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Gordon RJFH, Moss JN, Castelli F, Reeve T, Diss CE, Tyler CJ, Tillin NA. Heat acclimation reduces the effects of whole-body hyperthermia on knee-extensor relaxation rate, but does not affect voluntary torque production. Eur J Appl Physiol 2023; 123:1067-1080. [PMID: 36637508 PMCID: PMC10119217 DOI: 10.1007/s00421-022-05127-7] [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: 08/05/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023]
Abstract
PURPOSE This study investigated the effects of acute hyperthermia and heat acclimation (HA) on maximal and rapid voluntary torque production, and their neuromuscular determinants. METHODS Ten participants completed 10 days of isothermic HA (50 °C, 50% rh) and had their knee-extensor neuromuscular function assessed in normothermic and hyperthermic conditions, pre-, after 5 and after 10 days of HA. Electrically evoked twitch and octet (300 Hz) contractions were delivered at rest. Maximum voluntary torque (MVT), surface electromyography (EMG) normalised to maximal M-wave, and voluntary activation (VA) were assessed during brief maximal isometric voluntary contractions. Rate of torque development (RTD) and normalised EMG were measured during rapid voluntary contractions. RESULTS Acute hyperthermia reduced neural drive (EMG at MVT and during rapid voluntary contractions; P < 0.05), increased evoked torques (P < 0.05), and shortened contraction and relaxation rates (P < 0.05). HA lowered resting rectal temperature and heart rate after 10 days (P < 0.05), and increased sweating rate after 5 and 10 days (P < 0.05), no differences were observed between 5 and 10 days. The hyperthermia-induced reduction in twitch half-relaxation was attenuated after 5 and 10 days of HA, but there were no other effects on neuromuscular function either in normothermic or hyperthermic conditions. CONCLUSION HA-induced favourable adaptations to the heat after 5 and 10 days of exposure, but there was no measurable benefit on voluntary neuromuscular function in normothermic or hyperthermic conditions. HA did reduce the hyperthermic-induced reduction in twitch half-relaxation time, which may benefit twitch force summation and thus help preserve voluntary torque in hot environmental conditions.
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Affiliation(s)
- Ralph Joseph Frederick Hills Gordon
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK. .,Faculty of Science and Engineering, School of Psychology & Sport Science, Anglia Ruskin University, East Road, Cambridge, CB1 1PT, UK.
| | - Jodie Natasha Moss
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Federico Castelli
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Thomas Reeve
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Ceri Elen Diss
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Christopher James Tyler
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
| | - Neale Anthony Tillin
- School of Life and Health Life Sciences, University of Roehampton, Holybourne Avenue, London, SW15 4JD, England, UK
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Racinais S, Hosokawa Y, Akama T, Bermon S, Bigard X, Casa DJ, Grundstein A, Jay O, Massey A, Migliorini S, Mountjoy M, Nikolic N, Pitsiladis YP, Schobersberger W, Steinacker JM, Yamasawa F, Zideman DA, Engebretsen L, Budgett R. IOC consensus statement on recommendations and regulations for sport events in the heat. Br J Sports Med 2023; 57:8-25. [PMID: 36150754 PMCID: PMC9811094 DOI: 10.1136/bjsports-2022-105942] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2022] [Indexed: 01/07/2023]
Abstract
This document presents the recommendations developed by the IOC Medical and Scientific Commission and several international federations (IF) on the protection of athletes competing in the heat. It is based on a working group, meetings, field experience and a Delphi process. The first section presents recommendations for event organisers to monitor environmental conditions before and during an event; to provide sufficient ice, shading and cooling; and to work with the IF to remove regulatory and logistical limitations. The second section summarises recommendations that are directly associated with athletes' behaviours, which include the role and methods for heat acclimation; the management of hydration; and adaptation to the warm-up and clothing. The third section explains the specific medical management of exertional heat stroke (EHS) from the field of play triage to the prehospital management in a dedicated heat deck, complementing the usual medical services. The fourth section provides an example for developing an environmental heat risk analysis for sport competitions across all IFs. In summary, while EHS is one of the leading life-threatening conditions for athletes, it is preventable and treatable with the proper risk mitigation and medical response. The protection of athletes competing in the heat involves the close cooperation of the local organising committee, the national and international federations, the athletes and their entourages and the medical team.
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Affiliation(s)
- Sebastien Racinais
- Research and Scientific Support Department, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Ad Dawhah, Qatar
| | - Yuri Hosokawa
- Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan
| | - Takao Akama
- Faculty of Sport Sciences, Waseda University, Tokorozawa, Saitama, Japan
| | | | - Xavier Bigard
- Union Cycliste Internationale (UCI), Aigle, Switzerland
| | - Douglas J Casa
- Korey Stringer Institiute, Department of Kinesiology, University of Connecticut, Storrs, Connecticut, USA
| | - Andrew Grundstein
- Department of Geography, University of Georgia, Athens, Georgia, USA
| | - Ollie Jay
- Heat and Health Research Incubator, Faculty of Medicine and Health, The University of Sydney, Camperdown, New South Wales, Australia
| | - Andrew Massey
- Medical Department, Federation Internationale de Football Association, Zurich, Switzerland
| | | | | | | | | | - Wolfgang Schobersberger
- Institute for Sports Medicine, Alpine Medicine & Health Tourism (ISAG), UMIT Tirol – Private University for Health Sciences and technology, Hall, Austria,University Hospital/Tirol Kliniken, Innsbruck, Austria
| | | | | | - David Anthony Zideman
- International Olympic Committee Medical and Scientific Games Group, Pinner, Middlesex, UK
| | - Lars Engebretsen
- Medical and Scientific Department, International Olympic Committee, Lausanne, Switzerland
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Aoki M, Yamazaki Y, Otsuka J, Okamoto Y, Takada S, Shirai N, Fujimoto T, Ochi G, Yamashiro K, Sato D, Amano T. Influence of Heat Exposure on Motor Control Performance and Learning as Well as Physiological Responses to Visuomotor Accuracy Tracking Task. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:12328. [PMID: 36231630 PMCID: PMC9566463 DOI: 10.3390/ijerph191912328] [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: 08/10/2022] [Revised: 09/21/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
This study aimed to determine whether heat exposure attenuates motor control performance and learning, and blunts cardiovascular and thermoregulatory responses to visuomotor accuracy tracking (VAT) tasks. Twenty-nine healthy young adults (22 males) were divided into two groups performing VAT tasks (5 trials × 10 blocks) in thermoneutral (NEUT: 25 °C, 45% RH, n = 14) and hot (HOT: 35 °C, 45% RH, n = 15) environments (acquisition phase). One block of the VAT task was repeated at 1, 2, and 4 h after the acquisition phase (retention phase). Heat exposure elevated skin temperature to ~3 °C with a marginally increased core body temperature. VAT performance (error distance of curve tracking) was more attenuated overall in HOT than in NEUT in the acquisition phase without improvement in magnitude alteration. Heat exposure did not affect VAT performance in the retention phase. The mean arterial blood pressure and heart rate, but not for sweating and cutaneous vascular responses to VAT acquisition trials, were more attenuated in HOT than in NEUT without any retention phase alternations. We conclude that skin temperature elevation exacerbates motor control performance and blunts cardiovascular response during the motor skill acquisition period. However, these alternations are not sustainable thereafter.
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Affiliation(s)
- Mao Aoki
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
| | - Yudai Yamazaki
- Laboratory of Exercise Biochemistry and Neuroendocrinology, Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City 305-8574, Japan
- Japan Society for the Promotion of Science, Tokyo 102-0083, Japan
| | - Junto Otsuka
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
| | - Yumi Okamoto
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
| | - Shota Takada
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
| | - Nobu Shirai
- Department of Psychology, College of Contemporary Psychology, Rikkyo University, Saitama 352-8558, Japan
| | - Tomomi Fujimoto
- Institute for Human Movement and Medical Sciences, Department of Health and Sports, Niigata University of Health and Welfare, Niigata 950-3198, Japan
| | - Genta Ochi
- Institute for Human Movement and Medical Sciences, Department of Health and Sports, Niigata University of Health and Welfare, Niigata 950-3198, Japan
| | - Koya Yamashiro
- Institute for Human Movement and Medical Sciences, Department of Health and Sports, Niigata University of Health and Welfare, Niigata 950-3198, Japan
| | - Daisuke Sato
- Institute for Human Movement and Medical Sciences, Department of Health and Sports, Niigata University of Health and Welfare, Niigata 950-3198, Japan
| | - Tatsuro Amano
- Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata 950-2181, Japan
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Girard O, Gaoua N, Grantham J, Knez W, Walsh A, Racinais S. Effects of living and working in a hot environment on cognitive function in a quiet and temperature-controlled room: An oil and gas industry study. Temperature (Austin) 2021; 8:372-380. [PMID: 34901319 DOI: 10.1080/23328940.2021.1959289] [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] [Indexed: 10/20/2022] Open
Abstract
We investigate the effects of seasonal heat stress on cognitive function in outdoor workers. Thirty-nine workers from an oil and gas industry in the Middle-East volunteered for cognitive testing before (5.30 to 7.00 am) and after (3.30 to 5.00 pm) their daily work-shift in hot (August - average daily temperature: ~41°C) and temperate (January - average daily temperature: ~22°C) seasons. While physical activity was reduced in hot compared to temperate season (average normalized acceleration: 96 ± 33 vs. 112 ± 31 × 10-3 g; -12.5 ± 4.7%; P = 0.010), the average core temperature during the work-shift was higher in the hot season (37.4 ± 0.2 vs. 37.2 ± 0.2°C; P = 0.002). Peak core temperature was 38.0 ± 0.1°C and 37.8 ± 0.1°C in hot and temperate seasons, respectively. Cognitive performance did not differ between seasons for tests of recognition memory (P = 0.169), working memory (P = 0.797) and executive function (P = 0.145), independent of testing time. Whereas there was no significant main effect of testing time for tests of recognition memory (P = 0.503) and working memory (P = 0.849), the number of problems solved on the first choice for the executive function test was lower in the afternoon than the morning (-9.2 ± 5.3%; P = 0.039). There was no season × testing time interaction for any cognitive tests (P ≥ 0.145). In the absence of hyperthermia, living and working in a hot environment does not alter cognitive function in oil and gas industry workers tested in a quiet and temperature-controlled room, with reduced clothing encumbrance (relative to work). Conclusions should not be extrapolated to more stressful situations (i.e., thermal stressor present, pronounced dehydration, noise).
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Affiliation(s)
- Olivier Girard
- School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, Western Australia, Australia.,Research and Scientific Support Department, Aspetar Orthopaedic and Sport Medicine Hospital, Doha, Qatar
| | - Nadia Gaoua
- Research and Scientific Support Department, Aspetar Orthopaedic and Sport Medicine Hospital, Doha, Qatar.,Sport and Exercise Science Research Centre (SESRC), London South Bank University, London, UK
| | - Justin Grantham
- Research and Scientific Support Department, Aspetar Orthopaedic and Sport Medicine Hospital, Doha, Qatar.,RelatePerform, Relate Perform Ltd, Hong Kong
| | - Wade Knez
- Research and Scientific Support Department, Aspetar Orthopaedic and Sport Medicine Hospital, Doha, Qatar
| | - Andrew Walsh
- Research and Scientific Support Department, Aspetar Orthopaedic and Sport Medicine Hospital, Doha, Qatar.,Brisbane Lions Football Club, Brisbane, Queensland, Australia
| | - Sebastien Racinais
- Research and Scientific Support Department, Aspetar Orthopaedic and Sport Medicine Hospital, Doha, Qatar
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Schlader ZJ, Schwob J, Hostler D, Cavuoto L. Simultaneous assessment of motor and cognitive tasks reveals reductions in working memory performance following exercise in the heat. Temperature (Austin) 2021; 9:344-356. [PMID: 36339090 PMCID: PMC9629122 DOI: 10.1080/23328940.2021.1992239] [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: 12/13/2022] Open
Abstract
This study tested the hypothesis that, following exercise in the heat, motor task performance will be impaired when assessed simultaneously with a cognitive task. In a randomized, crossover and counterbalanced design, twelve healthy adults (23 ± 2 years, 5 women) completed four 10-minute exercise circuits involving upper and lower body exercise in a moderate (18.1 ± 1.7°C, 38 ± 10% relative humidity) and a hot (40.3 ± 1.1°C, 26 ± 5% relative humidity) environment. Experimental testing was completed in a temperate thermal environment before exercise (~25°C) and in either the moderate or hot environment following exercise. The 3 Back test (a test of working memory) was used as the cognitive task and postural sway was used as the motor task. Cognitive and motor task performance assessments were conducted both individually (solo) and simultaneously (dual). At the end of exercise, core temperature (by 0.4 ± 0.3°C, P < 0.001), heart rate (by 12 ± 18 bpm, P = 0.025), and mean skin temperature (by 7.6 ± 0.8°C, P < 0.001) were higher in the Hot trial compared to Moderate. During solo testing, postural sway increased from pre- to post-exercise in the Hot (P ≤ 0.028), but not the Moderate (P ≥ 0.261) trial. During dual testing, postural sway did not differ between trials (P ≥ 0.065) or over time (P ≥ 0.094). During solo testing, 3 Back performance did not differ between trials (P = 0.810) or over time (P = 0.707), but during dual testing 3 Back performance following exercise was reduced in the Hot compared to the Moderate trial (P = 0.028). Simultaneous assessment of motor and cognitive tasks reveals that motor performance is reduced following exercise in the heat. .
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Affiliation(s)
- Zachary J. Schlader
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, USA,Department of Kinesiology, School of Public Health, Indiana University, Bloomington, USA
| | - Jacqueline Schwob
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, USA
| | - David Hostler
- Center for Research and Education in Special Environments, Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, USA,Department of Emergency Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, USA
| | - Lora Cavuoto
- Department of Industrial and Systems Engineering, School of Engineering and Applied Sciences, University at Buffalo, Buffalo, USA,CONTACT Lora Cavuoto
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Palacios Temprano J, Eichholtz P, Willeboordse M, Kok N. Indoor environmental quality and learning outcomes: protocol on large-scale sensor deployment in schools. BMJ Open 2020; 10:e031233. [PMID: 32184302 PMCID: PMC7076238 DOI: 10.1136/bmjopen-2019-031233] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Exposure to poor environmental conditions has been associated with deterioration of physical and mental health, and with reduction of cognitive performance. Environmental conditions may also influence cognitive development of children, but epidemiological evidence is scant. In developed countries, children spend 930 hours per year in a classroom, second only to time spent in their bedroom. Using continuous sensing technology, we investigate the relationship between indoor environmental quality (IEQ) and cognitive performance of school-aged children. The proposed study will result in a better understanding of the effects of environmental characteristics on cognitive performance, thereby paving the way for experimental studies. METHODS AND ANALYSIS A study protocol is presented to reliably measure IEQ in schools. We will monitor the IEQ of 280 classrooms for 5 years, covering approximately 10 000 children. Each classroom in the sample is permanently equipped with a sensor measuring air quality (carbon dioxide and coarse particles), temperature, relative humidity, light intensity and noise levels, all at 1 min intervals. The location of sensing equipment within and across rooms has been validated by a pilot study. Academic performance of school-aged children is measured through standardised cognitive tests. In addition, a series of health indicators is collected (eg, school absence and demand for healthcare), together with an extensive set of sociodemographic characteristics (eg, parental income, education, occupational status). ETHICS AND DISSEMINATION Medical Ethical Approval for the current study was waived by the Medical Ethical Committee azM/UM (METC 2018-0681). In addition, data on student performance and health stems from an already existing data infrastructure that are granted with ethical approval by the Ethical Review Committee Inner City faculties (ERCIC_092_12_07_2018). Health data are obtained from the 'The Healthy Primary School of the Future' (HPSF) project. Medical Ethical Approval for HPSF was waived by the Medical Ethical Committee of Zuyderland, Heerlen (METC 14 N-142). The HPSF study protocol was registered in the database ClinicalTrials.gov on 14-06-2016 with reference number NCT02800616, this study is currently in the Results stage. Data collection from Gemeentelijke Gezondheidsdienst Zuid-Limburg (GGD-ZL) is executed by researchers of HPSF, this procedure has been fully approved by the Medical Ethical Committee of Zuyderland. The questionnaires on level of comfort will be filled in anonymously by students and teachers. The study will follow the EU General Data Protection Regulation (EU GDPR) and Dutch data protection law to ensure protection of personal data, as well as maintain proper data management and anonymisation.The protocol discussed in this paper includes significant efforts focused on integrating results and making them available to both the scientific community and the wider public, including policy makers. The results will lead to multiple scientific articles that will be disseminated through peer-reviewed international journals, as well as through conference presentations. In addition, we will exploit ongoing collaboration with project stakeholders and project partners to disseminate information to the target audience. For example, the results will be presented to school boards in the Netherlands, through engagement with the Coalition for Green Schools, as well as to school boards in USA, through engagement with the Center for Green Schools. TRIAL REGISTRATION NUMBER NCT02800616; Results.
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Affiliation(s)
- Juan Palacios Temprano
- Department of Finance, Maastricht University School of Business and Economics, Maastricht, The Netherlands
| | - Piet Eichholtz
- Department of Finance, Maastricht University School of Business and Economics, Maastricht, The Netherlands
| | - Maartje Willeboordse
- Department of Family Medicine, Maastricht University, School for Public Health and Primary Care, Maastricht, The Netherlands
| | - Nils Kok
- Department of Finance, Maastricht University School of Business and Economics, Maastricht, The Netherlands
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7
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Martin K, McLeod E, Périard J, Rattray B, Keegan R, Pyne DB. The Impact of Environmental Stress on Cognitive Performance: A Systematic Review. HUMAN FACTORS 2019; 61:1205-1246. [PMID: 31002273 DOI: 10.1177/0018720819839817] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
OBJECTIVE In this review, we detail the impact of environmental stress on cognitive and military task performance and highlight any individual characteristics or interventions which may mitigate any negative effect. BACKGROUND Military personnel are often deployed in regions markedly different from their own, experiencing hot days, cold nights, and trips both above and below sea level. In spite of these stressors, high-level cognitive and operational performance must be maintained. METHOD A systematic review of the electronic databases Medline (PubMed), EMBASE (Scopus), PsycINFO, and Web of Science was conducted from inception up to September 2018. Eligibility criteria included a healthy human cohort, an outcome of cognition or military task performance and assessment of an environmental condition. RESULTS The search returned 113,850 records, of which 124 were included in the systematic review. Thirty-one studies examined the impact of heat stress on cognition; 20 of cold stress; 59 of altitude exposure; and 18 of being below sea level. CONCLUSION The severity and duration of exposure to the environmental stressor affects the degree to which cognitive performance can be impaired, as does the complexity of the cognitive task and the skill or familiarity of the individual performing the task. APPLICATION Strategies to improve cognitive performance in extreme environmental conditions should focus on reducing the magnitude of the physiological and perceptual disturbance caused by the stressor. Strategies may include acclimatization and habituation, being well skilled on the task, and reducing sensations of thermal stress with approaches such as head and neck cooling.
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Affiliation(s)
- Kristy Martin
- University of Canberra, Australian Capital Territory, Australia
| | - Emily McLeod
- University of Canberra, Australian Capital Territory, Australia
| | - Julien Périard
- University of Canberra, Australian Capital Territory, Australia
| | - Ben Rattray
- University of Canberra, Australian Capital Territory, Australia
| | - Richard Keegan
- University of Canberra, Australian Capital Territory, Australia
| | - David B Pyne
- University of Canberra, Australian Capital Territory, Australia
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Caldwell AR, Burchfield J, Moyen NE, Tucker MA, Butts CL, Elbin RJ, Ganio MS. Obesity, but not hypohydration, mediates changes in mental task load during passive heating in females. PeerJ 2018; 6:e5394. [PMID: 30128190 PMCID: PMC6098944 DOI: 10.7717/peerj.5394] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 07/16/2018] [Indexed: 12/18/2022] Open
Abstract
Background The independent effects of hypohydration and hyperthermia on cognition and mood is unclear since the two stresses often confound each other. Further, it is unknown if obese individuals have the same impairments during hyperthermia and hypohydration that is often observed in non-obese individuals. Methods The current study was designed to assess the independent and combined effects of mild hypohydration and hyperthermia on cognition, mood, and mental task load in obese and non-obese females. Twenty-one healthy females participated in two passive heating trials, wherein they were either euhydrated or hypohydrated prior to and throughout passive heating. Cognition (ImPACT), mental task load (NASA-TLX), and mood (Brunel Mood Scale; BRUMS) were measured before and after a 1.0 °C increase in core temperature (TC). Results After a 1.0 °C TC elevation, hypohydration resulted in greater (p < 0.05) body mass loss (-1.14 ± 0.48 vs -0.58 ± 0.48 kg; hypohydrated and euhydrated, respectively) and elevation in serum osmolality (292 ± 4 vs 282 ± 3 mOsm; p < 0.05) versus euhydration. Hypohydration, independent of hyperthermia, did not affect mental task load or mood (p > 0.05). Hyperthermia, regardless of hydration status, impaired (∼5 A.U) measures of memory-based cognition (verbal and visual memory), and increased mental task load, while worsening mood (p < 0.05). Interestingly, obese individuals had increased mental task load while hyperthermic compared to the non-obese individuals (p < 0.05) even while euhydrated. Hypohydration did not exacerbate any heat-related effects on cognition between obese and non-obese females (p > 0.05). Conclusion These data indicate that hyperthermia independently impairs memory-based aspects of cognitive performance, mental task load, and leads to a negative mood state. Mild hypohydration did not exacerbate the effects of hyperthermia. However, obese individuals had increased mental task load during hyperthermia.
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Affiliation(s)
- Aaron R Caldwell
- Exercise Science Research Center, University of Arkansas at Fayetteville, Fayetteville, AR, United States of America
| | - Jenna Burchfield
- Exercise Science Research Center, University of Arkansas at Fayetteville, Fayetteville, AR, United States of America
| | - Nicole E Moyen
- Exercise Science Research Center, University of Arkansas at Fayetteville, Fayetteville, AR, United States of America
| | - Matthew A Tucker
- Exercise Science Research Center, University of Arkansas at Fayetteville, Fayetteville, AR, United States of America.,Georgia Prevention Institute, Augusta University, Augusta, GA, United States of America
| | - Cory L Butts
- Exercise Science Research Center, University of Arkansas at Fayetteville, Fayetteville, AR, United States of America
| | - R J Elbin
- Exercise Science Research Center, University of Arkansas at Fayetteville, Fayetteville, AR, United States of America
| | - Matthew S Ganio
- Exercise Science Research Center, University of Arkansas at Fayetteville, Fayetteville, AR, United States of America
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9
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Effects of heat stress and dehydration on cognitive function in elite female field hockey players. BMC Sports Sci Med Rehabil 2018; 10:12. [PMID: 29946473 PMCID: PMC6007074 DOI: 10.1186/s13102-018-0101-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 06/07/2018] [Indexed: 11/10/2022]
Abstract
Background It has previously been suggested that heat exposure and hypohydration have negative effects on cognitive performance, which may impact upon sporting performance. The aim of the present study was to examine the independent effects of heat stress and hypohydration on cognitive performance in elite female field hockey players. Methods Eight unacclimatised elite field hockey players (age: 22 ± 3 y; height: 1.68 ± 0.05 m; body mass: 63.1 ± 6.0 kg) completed a cognitive test battery before and after 50 min of field hockey specific exercise on a treadmill in four experimental trials; two in hot conditions (33.3 ± 0.1 °C), and two in moderate (16.0 ± 3.0 °C), both with and without ad libitum water intake. Results On the visual search test, participants were faster overall in the heat (1941 vs. 2104 ms, p = 0.001). Response times were quicker in the heat on the Sternberg paradigm (463 vs. 473 ms, p = 0.024) and accuracy was improved (by 1.9%, p = 0.004). There was no effect of hydration status on any of the markers of cognitive function. Conclusions Overall, the findings suggest that in elite field hockey players exposure to heat enhances response times and/or accuracy on a battery of cognitive function tests. However, hypohydration does not appear to affect cognitive performance in elite field hockey players.
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10
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Gaoua N, Herrera CP, Périard JD, El Massioui F, Racinais S. Effect of Passive Hyperthermia on Working Memory Resources during Simple and Complex Cognitive Tasks. Front Psychol 2018; 8:2290. [PMID: 29375423 PMCID: PMC5769221 DOI: 10.3389/fpsyg.2017.02290] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 12/18/2017] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to verify the hypothesis that hyperthermia represents a cognitive load limiting available resources for executing concurrent cognitive tasks. Electroencephalographic activity (EEG: alpha and theta power) was obtained in 10 hyperthermic participants in HOT (50°C, 50% RH) conditions and in a normothermic state in CON (25°C, 50% RH) conditions in counterbalanced order. In each trial, EEG was measured over the frontal lobe prior to task engagement (PRE) in each condition and during simple (One Touch Stockings of Cambridge, OTS-4) and complex (OTS-6) cognitive tasks. Core (39.5 ± 0.5 vs. 36.9 ± 0.2°C) and mean skin (39.06 ± 0.3 vs. 31.6 ± 0.6°C) temperatures were significantly higher in HOT than CON (p < 0.005). Theta power significantly increased with task demand (p = 0.017, η2 = 0.36) and was significantly higher in HOT than CON (p = 0.041, η2 = 0.39). The difference between HOT and CON was large (η2 = 0.40) and significant (p = 0.036) PRE, large (η2 = 0.20) but not significant (p = 0.17) during OTS-4, and disappeared during OTS-6 (p = 0.87, η2 = 0.00). Those changes in theta power suggest that hyperthermia may act as an additional cognitive load. However, this load disappeared during OTS-6 together with an impaired performance, suggesting a potential saturation of the available resources.
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Affiliation(s)
- Nadia Gaoua
- School of Applied Sciences, London South Bank University, London, United Kingdom.,Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Christopher P Herrera
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.,Department of Kinesiology & Human Performance, Sul Ross State University, Alpine, TX, United States
| | - Julien D Périard
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.,Research Institute for Sport and Exercise, University of Canberra, Canberra, ACT, Australia
| | - Farid El Massioui
- Cognition Humaine et Artificielle (CHArt), UFR de Psychologie, Université Paris 8, Paris, France
| | - Sebastien Racinais
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
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11
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Piil JF, Lundbye-Jensen J, Trangmar SJ, Nybo L. Performance in complex motor tasks deteriorates in hyperthermic humans. Temperature (Austin) 2017; 4:420-428. [PMID: 29435481 PMCID: PMC5800368 DOI: 10.1080/23328940.2017.1368877] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 08/11/2017] [Accepted: 08/11/2017] [Indexed: 10/25/2022] Open
Abstract
Heat stress, leading to elevations in whole-body temperature, has a marked impact on both physical performance and cognition in ecological settings. Lab experiments confirm this for physically demanding activities, whereas observations are inconsistent for tasks involving cognitive processing of information or decision-making prior to responding. We hypothesized that divergences could relate to task complexity and developed a protocol consisting of 1) simple motor task [TARGET_pinch], 2) complex motor task [Visuo-motor tracking], 3) simple math task [MATH_type], 4) combined motor-math task [MATH_pinch]. Furthermore, visuo-motor tracking performance was assessed both in a separate- and a multipart protocol (complex motor tasks alternating with the three other tasks). Following familiarization, each of the 10 male subjects completed separate and multipart protocols in randomized order in the heat (40°C) or control condition (20°C) with testing at baseline (seated rest) and similar seated position, following exercise-induced hyperthermia (core temperature ∼ 39.5°C in the heat and 38.2°C in control condition). All task scores were unaffected by control exercise or passive heat exposure, but visuo-motor tracking performance was reduced by 10.7 ± 6.5% following exercise-induced hyperthermia when integrated in the multipart protocol and 4.4 ± 5.7% when tested separately (both P < 0.05). TARGET_pinch precision declined by 2.6 ± 1.3% (P < 0.05), while no significant changes were observed for the math tasks. These results indicate that heat per se has little impact on simple motor or cognitive test performance, but complex motor performance is impaired by hyperthermia and especially so when multiple tasks are combined.
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Affiliation(s)
- Jacob F Piil
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Lundbye-Jensen
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
| | - Steven J Trangmar
- Department of Life Sciences, University of Roehampton, London, United Kingdom
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen, Copenhagen, Denmark
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12
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Gaoua N, de Oliveira RF, Hunter S. Perception, Action, and Cognition of Football Referees in Extreme Temperatures: Impact on Decision Performance. Front Psychol 2017; 8:1479. [PMID: 28912742 PMCID: PMC5583592 DOI: 10.3389/fpsyg.2017.01479] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 08/16/2017] [Indexed: 11/13/2022] Open
Abstract
Different professional domains require high levels of physical performance alongside fast and accurate decision-making. Construction workers, police officers, firefighters, elite sports men and women, the military and emergency medical professionals are often exposed to hostile environments with limited options for behavioral coping strategies. In this (mini) review we use football refereeing as an example to discuss the combined effect of intense physical activity and extreme temperatures on decision-making and suggest an explicative model. In professional football competitions can be played in temperatures ranging from -5°C in Norway to 30°C in Spain for example. Despite these conditions, the referee's responsibility is to consistently apply the laws fairly and uniformly, and to ensure the rules are followed without waning or adversely influencing the competitiveness of the play. However, strenuous exercise in extreme environments imposes increased physiological and psychological stress that can affect decision-making. Therefore, the physical exertion required to follow the game and the thermal strain from the extreme temperatures may hinder the ability of referees to make fast and accurate decisions. Here, we review literature on the physical and cognitive requirements of football refereeing and how extreme temperatures may affect referees' decisions. Research suggests that both hot and cold environments have a negative impact on decision-making but data specific to decision-making is still lacking. A theoretical model of decision-making under the constraint of intense physical activity and thermal stress is suggested. Future naturalistic studies are needed to validate this model and provide clear recommendations for mitigating strategies.
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Affiliation(s)
- Nadia Gaoua
- School of Applied Sciences, London South Bank UniversityLondon, United Kingdom
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13
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Racinais S, Cocking S, Périard JD. Sports and environmental temperature: From warming-up to heating-up. Temperature (Austin) 2017; 4:227-257. [PMID: 28944269 DOI: 10.1080/23328940.2017.1356427] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/09/2017] [Accepted: 07/09/2017] [Indexed: 01/22/2023] Open
Abstract
Most professional and recreational athletes perform pre-conditioning exercises, often collectively termed a 'warm-up' to prepare for a competitive task. The main objective of warming-up is to induce both temperature and non-temperature related responses to optimize performance. These responses include increasing muscle temperature, initiating metabolic and circulatory adjustments, and preparing psychologically for the upcoming task. However, warming-up in hot and/or humid ambient conditions increases thermal and circulatory strain. As a result, this may precipitate neuromuscular and cardiovascular impairments limiting endurance capacity. Preparations for competing in the heat should include an acclimatization regimen. Athletes should also consider cooling interventions to curtail heat gain during the warm-up and minimize dehydration. Indeed, although it forms an important part of the pre-competition preparation in all environmental conditions, the rise in whole-body temperature should be limited in hot environments. This review provides recommendations on how to build an effective warm-up following a 3 stage RAMP model (Raise, Activate and Mobilize, Potentiate), including general and context specific exercises, along with dynamic flexibility work. In addition, this review provides suggestion to manipulate the warm-up to suit the demands of competition in hot environments, along with other strategies to avoid heating-up.
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Affiliation(s)
- Sébastien Racinais
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance (EA 7370), Paris, France
| | - Scott Cocking
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,Research Institute for Sport and Exercise Science, Liverpool John Moores University, United Kingdom
| | - Julien D Périard
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,University of Canberra, Research Institute for Sport and Exercise, Canberra, Australia
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14
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Racinais S, Wilson MG, Gaoua N, Périard JD. Heat acclimation has a protective effect on the central but not peripheral nervous system. J Appl Physiol (1985) 2017; 123:816-824. [PMID: 28684590 DOI: 10.1152/japplphysiol.00430.2017] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/05/2017] [Accepted: 07/05/2017] [Indexed: 11/22/2022] Open
Abstract
This study aimed to clarify the pathway mediating hyperthermia-induced alterations in neural drive transmission and determine if heat acclimation protects voluntary muscle activation and cognitive function in hyperthermic humans. Electrically evoked potentials (H reflex and M wave), executive function (special planning and working memory), and maximal voluntary isometric contractions (120 s) were assessed in 14 participants in control conditions [CON, 24°C, 40% relative humidity (RH)] and in a hyperthermic state (HYP, 44-50°C, 50% RH) on consecutive days in a counterbalanced order. Thereafter, participants were passively heat acclimated for 11 days (1 h per day, 48-50°C, 50% RH) before repeating the initial assessments. Heat acclimation decreased rectal temperature in CON (-0.2°C, P < 0.05), but participants were maintained at ~39°C in HYP. Heat acclimation increased the time required to reach 39°C (+9 min), along with sweat rate (+0.7 l/h), and serum extracellular expression of heat shock protein 72 (eHSP72; +20%) in HYP (P < 0.05). M-wave and H-reflex amplitudes were lower in HYP than CON (P < 0.05) and were not protected by heat acclimation. Nerve conduction velocity was faster in HYP than CON (P < 0.05) without being influenced by heat acclimation. These results suggest that peripheral neural drive transmission in the hyperthermic state is primarily affected by axonal conduction velocity rather than synaptic failure. Executive function, voluntary activation, and the ability to sustain torque were impaired in HYP (P < 0.05). However, despite no perceptual changes (P > 0.05), heat acclimation restored executive function, while protecting the ability to sustain voluntary activation and torque production during a prolonged contraction in hyperthermia (P < 0.05). Ultimately, heat acclimation induces beneficial central but not peripheral neural adaptations.NEW & NOTEWORTHY Heat acclimation restores planning accuracy and working memory in hyperthermic humans, together with the supraspinal capacity to sustain motor drive during a sustained maximal voluntary contraction. Electrically evoked potential data (M wave, H reflex) indicate that heat acclimation does not protect against hyperthermia-induced impairments in peripheral neural drive transmission. Heat acclimation induces beneficial central but not peripheral neural adaptations.
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Affiliation(s)
- Sebastien Racinais
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar; .,University of Queensland, Centre for Sensorimotor Neuroscience, School of Human Movement Studies, Brisbane, Australia
| | - Mathew G Wilson
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar
| | - Nadia Gaoua
- School of Applied Sciences, London South Bank University, London, United Kingdom; and
| | - Julien D Périard
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,University of Canberra, Research Institute for Sport and Exercise, Canberra, Australian Capital Territory, Australia
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15
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van den Heuvel AMJ, Haberley BJ, Hoyle DJR, Taylor NAS, Croft RJ. The independent influences of heat strain and dehydration upon cognition. Eur J Appl Physiol 2017; 117:1025-1037. [DOI: 10.1007/s00421-017-3592-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/18/2017] [Indexed: 01/08/2023]
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16
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Schlader ZJ, Temple JL, Hostler D. Exercise in personal protective equipment in a hot, humid environment does not affect risk propensity. Temperature (Austin) 2016; 3:262-270. [PMID: 27857956 PMCID: PMC4964995 DOI: 10.1080/23328940.2016.1148526] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/25/2016] [Accepted: 01/25/2016] [Indexed: 10/26/2022] Open
Abstract
We tested the hypothesis that heat stress created by light exertion in encapsulating personal protective equipment (PPE) in a hot, humid environment increases risk propensity. Ten healthy subjects (29 ± 7 y) completed 2 trials presented in a counter-balanced manner. Subjects donned encapsulating PPE, and in one trial they wore a tube-lined shirt underneath that was perfused with 5°C water. Subjects completed 2 15 min bouts of walking exercise on a treadmill at ˜50% maximal heart rate in a 32°C, 81% RH environment. Subjects completed the Balloon Analog Risk Task (BART), an objective measure of risk-taking, before, between the 2 exercise bouts, and following the final exercise bout. Personal cooling lowered (P < 0.01) mean skin temperature by 8.0 ± 1.6°C. Intestinal temperature rose (P < 0.01) in both trials, but was lower (P < 0.01) at the end of exercise in the cooling trial (38.0 ± 0.3°C vs. 37.6 ± 0.3°C). BART derived indices of risk propensity were not affected by trial or time (trial × time interaction: P ≥ 0.33). These data indicate that 60 min of exposure to mild heat stress created by light exertion in encapsulating PPE does not affect risk-taking behavior.
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Affiliation(s)
- Zachary J Schlader
- Emergency Responder Human Performance Lab, Department of Exercise and Nutrition Sciences, University at Buffalo , Buffalo, NY, USA
| | - Jennifer L Temple
- Emergency Responder Human Performance Lab, Department of Exercise and Nutrition Sciences, University at Buffalo , Buffalo, NY, USA
| | - David Hostler
- Emergency Responder Human Performance Lab, Department of Exercise and Nutrition Sciences, University at Buffalo , Buffalo, NY, USA
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17
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Bain AR, Nybo L, Ainslie PN. Cerebral Vascular Control and Metabolism in Heat Stress. Compr Physiol 2016; 5:1345-80. [PMID: 26140721 DOI: 10.1002/cphy.c140066] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review provides an in-depth update on the impact of heat stress on cerebrovascular functioning. The regulation of cerebral temperature, blood flow, and metabolism are discussed. We further provide an overview of vascular permeability, the neurocognitive changes, and the key clinical implications and pathologies known to confound cerebral functioning during hyperthermia. A reduction in cerebral blood flow (CBF), derived primarily from a respiratory-induced alkalosis, underscores the cerebrovascular changes to hyperthermia. Arterial pressures may also become compromised because of reduced peripheral resistance secondary to skin vasodilatation. Therefore, when hyperthermia is combined with conditions that increase cardiovascular strain, for example, orthostasis or dehydration, the inability to preserve cerebral perfusion pressure further reduces CBF. A reduced cerebral perfusion pressure is in turn the primary mechanism for impaired tolerance to orthostatic challenges. Any reduction in CBF attenuates the brain's convective heat loss, while the hyperthermic-induced increase in metabolic rate increases the cerebral heat gain. This paradoxical uncoupling of CBF to metabolism increases brain temperature, and potentiates a condition whereby cerebral oxygenation may be compromised. With levels of experimentally viable passive hyperthermia (up to 39.5-40.0 °C core temperature), the associated reduction in CBF (∼ 30%) and increase in cerebral metabolic demand (∼ 10%) is likely compensated by increases in cerebral oxygen extraction. However, severe increases in whole-body and brain temperature may increase blood-brain barrier permeability, potentially leading to cerebral vasogenic edema. The cerebrovascular challenges associated with hyperthermia are of paramount importance for populations with compromised thermoregulatory control--for example, spinal cord injury, elderly, and those with preexisting cardiovascular diseases.
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Affiliation(s)
- Anthony R Bain
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna, Canada
| | - Lars Nybo
- Department of Nutrition, Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Philip N Ainslie
- Centre for Heart Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna, Canada
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18
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Brocherie F, Girard O, Pezzoli A, Millet GP. Outdoor exercise performance in ambient heat: time to overcome challenging factors? Int J Hyperthermia 2015; 30:547-9. [PMID: 25430987 DOI: 10.3109/02656736.2014.979257] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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19
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Schlader ZJ, Gagnon D, Adams A, Rivas E, Cullum CM, Crandall CG. Cognitive and perceptual responses during passive heat stress in younger and older adults. Am J Physiol Regul Integr Comp Physiol 2015; 308:R847-54. [PMID: 25786484 PMCID: PMC4436980 DOI: 10.1152/ajpregu.00010.2015] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 03/15/2015] [Indexed: 12/22/2022]
Abstract
We tested the hypothesis that attention, memory, and executive function are impaired to a greater extent in passively heat-stressed older adults than in passively heat-stressed younger adults. In a randomized, crossover design, 15 older (age: 69 ± 5 yr) and 14 younger (age: 30 ± 4 yr) healthy subjects underwent passive heat stress and time control trials. Cognitive tests (outcomes: accuracy and reaction time) from the CANTAB battery evaluated attention [rapid visual processing (RVP), choice reaction time (CRT)], memory [spatial span (SSP), pattern recognition memory (PRM)], and executive function [one touch stockings of Cambridge (OTS)]. Testing was undertaken on two occasions during each trial, at baseline and after internal temperature had increased by 1.0 ± 0.2°C or after a time control period. For tests that measured attention, reaction time during RVP and CRT was slower (P ≤ 0.01) in the older group. During heat stress, RVP reaction time improved (P < 0.01) in both groups. Heat stress had no effect (P ≥ 0.09) on RVP or CRT accuracy in either group. For tests that measured memory, accuracy on SSP and PRM was lower (P < 0.01) in the older group, but there was no effect of heat stress (P ≥ 0.14). For tests that measured executive function, overall, accuracy on OTS was lower, and reaction time was slower in the older group (P ≤ 0.05). Reaction time generally improved during heat stress, but there was no effect of heat stress on accuracy in either group. These data indicate that moderate increases in body temperature during passive heat stress do not differentially compromise cognitive function in younger and older adults.
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Affiliation(s)
- Zachary J Schlader
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, New York
| | - Daniel Gagnon
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Amy Adams
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Eric Rivas
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; Department of Kinesiology, Texas Woman's University, Denton, Texas; and
| | - C Munro Cullum
- Departments of Psychiatry and Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas;
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20
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The interactive effect of cooling and hypoxia on forearm fatigue development. Eur J Appl Physiol 2015; 115:2007-18. [DOI: 10.1007/s00421-015-3181-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 04/30/2015] [Indexed: 11/25/2022]
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21
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Brazaitis M, Eimantas N, Daniuseviciute L, Vitkauskiene A, Paulauskas H, Skurvydas A. Two strategies for the acute response to cold exposure but one strategy for the response to heat stress. Int J Hyperthermia 2015; 31:325-35. [DOI: 10.3109/02656736.2015.1004135] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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22
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Matsuura R, Arimitsu T, Yunoki T, Kimura T, Yamanaka R, Yano T. Effects of heat exposure in the absence of hyperthermia on power output during repeated cycling sprints. Biol Sport 2014; 32:15-20. [PMID: 25729145 PMCID: PMC4314599 DOI: 10.5604/20831862.1125286] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 05/14/2014] [Accepted: 06/17/2014] [Indexed: 11/13/2022] Open
Abstract
The aim of this study was to investigate the effects of heat exposure in the absence of hyperthermia on power output during repeated cycling sprints. Seven males performed four 10-s cycling sprints interspersed by 30 s of active recovery on a cycle ergometer in hot-dry and thermoneutral environments. Changes in rectal temperature were similar under the two ambient conditions. The mean 2-s power output over the 1st–4th sprints was significantly lower under the hot-dry condition than under the thermoneutral condition. The amplitude of the electromyogram was lower under the hot-dry condition than under the thermoneutral condition during the early phase (0–3 s) of each cycling sprint. No significant difference was observed for blood lactate concentration between the two ambient conditions. Power output at the onset of a cycling sprint during repeated cycling sprints is decreased due to heat exposure in the absence of hyperthermia.
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Affiliation(s)
- R Matsuura
- Living and Health Sciences Education, Specialized Subject Fields of Education, Graduate School of Education, Joetsu University of Education, 1 Yamayashiki-machi, Joetsu, 943-8512, Japan
| | - T Arimitsu
- Department of Sports Science, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, Kita-ku, Tokyo 115-0056, Japan
| | - T Yunoki
- Department of Human Developmental Sciences, Faculty of Education, Hokkaido University Kita-11, Nishi-7, Kita-ku, Sapporo 060-0811, Japan
| | - T Kimura
- Second Division of Physical Therapy, School of Health Science, Sapporo Medical University, Minami-1, Nishi-17, Chuo-ku, Sapporo 060-8556, Japan
| | - R Yamanaka
- Department of Sports Science, Japan Institute of Sports Sciences, 3-15-1 Nishigaoka, Kita-ku, Tokyo 115-0056, Japan
| | - T Yano
- Department of Human Developmental Sciences, Faculty of Education, Hokkaido University Kita-11, Nishi-7, Kita-ku, Sapporo 060-0811, Japan
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23
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Abstract
PURPOSE This paper investigates the thermal conditions inside a passenger car driven after it was left a few hours in a shade-less parking lot, and the related implications for the driving performance. MATERIALS AND METHODS Experimental results for twelve tests carried out in four different vehicles are presented and discussed. Each test is characterized by means of the predicted core temperature tcore of the driver after 60 minutes, as calculated by a heat stress model. The fractional performance loss is calculated by adjusting existing algorithms for office tasks to accommodate literature data on driving-related tasks, and then re-casting the algorithm as a function of tcore instead of the air temperature ta. RESULTS Based on measured temperatures and humidities, fractional performance losses up to 50% are predicted even for relatively simple tasks such as keeping the vehicle on a straight course. Performance losses in excess of 75% are predicted, under the most extreme thermal conditions, for demanding tasks, such as correctly identifying a signal and reacting in due time. CONCLUSIONS The implementation in technical standards on heat stress assessment of two new thresholds is recommended. The lower threshold, to be set at tcore ≅ 37.1 °C, is aimed at ensuring that the subject is able to carry out demanding mental tasks without appreciable performance loss, while the higher threshold, to be set at tcore ≅ 37.2 °C applies to simpler tasks.
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Affiliation(s)
- Paolo Lenzuni
- Department of Florence, INAIL-Research Area , Florence , Italy
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24
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KNEZ W, GIRARD O, RACINAIS S, WALSH A, GAOUA N, GRANTHAM J. Does living and working in a hot environment induce clinically relevant changes in immune function and voluntary force production capacity? INDUSTRIAL HEALTH 2014; 52:235-239. [PMID: 24583514 PMCID: PMC4209581 DOI: 10.2486/indhealth.2012-0032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2012] [Accepted: 02/06/2014] [Indexed: 05/29/2023]
Abstract
This study investigated the effect of living (summer vs. winter) and working (morning vs. afternoon) in a hot environment on markers of immune function and forearm strength. Thirty-one healthy male gas field employees were screened before (between 05:30 and 07:00) and after their working day (between 15:30 and 17:00) during both seasons. Body core temperature and physical activity were recorded throughout the working days. The hot condition (i.e. summer) led a higher (p≤0.05) average body core temperature (~37.2 vs. ~37.4 °C) but reduced physical activity (-14.8%) during the work-shift. Our data showed an increase (p≤0.05) in lymphocyte and monocyte counts in the summer. Additionally, work-shift resulted in significant (p≤0.001) changes in leukocytes, lymphocytes and monocytes independently of the environment. Handgrip (p=0.069) and pinch (p=0.077) forces tended to be reduced from pre-to post-work, while only force produced during handgrip manoeuvres was significantly reduced (p≤0.05) during the hot compared to the temperate season. No interactions were observed between the environment and work-shift for any marker of immune function or forearm strength. In summary, working and living in hot conditions impact on markers of immune function and work capacity; however by self-regulating energy expenditure, immune markers remained in a healthy reference range.
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Affiliation(s)
- Wade KNEZ
- Aspetar, Orthopaedic and Sports Medicine Hospital, Athlete
Health and Performance, Qatar
| | - Olivier GIRARD
- Aspetar, Orthopaedic and Sports Medicine Hospital, Athlete
Health and Performance, Qatar
| | - Sebastien RACINAIS
- Aspetar, Orthopaedic and Sports Medicine Hospital, Athlete
Health and Performance, Qatar
| | - Andrew WALSH
- Aspetar, Orthopaedic and Sports Medicine Hospital, Athlete
Health and Performance, Qatar
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25
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Morrison SA, Cheung SS, Hurst RD, Cotter JD. Cognitive function and blood-brain barrier permeability during exercise in the heat: Effect of fitness and bovine colostrum supplementation. J Therm Biol 2013. [DOI: 10.1016/j.jtherbio.2013.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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26
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Schlader ZJ, Lucas RAI, Pearson J, Crandall CG. Hyperthermia does not alter the increase in cerebral perfusion during cognitive activation. Exp Physiol 2013; 98:1597-607. [PMID: 23851918 DOI: 10.1113/expphysiol.2013.074104] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This study tested the hypothesis that hyperthermia attenuates the increase in cerebral perfusion during cognitive activation. Mean middle cerebral artery blood velocity (MCAV(mean)) served as an index of cerebral perfusion, while the nBack test (a test of working memory) was the cognitive task. Hyperthermia was characterized by elevations (P < 0.001) in skin (by 5.0 ± 0.8 °C) and intestinal temperatures (by 1.3 ± 0.1 °C) and reductions (P < 0.020) in mean arterial pressure (by 11 ± 10 mmHg), end-tidal CO2 tension (by 3 ± 6 mmHg) and MCAV(mean) (by 10 ± 9 cm s(-1)). Hyperthermia had no influence on nBack test performance (mean difference from normothermia to hyperthermia, -1 ± 11%; P = 0.276) or, counter to the hypothesis, the increase in MCAV(mean) during nBack testing (mean difference from normothermia to hyperthermia: 0 ± 16 cm s(-1); P = 0.608). These findings indicate that the capacity to increase cerebral perfusion during cognitive activation is unaffected by hyperthermia.
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Affiliation(s)
- Zachary J Schlader
- C. G. Crandall: Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, 7232 Greenville Avenue, Dallas, TX 75231, USA.
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27
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Racinais S, Cresswell AG. Temperature affects maximum H-reflex amplitude but not homosynaptic postactivation depression. Physiol Rep 2013; 1:e00019. [PMID: 24303108 PMCID: PMC3831915 DOI: 10.1002/phy2.19] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 05/26/2013] [Accepted: 06/04/2013] [Indexed: 11/06/2022] Open
Abstract
This study aimed to determinate the effect of hyperthermia on transmission efficacy of the Ia-afferent spinal pathway. Recruitment curves of the Hoffman reflex (H-reflex) and compound motor potential (M-wave) along with homosynaptic postactivation depression (HPAD) recovery curves were obtained in 14 volunteers in two controlled ambient temperatures that resulted in significantly different core temperatures (CON, core temperature ∼37.3°C; and HOT, core temperature ∼39.0°C). Electromyographic responses were obtained from the soleus (SOL) and medial gastrocnemius (MG) muscles following electrical stimulation of the tibial nerve at varying intensities and paired pulse frequencies (0.07-10 Hz). Results showed that maximal amplitude of the H-reflex was reached for a similar intensity of stimulation in CON and HOT (both muscles P > 0.47), with a similar associated M-wave (both muscles P > 0.69) but was significantly decreased in HOT as compared to CON (all P < 0.05), whether expressed in absolute terms (-50% in SOL, -32% in MG) or when normalized to the maximum M-wave (-23% in SOL, -32% in MG). The HPAD recovery curve was not affected by the elevated core temperature (both muscles P > 0.23). Taken together, these results suggest that hyperthermia can alter neuromuscular transmission across the neuromuscular junction and/or muscle membrane as well as transmission efficacy of the Ia-afferent pathway, albeit the latter not via an increase in HPAD.
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Girard O, Bishop DJ, Racinais S. Hot conditions improve power output during repeated cycling sprints without modifying neuromuscular fatigue characteristics. Eur J Appl Physiol 2012; 113:359-69. [PMID: 22743981 DOI: 10.1007/s00421-012-2444-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 06/13/2012] [Indexed: 11/24/2022]
Abstract
This study investigated the effect of hot conditions on repeated sprint cycling performance and post-exercise alterations in isometric knee extension function. Twelve physically active participants performed 10 × 6-s "all-out" sprints on a cycle ergometer (recovery = 30 s), followed 6 min later by 5 × 6-s sprints (recovery = 30 s) in either a neutral (24 °C/30 %rH) or a hot (35 °C/40 %rH) environment. Neuromuscular tests including voluntary and electrically evoked isometric contractions of the knee extensors were performed before and after exercise. Average core temperature during exercise was higher (38.0 ± 0.1 vs. 37.7 ± 0.1 °C, respectively; P < 0.05) in hot versus neutral environments. Peak power output decreased (-17.9 % from sprint 1 to sprint 10 and -17.0 % from sprint 11 to sprint 15; P < 0.001) across repetitions. Average peak power output during the first ten sprints was higher (+3.1 %; P < 0.01) in the hot ambient temperature condition. Maximal strength (-12 %) and rate of force development (-15 to -26 %, 30-200 ms from the onset of contraction) decreased (P < 0.001) during brief contractions after exercise, irrespectively of the ambient temperature. During brief maximal contractions, changes in voluntary activation (~80 %) were not affected by exercise or temperature. Voluntary activation declined (P < 0.01) during the sustained contraction, with these reductions being more pronounced (P < 0.05) after exercise but not affected by the ambient temperature. Resting twitch amplitude declined (P < 0.001) by ~42 %, independently of the ambient temperature. In conclusion, heat exposure has no effect on the pattern and the extent of isometric knee extensor fatigue following repeated cycling sprints in the absence of hyperthermia.
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Affiliation(s)
- Olivier Girard
- Research and Education Centre, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
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Kazama A, Takatsu S, Hasegawa H. Effect of increase in body temperature on cognitive function during prolonged exercise. ACTA ACUST UNITED AC 2012. [DOI: 10.7600/jspfsm.61.459] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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