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Guan L, Tan J, Qi B, Chen Y, Cao M, Zhang Q, Zou Y. Effects of an external static EF on the conformational transition of 5-HT1A receptor: A molecular dynamics simulation study. Biophys Chem 2024; 312:107283. [PMID: 38941873 DOI: 10.1016/j.bpc.2024.107283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/13/2024] [Accepted: 06/16/2024] [Indexed: 06/30/2024]
Abstract
The serotonin receptor subtype 1A (5-HT1AR), one of the G-protein-coupled receptor (GPCR) family, has been implicated in several neurological conditions. Understanding the activation and inactivation mechanism of 5-HT1AR at the molecular level is critical for discovering novel therapeutics in many diseases. Recently there has been a growing appreciation for the role of external electric fields (EFs) in influencing the structure and activity of biomolecules. In this study, we used molecular dynamics (MD) simulations to examine conformational features of active states of 5-HT1AR and investigate the effect of an external static EF with 0.02 V/nm applied on the active state of 5-HT1AR. Our results showed that the active state of 5-HT1AR maintained the native structure, while the EF led to structural modifications in 5-HT1AR, particularly inducing the inward movement of transmembrane helix 6 (TM6). Furthermore, it disturbed the conformational switches associated with activation in the CWxP, DRY, PIF, and NPxxY motifs, consequently predisposing an inclination towards the inactive-like conformation. We also found that the EF led to an overall increase in the dipole moment of 5-HT1AR, encompassing TM6 and pivotal amino acids. The analyses of conformational properties of TM6 showed that the changed secondary structure and decreased solvent exposure occurred upon the EF condition. The interaction of 5-HT1AR with the membrane lipid bilayer was also altered under the EF. Our findings reveal the molecular mechanism underlying the transition of 5-HT1AR conformation induced by external EFs, which offer potential novel insights into the prospect of employing structure-based EF applications for GPCRs.
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Affiliation(s)
- Lulu Guan
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China
| | - Jingwang Tan
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China
| | - Bote Qi
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China
| | - Yukang Chen
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China
| | - Meng Cao
- Department of Physical Education, College of Sport, Shenzhen University, 3688 Nanhai Road, Shenzhen, Guangdong 518061, PR China
| | - Qingwen Zhang
- College of Physical Education, Shanghai University of Sport, 399 Changhai Road, Shanghai 200438, PR China
| | - Yu Zou
- Department of Sport and Exercise Science, College of Education, Zhejiang University, 866 Yuhangtang Road, Hangzhou, Zhejiang 310058, PR China.
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Chiang MH, Lin YC, Chen SF, Lee PS, Fu TF, Wu T, Wu CL. Independent insulin signaling modulators govern hot avoidance under different feeding states. PLoS Biol 2023; 21:e3002332. [PMID: 37847673 PMCID: PMC10581474 DOI: 10.1371/journal.pbio.3002332] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 09/11/2023] [Indexed: 10/19/2023] Open
Abstract
Thermosensation is critical for the survival of animals. However, mechanisms through which nutritional status modulates thermosensation remain unclear. Herein, we showed that hungry Drosophila exhibit a strong hot avoidance behavior (HAB) compared to food-sated flies. We identified that hot stimulus increases the activity of α'β' mushroom body neurons (MBns), with weak activity in the sated state and strong activity in the hungry state. Furthermore, we showed that α'β' MBn receives the same level of hot input from the mALT projection neurons via cholinergic transmission in sated and hungry states. Differences in α'β' MBn activity between food-sated and hungry flies following heat stimuli are regulated by distinct Drosophila insulin-like peptides (Dilps). Dilp2 is secreted by insulin-producing cells (IPCs) and regulates HAB during satiety, whereas Dilp6 is secreted by the fat body and regulates HAB during the hungry state. We observed that Dilp2 induces PI3K/AKT signaling, whereas Dilp6 induces Ras/ERK signaling in α'β' MBn to regulate HAB in different feeding conditions. Finally, we showed that the 2 α'β'-related MB output neurons (MBONs), MBON-α'3 and MBON-β'1, are necessary for the output of integrated hot avoidance information from α'β' MBn. Our results demonstrate the presence of dual insulin modulation pathways in α'β' MBn, which are important for suitable behavioral responses in Drosophila during thermoregulation under different feeding states.
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Affiliation(s)
- Meng-Hsuan Chiang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Yu-Chun Lin
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Sheng-Fu Chen
- NHRI Institute of Biomedical Engineering & Nanomedicine, Miaoli, Taiwan
| | - Peng-Shiuan Lee
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Tsai-Feng Fu
- Department of Applied Chemistry, National Chi Nan University, Nantou, Taiwan
| | - Tony Wu
- Department of Neurology, New Taipei Municipal TuCheng Hospital, Chang Gung Memorial Hospital, New Taipei City, Taiwan
| | - Chia-Lin Wu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Department of Neurology, New Taipei Municipal TuCheng Hospital, Chang Gung Memorial Hospital, New Taipei City, Taiwan
- Department of Biochemistry, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Brain Research Center, National Tsing Hua University, Hsinchu, Taiwan
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Roriz M, Brito P, Teixeira FJ, Brito J, Teixeira VH. Performance effects of internal pre- and per-cooling across different exercise and environmental conditions: A systematic review. Front Nutr 2022; 9:959516. [PMID: 36337635 PMCID: PMC9632747 DOI: 10.3389/fnut.2022.959516] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 09/19/2022] [Indexed: 11/13/2022] Open
Abstract
Exercise in a hot and humid environment may endanger athlete's health and affect physical performance. This systematic review aimed to examine whether internal administration of ice, cold beverages or menthol solutions may be beneficial for physical performance when exercising in different environmental conditions and sports backgrounds. A systematic search was performed in PubMed, Web of Science, Scopus and SPORTDiscus databases, from inception to April 2022, to identify studies meeting the following inclusion criteria: healthy male and female physically active individuals or athletes (aged ≥18 years); an intervention consisting in the internal administration (i.e., ingestion or mouth rinse) of ice slush, ice slurry or crushed ice and/or cold beverages and/or menthol solutions before and/or during exercise; a randomized crossover design with a control or placebo condition; the report of at least one physical performance outcome; and to be written in English. Our search retrieved 2,714 articles in total; after selection, 43 studies were considered, including 472 participants, 408 men and 64 women, aged 18-42 years, with a VO2max ranging from 46.2 to 67.2 mL⋅kg-1⋅min-1. Average ambient temperature and relative humidity during the exercise tasks were 32.4 ± 3.5°C (ranging from 22°C to 38°C) and 50.8 ± 13.4% (varying from 20.0% to 80.0%), respectively. Across the 43 studies, 7 exclusively included a menthol solution mouth rinse, 30 exclusively involved ice slurry/ice slush/crushed ice/cold beverages intake, and 6 examined both the effect of thermal and non-thermal internal techniques in the same protocol. Rinsing a menthol solution (0.01%) improved physical performance during continuous endurance exercise in the heat. Conversely, the ingestion of ice or cold beverages did not seem to consistently increase performance, being more likely to improve performance in continuous endurance trials, especially when consumed during exercises. Co-administration of menthol with or within ice beverages seems to exert a synergistic effect by improving physical performance. Even in environmental conditions that are not extreme, internal cooling strategies may have an ergogenic effect. Further studies exploring both intermittent and outdoor exercise protocols, involving elite male and female athletes and performed under not extreme environmental conditions are warranted. Systematic review registration: [https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021268197], identifier [CRD42021268197].
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Affiliation(s)
- Maria Roriz
- Faculty of Nutrition and Food Sciences, University of Porto (FCNAUP), Porto, Portugal
- Futebol Clube do Porto, Porto, Portugal
| | - Pedro Brito
- Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University of Maia, ISMAI, Maia, Portugal
| | - Filipe J. Teixeira
- Interdisciplinary Center for the Study of Human Performance (CIPER), Faculdade de Motricidade Humana, Universidade de Lisboa, Cruz-Quebrada, Portugal
- Atlântica, Instituto Universitário, Fábrica da Pólvora de Barcarena, Barcarena, Portugal
- Bettery Lifelab, Bettery S.A., Lisbon, Portugal
| | - João Brito
- Portugal Football School, Portuguese Football Federation, Oeiras, Portugal
| | - Vitor Hugo Teixeira
- Faculty of Nutrition and Food Sciences, University of Porto (FCNAUP), Porto, Portugal
- Futebol Clube do Porto, Porto, Portugal
- Research Centre in Physical Activity, Health and Leisure (CIAFEL), Faculty of Sports, University of Porto (FADEUP), Porto, Portugal
- Laboratory for Integrative and Translational Research in Population Health (ITR), Porto, Portugal
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Robin N, Dominique L, Hue O. Influence of Face Mask and Tropical Climate on Subjective States: Affect, Motivation, and Selective Attention. AMERICAN JOURNAL OF PSYCHOLOGY 2022. [DOI: 10.5406/19398298.135.3.05] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
We investigated whether face mask wearing in a hot and humid environment would influence subjective states: motivation, affect, and the performance of cognitive tasks requiring attentional processes. Forty volunteers performed the tasks under 4 repeated conditions: in an air-conditioned (AC) room or a tropical climate (TC; hot and wet environment) while wearing a mask or not (counterbalanced). For each condition, they completed questionnaires on subjective states (affect, motivation, and attentional processes) by performing the Bells and d2 tests, and a comparison of men and women was an indirect focus of this study. Results showed that the participants had higher sensations of fatigue, thermal discomfort, and a negative affect when wearing a mask in the TC condition. Additionally, lower performance scores were noted in the Bells test when participants wore a mask in a TC compared with all other conditions. Lastly, the participants’ performance on the d2 test involving selective and sustained attention improved without a mask in AC and in TC conditions. Consequently, the results revealed that wearing a mask in a TC can induce anxiety, headaches, discomfort, and lower motivation.
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Affiliation(s)
| | | | - Olivier Hue
- Université des Antilles, Laboratoire ACTES, France
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5
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Miyazawa T, Mizutani M, Sheahan JP, Ichikawa D. Intermittent face cooling reduces perceived exertion during exercise in a hot environment. J Physiol Anthropol 2021; 40:12. [PMID: 34488878 PMCID: PMC8420073 DOI: 10.1186/s40101-021-00262-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 08/23/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Facial cooling (FC) is effective in improving endurance exercise performance in hot environments. In this study, we evaluated the impact of intermittent short-lasting FC on the ratings of perceived exertion (RPE) during exercise. METHODS Ten healthy men performed 40 continuous minutes of ergometric cycle exercise at 65% of the peak heart rate in a climatic chamber controlled at an ambient temperature of 35 °C and a relative humidity of 50%. In the control (CONT) trial, the participants performed the exercise without FC. In two cooling trials, each participant underwent 10 s of FC at 2- (FC2) and 4-min (FC4) intervals while continuing to exercise. FC was achieved by applying two soft-gel packs (cooled to 0 °C) directly and bilaterally on the forehead, eyes, and cheeks. In another cooling trial, 10 s of FC was performed at 2-min intervals using two soft-gel packs cooled to 20 °C (FC2-20). RESULTS The RPE values in the FC4 trial were significantly lower than those in the CONT trial at 20 min (FC4, 11.6 ± 2.2 points; CONT, 14.2 ± 1.3 points; P < 0.01). Further, significant differences in the RPE values were observed between the FC4 and CONT trials at 5-15 min and 25-40 min (P < 0.05). RPE values were also significantly lower in the FC2 trial than in the CONT trial (5-40 min). Although the RPE values in the FC2-20 trial were significantly lower (5-10 min; 15-20 min) than those in the CONT trial, there were no significant differences in the RPE between the FC2-20 and CONT trials at 25-40 min. At 35 min, the RPE values were significantly higher in the FC2-20 trial than in the FC2 trial (P < 0.05). CONCLUSION Intermittent short-lasting FC was associated with a decrease in RPE, with shorter intervals and lower temperatures eliciting greater attenuation of increase in the RPE.
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Affiliation(s)
- Taiki Miyazawa
- Department of Health and Sports Science, Faculty of Wellness, Shigakkan University, Obu, Japan.
| | - Mirai Mizutani
- Department of Physical Education, Shigakkan University Junior College, Obu, Japan
| | | | - Daisuke Ichikawa
- Department of Biomedical Engineering, Toyo University, Kawagoe, Japan
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Périard JD, Eijsvogels TMH, Daanen HAM. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiol Rev 2021; 101:1873-1979. [PMID: 33829868 DOI: 10.1152/physrev.00038.2020] [Citation(s) in RCA: 138] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances, and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat by examining the benefits of heat acclimation, cooling strategies, and hyperhydration. Finally, contemporary controversies are summarized and future research directions are provided.
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Affiliation(s)
- Julien D Périard
- University of Canberra Research Institute for Sport and Exercise, Bruce, Australia
| | - Thijs M H Eijsvogels
- Department of Physiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hein A M Daanen
- Department of Human Movement Sciences, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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Pathophysiological Responses to a Record-Breaking Multi-hour Underwater Endurance Performance: A Case Study. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1289:79-88. [PMID: 32488605 DOI: 10.1007/5584_2020_546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The "Endless Diving Project-Step 36" took place in the harbor waters of the town of Maratea in Italy in September 2014. The goal of the project was an attempt by an experienced male diver, equipped with a wet 7-mm suit and a normal gas tank, to set the world record-breaking of nonstop underwater performance. We studied inflammatory, hematological, and endocrine responses during the extreme condition of the attempt. Venous blood samples were collected at baseline, the day before the attempt; immediately after the return from underwater; then at Day 1, Day 4, and Day 12; and later at Month 1 and Month 41 of follow-up. We found that there was an increase in the content of blood neutrophils, monocytes, and eosinophils and a decrease in lymphocytes at Day 1 and a late increase in basophils at Day 12 after the dive. Inflammatory markers and hematocrit and hemoglobin increased immediately after the dive, dropped at Day 1, and reverted gradually to the control level from Day 4 to Day 12. Serotonin and dopamine decreased, while adrenaline increased at Day 1, gradually recovering in the days of follow-up. Insulin, luteinizing hormone, growth hormone, and prolactin increased, while testosterone, cortisol, 17β-estradiol, thyroid-stimulating hormone, and adrenocorticotropic hormone decreased at Day 1, with a partial recovery at Day 4. We conclude that the homeostatic response to the extreme, prolonged underwater performance showed signs of psychological and pro-inflammatory stress. The hormonal response reflected an acute testicular insufficiency. These responses resembled those characteristics for ultra-endurance exercise accompanied by vasculitis and dehydration.
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Wallace PJ, Schultz Martins R, Scott JS, Steele SW, Greenway MJ, Cheung SS. The effects of acute dopamine reuptake inhibition on cognitive function during passive hyperthermia. Appl Physiol Nutr Metab 2020; 46:511-520. [PMID: 33232172 DOI: 10.1139/apnm-2020-0869] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dopamine activity can modulate physical performance in the heat, but less is known about its effects on cognition during thermal stress. Twelves males completed a randomized, double-blinded protocol consisting of oral ingestion of 20 mg of methylphenidate (MPH) or placebo (lactose pill) during passive heating using a water-perfused suit (water temperature ∼49 °C). To identify the impact of peripheral versus central thermal strain, a cognitive test battery was completed at 4 different thermal states: baseline (BASE; 37.2 ± 0.6 °C core, 32.9 ± 0.7 °C skin), neutral core-hot skin (NC-HS; 37.2 ± 0.3 °C, 37.4 ± 0.3 °C), hyperthermic core-hot skin (HC-HS; 38.7 ± 0.4 °C, 38.7 ± 0.2 °C), and hyperthermic core-cooled skin (HC-CS; 38.5 ± 0.4 °C, 35.1 ± 0.8 °C). The cognitive test battery consisted of the 2-back task (i.e., working memory), set-shifting (i.e., executive function), Groton Maze Learning Task (i.e., executive function) and detection task (i.e., psychomotor processing). MPH led to significantly higher heart rates (∼5-15 b·min-1) at BASE, NC-HS, and HC-HS (all p < 0.05). There were no significant differences in the number of errors made on each task (all p < 0.05). Participants were significantly faster (p < 0.05) on the set-shifting task in the HC-HS timepoint, irrespective of drug condition (p > 0.05). In summary, we demonstrated that 20 mg of MPH did not significantly alter cognitive function during either normothermia or moderate hyperthermia. Novelty: Twenty milligrams of MPH did not significantly alter cognitive function during passive heat stress. MPH led to significant higher heart rates (∼5-15 b·min-1) in thermoneutral and during passive heat stress. Future studies are needed to determine the mechanisms of why MPH improves physical but not cognitive performance during heat stress.
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Affiliation(s)
- Phillip J Wallace
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Ricardo Schultz Martins
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Jake S Scott
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Scott W Steele
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Mathew J Greenway
- Department of Family Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Stephen S Cheung
- Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
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Barzegarpoor H, Amoozi H, Rajabi H, Button D, Fayazmilani R. The Effects of Performing Mental Exertion during Cycling Exercise on Fatigue Indices. Int J Sports Med 2020; 41:846-857. [DOI: 10.1055/a-1179-8326] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
AbstractThis study investigated the effect of performing prolonged mental exertion during
submaximal cycling exercise on exercise tolerance and fatigue. Participants
performed 5 experimental sessions. Session 1: determination of cycling peak
power output. Sessions 2 and 3: cycling to exhaustion at 65% peak power
output with mental exertion or watching a movie. Sessions 4 and 5: cycling for
45 min at 65% peak power output with mental exertion or while watching a
movie. During sessions 2–5, rate of perceived exertion and heart rate
were recorded while cycling and cortisol and prolactin concentrations,
psychomotor vigilance task performance, and maximal voluntary contraction were
measured pre-and post-sessions. During sessions 2 and 3, time to exhaustion was
reduced (p<0.01) and rate of perceived exertion was increased
(p<0.01) in session 2 compared to 3. Cortisol, prolactin and
heart rate increased and psychomotor vigilance task and maximal voluntary
contraction decreased from pre-to post-sessions with no difference between
sessions. Cortisol, prolactin and rate of perceived exertion were higher
(p<0.03) in session 4 than 5. Heart rate increased and
maximal voluntary contraction decreased from pre-to post-sessions with no
difference between sessions. Prolonged mental exertion during cycling exercise
reduces exercise tolerance, which appears to be mediated psychologically rather
than physiologically.
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Affiliation(s)
- Hamidreza Barzegarpoor
- Sport Sciences and Health, Shahid Beheshti University, Tehran, Iran
(the Islamic Republic of)
- School of Human Kinetics and Recreation, Memorial University of
Newfoundland, St. John’s, Canada
| | - Hamid Amoozi
- Sport Sciences and Health, Shahid Beheshti University, Tehran, Iran
(the Islamic Republic of)
| | - Hamid Rajabi
- Sport sciences, Kharazmi University, Tehran, Iran (the Islamic Republic
of)
| | - Duane Button
- School of Human Kinetics and Recreation, Memorial University of
Newfoundland, St. John’s, Canada
| | - Rana Fayazmilani
- Sport Sciences and Health, Shahid Beheshti University, Tehran, Iran
(the Islamic Republic of)
- Department of Biological Sciences in Sport, Faculty of Sports Sciences
and Health, Shahid Beheshti University, Tehran, Iran
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Douzi W, Dupuy O, Theurot D, Smolander J, Dugué B. Per-Cooling (Using Cooling Systems during Physical Exercise) Enhances Physical and Cognitive Performances in Hot Environments. A Narrative Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:E1031. [PMID: 32041228 PMCID: PMC7036802 DOI: 10.3390/ijerph17031031] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/25/2020] [Accepted: 01/29/2020] [Indexed: 12/19/2022]
Abstract
There are many important sport events that are organized in environments with a very hot ambient temperature (Summer Olympics, FIFA World Cup, Tour de France, etc.) and in hot locations (e.g., Qatar). Additionally, in the context of global warming and heat wave periods, athletes are often subjected to hot ambient temperatures. It is known that exercising in the heat induces disturbances that may provoke premature fatigue and negatively affects overall performance in both endurance and high intensity exercises. Deterioration in several cognitive functions may also occur, and individuals may be at risk for heat illnesses. To train, perform, work and recover and in a safe and effective way, cooling strategies have been proposed and have been routinely applied before, during and after exercise. However, there is a limited understanding of the influences of per-cooling on performance, and it is the subject of the present review. This work examines the influences of per-cooling of different areas of the body on performance in terms of intense short-term exercises ("anaerobic" exercises), endurance exercises ("aerobic" exercises), and cognitive functioning and provides detailed strategies that can be applied when individuals train and/or perform in high ambient temperatures.
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Affiliation(s)
| | | | | | | | - Benoit Dugué
- University of Poitiers, Laboratoire Mobilité Vieillissement Exercice (MOVE)-EA6314, Faculty of Sport Sciences, 8 Allée Jean Monnet, 86000 Poitiers, France; (W.D.); (O.D.); (D.T.); (J.S.)
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11
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Tumilty L, Gregory N, Beckmann M, Thatcher R. No Influence of Low-, Medium-, or High-Dose Tyrosine on Exercise in a Warm Environment. Med Sci Sports Exerc 2019; 52:1404-1413. [PMID: 31834099 DOI: 10.1249/mss.0000000000002245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Tyrosine administration may counter exercise fatigue in a warm environment, but the typical dose is inconclusive, with little known about higher doses. We explored how three tyrosine doses influenced the circulating ratio of tyrosine/amino acids competing for brain uptake and hypothesized that a medium and high dose would enhance exercise performance in a warm environment. METHODS Eight recreationally trained, non-heat-acclimated male individuals (mean ± SD age, 23 ± 4 yr; stature, 181 ± 7 cm; body mass, 76.1 ± 5.9 kg; peak oxygen uptake, 4.1 ± 0.5 L·min) performed a peak oxygen uptake test, two familiarization trials, then four experimental trials in a randomized order separated by 7 d. Before exercise, subjects drank 2 × 300 mL sugar-free drinks delivering 0 (PLA), 150 (LOW), 300 (MED), or 400 (HIGH) mg·kg body mass tyrosine in a double-blind fashion. Subjects performed a 60-min constant intensity cycling then a simulated time trial in 30°C and 60% relative humidity. RESULTS Time trial performance (P = 0.579) was not influenced by tyrosine ingestion. The plasma ratio of tyrosine/∑(free-tryptophan, leucine, isoleucine, valine, phenylalanine, methionine), a key determinant of brain tyrosine influx, increased relative to PLA (P < 0.001). The increase was similar (P > 0.05) in MED (7.7-fold) and HIGH (8.2-fold), and greater than that in LOW (5.3-fold; P < 0.05). No differences existed between trials in core and skin temperature, heart rate, RPE, or thermal sensation (P > 0.05). CONCLUSION Exercise performance in a warm environment was not influenced by tyrosine availability in recreationally trained male individuals. The results provide novel data informing future studies, on the tyrosine dose maximizing the circulating ratio of tyrosine/amino acids competing for brain uptake.
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Affiliation(s)
- Les Tumilty
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Wales, UNITED KINGDOM
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12
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Brazaitis M, Eimantas N, Baranauskiene N, Kilikeviciene S, Vitkauskiene A, Daniuseviciute L. Effects of severe whole-body hyperthermia on ovarian hormone and extracellular Hsp72 responses in young adult women. Int J Hyperthermia 2019; 36:660-665. [DOI: 10.1080/02656736.2019.1627431] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Marius Brazaitis
- Institute of Sports Science and Innovations Lithuanian Sports University, Kaunas, Lithuania
| | - Nerijus Eimantas
- Institute of Sports Science and Innovations Lithuanian Sports University, Kaunas, Lithuania
| | - Neringa Baranauskiene
- Institute of Sports Science and Innovations Lithuanian Sports University, Kaunas, Lithuania
| | - Sandra Kilikeviciene
- Institute of Sports Science and Innovations Lithuanian Sports University, Kaunas, Lithuania
| | - Astra Vitkauskiene
- Department of Laboratory Medicine, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Laura Daniuseviciute
- Department of Educational Studies, Kaunas University of Technology, Kaunas, Lithuania
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13
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Yang F, Zhou L, Song J, WangJinMei A, Yang Y, Tang ZW, Huang QY. Liver CEBPβ Modulates the Kynurenine Metabolism and Mediates the Motility for Hypoxia-Induced Central Fatigue in Mice. Front Physiol 2019; 10:243. [PMID: 30930794 PMCID: PMC6428026 DOI: 10.3389/fphys.2019.00243] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Accepted: 02/25/2019] [Indexed: 12/29/2022] Open
Abstract
Central fatigue is defined as a failure of the central nervous system to adequately drive the muscle, manifesting limited development, and maintenance of locomotor activity. A plateau in hypoxia leads to central fatigue and followed by maximal motility recession. However, the underlying mechanism is still unclear. The present study describes a mechanism by which liver CEBPβ (CCAAT/enhancer-binding protein beta) induced by hypoxic environment alters the kynurenine (KYN) metabolism and causes the suppression of motility function recession. The activation of CEBPβ under hypoxia increases the liver expression of tryptophan dioxygenase, thereby enhancing the conversion of tryptophan into KYN; the KYN metabolite can traverse the blood-brain barrier and result in the suppression of motility function. However, the knockdown of CEBPβ by injecting pAAV-shRNA-CEBPβ via the hepatic portal vein reduces the KYN production and improves the motility function. KYN is a neurochemical that which restricts the exercise capacity after injection in the basal ganglia in mice. Reducing the plasma KYN protects the brain from hypoxia-induced changes associated with fatigue, and the knockdown liver of CEBPβ in mice renders resistance to fatigue post-acute hypoxia or tryptophan treatment. This study reveals resistance to central fatigue as a strategy for acclimatization to hypoxia mediated by transcription factor CEBPβ in the liver.
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Affiliation(s)
- Fan Yang
- Joint Surgery, General Hospital of Tibetan Military Command Lhasa, Lhasa, China.,Department of Cold Environment Medicine, College of High Altitude Military Medicine, Third Military Medical University and Key Laboratory of High Altitude Medicine, Ministry of Education, Key Laboratory of High Altitude Medicine, PLA, Chongqing, China
| | - Li Zhou
- Department of Pharmacy, General Hospital of Tibetan Military Command Lhasa, Lhasa, China
| | - Jun Song
- Joint Surgery, General Hospital of Tibetan Military Command Lhasa, Lhasa, China
| | - A WangJinMei
- Joint Surgery, General Hospital of Tibetan Military Command Lhasa, Lhasa, China
| | - Yuan Yang
- Joint Surgery, General Hospital of Tibetan Military Command Lhasa, Lhasa, China
| | - Zhong-Wei Tang
- Department of Cold Environment Medicine, College of High Altitude Military Medicine, Third Military Medical University and Key Laboratory of High Altitude Medicine, Ministry of Education, Key Laboratory of High Altitude Medicine, PLA, Chongqing, China
| | - Qing-Yuan Huang
- Department of Cold Environment Medicine, College of High Altitude Military Medicine, Third Military Medical University and Key Laboratory of High Altitude Medicine, Ministry of Education, Key Laboratory of High Altitude Medicine, PLA, Chongqing, China
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14
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Accelerated muscle contractility and decreased muscle steadiness following sauna recovery do not induce greater neuromuscular fatigability during sustained submaximal contractions. Hum Mov Sci 2018; 63:10-19. [PMID: 30481721 DOI: 10.1016/j.humov.2018.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/19/2018] [Accepted: 11/21/2018] [Indexed: 12/20/2022]
Abstract
Acute whole-body hyperthermia (WBH) increases blood markers concentration of stress, impairs motor drive to exercising muscles, and decreases resistance to neuromuscular fatigability. The functional natural residual consequences of WBH on neuromuscular functions remain unclear. We aimed to investigate the effects of residual WBH on voluntary and electrically induced ankle plantar flexor contractility properties, motor drive transmission (reflexes), muscle torque steadiness, resistance to neuromuscular fatigability, and markers of stress as the body temperature recovers naturally to normothermia. WBH was induced by Finnish sauna bathing in 16 apparently healthy young (24 ± 4 years) adult men. Motor performance was monitored before and 2 h after the sauna, and immediately after submaximal exercise (120 s at 50% of maximal voluntary contraction). Markers of stress were monitored before and 2 h after the sauna. Finnish sauna exposure induced moderate to severe WBH (rectal temperature, 38.5-39.6 °C). At 2 h after the sauna, rectal temperature had recovered to the preheating level (preheating 37.11 ± 0.33 °C versus postheating 37.00 ± 0.29 °C, p > .05). Post-sauna recovery was accompanied by slowed salivary free cortisol diurnal kinetics, whereas noradrenaline, dopamine, and serotonin did not persist into the 2 h recovery after the sauna. Although recovery to normothermia after a sauna led to a greater acceleration of muscle contractility properties and decreased muscle steadiness, sustained isometric submaximal contraction did not provoke greater neuromuscular fatigability.
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15
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Kim YS, O'Sullivan DM, Shin SK. Can 24 weeks strength training reduce feelings of depression and increase neurotransmitter in elderly females? Exp Gerontol 2018; 115:62-68. [PMID: 30453010 DOI: 10.1016/j.exger.2018.11.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 10/01/2018] [Accepted: 11/12/2018] [Indexed: 10/27/2022]
Abstract
BACKGROUND Geriatric depression is common due to the high rate of chronic diseases suffered by the older population. There is a well-established effect of exercise on one's wellbeing, however, for the elderly females there is dearth in research addressing exercise and its effect on their neurotransmitters and depression score. Therefore, this study aimed to investigate the effects of 24 weeks of the Growing Stronger program on neurotransmitter and depression of older women. METHODS Twenty-one older women, aged between 67 and 81, participated in this study. The participants were randomly assigned into a strength exercise (n = 11) and control group (n = 10) (age 76.40 ± 3.27, height 152.77 ± 5.63 kg, Weight 52.35 ± 2.86Kg, BMI 22.50 ± 1.88). The strength exercise group (age 76.10 ± 3.85, height 151.14 ± 5.42 kg, Weight 54.74 ± 6.73Kg, BMI 23.96 ± 2.70) participated for 50-80 min a day three times per week for a total of 24 weeks. All participants had their height, weight, blood testing and depression score tested before and after the training program. Two-way ANOVA with effect sizes was used to identify differences between times in each group and the statistical significance was set at 0.05. RESULTS In neurotransmitter factor, serotonin, dopamine, epinephrine, and norepinephrine significantly decreased in the strength exercise group but not for the control group. Notably, one participant whose serotonin level was lower than normal range before the exercise program showed normal level in serotonin after the program. In depression factor, there were no significant differences for both the strength exercise group and control group. CONCLUSION The results suggest that the effect of strength exercise on neurotransmitter and depression score remain unclear, but highlight the need for future studies investigating the relationship between strength training and depression.
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Affiliation(s)
- Yun-Sik Kim
- Division of Sports Science, Pusan National University, Busan, Republic of Korea
| | | | - Sang-Keun Shin
- Division of Sports Science, Pusan National University, Busan, Republic of Korea
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16
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Kyguoliene L, Skurvydas A, Eimantas N, Baranauskiene N, Steponaviciute R, Daniuseviciute L, Paulauskas H, Cernych M, Brazaitis M. Three different motor task strategies to assess neuromuscular adjustments during fatiguing muscle contractions in young and older men. Exp Brain Res 2018; 236:2085-2096. [PMID: 29754195 DOI: 10.1007/s00221-018-5285-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 05/07/2018] [Indexed: 10/16/2022]
Abstract
Healthy aging is associated with a marked decline in motor performance. The functional consequences of applying varying novel or unexpected motor stimuli during intermittent isometric prolonged (fatiguing) motor tasks for lower limb neuromuscular fatigability and steadiness, perception of effort, and blood markers of stress in healthy aged men compared with young men have not been investigated. The participants in this study were 15 young men (aged 22 ± 4 years) and 10 older men (aged 67 ± 6 years). They performed 100 intermittent isometric knee extensions under three experimental conditions involving intermittent isometric contraction tasks according to constant, predictable, and unpredictable torque target sequences. The variability in maximal voluntary contraction averaged 50%, and was 25, 50, and 75% for the three strategies. All included a 5-s contraction and 20-s rest. The main variables were measured before exercise, after 100 repetitions, and 1 h after exercise. In all experimental trials, the decreases in the maximal voluntary contraction and central activation ratio, and the increases in effort sensation and muscle temperature, were smaller in older men than in younger men. The coefficient of variation during the motor performance did not differ between age groups. However, in all three strategies, the dopamine concentration was significantly higher in older than in younger men. The prolactin concentration did not differ significantly between age groups or conditions, although its decrease during loading correlated negatively with the central activation ratio.
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Affiliation(s)
- Laura Kyguoliene
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Albertas Skurvydas
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania.,Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Nerijus Eimantas
- Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Neringa Baranauskiene
- Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Rasa Steponaviciute
- Department of Laboratory Medicines, Medical Academy, Lithuanian University of Health Science, Kaunas, Lithuania
| | - Laura Daniuseviciute
- Department of Physical Education, Kaunas University of Technology, Kaunas, Lithuania
| | - Henrikas Paulauskas
- Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Margarita Cernych
- Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania
| | - Marius Brazaitis
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania. .,Institute of Sports Science and Innovation, Lithuanian Sports University, Sporto Str. 6, 44221, Kaunas, Lithuania.
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17
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Wallace PJ, McKinlay BJ, Coletta NA, Vlaar JI, Taber MJ, Wilson PM, Cheung SS. Effects of Motivational Self-Talk on Endurance and Cognitive Performance in the Heat. Med Sci Sports Exerc 2017; 49:191-199. [PMID: 27580154 DOI: 10.1249/mss.0000000000001087] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE We tested the effectiveness of a 2-wk motivational self-talk (MST) intervention-specific to heat tolerance-on endurance capacity and cognitive function in the heat. METHODS Eighteen trained male (n = 14) and female (n = 4) cyclists randomly received 2 wk of MST training (n = 9) or a control regimen (CON, n = 9). The experimental protocol was a PRE/POST design consisting of 30 min of cycling at 60% peak power output (PPO) in the heat (35°C, 50% relative humidity, ~3.0 m·s airflow), a 30-min rest period, followed by a time to exhaustion (TTE) test at 80% PPO, and an identical rest period. Executive function, reaction time, and working memory were tested at baseline and each rest period. Key measures included TTE, speed and accuracy on the cognitive tests, rectal temperature, HR, oxygen consumption, and RPE. RESULTS Group (MST vs CON) × test (PRE vs POST) × time repeated-measures ANOVA revealed that MST significantly increased TTE from PRE (487 ± 173 s) to POST (679 ± 251 s, P = 0.021) concurrent with a higher terminating rectal temperature (PRE, 38.5°C ± 0.2°C; POST, 38.8°C ± 0.4°C; P = 0.023); no TTE (PRE, 531 ± 178 s; POST, 510 ± 216 s; P = 0.28) or rectal temperature (PRE, 38.4°C ± 0.3°C; POST, 38.4°C ± 0.2°C; P = 1.000) changes were found in CON. MST significantly improved both speed and accuracy for executive function from PRE/POST, with no PRE/POST differences for CON on any cognitive measure. There were no interactions (all P > 0.05) for other key measures. CONCLUSION Motivational self-talk is effective in altering the internal psychophysiological control of exercise and plays a role in improving endurance capacity and executive function in the heat.
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Affiliation(s)
- Phillip J Wallace
- 1Environmental Ergonomics Laboratory, Department of Kinesiology, Brock University, St. Catharines, Ontario, CANADA; 2Applied Physiology Lab, Department of Kinesiology, Brock University, St. Catharines, Ontario, CANADA; 3Falck Safety Services Canada, Mount Pearl, Newfoundland and Labrador, CANADA; and 4Behavioural Health Sciences Research Lab, Department of Kinesiology, Brock University, St. Catharines, Ontario, CANADA
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18
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Stevens CJ, Bennett KJ, Sculley DV, Callister R, Taylor L, Dascombe BJ. A Comparison of Mixed-Method Cooling Interventions on Preloaded Running Performance in the Heat. J Strength Cond Res 2017; 31:620-629. [DOI: 10.1519/jsc.0000000000001532] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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19
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Effect of constant, predictable, and unpredictable motor tasks on motor performance and blood markers of stress. Exp Brain Res 2017; 235:1323-1336. [PMID: 28204862 DOI: 10.1007/s00221-017-4894-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 01/24/2017] [Indexed: 12/25/2022]
Abstract
An unfamiliar or novel physical stimulus induces activation of dopaminergic neurons within the brain and greater activity in areas involved in emotion; considering this, we aimed to establish whether unpredictable prolonged (fatiguing) motor task (vs. constant vs. predictable) evokes greater dopaminergic activity, enhances neuromuscular performance, motor accuracy, and perception of effort, and delays overall central fatigue. Fifteen healthy male volunteers (aged 22 ± 4 years) were required to perform 1 of 3 exercise trials (at least 1 week apart) of 100 intermittent isometric contraction (IIC) tasks involving knee extensions at 60° flexion. Trials were structured differently by simulated contraction intensity. A fatigue task involved 5-s contractions and 20-s rest. Variables measured before, during, and after IIC were electrically induced force, maximal voluntary contraction, central activation ratio, intramuscular temperature, and blood levels of dopamine, cortisol, and prolactin, and intraindividual motor variability and accuracy (constant and absolute error). We found that IIC increased central and peripheral fatigue, force sensation, and T mu, and decreased absolute and constant error without visual feedback, but did not affect motor variability. There were no significant differences between the three IIC tasks. However, only unpredictable tasks increased dopaminergic activity, which was insufficient to affect central motivation to perform isometric exercise and alter centrally mediated components of fatigue.
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20
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D'Amico JM, Butler AA, Héroux ME, Cotel F, Perrier JFM, Butler JE, Gandevia SC, Taylor JL. Human motoneurone excitability is depressed by activation of serotonin 1A receptors with buspirone. J Physiol 2016; 595:1763-1773. [PMID: 27859267 DOI: 10.1113/jp273200] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/14/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS In the adult turtle spinal cord, action potential generation in motoneurones is inhibited by spillover of serotonin to extrasynaptic serotonin 1A (5-HT1A ) receptors at the axon initial segment. We explored whether ingestion of the 5-HT1A receptor partial agonist, buspirone, decreases motoneurone excitability in humans. Following ingestion of buspirone, two tests of motoneurone excitability showed decreases. F-wave areas and persistence in an intrinsic muscle of the hand were reduced, as was the area of cervicomedullary motor evoked potentials in biceps brachii. Our findings suggest that activation of 5-HT1A receptors depresses human motoneurone excitability. Such a depression could contribute to decreased motoneurone output during fatiguing exercise if there is high serotonergic drive to the motoneurones. ABSTRACT Intense serotonergic drive in the turtle spinal cord results in serotonin spillover to the axon initial segment of the motoneurones where it activates serotonin 1A (5-HT1A ) receptors and inhibits generation of action potentials. We examined whether activation of 5-HT1A receptors decreases motoneurone excitability in humans by determining the effects of a 5-HT1A receptor partial agonist, buspirone, on F waves and cervicomedullary motor evoked potentials (CMEPs). In a placebo-controlled double-blind study, 10 participants were tested on two occasions where either placebo or 20 mg of buspirone was administered orally. The ulnar nerve was stimulated supramaximally to evoke F waves in abductor digiti minimi (ADM). CMEPs and the maximal M wave were elicited in biceps brachii by cervicomedullary stimulation and brachial plexus stimulation, respectively. Following buspirone intake, F-wave area and persistence, as well as CMEP area, were significantly decreased. The mean post-pill difference in normalized F-wave areas and persistence between buspirone and placebo days was -27% (-42, -12; 95% confidence interval) and -9% (-16, -2), respectively. The mean post-pill difference in normalized CMEP area between buspirone and placebo days showed greater variation and was -31% (-60, -2). In conclusion, buspirone reduces motoneurone excitability in humans probably via activation of 5-HT1A receptors at the axon initial segment. This has implications for motor output during high drive to the motoneurones when serotonin may spill over to these inhibitory receptors and consequently inhibit motoneurone output. Such a mechanism could potentially contribute to fatigue with exercise.
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Affiliation(s)
- Jessica M D'Amico
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia
| | - Annie A Butler
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | - Martin E Héroux
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | | | | | - Jane E Butler
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | - Simon C Gandevia
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | - Janet L Taylor
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
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21
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Stevens CJ, Taylor L, Dascombe BJ. Cooling During Exercise: An Overlooked Strategy for Enhancing Endurance Performance in the Heat. Sports Med 2016; 47:829-841. [DOI: 10.1007/s40279-016-0625-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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22
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Stevens CJ, Kittel A, Sculley DV, Callister R, Taylor L, Dascombe BJ. Running performance in the heat is improved by similar magnitude with pre-exercise cold-water immersion and mid-exercise facial water spray. J Sports Sci 2016; 35:798-805. [PMID: 27267974 DOI: 10.1080/02640414.2016.1192294] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
This investigation compared the effects of external pre-cooling and mid-exercise cooling methods on running time trial performance and associated physiological responses. Nine trained male runners completed familiarisation and three randomised 5 km running time trials on a non-motorised treadmill in the heat (33°C). The trials included pre-cooling by cold-water immersion (CWI), mid-exercise cooling by intermittent facial water spray (SPRAY), and a control of no cooling (CON). Temperature, cardiorespiratory, muscular activation, and perceptual responses were measured as well as blood concentrations of lactate and prolactin. Performance time was significantly faster with CWI (24.5 ± 2.8 min; P = 0.01) and SPRAY (24.6 ± 3.3 min; P = 0.01) compared to CON (25.2 ± 3.2 min). Both cooling strategies significantly (P < 0.05) reduced forehead temperatures and thermal sensation, and increased muscle activation. Only pre-cooling significantly lowered rectal temperature both pre-exercise (by 0.5 ± 0.3°C; P < 0.01) and throughout exercise, and reduced sweat rate (P < 0.05). Both cooling strategies improved performance by a similar magnitude, and are ergogenic for athletes. The observed physiological changes suggest some involvement of central and psychophysiological mechanisms of performance improvement.
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Affiliation(s)
- Christopher J Stevens
- a Applied Sports Science and Exercise Testing Laboratory, Faculty of Science and Information Technology , University of Newcastle , Ourimbah , Australia.,b School of Health and Human Sciences , Southern Cross University , Coffs Harbour , Australia
| | - Aden Kittel
- a Applied Sports Science and Exercise Testing Laboratory, Faculty of Science and Information Technology , University of Newcastle , Ourimbah , Australia
| | - Dean V Sculley
- c School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine , University of Newcastle , Callaghan , Australia
| | - Robin Callister
- c School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine , University of Newcastle , Callaghan , Australia
| | - Lee Taylor
- d Athlete Health and Performance Research Centre , ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital , Doha , Qatar
| | - Ben J Dascombe
- a Applied Sports Science and Exercise Testing Laboratory, Faculty of Science and Information Technology , University of Newcastle , Ourimbah , Australia.,e Department of Rehabilitation, Nutrition and Sport , La Trobe University , Bundoora , Australia
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23
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Roelands B, De Pauw K, Meeusen R. Neurophysiological effects of exercise in the heat. Scand J Med Sci Sports 2016; 25 Suppl 1:65-78. [PMID: 25943657 DOI: 10.1111/sms.12350] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/18/2014] [Indexed: 11/29/2022]
Abstract
Fatigue during prolonged exercise is a multifactorial phenomenon. The complex interplay between factors originating from both the periphery and the brain will determine the onset of fatigue. In recent years, electrophysiological and imaging tools have been fine-tuned, allowing for an improved understanding of what happens in the brain. In the first part of the review, we present literature that studied the changes in electrocortical activity during and after exercise in normal and high ambient temperature. In general, exercise in a thermo-neutral environment or at light to moderate intensity increases the activity in the β frequency range, while exercising at high intensity or in the heat reduces β activity. In the second part, we review literature that manipulated brain neurotransmission, through either pharmacological or nutritional means, during exercise in the heat. The dominant outcomes were that manipulations changing brain dopamine concentration have the potential to delay fatigue, while the manipulation of serotonin had no effect and noradrenaline reuptake inhibition was detrimental for performance in the heat. Research on the effects of neurotransmitter manipulations on brain activity during or after exercise is scarce. The combination of brain imaging techniques with electrophysiological measures presents one of the major future challenges in exercise physiology/neurophysiology.
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Affiliation(s)
- B Roelands
- Department of Human Physiology, Vrije Universiteit Brussel, Brussels, Belgium; Fund for Scientific Research Flanders (FWO), Brussels, Belgium
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24
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Zhao J, Lai L, Cheung SS, Cui S, An N, Feng W, Lorenzo S. Hot environments decrease exercise capacity and elevate multiple neurotransmitters. Life Sci 2015; 141:74-80. [DOI: 10.1016/j.lfs.2015.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 08/24/2015] [Accepted: 09/08/2015] [Indexed: 02/09/2023]
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25
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Stevens CJ, Thoseby B, Sculley DV, Callister R, Taylor L, Dascombe BJ. Running performance and thermal sensation in the heat are improved with menthol mouth rinse but not ice slurry ingestion. Scand J Med Sci Sports 2015; 26:1209-16. [PMID: 26408395 DOI: 10.1111/sms.12555] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/18/2015] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to compare the effects of a cooling strategy designed to predominately lower thermal state with a strategy designed to lower thermal sensation on endurance running performance and physiology in the heat. Eleven moderately trained male runners completed familiarization and three randomized, crossover 5-km running time trials on a non-motorized treadmill in hot conditions (33 °C). The trials included ice slurry ingestion before exercise (ICE), menthol mouth rinse during exercise (MEN), and no intervention (CON). Running performance was significantly improved with MEN (25.3 ± 3.5 min; P = 0.01), but not ICE (26.3 ± 3.2 min; P = 0.45) when compared with CON (26.0 ± 3.4 min). Rectal temperature was significantly decreased with ICE (by 0.3 ± 0.2 °C; P < 0.01), which persisted for 2 km of the run and MEN significantly decreased perceived thermal sensation (between 4 and 5 km) and ventilation (between 1 and 2 km) during the time trial. End-exercise blood prolactin concentration was elevated with MEN compared with CON (by 25.1 ± 24.4 ng/mL; P = 0.02). The data demonstrate that a change in the perception of thermal sensation during exercise from menthol mouth rinse was associated with improved endurance running performance in the heat. Ice slurry ingestion reduced core temperature but did not decrease thermal sensation during exercise or improve running performance.
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Affiliation(s)
- C J Stevens
- Applied Sports Science and Exercise Testing Laboratory, Faculty of Science and Information Technology, University of Newcastle, Ourimbah, Australia.
| | - B Thoseby
- Applied Sports Science and Exercise Testing Laboratory, Faculty of Science and Information Technology, University of Newcastle, Ourimbah, Australia
| | - D V Sculley
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, Australia
| | - R Callister
- Priority Research Centre in Physical Activity and Nutrition, University of Newcastle, Callaghan, Australia.,School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, University of Newcastle, Callaghan, Australia
| | - L Taylor
- Applied Sport and Exercise Physiology (ASEP) Research Group, Department of Sport Science and Physical Activity, Institute for Sport and Physical Activity Research (ISPAR), University of Bedfordshire, Bedford, UK
| | - B J Dascombe
- Applied Sports Science and Exercise Testing Laboratory, Faculty of Science and Information Technology, University of Newcastle, Ourimbah, Australia.,Priority Research Centre in Physical Activity and Nutrition, University of Newcastle, Callaghan, Australia
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26
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Wang H, Wang B, Jackson K, Miller CM, Hasadsri L, Llano D, Rubin R, Zimmerman J, Johnson C, Sutton B. A novel head-neck cooling device for concussion injury in contact sports. Transl Neurosci 2015; 6:20-31. [PMID: 28123788 PMCID: PMC4936612 DOI: 10.1515/tnsci-2015-0004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Accepted: 11/29/2014] [Indexed: 12/21/2022] Open
Abstract
Emerging research on the long-term impact of concussions on athletes has allowed public recognition of the potentially devastating effects of these and other mild head injuries. Mild traumatic brain injury (mTBI) is a multifaceted disease for which management remains a clinical challenge. Recent pre-clinical and clinical data strongly suggest a destructive synergism between brain temperature elevation and mTBI; conversely, brain hypothermia, with its broader, pleiotropic effects, represents the most potent neuro-protectant in laboratory studies to date. Although well-established in selected clinical conditions, a systemic approach to accomplish regional hypothermia has failed to yield an effective treatment strategy in traumatic brain injury (TBI). Furthermore, although systemic hypothermia remains a potentially valid treatment strategy for moderate to severe TBIs, it is neither practical nor safe for mTBIs. Therefore, selective head-neck cooling may represent an ideal strategy to provide therapeutic benefits to the brain. Optimizing brain temperature management using a National Aeronautics and Space Administration (NASA) spacesuit spinoff head-neck cooling technology before and/or after mTBI in contact sports may represent a sensible, practical, and effective method to potentially enhance recover and minimize post-injury deficits. In this paper, we discuss and summarize the anatomical, physiological, preclinical, and clinical data concerning NASA spinoff head-neck cooling technology as a potential treatment for mTBIs, particularly in the context of contact sports.
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Affiliation(s)
- Huan Wang
- Department of Neurosurgery, Carle Foundation Hospital, University of Illinois College of Medicine at Urbana-Champaign, Urbana, USA; Thermal Neuroscience Laboratory, Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Bonnie Wang
- Department of Internal Medicine, Carle Foundation Hospital, University of Illinois College of Medicine at Urbana-Champaign, Urbana, USA
| | - Kevin Jackson
- Thermal Neuroscience Laboratory, Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Claire M Miller
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Linda Hasadsri
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
| | - Daniel Llano
- Department of Molecular and Integrative Physiology, University of Illinois College of Medicine at Urbana-Champaign, Carle Foundation Hospital, Urbana, USA; The Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Rachael Rubin
- The Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Jarred Zimmerman
- Department of Sports Medicine, Carle Foundation Hospital, Urbana, USA
| | - Curtis Johnson
- The Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, USA; Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, USA
| | - Brad Sutton
- The Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, USA; Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, USA
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Effects of heat acclimation on time perception. Int J Psychophysiol 2014; 95:261-9. [PMID: 25451787 DOI: 10.1016/j.ijpsycho.2014.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 11/05/2014] [Accepted: 11/07/2014] [Indexed: 11/23/2022]
Abstract
Cognitive performance is impaired during prolonged exercise in hot environment compared to temperate conditions. These effects are related to both peripheral markers of heats stress and alterations in CNS functioning. Repeated-exposure to heat stress results in physiological adaptations, and therefore improvement in exercise capacity and cognitive functioning are observed. The objective of the current study was to clarify the factors contributing to time perception under heat stress and examine the effect of heat acclimation. 20 young healthy male subjects completed three exercise tests on a treadmill: H1 (at 60% VO(2)peak until exhaustion at 42°C), N (at 22°C; duration equal to H1) and H2 (walk until exhaustion at 42°C) following a 10-day heat acclimation program. Core temperature (T(C)) and heart rate (HR), ratings of perceived fatigue and exertion were obtained continuously during the exercise, and blood samples of hormones were taken before, during and after the exercise test for estimating the prolactin, growth hormone and cortisol response to acute exercise-heat stress. Interval production task was performed before, during and after the exercise test. Lower rate of rise in core temperature, heart rate, hormone response and subjective ratings indicated that the subjects had successfully acclimated. Before heat acclimation, significant distortions in produced intervals occurred after 60 minutes of exercise relative to pre-trial coefficients, indicating speeded temporal processing. However, this effect was absent after in acclimated subjects. Blood prolactin concentration predicted temporal performance in both conditions. Heat acclimation slows down the increase in physiological measures, and improvement in temporal processing is also evident. The results are explained within the internal clock model in terms of the pacemaker-accumulator functioning.
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Roelands B, de Koning J, Foster C, Hettinga F, Meeusen R. Neurophysiological determinants of theoretical concepts and mechanisms involved in pacing. Sports Med 2013; 43:301-11. [PMID: 23456493 DOI: 10.1007/s40279-013-0030-4] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Fatigue during prolonged exercise is often described as an acute impairment of exercise performance that leads to an inability to produce or maintain a desired power output. In the past few decades, interest in how athletes experience fatigue during competition has grown enormously. Research has evolved from a dominant focus on peripheral causes of fatigue towards a complex interplay between peripheral and central limitations of performance. Apparently, both feedforward and feedback mechanisms, based on the principle of teleoanticipation, regulate power output (e.g., speed) during a performance. This concept is called 'pacing' and represents the use of energetic resources during exercise, in a way such that all energy stores are used before finishing a race, but not so far from the end of a race that a meaningful slowdown can occur.It is believed that the pacing selected by athletes is largely dependent on the anticipated exercise duration and on the presence of an experientially developed performance template. Most studies investigating pacing during prolonged exercise in ambient temperatures, have observed a fast start, followed by an even pace strategy in the middle of the event with an end sprint in the final minutes of the race. A reduction in pace observed at commencement of the event is often more evident during exercise in hot environmental conditions. Further, reductions in power output and muscle activation occur before critical core temperatures are reached, indicating that subjects can anticipate the exercise intensity and heat stress they will be exposed to, resulting in a tactical adjustment of the power output. Recent research has shown that not only climatic stress but also pharmacological manipulation of the central nervous system has the ability to cause changes in endurance performance. Subjects seem to adapt their strategy specifically in the early phases of an exercise task. In high-ambient temperatures, dopaminergic manipulations clearly improve performance. The distribution of the power output reveals that after dopamine reuptake inhibition, subjects are able to maintain a higher power output compared with placebo. Manipulations of serotonin and, especially, noradrenaline, have the opposite effect and force subjects to decrease power output early in the time trial. Interestingly, after manipulation of brain serotonin, subjects are often unable to perform an end sprint, indicating an absence of a reserve capacity or motivation to increase power output. Taken together, it appears that many factors, such as ambient conditions and manipulation of brain neurotransmitters, have the potential to influence power output during exercise, and might thus be involved as regulatory mechanisms in the complex skill of pacing.
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Affiliation(s)
- Bart Roelands
- Department of Human Physiology, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
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Sun G, Qian S, Jiang Q, Liu K, Li B, Li M, Zhao L, Zhou Z, von Deneen KM, Liu Y. Hyperthermia-induced disruption of functional connectivity in the human brain network. PLoS One 2013; 8:e61157. [PMID: 23593416 PMCID: PMC3620175 DOI: 10.1371/journal.pone.0061157] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 03/06/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Passive hyperthermia is a potential risk factor to human cognitive performance and work behavior in many extreme work environments. Previous studies have demonstrated significant effects of passive hyperthermia on human cognitive performance and work behavior. However, there is a lack of a clear understanding of the exact affected brain regions and inter-regional connectivities. METHODOLOGY AND PRINCIPAL FINDINGS We simulated 1 hour environmental heat exposure to thirty-six participants under two environmental temperature conditions (25 °C and 50 °C), and collected resting-state functional brain activity. The functional connectivities with a preselected region of interest (ROI) in the posterior cingulate cortex and precuneus (PCC/PCu), furthermore, inter-regional connectivities throughout the entire brain using a prior Anatomical Automatic Labeling (AAL) atlas were calculated. We identified decreased correlations of a set of regions with the PCC/PCu, including the medial orbitofrontal cortex (mOFC) and bilateral medial temporal cortex, as well as increased correlations with the partial orbitofrontal cortex particularly in the bilateral orbital superior frontal gyrus. Compared with the normal control (NC) group, the hyperthermia (HT) group showed 65 disturbed functional connectivities with 50 of them being decreased and 15 of them being increased. While the decreased correlations mainly involved with the mOFC, temporal lobe and occipital lobe, increased correlations were mainly located within the limbic system. In consideration of physiological system changes, we explored the correlations of the number of significantly altered inter-regional connectivities with differential rectal temperatures and weight loss, but failed to obtain significant correlations. More importantly, during the attention network test (ANT) we found that the number of significantly altered functional connectivities was positively correlated with an increase in executive control reaction time. CONCLUSIONS/SIGNIFICANCE We first identified the hyperthermia-induced altered functional connectivity patterns. The changes in the functional connectivity network might be a possible explanation for the cognitive performance and work behavior alteration.
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Affiliation(s)
- Gang Sun
- Department of Medical Imaging, Jinan Military General Hospital, Jinan, Shandong, People's Republic of China
- * E-mail: (GS); (LZ)
| | - Shaowen Qian
- Department of Medical Imaging, Jinan Military General Hospital, Jinan, Shandong, People's Republic of China
| | - Qingjun Jiang
- Department of Medical Imaging, Jinan Military General Hospital, Jinan, Shandong, People's Republic of China
| | - Kai Liu
- Department of Medical Imaging, Jinan Military General Hospital, Jinan, Shandong, People's Republic of China
| | - Bo Li
- Department of Medical Imaging, Jinan Military General Hospital, Jinan, Shandong, People's Republic of China
| | - Min Li
- Department of Medical Imaging, Jinan Military General Hospital, Jinan, Shandong, People's Republic of China
| | - Lun Zhao
- Department of Medical Imaging, Jinan Military General Hospital, Jinan, Shandong, People's Republic of China
- * E-mail: (GS); (LZ)
| | - Zhenyu Zhou
- McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
| | - Karen M. von Deneen
- McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
| | - Yijun Liu
- McKnight Brain Institute, University of Florida, Gainesville, Florida, United States of America
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Iguchi M, Littmann AE, Chang SH, Wester LA, Knipper JS, Shields RK. Heat stress and cardiovascular, hormonal, and heat shock proteins in humans. J Athl Train 2013; 47:184-90. [PMID: 22488284 DOI: 10.4085/1062-6050-47.2.184] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT Conditions such as osteoarthritis, obesity, and spinal cord injury limit the ability of patients to exercise, preventing them from experiencing many well-documented physiologic stressors. Recent evidence indicates that some of these stressors might derive from exercise-induced body temperature increases. OBJECTIVE To determine whether whole-body heat stress without exercise triggers cardiovascular, hormonal, and extracellular protein responses of exercise. DESIGN Randomized controlled trial. SETTING University research laboratory. PATIENTS OR OTHER PARTICIPANTS Twenty-five young, healthy adults (13 men, 12 women; age = 22.1 ± 2.4 years, height = 175.2 ± 11.6 cm, mass = 69.4 ± 14.8 kg, body mass index = 22.6 ± 4.0) volunteered. INTERVENTION(S) Participants sat in a heat stress chamber with heat (73°C) and without heat (26°C) stress for 30 minutes on separate days. We obtained blood samples from a subset of 13 participants (7 men, 6 women) before and after exposure to heat stress. MAIN OUTCOME MEASURE(S) Extracellular heat shock protein (HSP72) and catecholamine plasma concentration, heart rate, blood pressure, and heat perception. RESULTS After 30 minutes of heat stress, body temperature measured via rectal sensor increased by 0.8°C. Heart rate increased linearly to 131.4 ± 22.4 beats per minute (F₆,₂₄ = 186, P < .001) and systolic and diastolic blood pressure decreased by 16 mm Hg (F₆,₂₄ = 10.1, P < .001) and 5 mm Hg (F₆,₂₄ = 5.4, P < .001), respectively. Norepinephrine (F₁,₁₂ = 12.1, P = .004) and prolactin (F₁,₁₂ = 30.2, P < .001) increased in the plasma (58% and 285%, respectively) (P < .05). The HSP72 (F₁,₁₂ = 44.7, P < .001) level increased with heat stress by 48.7% ± 53.9%. No cardiovascular or blood variables showed changes during the control trials (quiet sitting in the heat chamber with no heat stress), resulting in differences between heat and control trials. CONCLUSIONS We found that whole-body heat stress triggers some of the physiologic responses observed with exercise. Future studies are necessary to investigate whether carefully prescribed heat stress constitutes a method to augment or supplement exercise.
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Affiliation(s)
- Masaki Iguchi
- Physical Therapy and Rehabilitation Science Department, University of Iowa, Iowa City, USA
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Acute oral administration of a tyrosine and phenylalanine-free amino acid mixture reduces exercise capacity in the heat. Eur J Appl Physiol 2013; 113:1511-22. [DOI: 10.1007/s00421-012-2577-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 12/21/2012] [Indexed: 01/09/2023]
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32
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Hasegawa H, Cheung SS. Hyperthermia effects on brain function and exercise capacity. JOURNAL OF PHYSICAL FITNESS AND SPORTS MEDICINE 2013. [DOI: 10.7600/jpfsm.2.429] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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33
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Acute tryptophan depletion does not improve endurance cycling capacity in a warm environment. Amino Acids 2012. [DOI: 10.1007/s00726-012-1429-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Wright HE, McLellan TM, Friesen BJ, Casa DJ, Kenny GP. Influence of circulating cytokines on prolactin during slow vs. fast exertional heat stress followed by active or passive recovery. J Appl Physiol (1985) 2012; 113:574-83. [PMID: 22723625 DOI: 10.1152/japplphysiol.00523.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prolactin (PRL) has been suggested as an indicator of fatigue during exertional heat stress (EHS), given its strong relationship with body core temperature (T(c)); however, the strength of this relationship during different rates of T(c) increase and subsequent recovery is unknown. In addition, given the influence that systemic cytokines, such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α, have on the pituitary gland, it would be of interest to determine the relationship between PRL, IL-6, and TNF-α during EHS. The purpose was to examine the PRL, IL-6, and TNF-α heat stress responses during slow and fast heating and subsequent resting or cold water immersion recovery. On 4 days, nine individuals walked at ≈ 45% (slow heating) or ran at ≈ 65% (fast heating) maximal oxygen consumption on a treadmill in the heat (40°C, 30% relative humidity) until rectal temperature (T(re)) reached 39.5°C (esophageal temperature; fast = 39.41 ± 0.04°C, slow = 39.82 ± 0.09°C). Post-EHS, subjects were either immersed in 2°C water or rested seated until T(re) returned to 38.0°C. Venous blood, analyzed for PRL, IL-6, and TNF-α, was obtained at rest, during exercise (T(re) 38.0, 39.0, 39.5°C), the start of recovery (≈ 5 min after 39.5°C), and subsequent recovery (T(re) 39.0, 38.0°C). IL-6 exhibited myokine properties, given the greater increases with slow heating and lack of increase in TNF-α. A strong temperature-dependent PRL response during slow and fast heating provides additional support for the use of PRL as a peripheral marker of impending fatigue, which is independent of IL-6 and TNF-α cytokine responses.
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Affiliation(s)
- Heather E Wright
- Faculty of Health Sciences, Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Ontario, Canada
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35
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Rouviere C, Corona BT, Ingalls CP. Oxidative capacity and fatigability in run-trained malignant hyperthermia-susceptible mice. Muscle Nerve 2012; 45:586-96. [PMID: 22431093 DOI: 10.1002/mus.22343] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
INTRODUCTION The purpose of this study was to test the hypothesis that malignant hyperthermia model mice (RyR1Y522S/wt) are more vulnerable to exercise-induced muscle injury and fatigability and adapt less to run training. METHODS After 6 weeks of voluntary wheel running, we measured anterior crural muscle fatigability, muscle injury, and cytochrome oxidase (COX) and citrate synthase (CS). RESULTS Although RyR1Y522S/wt mice ran without undergoing MH episodes, they ran 42% less distance than wild-type (WT) mice. Muscles from WT mice exhibited increased fatigue resistance and COX content after training. Muscles from RyR1Y522S/wt mice demonstrated no significant change in fatigability or COX and CS after training. However, muscles from RyR1Y522S/wt mice displayed less intrinsic fatigability and greater COX/CS content and muscle damage than WT mice. CONCLUSIONS RyR1Y522S/wt mice can run without having rhabdomyolysis, and their inability to adapt to training appears to stem from intrinsic enhancement of mitochondrial enzymes and fatigue resistance.
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Affiliation(s)
- Clement Rouviere
- Muscle Biology Laboratory, Department of Kinesiology and Health, Georgia State University, P.O. Box 3975, Atlanta, Georgia 30302-3975, USA
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36
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Effects of heat acclimation on endurance capacity and prolactin response to exercise in the heat. Eur J Appl Physiol 2012; 112:4091-101. [DOI: 10.1007/s00421-012-2371-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 02/27/2012] [Indexed: 10/28/2022]
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Caffeine, dopamine and thermoregulation. Eur J Appl Physiol 2011; 112:1979-80. [PMID: 21874329 DOI: 10.1007/s00421-011-2127-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 08/12/2011] [Indexed: 10/17/2022]
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Iguchi M, Shields RK. Prior heat stress effects fatigue recovery of the elbow flexor muscles. Muscle Nerve 2011; 44:115-25. [PMID: 21674526 DOI: 10.1002/mus.22029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
INTRODUCTION Long-lasting alterations in hormones, neurotransmitters, and stress proteins after hyperthermia may be responsible for the impairment in motor performance during muscle fatigue. METHODS Subjects (n = 25) performed a maximal intermittent fatigue task of elbow flexion after sitting in either 73° or 26°C to examine the effects of prior heat stress on fatigue mechanisms. RESULTS The heat stress increased the tympanic and rectal temperatures by 2.3° and 0.82°C, respectively, but there was full recovery prior to the fatigue task. Although prior heat stress had no effects on fatigue-related changes in volitional torque, electromyographic (EMG) activity, torque relaxation rate, motor evoked potential (MEP) size, and silent period (SP) duration, prior heat stress acutely increased the pre-fatigue relaxation rate and chronically prevented long-duration fatigue (P < 0.05). CONCLUSIONS These findings indicate that prior passive heat stress alone does not alter voluntary activation during fatigue, but prior heat stress and exercise produce longer-term protection against long-duration fatigue.
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Affiliation(s)
- Masaki Iguchi
- Physical Therapy and Rehabilitation Science, Carver College of Medicine, 1-252 Medical Education Building, University of Iowa, Iowa City, Iowa 52242-1190, USA
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Wright HE, Selkirk GA, Rhind SG, McLellan TM. Peripheral markers of central fatigue in trained and untrained during uncompensable heat stress. Eur J Appl Physiol 2011; 112:1047-57. [PMID: 21735219 DOI: 10.1007/s00421-011-2049-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 06/11/2011] [Indexed: 11/26/2022]
Abstract
The development of fatigue is more pronounced in the heat than thermoneutral environments; however, it is unclear whether biomarkers of central fatigue are consistent with the higher core temperature (T (c)) tolerated by endurance trained (TR) versus untrained (UT) during exertional heat stress (EHS). The purpose of this study was to examine the indicators of central fatigue during EHS in TR versus UT. Twelve TR and 11 UT males (mean ± SE [Formula: see text] = 70 ± 2 and 50 ± 1 mL kg LBM(-1) min(-1), respectively) walked on a treadmill to exhaustion (EXH) in 40°C (dry) wearing protective clothing. Venous blood was obtained at PRE and 0.5°C T (c) increments from 38 to 40°C/EXH. Free tryptophan (f-TRP) decreased dramatically at 39.5°C for the TR. Branch chain amino acids decreased with T (c) and were greater for UT than TR at EXH. Tyrosine and phenylalanine remained unchanged. Serum S100β was undetectable (<5 pg mL(-1)). Albumin was greater for the UT from PRE to 39.0°C and at EXH. Prolactin (PRL) responded to relative thermal strain with similar EXH values despite higher T (c) tolerated for TR (39.7 ± 0.09°C) than UT (39.0 ± 0.09°C). The high EXH PRL values for both groups support its use as a biomarker of the serotonin and dopamine interplay within the brain during the development of central fatigue.
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Affiliation(s)
- Heather E Wright
- Faculty of Health, Kinesiology and Health Science, York University, Toronto, ON, M3J 1P3, Canada.
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40
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Tumilty L, Davison G, Beckmann M, Thatcher R. Oral tyrosine supplementation improves exercise capacity in the heat. Eur J Appl Physiol 2011; 111:2941-50. [PMID: 21437603 DOI: 10.1007/s00421-011-1921-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 03/08/2011] [Indexed: 11/29/2022]
Abstract
Increased brain dopamine availability improves prolonged exercise tolerance in the heat. It is unclear whether supplementing the amino-acid precursor of dopamine increases exercise capacity in the heat. Eight healthy male volunteers [mean age 32 ± 11 (SD) years; body mass 75.3 ± 8.1 kg; peak oxygen uptake ([Formula: see text]) 3.5 ± 0.3 L min(-1)] performed two exercise trials separated by at least 7 days in a randomised, crossover design. Subjects consumed 500 mL of a flavoured sugar-free drink (PLA), or the same drink with 150 mg kg body mass(-1) tyrosine (TYR) in a double-blind manner 1 h before cycling to exhaustion at a constant exercise intensity equivalent to 68 ± 5% [Formula: see text] in 30°C and 60% relative humidity. Pre-exercise plasma tyrosine:large neutral amino acids increased 2.9-fold in TYR (P < 0.01), while there was no change in PLA (P > 0.05). Subjects cycled longer in TYR compared to PLA (80.3 ± 19.7 min vs. 69.2 ± 14.0 min; P < 0.01). Core temperature, mean weighted skin temperature, heart rate, ratings of perceived exertion and thermal sensation were similar in TYR and PLA during exercise and at exhaustion (P > 0.05) despite longer exercise time in TYR. The results show that acute tyrosine supplementation is associated with increased endurance capacity in the heat in moderately trained subjects. The results also suggest for the first time that the availability of tyrosine, a nutritional dopamine precursor, can influence the ability to subjectively tolerate prolonged submaximal constant-load exercise in the heat.
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Affiliation(s)
- Les Tumilty
- Department of Sport and Exercise Science, Aberystwyth University, Carwyn James Building, Penglais Campus, Aberystwyth, Ceridigion, SY23 3FD, Wales, UK.
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Meeusen R, Roelands B. Central fatigue and neurotransmitters, can thermoregulation be manipulated? Scand J Med Sci Sports 2011; 20 Suppl 3:19-28. [PMID: 21029187 DOI: 10.1111/j.1600-0838.2010.01205.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Fatigue is a complex phenomenon that can be evoked by peripheral and central factors. Although it is obvious that fatigue has peripheral causes such as glycogen depletion and cardiovascular strain, recent literature also focuses on the central origin of fatigue. It is clear that different brain neurotransmitters--such as serotonin, dopamine and noradrenaline--are implicated in the occurrence of fatigue, but manipulation of these neurotransmitters produced no conclusive results on performance in normal ambient temperature. Exercise in the heat not only adds an extra challenge to the cardiorespiratory system, but also to the brain. This provides a useful tool to investigate the association between exercise-induced hyperthermia and central fatigue. This review focuses on the effects of pharmacological manipulations on performance and thermoregulation in different ambient temperatures. Dopaminergic reuptake inhibition appears to counteract hyperthermia-induced fatigue in 30 °C, while noradrenergic neurotransmission shows negative effects on performance in both normal and high temperature, and serotonergic manipulations did not lead to significant changes in performance. It is, however, unlikely that one neurotransmitter system is responsible for the delay or onset of fatigue. Further research is required to determine the exact mechanisms of fatigue in different environmental conditions.
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Affiliation(s)
- R Meeusen
- Department of Human Physiology & Sports Medicine, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium.
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Effects of blockade of central dopamine D1 and D2 receptors on thermoregulation, metabolic rate and running performance. Pharmacol Rep 2010; 62:54-61. [PMID: 20360615 DOI: 10.1016/s1734-1140(10)70242-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 01/17/2010] [Indexed: 11/20/2022]
Abstract
To assess the effects of a blockade of central D1- and D2-dopaminergic receptors on metabolic rate, heat balance and running performance, 10 nmol (2 microl) of a solution of the D(1) antagonist SCH-23390 hydrochloride (SCH, n = 6), D2 antagonist eticlopride hydrochloride (Eti, n = 6), or 2 microl of 0.15 M NaCl (SAL, n = 6) was injected intracerebroventricularly into Wistar rats before the animals began graded running until fatigue (starting at 10 m/min, increasing by 1 m/min increment every 3 min until fatigue, 5% inclination). Oxygen consumption and body temperature were recorded at rest, during exercise and following 30 min of recovery. Control experiments with injection of two doses (10 and 20 nmol/rat) of either SCH or Eti solution were carried out in resting rats as well. Body heating rate, heat storage, workload and mechanical efficiency were calculated. Although SCH and Eti treatments did not induce thermal effects in resting animals, they markedly reduced running performance (-83%, SCH; -59% Eti, p < 0.05) and decreased maximal oxygen uptake (-79%, SCH; -45%, Eti, p < 0.05) in running rats. In addition, these treatments induced a higher body heating rate and persistent hyperthermia during the recovery period. Our data demonstrate that the alteration in dopamine transmission induced by the central blockade of dopamine- D1 and D2 receptors impairs running performance by decreasing the tolerance to heat storage. This blockade also impairs the dissipation of exercise-induced heat and metabolic rate recovery during the post-exercise period. Our results provide evidence that central activation of either dopamine- D1 or D2 receptors is essential for heat balance and exercise performance.
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Roelands B, Meeusen R. Alterations in central fatigue by pharmacological manipulations of neurotransmitters in normal and high ambient temperature. Sports Med 2010; 40:229-46. [PMID: 20199121 DOI: 10.2165/11533670-000000000-00000] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The scientific evidence is reviewed for the involvement of the brain monoamines serotonin, dopamine and noradrenaline (norepinephrine) in the onset of fatigue, in both normal and high ambient temperatures. The main focus is the pharmacological manipulations used to explore the central fatigue hypothesis. The original central fatigue hypothesis emphasizes that an exercise-induced increase in serotonin is responsible for the development of fatigue. However, several pharmacological studies attempted and failed to alter exercise capacity through changes in serotonergic neurotransmission in humans, indicating that the role of serotonin is often overrated. Recent studies, investigating the inhibition of the reuptake of both dopamine and noradrenaline, were capable of detecting changes in performance, specifically when ambient temperature was high. Dopamine and noradrenaline are prominent in innervated areas of the hypothalamus, therefore changes in the catecholaminergic concentrations may also be expected to be involved with the regulation of body core temperature during exercise in the heat. Evidence from different studies suggests that it is very unlikely that one neurotransmitter system is responsible for the appearance of central fatigue. The exact mechanism of fatigue is not known; presumably a complex interplay between both peripheral and central factors induces fatigue. Central fatigue will be determined by the collaboration of the different neurotransmitter systems, with the most important role possibly being for the catecholamines dopamine and noradrenaline.
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Affiliation(s)
- Bart Roelands
- Department of Human Physiology and Sports Medicine, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium
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Physiological responses to cold water immersion following cycling in the heat. Int J Sports Physiol Perform 2009; 3:331-46. [PMID: 19211945 DOI: 10.1123/ijspp.3.3.331] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED Cold water immersion (CWI) has become a popular means of enhancing recovery from various forms of exercise. However, there is minimal scientific information on the physiological effects of CWI following cycling in the heat. PURPOSE To examine the safety and acute thermoregulatory, cardiovascular, metabolic, endocrine, and inflammatory responses to CWI following cycling in the heat. METHODS Eleven male endurance trained cyclists completed two simulated approximately 40-min time trials at 34.3 +/- 1.1 degrees C. All subjects completed both a CWI trial (11.5 degrees C for 60 s repeated three times) and a control condition (CONT; passive recovery in 24.2 +/- 1.8 degrees C) in a randomized cross-over design. Capillary blood samples were assayed for lactate, glucose, pH, and blood gases. Venous blood samples were assayed for catecholamines, cortisol, testosterone, creatine kinase, C-reactive protein, IL-6, and IGF-1 on 7 of the 11 subjects. Heart rate (HR), rectal (Tre), and skin temperatures (Tsk) were measured throughout recovery. RESULTS CWI elicited a significantly lower HR (CWI: Delta 116 +/- 9 bpm vs. CONT: Delta 106 +/- 4 bpm; P = .02), Tre (CWI: Delta 1.99 +/- 0.50 degrees C vs. CONT: Delta 1.49 +/- 0.50 degrees C; P = .01) and Tsk. However, all other measures were not significantly different between conditions. All participants subjectively reported enhanced sensations of recovery following CWI. CONCLUSION CWI did not result in hypothermia and can be considered safe following high intensity cycling in the heat, using the above protocol. CWI significantly reduced heart rate and core temperature; however, all other metabolic and endocrine markers were not affected by CWI.
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Hadjicharalambous M, Kilduff LP, Pitsiladis YP. Brain serotonin and dopamine modulators, perceptual responses and endurance performance during exercise in the heat following creatine supplementation. J Int Soc Sports Nutr 2008; 5:14. [PMID: 18826587 PMCID: PMC2570654 DOI: 10.1186/1550-2783-5-14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 09/30/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The present experiment examined the responses of peripheral modulators and indices of brain serotonin (5-HT) and dopamine (DA) function and their association with perception of effort during prolonged exercise in the heat after creatine (Cr) supplementation. METHODS Twenty one endurance-trained males performed, in a double-blind fashion, two constant-load exercise tests to exhaustion at 63 +/- 5% V(O2) max in the heat (ambient temperature: 30.3 +/- 0.5 degrees C, relative humidity: 70 +/- 2%) before and after 7 days of Cr (20 g.d-1 Cr + 140 g.d-1 glucose polymer) or placebo (Plc) (160 g.d-1 glucose polymer) supplementation. RESULTS 3-way interaction has shown that Cr supplementation reduced rectal temperature, heart rate, ratings of perceived leg fatigue (P < 0.05), plasma free-tryptophan (Trp) (P < 0.01) and free-Trp:tyrosine ratio (P < 0.01) but did not influence the ratio of free-Trp:large neutral amino acids or contribute in improving endurance performance (Plc group, n = 10: 50.4 +/- 8.4 min vs. 51.2 +/- 8.0 min, P > 0.05; Cr group, n = 11: 47.0 +/- 4.7 min vs. 49.7 +/- 7.5 min, P > 0.05). However, after dividing the participants into "responders" and "non-responders" to Cr, based on their intramuscular Cr uptake, performance was higher in the "responders" relative to "non-responders" group (51.7 +/- 7.4 min vs.47.3 +/- 4.9 min, p < 0.05). CONCLUSION Although Cr influenced key modulators of brain 5-HT and DA function and reduced various thermophysiological parameters which all may have contributed to the reduced effort perception during exercise in the heat, performance was improved only in the "responders" to Cr supplementation. The present results may also suggest the demanding of the pre-experimental identification of the participants into "responders" and "non-responders" to Cr supplementation before performing the main experimentation. Otherwise, the possibility of the type II error may be enhanced.
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Barwood MJ, Thelwell RC, Tipton MJ. Psychological skills training improves exercise performance in the heat. Med Sci Sports Exerc 2008; 40:387-96. [PMID: 18202561 DOI: 10.1249/mss.0b013e31815adf31] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Fatigue occurs earlier when working at corresponding exercise intensities in hot compared with cool conditions. Psychological skills training (PST) can modify the responses evoked by thermal stimuli such as the respiratory responses on immersion to cold water. This study tested the hypothesis that a 4-d PST package would significantly increase the distance covered during 90 min of running in the heat. METHOD Eighteen subjects completed three maximal-effort runs (R1, R2, R3) of 90 min in the heat (30 degrees C; 40% RH). After R2, subjects were matched and randomly allocated to either a control group (CG) or psychological skills group (PSG). Between R2 and R3, the CG (N = 8) continued their normal activities, and the PSG (N = 10) received PST to help them tolerate unpleasant sensations arising from exercising in the heat, and to suppress the temptation to lower their work intensity. Key measures include distance covered, .VO2, skin (T(sk)) and aural temperature (T(au)), RPE, sweat production and evaporation, interleukin-6 (IL-6), and prolactin (PRL) in whole blood. RESULTS The distances covered in the CG did not differ between runs. In the PSG, there were no differences in the distance run between R1 and R2, but they ran significantly farther in R3 (8%; 1.15 km); there were no between-group differences. There were no significant differences between R1 and R3 in peak T(au), T(sk), sweat volumes, IL-6, and PRL (P > 0.05) in either group. CONCLUSION PST suppressed the temptation to reduce exercise intensity during R3. It is concluded that PST can improve running performance in the heat. The precise mechanisms underpinning these improvements are unclear; however, their implications for unblinded experimental design are not.
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Affiliation(s)
- Martin J Barwood
- University of Portsmouth, Department of Sport and Exercise Science, Institute of Biomedical and Biomolecular Sciences, Cambridge Road, Portsmouth, UK.
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Hasegawa H, Piacentini MF, Sarre S, Michotte Y, Ishiwata T, Meeusen R. Influence of brain catecholamines on the development of fatigue in exercising rats in the heat. J Physiol 2008; 586:141-9. [PMID: 17947314 PMCID: PMC2375558 DOI: 10.1113/jphysiol.2007.142190] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Accepted: 10/12/2007] [Indexed: 11/08/2022] Open
Abstract
The purpose of the present study was to identify the effects of an acute injection of a dual dopamine (DA)/noradrenaline (NA) reuptake inhibitor (bupropion) on exercise performance, thermoregulation and neurotransmitters in the preoptic area and anterior hypothalamus (PO/AH) of the rat during exercise in the heat. Body core temperature (T(core)), brain temperature (T(brain)) and tail skin temperature (T(tail)) were measured. A microdialysis probe was inserted in the PO/AH, and samples for measurement of extracellular DA, NA and serotonin (5-HT) levels were collected. Rats received either bupropion (17 mg kg(-1); hot-BUP) or saline (1 ml kg(-1); hot) 20 min before the start of exercise and ran at a speed of 26 m min(-1) until exhaustion in a warm environment (30 degrees C). Rats also ran until exhaustion in a cool environment (18 degrees C; cool). Running time to exhaustion was significantly influenced by the ambient temperature, and it was increased by bupropion in the heat (cool, 143.6 +/- 21 min; hot, 65.8 +/- 13 min; hot-BUP, 86.3 +/- 7.2 min). T(core) and T(brain) at exhaustion were significantly higher in the bupropion group compared to the cool and hot groups, respectively. T(tail) measured at exhaustion was not significantly different between the two hot conditions. Extracellular concentrations of DA and NA in the PO/AH increased during exercise, and was significantly higher in the bupropion than in cool and hot groups (P < 0.05). No differences were observed between groups for 5-HT levels. These results suggest that DA and NA in the PO/AH might be responsible for the increase in exercise performance and T(core) and T(brain) in the bupropion group in hyperthermia. Moreover, these results support previous findings in humans that acute bupropion ingestion increases T(core) during exercise in the heat, indicating the possibility of an important role for DA and NA in thermoregulation.
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Affiliation(s)
- Hiroshi Hasegawa
- Laboratoruy of Exercise Physiology, Graduate School of Faculty of Integrated Arts and Sciences, Hiroshima University, Higashi-hiroshima, Japan
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Tops M, Boksem MAS, Wijers AA, van Duinen H, Den Boer JA, Meijman TF, Korf J. The psychobiology of burnout: are there two different syndromes? Neuropsychobiology 2007; 55:143-50. [PMID: 17641533 DOI: 10.1159/000106056] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Accepted: 01/27/2007] [Indexed: 11/19/2022]
Abstract
BACKGROUND Plasma prolactin levels are sensitive to dopamine and serotonin function, and fatigue. Low cortisol, dopamine and/or serotonin may be involved in burnout and detachment. METHODS In this double-blind within-subject study, we treated 9 female burnout subjects and 9 controls with 35 mg cortisol and placebo orally. We measured state affect and plasma prolactin, oxytocin, cortisol and adrenocorticotropic hormone levels, and administered an attachment questionnaire. RESULTS The burnout subjects displayed an extreme distribution of basal prolactin levels, displaying higher or lower levels compared to the controls. The low prolactin burnouts had profoundly low attachment scores and tended to have low oxytocin levels. The high prolactin burnout subjects tended to show cortisol-induced decreased prolactin and fatigue, and increased vigor. CONCLUSION Results are consistent with the hypothesis that burnout subjects are either characterized by low serotonergic function or by low dopaminergic function, and that the latter group benefits from cortisol replacement. These preliminary results suggest that differentiating between two syndromes may resolve inconsistencies in research on burnout, and be necessary for selecting the right treatment strategy.
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Affiliation(s)
- Mattie Tops
- Department of Experimental and Work Psychology, University of Groningen, Groningen, The Netherlands.
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Abstract
The present review addresses mechanisms of importance for hyperthermia-induced fatigue during short intense activities and prolonged exercise in the heat. Inferior performance during physical activities with intensities that elicit maximal oxygen uptake is to a large extent related to perturbation of the cardiovascular function, which eventually reduces arterial oxygen delivery to the exercising muscles. Accordingly, aerobic energy turnover is impaired and anaerobic metabolism provokes peripheral fatigue. In contrast, metabolic disturbances of muscle homeostasis are less important during prolonged exercise in the heat, because increased oxygen extraction compensates for the reduction in systemic blood flow. The decrease in endurance seems to involve changes in the function of the central nervous system (CNS) that lead to fatigue. The CNS fatigue appears to be influenced by neurotransmitter activity of the dopaminergic system, but may primarily relate to inhibitory signals from the hypothalamus arising secondary to an increase in brain temperature. Fatigue is an integrated phenomenon, and psychological factors, including the anticipation of fatigue, should not be neglected and the interaction between central and peripheral physiological factors also needs to be considered.
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Affiliation(s)
- Lars Nybo
- Department of Human Physiology, Institute of Exercise and Sport Sciences, University of Copenhagen, Universitetsparken 13, Copenhagen Ø, Denmark.
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Meeusen R, Watson P, Hasegawa H, Roelands B, Piacentini MF. Central fatigue: the serotonin hypothesis and beyond. Sports Med 2007; 36:881-909. [PMID: 17004850 DOI: 10.2165/00007256-200636100-00006] [Citation(s) in RCA: 247] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The original central fatigue hypothesis suggested that an exercise-induced increase in extracellular serotonin concentrations in several brain regions contributed to the development of fatigue during prolonged exercise. Serotonin has been linked to fatigue because of its well known effects on sleep, lethargy and drowsiness and loss of motivation. Several nutritional and pharmacological studies have attempted to manipulate central serotonergic activity during exercise, but this work has yet to provide robust evidence for a significant role of serotonin in the fatigue process. However, it is important to note that brain function is not determined by a single neurotransmitter system and the interaction between brain serotonin and dopamine during prolonged exercise has also been explored as having a regulative role in the development of fatigue. This revised central fatigue hypothesis suggests that an increase in central ratio of serotonin to dopamine is associated with feelings of tiredness and lethargy, accelerating the onset of fatigue, whereas a low ratio favours improved performance through the maintenance of motivation and arousal. Convincing evidence for a role of dopamine in the development of fatigue comes from work investigating the physiological responses to amphetamine use, but other strategies to manipulate central catecholamines have yet to influence exercise capacity during exercise in temperate conditions. Recent findings have, however, provided support for a significant role of dopamine and noradrenaline (norepinephrine) in performance during exercise in the heat. As serotonergic and catecholaminergic projections innervate areas of the hypothalamus, the thermoregulatory centre, a change in the activity of these neurons may be expected to contribute to the control of body temperature whilst at rest and during exercise. Fatigue during prolonged exercise clearly is influenced by a complex interaction between peripheral and central factors.
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Affiliation(s)
- Romain Meeusen
- Department Human Physiology and Sportsmedicine, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel, Brussels, Belgium.
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