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Ojanen T, Pihlainen K, Vaara JP, Kyröläinen H. Physiological and physical performance changes during a 20-day winter military training course and its subsequent 10-day recovery period. Int J Circumpolar Health 2023; 82:2207287. [PMID: 37119213 PMCID: PMC10150620 DOI: 10.1080/22423982.2023.2207287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023] Open
Abstract
The present study investigated physiological, mental and physical performance changes during a 20-day winter military training course and the following 10-day recovery period. Fifty-eight (age 19 ± 1 years, height 182 ± 6 cm, body mass 78.5 ± 7.2 kg) male soldiers volunteered. Body composition, serum biomarker levels and performance tests were measured four times during the study. In addition, questionnaires were collected daily for subjective stress and rate of perceived exertion. The course induced significant declines in body (-3.9%, p < 0.05) and fat mass (-31.6%, p < 0.05) as well as in all assessed physical performance variables (-9.2 - -20.2%, p < 0.05), testosterone (-73.7%, p < 0.001) and IGF-1 concentrations (-43.6%, p < 0.001). At the same time, the sex hormone-binding globulin, creatine kinase, and C-reactive protein values increased significantly (46.3-1952.7%, p < 0.05). After the 10-day recovery period, the body composition and hormonal values returned to the baseline (p < 0.05), as did some physical performance variables, such as 2 min sit-ups and the evacuation test (p < 0.05). However, explosive force production in the upper and lower bodies remained unrecovered. The 20-day winter military training caused significant physiological and mental stress, as well as a drastic decline in physical performance even for highly physically fit soldiers, and the 10-day recovery period did not establish full recovery.
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Affiliation(s)
- Tommi Ojanen
- Human Performance Division, Finnish Defence Research Agency, Tuusula, Finland
| | - Kai Pihlainen
- Training Division, Defence Command, Helsinki, Finland
| | - Jani P Vaara
- Department of Leadership and Military Pedagogy, National Defence University, Helsinki, Finland
| | - Heikki Kyröläinen
- Department of Leadership and Military Pedagogy, National Defence University, Helsinki, Finland
- Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
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Tramel W, Schram B, Canetti E, Orr R. An Examination of Subjective and Objective Measures of Stress in Tactical Populations: A Scoping Review. Healthcare (Basel) 2023; 11:2515. [PMID: 37761712 PMCID: PMC10530665 DOI: 10.3390/healthcare11182515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 09/06/2023] [Accepted: 09/09/2023] [Indexed: 09/29/2023] Open
Abstract
Persons working in tactical occupations are often exposed to high-stress situations. If this stress is to be measured, an understanding of the stress outcomes used in these occupations is needed. The aim of this review was to capture and critically appraise research investigating subjective and objective outcome measures of physiological stress in tactical occupations. Several literature databases (PubMed, EMBASE, EBsco) were searched using key search words and terms. Studies meeting inclusion criteria were critically evaluated and scored by two authors using the Joanne Briggs Institute (JBI) critical appraisal tool. Of 17,171 articles, 42 studies were retained. The Cohen's Kappa agreement between authors was 0.829 with a mean JBI Score of included studies of 8.1/9 ± 0.37 points. Multiple subjective and objective measures were assessed during a variety of high-stress tasks and environments across different occupations, including police officers, emergency service personnel, firefighters, and soldiers in the military. Common objective outcomes measures were heart rate, cortisol, and body temperature, and subjective measures were ratings of perceived exertion, and the Self Trait Anxiety Inventory. Often used in combination (i.e., subjective and objective), these outcome measures can be used to monitor stressors faced by tactical personnel undergoing on-the-job training.
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Affiliation(s)
- Whitney Tramel
- Faculty of Health Sciences and Medicine, Bond University, Robina, QLD 4226, Australia; (B.S.); (E.C.); (R.O.)
| | - Ben Schram
- Faculty of Health Sciences and Medicine, Bond University, Robina, QLD 4226, Australia; (B.S.); (E.C.); (R.O.)
- Tactical Research Unit, Bond University, Robina, QLD 4226, Australia
| | - Elisa Canetti
- Faculty of Health Sciences and Medicine, Bond University, Robina, QLD 4226, Australia; (B.S.); (E.C.); (R.O.)
- Tactical Research Unit, Bond University, Robina, QLD 4226, Australia
| | - Robin Orr
- Faculty of Health Sciences and Medicine, Bond University, Robina, QLD 4226, Australia; (B.S.); (E.C.); (R.O.)
- Tactical Research Unit, Bond University, Robina, QLD 4226, Australia
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Nykänen T, Ojanen T, Vaara JP, Pihlainen K, Heikkinen R, Kyröläinen H, Fogelholm M. Energy Balance, Hormonal Status, and Military Performance in Strenuous Winter Training. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:4086. [PMID: 36901097 PMCID: PMC10001933 DOI: 10.3390/ijerph20054086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/16/2023] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
Severe energy deficit may impair hormonal regulation and physical performance in military trainings. The aim of this study was to examine the associations between energy intake, expenditure, and balance, hormones and military performance during a winter survival training. Two groups were studied: the FEX group (n = 46) had 8-day garrison and field training, whereas the RECO group (n = 26) had a 36-h recovery period after the 6-day garrison and field training phase. Energy intake was assessed by food diaries, expenditure via heart rate variability, body composition by bioimpedance, and hormones by blood samples. Strength, endurance and shooting tests were done for evaluating military performance. PRE 0 d, MID 6 d, POST 8 d measurements were carried out. Energy balance was negative in PRE and MID (FEX -1070 ± 866, -4323 ± 1515; RECO -1427 ± 1200, -4635 ± 1742 kcal·d-1). In POST, energy balance differed between the groups (FEX -4222 ± 1815; RECO -608 ± 1107 kcal·d-1 (p < 0.001)), as well as leptin, testosterone/cortisol ratio, and endurance performance (p = 0.003, p < 0.001, p = 0.003, respectively). Changes in energy intake and expenditure were partially associated with changes in leptin and the testosterone/cortisol ratio, but not with physical performance variables. The 36-h recovery restored energy balance and hormonal status after strenuous military training, but these outcomes were not associated with strength or shooting performance.
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Affiliation(s)
- Tarja Nykänen
- Army Academy, Finnish Defence Forces, 53600 Lappeenranta, Finland
| | - Tommi Ojanen
- Finnish Defence Research Agency, Finnish Defence Forces, 04310 Tuusula, Finland
| | - Jani P. Vaara
- Department of Leadership and Military Pedagogy, National Defence University, Finnish Defence Forces, 00861 Helsinki, Finland
| | - Kai Pihlainen
- Defence Command, Finnish Defence Forces, 00130 Helsinki, Finland
| | - Risto Heikkinen
- Statistical Analysis Services, Analyysitoimisto Statisti Oy, 40720 Jyväskylä, Finland
| | - Heikki Kyröläinen
- Department of Leadership and Military Pedagogy, National Defence University, Finnish Defence Forces, 00861 Helsinki, Finland
- Faculty of Sport and Health Sciences, University of Jyväskylä, 40114 Jyväskylä, Finland
| | - Mikael Fogelholm
- Department of Food and Nutrition, University of Helsinki, 00014 Helsinki, Finland
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Zurek G, Lenart D, Lachowicz M, Zebrowski K, Jamro D. Factors Influencing the Executive Functions of Male and Female Cadets. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:17043. [PMID: 36554935 PMCID: PMC9779467 DOI: 10.3390/ijerph192417043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/10/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
Executive functions (EFs) are related to human abilities that allow individuals to achieve planned goals, contribute to creativity and the analysis of new ideas, and allow for adaptation to new situations in daily life. Thorough analyses of the factors affecting EFs can aid in the development of appropriate training programs for various social and professional groups, including the military. The purpose of this study was to determine the factors affecting the EFs of cadets (18 women and 108 men) studying at a military academy in Poland after the first and second terms of military training, and to investigate gender differences in the level of EFs, shooting performance (SP), and components of physical fitness (PF). The Neuropsychological Color Trails Test (CTT-2) was used to determine some of the EFs of the test subjects. Meanwhile, the level of SP was represented by the score achieved during marksmanship training implemented during military training. Assessment of the subjects' PF was guided by the principles of the Health-Related Fitness assessment concept, i.e., health-related fitness. Differences between men and women in specific variables were calculated using the Mann-Whitney U test for independent samples, whilst the relationship between variables was analyzed using the best subset regression method. The results revealed that cadets' EFs were influenced by their SP and their level of strength. However, there were no significant differences between male and female cadets in the levels of EFs or SP.
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Affiliation(s)
- Grzegorz Zurek
- Department of Biostructure, Wroclaw University of Health and Sport Sciences, 51-612 Wroclaw, Poland
| | - Dariusz Lenart
- Department of Physical Education and Sport, General Tadeusz Kosciuszko Military University of Land Forces, 51-147 Wroclaw, Poland
| | - Maciej Lachowicz
- Department of Biostructure, Wroclaw University of Health and Sport Sciences, 51-612 Wroclaw, Poland
| | - Krzysztof Zebrowski
- Department of Physical Education and Sport, General Tadeusz Kosciuszko Military University of Land Forces, 51-147 Wroclaw, Poland
| | - Dariusz Jamro
- Department of Physical Education and Sport, General Tadeusz Kosciuszko Military University of Land Forces, 51-147 Wroclaw, Poland
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L Tait J, M Bulmer S, M Drake J, R Drain J, C Main L. Impact of 12 weeks of basic military training on testosterone and cortisol responses. BMJ Mil Health 2022:e002179. [PMID: 36316059 DOI: 10.1136/military-2022-002179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 10/10/2022] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Military personnel train and operate in challenging multistressor environments, which can affect hormonal levels, and subsequently compromise performance and recovery. The aims of this project were to evaluate concentrations of cortisol and testosterone and subjective perceptions of stress and recovery across basic military training (BMT). METHODS 32 male recruits undergoing BMT were tracked over a 12-week course. Saliva samples were collected weekly, on waking, 30 min postwaking and bedtime. Perceptions of stress and recovery were collected weekly. Daily physical activity (steps) were measured via wrist-mounted accelerometers across BMT. Physical fitness was assessed via the multistage fitness test and push-ups in weeks 2 and 8. RESULTS Concentrations of testosterone and cortisol, and the testosterone:cortisol ratio changed significantly across BMT, with variations in responses concurrent with programmatic demands. Perceptions of stress and recovery also fluctuated according to training elements. Recruits averaged 17 027 steps per day between weeks 2 and 12, with week-to-week variations. On average, recruits significantly increased predicted VO2max (3.6 (95% CI 1.0 to 6.1) mL/kg/min) and push-ups (5. 5 (95% CI 1.4 to 9.7) repetitions) between weeks 2 and 8. CONCLUSIONS Recruit stress responses oscillated over BMT in line with programmatic demands indicating that BMT was, at a group level, well-tolerated with no signs of enduring physiological strain or overtraining. The sensitivity of cortisol, testosterone and the testosterone:cortisol ratio to the stressors of military training, suggest they may have a role in monitoring physiological strain in military personnel. Subjective measures may also have utility within a monitoring framework to help ensure adaptive, rather than maladaptive (eg, injury, attrition), outcomes in military recruits.
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Affiliation(s)
- Jamie L Tait
- Deakin University, Institute for Physical Activity and Nutrition (IPAN), Burwood, Victoria, Australia
| | - S M Bulmer
- Deakin University, School of Exercise and Nutrition Sciences, Burwood, Victoria, Australia
| | - J M Drake
- Deakin University, School of Exercise and Nutrition Sciences, Burwood, Victoria, Australia
| | - J R Drain
- Defence Science and Technology Group, Melbourne, Victoria, Australia
| | - L C Main
- Deakin University, Institute for Physical Activity and Nutrition (IPAN), Burwood, Victoria, Australia
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Heilbronn B, Doma K, Sinclair W, Connor J, Irvine-Brown L, Leicht A. Acute Fatigue Responses to Occupational Training in Military Personnel: A Systematic Review and Meta-Analysis. Mil Med 2022; 188:969-977. [PMID: 35639912 DOI: 10.1093/milmed/usac144] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/08/2022] [Accepted: 05/11/2022] [Indexed: 11/14/2022] Open
Abstract
INTRODUCTION Military personnel are required to undertake rigorous physical training to meet the unique demands of combat, often leading to high levels of physiological stress. Inappropriate recovery periods with these high levels of physical stress may result in sub-optimal training and increased risk of injury in military personnel. However, no reviews have attempted to examine the magnitude of training-induced stress following military training activities. The aim of this systematic review was to assess the magnitude of physiological stress (physical, hormonal, and immunological) following task-specific training activities in military personnel. METHODS An extensive literature search was conducted within CINAHL, PubMed, Scopus, SportDiscus, and Web of Science databases with 7,220 records extracted and a total of 14 studies eligible for inclusion and evaluation. Study appraisal was conducted using the Kmet scale. Meta-analysis was conducted via forest plots, with standard mean difference (SMD, effect size) and inter-trial heterogeneity (I2) calculated between before (preactivity) and after (12-96 hours postactivity) military-specific activities for biomarkers of physiological stress (muscle damage, inflammation, and hormonal) and physical performance (muscular strength and power). RESULTS Military training activities resulted in significant levels of muscle damage (SMD = -1.28; P = .003) and significant impairments in strength and power (SMD = 0.91; P = .008) and testosterone levels (SMD = 1.48; P = .05) up to 96 hours postactivity. There were no significant differences in inflammation (SMD = -0.70; P = .11), cortisol (SMD = -0.18; P = .81), or insulin-like growth factor 1 (SMD = 0.65; P = .07) when compared to preactivity measures. CONCLUSIONS These findings indicate that assessments of muscle damage, anabolic hormones like testosterone, strength, and power are effective for determining the level of acute stress following military-specific activities. With regular monitoring of these measures, appropriate recovery periods may be implemented to optimize training adaptations and occupational performance, with minimal adverse training responses in military personnel.
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Affiliation(s)
- Brian Heilbronn
- Royal Australian Army Medical CORPS, Australian Army, Australian Defence Force, Australia.,Sport and Exercise Science, James Cook University, Townsville, QLD 4811, Australia
| | - Kenji Doma
- Sport and Exercise Science, James Cook University, Townsville, QLD 4811, Australia
| | - Wade Sinclair
- Sport and Exercise Science, James Cook University, Townsville, QLD 4811, Australia
| | - Jonathan Connor
- Sport and Exercise Science, James Cook University, Townsville, QLD 4811, Australia
| | - Lachlan Irvine-Brown
- Royal Australian Army Medical CORPS, Australian Army, Australian Defence Force, Australia
| | - Anthony Leicht
- Sport and Exercise Science, James Cook University, Townsville, QLD 4811, Australia.,Australian Institute of Tropical Health & Medicine, James Cook University, Townsville, QLD 4811, Australia
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James S, Damian C, Mathew B. Energy cost and knee extensor strength changes following multiple day military load carriage. APPLIED ERGONOMICS 2021; 97:103503. [PMID: 34237588 DOI: 10.1016/j.apergo.2021.103503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 06/13/2023]
Abstract
Military exercises and recruit training requires soldiers, including new recruits, to undergo multiple days of substantial physical stress. The aim of this study was to evaluate the physiological impact of multiple days of military load carriage by addressing the hypothesis: A second day of load carriage increases oxygen uptake and reduces knee extensor torque compared to a single day of load carriage. A load carriage group (n = 12) (carrying 32 kg) and unloaded group (n = 14) walked on a treadmill for 2 h on two consecutive days. Knee extensor and flexor torque were assessed by dynamometry at speeds of: 0°·s-1,60°·s-1 and 180°·s-1 before and after load carriage on day one and two, and 24 h following day 2. Oxygen uptake was assessed via respiratory gas assessment at the 6th and 119th minute of load carriage on day one and two. When assessed by mixed methods ANOVA (alpha: 0.05), an interaction effect was observed for oxygen uptake (p < 0.001), with post hoc assessment highlighting second day of load carriage significantly increased oxygen uptake compared to day one post in the loaded group (28.9(3.0) vs 25.8(3.4), p = 0.048). An interaction effect was observed for all knee extensor variables (all p < 0.05). All knee extensor peak torque variables were significantly associated to oxygen uptake at 0°s-1 (r = -0.576, p < 0.05), 60°s-1 (r = -0.552, p < 0.05), and 180°s-1 (r = -0.589, p < 0.05). Two days of load carriage significantly increases oxygen uptake and reduces knee extensor and flexor torque compared to a single day of load carriage. Subsequently, physical training programmes aimed at increasing knee extensor strength may protect against increases in oxygen uptake.
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Affiliation(s)
- Scales James
- Canterbury Christ Church University, North Holmes Road, Canterbury, Kent, CT1 1QU, UK.
| | - Coleman Damian
- Canterbury Christ Church University, North Holmes Road, Canterbury, Kent, CT1 1QU, UK
| | - Brown Mathew
- Canterbury Christ Church University, North Holmes Road, Canterbury, Kent, CT1 1QU, UK
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Rocha K, Marinho V, Magalhães F, Carvalho V, Fernandes T, Ayres M, Crespo E, Velasques B, Ribeiro P, Cagy M, Bastos VH, Gupta DS, Teixeira S. Unskilled shooters improve both accuracy and grouping shot having as reference skilled shooters cortical area: An EEG and tDCS study. Physiol Behav 2020; 224:113036. [PMID: 32598941 DOI: 10.1016/j.physbeh.2020.113036] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 12/18/2022]
Abstract
Transcranial direct current stimulation (tDCS) has been used as a non-invasive method for enhanced motor and cognitive abilities. However, no previous study has investigated if the tDCS application in unskilled shooters on cortical sites, selected based on the cortical activity of skilled shooters, improves the accuracy and shot grouping. Sixty participants were selected, which included 10 skilled shooters and 50 unskilled shooters. After we identified the right dorsolateral prefrontal cortex (DLPFC) as the area with the highest activity in skilled shooters, we applied anodal tDCS over the right DLPFC in the unskilled shooters under two conditions: sham-tDCS (placebo) and real-tDCS (anodal tDCS). We also analyzed electroencephalography. Our results indicated that anodal tDCS application enhanced the shot accuracy (p = 0.001). Furthermore, the beta power in the EEG recording was higher in the left DLPFC, left and right parietal cortex (p = 0,001) after applying anodal tDCS, while the low-gamma power was higher in the right DLPFC in sham-tDCS (p = 0.001) and right parietal cortex after anodal-tDCS (p = 0.001). Our findings indicate that anodal tDCS can improve accuracy and shot grouping when applied over the unskilled shooters' right DLPFC. Furthermore, beta and low-gamma bands are influenced by anodal tDCS over the right DLPFC, which may be predictive of skill improvement.
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Affiliation(s)
- Kaline Rocha
- Neuro-innovation Technology & Brain Mapping Laboratory, Federal University of Delta of Parnaíba, Parnaíba, Brazil; The Northeast Biotechnology Network, Federal University of Piauí, Teresina, Brazil.
| | - Victor Marinho
- Neuro-innovation Technology & Brain Mapping Laboratory, Federal University of Delta of Parnaíba, Parnaíba, Brazil; The Northeast Biotechnology Network, Federal University of Piauí, Teresina, Brazil
| | - Francisco Magalhães
- Neuro-innovation Technology & Brain Mapping Laboratory, Federal University of Delta of Parnaíba, Parnaíba, Brazil; The Northeast Biotechnology Network, Federal University of Piauí, Teresina, Brazil
| | - Valécia Carvalho
- Neuro-innovation Technology & Brain Mapping Laboratory, Federal University of Delta of Parnaíba, Parnaíba, Brazil; The Northeast Biotechnology Network, Federal University of Piauí, Teresina, Brazil
| | - Thayaná Fernandes
- Neuro-innovation Technology & Brain Mapping Laboratory, Federal University of Delta of Parnaíba, Parnaíba, Brazil
| | - Marcos Ayres
- Neuro-innovation Technology & Brain Mapping Laboratory, Federal University of Delta of Parnaíba, Parnaíba, Brazil; The Northeast Biotechnology Network, Federal University of Piauí, Teresina, Brazil
| | - Eric Crespo
- Neuro-innovation Technology & Brain Mapping Laboratory, Federal University of Delta of Parnaíba, Parnaíba, Brazil
| | - Bruna Velasques
- Brain Mapping and Sensory Motor Integration Laboratory, Institute of Psychiatry of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pedro Ribeiro
- Brain Mapping and Sensory Motor Integration Laboratory, Institute of Psychiatry of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Mauricio Cagy
- Biomedical Engineering Program, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Victor Hugo Bastos
- The Northeast Biotechnology Network, Federal University of Piauí, Teresina, Brazil; Brain Mapping and Functionality Laboratory, Federal University of Delta do Parnaíba, Parnaíba, Brazil
| | - Daya S Gupta
- Department of Biology, Camden County College, Blackwood, NJ, United States
| | - Silmar Teixeira
- Neuro-innovation Technology & Brain Mapping Laboratory, Federal University of Delta of Parnaíba, Parnaíba, Brazil; The Northeast Biotechnology Network, Federal University of Piauí, Teresina, Brazil
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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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Differences in Training Adaptations of Endurance Performance during Combined Strength and Endurance Training in a 6-Month Crisis Management Operation. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17051688. [PMID: 32150971 PMCID: PMC7084630 DOI: 10.3390/ijerph17051688] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 03/02/2020] [Accepted: 03/03/2020] [Indexed: 12/21/2022]
Abstract
Decreases in aerobic fitness during military operations have been observed in several studies. Thus, differences in training adaptations during a 6-month crisis-management operation were compared by using the change in endurance performance as the outcome measure. Sixty-six male soldiers volunteered for the study, consisting of pre-post assessments of blood biomarkers, body composition, physical performance, and the military simulation test (MST) performance. Physical training volume was self-reported. After the follow-up, the data were divided based on individual changes in endurance performance. Endurance performance was improved in the high-responder group (HiR, n = 25) and maintained or decreased in the low-responder group (LoR n = 24). During the operation, the LoR group decreased while the HiR group increased their endurance training frequency from the pre-deployment level (Δ 28 ± 57% vs. -40 ± 62%, p = 0.004). Fat mass decreased (-7.6 ± 11.7% vs. 14.2 ± 20.4%, p < 0.001), and 1-min push-up (27.7 ± 21.9% vs. 11.7 ± 26.1%, p = 0.004) and MST performance improved (-13.6 ± 6.8% vs. -7.5 ± 6.5%, p = 0.006) more in the HiR group. No differences were observed in the changes of other physical performance test results or analyzed biomarkers. In conclusion, soldiers who were initially leaner and fitter in terms of lower body strength and power were more likely to decrease their aerobic fitness during the operation.
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