Research Laboratory, Warrior Human Performance Research Center, University of Pittsburgh, Pittsburgh, PA, United States
| | - Julie M. Hughes
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA, United States
| | - Adam J. Sterczala
- Neuromuscular Research Laboratory, Warrior Human Performance Research Center, University of Pittsburgh, Pittsburgh, PA, United States
| | - Kelly H. Mroz
- Neuromuscular Research Laboratory, Warrior Human Performance Research Center, University of Pittsburgh, Pittsburgh, PA, United States
| | - Mita Lovalekar
- Neuromuscular Research Laboratory, Warrior Human Performance Research Center, University of Pittsburgh, Pittsburgh, PA, United States
| | - Jane Cauley
- Department of Epidemiology, School of Public Health, University of Pittsburgh, Pittsburgh, PA, United States
| | - Julie P. Greeves
- Army Health and Performance Research, UK Army, Andover, United Kingdom
| | - Bradley C. Nindl
- Neuromuscular Research Laboratory, Warrior Human Performance Research Center, University of Pittsburgh, Pittsburgh, PA, United States
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Dyches KD, Friedl KE, Greeves JP, Keller MF, McClung HL, McGurk MS, Popp KL, Teyhen DS. Physiology of Health and Performance: Enabling Success of Women in Combat Arms Roles. Mil Med 2023; 188:19-31. [PMID: 37490562 DOI: 10.1093/milmed/usac256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 02/28/2022] [Accepted: 08/16/2022] [Indexed: 07/27/2023] Open
Abstract
INTRODUCTION The modern female soldier has yet to be fully characterized as she steps up to fill new combat roles that have only recently been opened to women. Both U.S. and U.K. military operational research efforts are supporting a science-based evolution of physical training and standards for female warfighters. The increasing representation of women in all military occupations makes it possible to discover and document the limits of female physiological performance. METHOD An informal Delphi process was used to synthesize an integrated concept of current military female physiological research priorities and emerging findings using a panel of subject matter experts who presented their research and perspectives during the second Women in Combat Summit hosted by the TriService Nursing Research Program in February 2021. RESULTS The physical characteristics of the modern soldier are changing as women train for nontraditional military roles, and they are emerging as stronger and leaner. Capabilities and physique will likely continue to evolve in response to new Army standards and training programs designed around science-based sex-neutral requirements. Strong bones may be a feature of the female pioneers who successfully complete training and secure roles traditionally reserved for men. Injury risk can be reduced by smarter, targeted training and with attention directed to female-specific hormonal status, biomechanics, and musculoskeletal architecture. An "estrogen advantage" appears to metabolically support enhanced mental endurance in physically demanding high-stress field conditions; a healthy estrogen environment is also essential for musculoskeletal health. The performance of female soldiers can be further enhanced by attention to equipment that serves their needs with seemingly simple solutions such as a suitable sports bra and personal protective equipment that accommodates the female anatomy. CONCLUSIONS Female physiological limits and performance have yet to be adequately defined as women move into new roles that were previously developed and reserved for men. Emerging evidence indicates much greater physical capacity and physiological resilience than previously postulated.
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Affiliation(s)
- Karmon D Dyches
- Military Operational Medicine Research Program, U.S. Army Medical Research and Development Command, Fort Detrick, MD 21702, USA
| | - Karl E Friedl
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, USA
| | - Julie P Greeves
- Department of Army Health and Performance Research (AHPR), British Army, Andover, Hampshire SP11 8HT, UK
| | - Margaux F Keller
- Henry M Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD 20817, USA
| | - Holly L McClung
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, USA
| | - Michael S McGurk
- Research and Analysis Directorate, U.S. Army Center for Initial Military Training, Fort Eustis, VA 23604, USA
| | - Kristin L Popp
- Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, USA
| | - Deydre S Teyhen
- Chief, U.S. Army Medical Specialist Corps, U.S. Army Medical Command, Falls Church, VA 22042, USA
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Coombs CV, Wardle SL, Shroff R, Eisenhauer A, Tang JCY, Fraser WD, Greeves JP, O'Leary TJ. The effect of calcium supplementation on calcium and bone metabolism during load carriage in women: protocol for a randomised controlled crossover trial. BMC Musculoskelet Disord 2023; 24:496. [PMID: 37328859 DOI: 10.1186/s12891-023-06600-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 06/02/2023] [Indexed: 06/18/2023] Open
Abstract
BACKGROUND Military field exercises are characterised by high volumes of exercise and prolonged periods of load carriage. Exercise can decrease circulating serum calcium and increase parathyroid hormone and bone resorption. These disturbances to calcium and bone metabolism can be attenuated with calcium supplementation immediately before exercise. This randomised crossover trial will investigate the effect of calcium supplementation on calcium and bone metabolism, and bone mineral balance, during load carriage exercise in women. METHODS Thirty women (eumenorrheic or using the combined oral contraceptive pill, intrauterine system, or intrauterine device) will complete two experimental testing sessions either with, or without, a calcium supplement (1000 mg). Each experimental testing session will involve one 120 min session of load carriage exercise carrying 20 kg. Venous blood samples will be taken and analysed for biochemical markers of bone resorption and formation, calcium metabolism, and endocrine function. Urine will be collected pre- and post-load carriage to measure calcium isotopes for the calculation of bone calcium balance. DISCUSSION The results from this study will help identify whether supplementing women with calcium during load carriage is protective of bone and calcium homeostasis. TRIAL REGISTRATION NCT04823156 (clinicaltrials.gov).
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Affiliation(s)
- Charlotte V Coombs
- Army Health and Performance Research, Army Headquarters, Andover, SP11 8HT, UK
| | - Sophie L Wardle
- Army Health and Performance Research, Army Headquarters, Andover, SP11 8HT, UK
| | - Rukshana Shroff
- Renal Unit, UCL Great Ormond Street Hospital for Children NHS Foundation Trust and Institute of Child Health, London, UK
| | | | | | | | - Julie P Greeves
- Army Health and Performance Research, Army Headquarters, Andover, SP11 8HT, UK
| | - Thomas J O'Leary
- Army Health and Performance Research, Army Headquarters, Andover, SP11 8HT, UK.
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Popp KL, Cooke LM, Bouxsein ML, Hughes JM. Impact of Low Energy Availability on Skeletal Health in Physically Active Adults. Calcif Tissue Int 2022; 110:605-614. [PMID: 35171303 DOI: 10.1007/s00223-022-00957-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 02/04/2022] [Indexed: 12/13/2022]
Abstract
For decades researchers reported that pre-menopausal women who engage in extensive endurance exercise and have menstrual dysfunction can develop low bone mineral density (BMD) or osteoporosis. More recently, low energy availability has been recognized as the initiating factor for low BMD in these women. Furthermore, the relationship between low energy availability and poor skeletal health is not exclusive to women engaging in endurance exercise. Rather, both males and females commonly experience endocrine dysfunction resulting from low energy availability and high exercise levels that degrades skeletal health. Consequences to skeletal health can range from short-term changes in bone metabolism and increased risk of bone stress injuries to long-term consequences of low BMD, such as osteoporosis and related fragility fractures. The degree to which low energy availability degrades skeletal health may be dependent on the length and extent of the energy deficit. However, the complex relationships between under-fueling, short- and long-term skeletal consequences and the factors that mediate these relationships are not well described. In this review, we discuss the consequences of low energy availability on sex hormones and skeletal health in two highly-active populations-athletes and military trainees-and provide a summary of existing knowledge gaps for future study.
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Affiliation(s)
- Kristin L Popp
- United States Army Research Institute of Environmental Medicine, 10 General Greene Ave, Natick, MA, 01760, USA.
- Massachusetts General Hospital, Boston, MA, 02114, USA.
- Harvard Medical School, Boston, MA, 02215, USA.
| | - Laura M Cooke
- Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Mary L Bouxsein
- United States Army Research Institute of Environmental Medicine, 10 General Greene Ave, Natick, MA, 01760, USA
- Massachusetts General Hospital, Boston, MA, 02114, USA
- Harvard Medical School, Boston, MA, 02215, USA
- Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA
| | - Julie M Hughes
- United States Army Research Institute of Environmental Medicine, 10 General Greene Ave, Natick, MA, 01760, USA
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Wardle SL, O'Leary TJ, McClung JP, Pasiakos SM, Greeves JP. Feeding female soldiers: Consideration of sex-specific nutrition recommendations to optimise the health and performance of military personnel. J Sci Med Sport 2021; 24:995-1001. [PMID: 34452842 DOI: 10.1016/j.jsams.2021.08.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 06/25/2021] [Accepted: 08/11/2021] [Indexed: 12/25/2022]
Abstract
Appropriate nutrition recommendations are required to optimise the health and performance of military personnel, yet limited data are available on whether male and female military personnel have different nutrition requirements. OBJECTIVES To consider the evidence for sex-specific nutrition requirements to optimise the health and performance of military personnel. DESIGN Narrative review. METHODS Published literature was reviewed, with a focus on sex-specific requirements, in the following areas: nutrition for optimising muscle mass and function, nutrition during energy deficit, and nutrition for reproductive and bone health. RESULTS There are limited data on sex differences in protein requirements but extant data suggest that, despite less muscle mass, on average, in women, sex-specific protein feeding strategies are not required to optimise muscle mass in military-aged individuals. Similarly, despite sex differences in metabolic and endocrine responses to energy deficit, current data do not suggest a requirement for sex-specific feeding strategies during energy deficit. Energy deficit impairs health and performance, most notably bone and reproductive health and these impairments are greater for women. Vitamin D, iron and calcium are important nutrients to protect the bone health of female military personnel due to increased risk of stress fracture. CONCLUSIONS Women have an increased incidence of bone injuries, less muscle mass and are more susceptible to the negative effects of energy deficit, including compromised reproductive health. However, there are limited data on sex differences in response to various nutrition strategies designed to improve these elements of health and performance. Future studies should evaluate whether sex-specific feeding recommendations are required.
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Affiliation(s)
- Sophie L Wardle
- Army Health and Performance Research, Army Headquarters, United Kingdom; Division of Surgery and Interventional Science, University College London, United Kingdom.
| | - Thomas J O'Leary
- Army Health and Performance Research, Army Headquarters, United Kingdom; Division of Surgery and Interventional Science, University College London, United Kingdom
| | - James P McClung
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, United States of America
| | - Stefan M Pasiakos
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, United States of America
| | - Julie P Greeves
- Army Health and Performance Research, Army Headquarters, United Kingdom; Division of Surgery and Interventional Science, University College London, United Kingdom; Norwich Medical School, University of East Anglia, United Kingdom
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7
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Hughes JM, O'Leary TJ, Koltun KJ, Greeves JP. Promoting adaptive bone formation to prevent stress fractures in military personnel. Eur J Sport Sci 2021; 22:4-15. [PMID: 34269162 DOI: 10.1080/17461391.2021.1949637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Mechanical loading leads to adaptive bone formation - the formation of new bone on existing skeletal surfaces - which increases bone strength and fatigue resistance. The same mechanical loading can also cause microdamage to bone and development of a stress fracture through targeted remodelling. Stress fractures are common in military recruits and cause significant morbidity, lost training time, and discharge from military service. This narrative review proposes strategies to promote adaptive bone formation as a novel approach to mitigate the risk of stress fracture injuries during arduous military training. Exercise that is unaccustomed, dynamic, high-impact, multidirectional, intermittent, and includes extended rest periods to restore bone mechanosensitivity, is most osteogenic. New bone formation can take up to one year to mineralize, and so new exercise training programmes should be initiated well in advance of military activities with high risk of stress fracture. Bone mechanosensitivity is highest in adolescence, before puberty, and so increasing physical activity in youth is likely to protect skeletal health in later life, including for those in the military. Recent data show that adaptive bone formation takes place during initial military training. Adaptive bone formation can also be supported with adequate sleep, vitamin D, calcium, and energy availability. Further evidence on how strategies to promote adaptive bone formation affect stress fracture risk are required. Adaptive bone formation can be optimized with a range of training and nutritional strategies to help create a resilient skeleton, which may protect against stress fracture throughout military service.
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Affiliation(s)
- Julie M Hughes
- Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA, USA
| | - Thomas J O'Leary
- Army Health and Performance Research, Army Headquarters, Andover, UK.,Division of Surgery and Interventional Science, University College London, London, UK
| | - Kristen J Koltun
- Neuromuscular Research Laboratory/Warrior Human Performance Research Center, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PN, USA
| | - Julie P Greeves
- Army Health and Performance Research, Army Headquarters, Andover, UK.,Division of Surgery and Interventional Science, University College London, London, UK.,Norwich Medical School, University of East Anglia, Norwich, UK
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O'Leary TJ, Wardle SL, Gifford RM, Double RL, Reynolds RM, Woods DR, Greeves JP. Tibial Macrostructure and Microarchitecture Adaptations in Women During 44 Weeks of Arduous Military Training. J Bone Miner Res 2021; 36:1300-1315. [PMID: 33856703 DOI: 10.1002/jbmr.4290] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/01/2021] [Accepted: 03/12/2021] [Indexed: 12/14/2022]
Abstract
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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Affiliation(s)
- Thomas J O'Leary
- Army Health and Performance Research, Army Headquarters, Andover, UK.,Division of Surgery and Interventional Science, University College London (UCL), London, UK
| | - Sophie L Wardle
- Army Health and Performance Research, Army Headquarters, Andover, UK.,Division of Surgery and Interventional Science, University College London (UCL), London, UK
| | - Robert M Gifford
- University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK.,Research and Clinical Innovation, Royal Centre for Defence Medicine, Birmingham, UK
| | - Rebecca L Double
- Army Health and Performance Research, Army Headquarters, Andover, UK
| | - Rebecca M Reynolds
- University/British Heart Foundation Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - David R Woods
- Research and Clinical Innovation, Royal Centre for Defence Medicine, Birmingham, UK.,Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, UK.,Northumbria and Newcastle National Health Service (NHS) Trusts, Wansbeck General and Royal Victoria Infirmary, Newcastle, UK.,University of Newcastle, Newcastle, UK
| | - Julie P Greeves
- Army Health and Performance Research, Army Headquarters, Andover, UK.,Division of Surgery and Interventional Science, University College London (UCL), London, UK.,Norwich Medical School, University of East Anglia, Norwich, UK
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O'Leary TJ, Rice HM, Greeves JP. Biomechanical Basis of Predicting and Preventing Lower Limb Stress Fractures During Arduous Training. Curr Osteoporos Rep 2021; 19:308-317. [PMID: 33635518 DOI: 10.1007/s11914-021-00671-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/12/2021] [Indexed: 12/13/2022]
Abstract
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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Affiliation(s)
- Thomas J O'Leary
- Army Health and Performance Research, Army Headquarters, Andover, Hampshire, UK
- Division of Surgery and Interventional Science, UCL, London, UK
| | - Hannah M Rice
- Sport and Health Sciences, University of Exeter, Exeter, UK
| | - Julie P Greeves
- Army Health and Performance Research, Army Headquarters, Andover, Hampshire, UK.
- Division of Surgery and Interventional Science, UCL, London, UK.
- Norwich Medical School, University of East Anglia, Norwich, UK.
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10
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O'Leary TJ, Walsh NP, Casey A, Izard RM, Tang JCY, Fraser WD, Greeves JP. Supplementary Energy Increases Bone Formation during Arduous Military Training. Med Sci Sports Exerc 2021; 53:394-403. [PMID: 32701874 DOI: 10.1249/mss.0000000000002473] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
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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Affiliation(s)
- Thomas J O'Leary
- Army Health and Performance Research, Army Headquarters, Andover, UNITED KINGDOM
| | - Neil P Walsh
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, UNITED KINGDOM
| | - Anna Casey
- Army Health and Performance Research, Army Headquarters, Andover, UNITED KINGDOM
| | - Rachel M Izard
- Department of Occupational Medicine, HQ Army Recruiting and Initial Training Command, Upavon, UNITED KINGDOM
| | - Jonathan C Y Tang
- Norwich Medical School, University of East Anglia, Norwich, UNITED KINGDOM
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11
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O'Leary TJ, Wardle SL, Greeves JP. Energy Deficiency in Soldiers: The Risk of the Athlete Triad and Relative Energy Deficiency in Sport Syndromes in the Military. Front Nutr 2020; 7:142. [PMID: 32984399 PMCID: PMC7477333 DOI: 10.3389/fnut.2020.00142] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 07/21/2020] [Indexed: 12/15/2022] Open
Abstract
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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Affiliation(s)
- Thomas J O'Leary
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom.,Division of Surgery and Interventional Science, UCL, London, United Kingdom
| | - Sophie L Wardle
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom.,Division of Surgery and Interventional Science, UCL, London, United Kingdom
| | - Julie P Greeves
- Army Health and Performance Research, Army Headquarters, Andover, United Kingdom.,Division of Surgery and Interventional Science, UCL, London, United Kingdom.,Norwich Medical School, University of East Anglia, Norwich, United Kingdom
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Chapman S, Roberts J, Smith L, Rawcliffe A, Izard R. Sex differences in dietary intake in British Army recruits undergoing phase one training. J Int Soc Sports Nutr 2019; 16:59. [PMID: 31823790 PMCID: PMC6905050 DOI: 10.1186/s12970-019-0327-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/26/2019] [Indexed: 01/15/2023] Open
Abstract
Background British Army Phase One training exposes men and women to challenging distances of 13.5 km·d− 1 vs. 11.8 km·d− 1 and energy expenditures of ~ 4000 kcal·d− 1 and ~ 3000 kcal·d− 1, respectively. As such, it is essential that adequate nutrition is provided to support training demands. However, to date, there is a paucity of data on habitual dietary intake of British Army recruits. The aims of this study were to: (i) compare habitual dietary intake in British Army recruits undergoing Phase One training to Military Dietary Reference Values (MDRVs), and (ii) establish if there was a relative sex difference in dietary intake between men and women. Method Researcher led weighed food records and food diaries were used to assess dietary intake in twenty-eight women (age 21.4 ± 3.0 yrs., height: 163.7 ± 5.0 cm, body mass 65.0 ± 6.7 kg), and seventeen men (age 20.4 ± 2.3 yrs., height: 178.0 ± 7.9 cm, body mass 74.6 ± 8.1 kg) at the Army Training Centre, Pirbright for 8-days in week ten of training. Macro and micronutrient content were estimated using dietary analysis software (Nutritics, Dublin) and assessed via an independent sample t-test to establish if there was a sex difference in daily energy, macro or micronutrient intakes. Results Estimated daily energy intake was less than the MDRV for both men and women, with men consuming a greater amount of energy compared with women (2846 ± 573 vs. 2207 ± 585 kcal·day− 1, p < 0.001). Both sexes under consumed carbohydrate (CHO) when data was expressed relative to body mass with men consuming a greater amount than women (4.8 ± 1.3 vs. 3.8 ± 1.4 g·kg− 1·day− 1, p = 0.025, ES = 0.74). Both sexes also failed to meet MDRVs for protein intake with men consuming more than women (1.5 ± 0.3 vs. 1.3 ± 0.3 g·kg− 1·day− 1, p > 0.030, ES = 0.67). There were no differences in dietary fat intake between men and women (1.5 ± 0.2 vs. 1.5 ± 0.5 g·kg− 1·day− 1, p = 0.483, ES = 0.00). Conclusions Daily EI in men and women in Phase One training does not meet MDRVs. Interventions to increase macronutrient intakes should be considered along with research investigating the potential benefits for increasing different macronutrient intakes on training adaptations.
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Affiliation(s)
- Shaun Chapman
- HQ Army Recruiting and Initial Training Command, UK Ministry of Defence, Upavon, UK. .,Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, England.
| | - Justin Roberts
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, England
| | - Lee Smith
- Cambridge Centre for Sport and Exercise Sciences, School of Psychology and Sport Science, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, England
| | - Alex Rawcliffe
- HQ Army Recruiting and Initial Training Command, UK Ministry of Defence, Upavon, UK
| | - Rachel Izard
- HQ Army Recruiting and Initial Training Command, UK Ministry of Defence, Upavon, UK
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O'Leary TJ, Izard RM, Walsh NP, Tang JCY, Fraser WD, Greeves JP. Skeletal macro- and microstructure adaptations in men undergoing arduous military training. Bone 2019; 125:54-60. [PMID: 31077851 DOI: 10.1016/j.bone.2019.05.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/07/2019] [Accepted: 05/07/2019] [Indexed: 12/14/2022]
Abstract
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-1, P < 0.001) and total 25(OH)D increased (9.4 nmol∙l-1, 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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Affiliation(s)
- Thomas J O'Leary
- Army Personnel Research Capability, Army Headquarters, Andover, United Kingdom.
| | - Rachel M Izard
- Department of Occupational Medicine, HQ Army Recruiting and Initial Training Command, Upavon, United Kingdom.
| | - Neil P Walsh
- Extremes Research Group, Bangor University, Bangor, United Kingdom.
| | - John C Y Tang
- Norwich Medical School, University of East Anglia, Norwich, United Kingdom.
| | - William D Fraser
- Norwich Medical School, University of East Anglia, Norwich, United Kingdom; Norfolk and Norwich University Hospital, Norwich, United Kingdom.
| | - Julie P Greeves
- Army Personnel Research Capability, Army Headquarters, Andover, United Kingdom; Norwich Medical School, University of East Anglia, Norwich, United Kingdom.
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