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Toro-Román V, Prieto-González I, Siquier-Coll J, Bartolomé I, Grijota FJ, Maynar-Mariño M. Effects of High Temperature Exposure on the Wingate Test Performance in Male University Students. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:4782. [PMID: 36981697 PMCID: PMC10049338 DOI: 10.3390/ijerph20064782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/05/2023] [Accepted: 03/06/2023] [Indexed: 06/18/2023]
Abstract
It has been suggested that heat exposure prior to exercise could induce changes in anaerobic exercise. Therefore, the purpose of this study was to observe the effects of high temperature heat exposure prior to an anaerobic test. Twenty-one men (age: 19.76 ± 1.22 years; height: 1.69 ± 0.12 m; weight: 67.89 ± 11.78 kg) voluntarily participated in this investigation. All of them performed two Wingate tests, vertical jump and macronutrient intake control. On the first day, the test was performed under normal environmental conditions. On the second day, it was performed in a similar way, but with previous exposure to heat at high sauna temperatures (15 min; 100 ± 2 °C). There were no differences in the vertical jump and macronutrient intake. However, the results showed an improvement in power (W) (p < 0.05), relative power (W/kg) (p < 0.01) and revolutions per minute (p < 0.05) 10 s after the start of the test. There was also an increase in thigh (p < 0.01) and skin temperature (p < 0.01) with pre-heat exposure. The results obtained suggest that this pre-exercise protocol could improve power in short and intensive actions.
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Affiliation(s)
- Víctor Toro-Román
- Faculty of Sport Sciences, University of Extremadura, Avenida de la Universidad s/n, 10003 Cáceres, Spain; (V.T.-R.)
| | - Isaac Prieto-González
- Faculty of Sport Sciences, University of Extremadura, Avenida de la Universidad s/n, 10003 Cáceres, Spain; (V.T.-R.)
| | - Jesús Siquier-Coll
- SER Research Group, Center of Higher Education Alberta Giménez, Comillas Pontifical University, Costa de Saragossa 16, 07013 Palma Mallorca, Spain
| | - Ignacio Bartolomé
- Department of Sport Science, Faculty of Education, Pontifical University of Salamanca, C/Henry Collet, 52-70, 37007 Salamanca, Spain
| | - Francisco J. Grijota
- Faculty of Life and Nature Sciences, University of Nebrija, Campus La Berzosa, Calle del Hostal, Hoyo de Manzanares, 28248 Madrid, Spain
| | - Marcos Maynar-Mariño
- Faculty of Sport Sciences, University of Extremadura, Avenida de la Universidad s/n, 10003 Cáceres, Spain; (V.T.-R.)
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Muresanu DF, Sharma A, Tian ZR, Lafuente JV, Nozari A, Feng L, Buzoianu AD, Wiklund L, Sharma HS. Nanowired Delivery of Cerebrolysin with Mesenchymal Stem Cells Attenuates Heat Stress-Induced Exacerbation of Neuropathology Following Brain Blast Injury. ADVANCES IN NEUROBIOLOGY 2023; 32:231-270. [PMID: 37480463 DOI: 10.1007/978-3-031-32997-5_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
Blast brain injury (bBI) following explosive detonations in warfare is one of the prominent causes of multidimensional insults to the central nervous and other vital organs injury. Several military personnel suffered from bBI during the Middle East conflict at hot environment. The bBI largely occurs due to pressure waves, generation of heat together with release of shrapnel and gun powders explosion with penetrating and/or impact head trauma causing multiple brain damage. As a result, bBI-induced secondary injury causes breakdown of the blood-brain barrier (BBB) and edema formation that further results in neuronal, glial and axonal injuries. Previously, we reported endocrine imbalance and influence of diabetes on bBI-induced brain pathology that was significantly attenuated by nanowired delivery of cerebrolysin in model experiments. Cerebrolysin is a balanced composition of several neurotrophic factors, and active peptide fragment is capable of neuroprotection in several neurological insults. Exposure to heat stress alone causes BBB damage, edema formation and brain pathology. Thus, it is quite likely that hot environment further exacerbates the consequences of bBI. Thus, novel therapeutic strategies using nanodelivery of stem cell and cerebrolysin may further enhance superior neuroprotection in bBI at hot environment. Our observations are the first to show that combined nanowired delivery of mesenchymal stem cells (MSCs) and cerebrolysin significantly attenuated exacerbation of bBI in hot environment and induced superior neuroprotection, not reported earlier. The possible mechanisms of neuroprotection with MSCs and cerebrolysin in bBI are discussed in the light of current literature.
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Affiliation(s)
- Dafin F Muresanu
- Department of Clinical Neurosciences, University of Medicine & Pharmacy, Cluj-Napoca, Romania
- "RoNeuro" Institute for Neurological Research and Diagnostic, Cluj-Napoca, Romania
| | - Aruna Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Z Ryan Tian
- Department of Chemistry & Biochemistry, University of Arkansas, Fayetteville, AR, USA
| | - José Vicente Lafuente
- LaNCE, Department of Neuroscience, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
| | - Ala Nozari
- Anesthesiology & Intensive Care, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA, USA
| | - Lianyuan Feng
- Department of Neurology, Bethune International Peace Hospital, Zhongshan, Hebei Province, China
| | - Anca D Buzoianu
- Department of Clinical Pharmacology and Toxicology, "Iuliu Hatieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Lars Wiklund
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Hari Shanker Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden.
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Richard NA, Koehle MS. Influence and Mechanisms of Action of Environmental Stimuli on Work Near and Above the Severe Domain Boundary (Critical Power). SPORTS MEDICINE - OPEN 2022; 8:42. [PMID: 35347469 PMCID: PMC8960528 DOI: 10.1186/s40798-022-00430-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 02/26/2022] [Indexed: 11/10/2022]
Abstract
Abstract
The critical power (CP) concept represents the uppermost rate of steady state aerobic metabolism during work. Work above CP is limited by a fixed capacity (W′) with exercise intensity being an accelerant of its depletion rate. Exercise at CP is a considerable insult to homeostasis and any work done above it will rapidly become intolerable. Humans live and exercise in situations of hypoxia, heat, cold and air pollution all of which impose a new environmental stress in addition to that of exercise. Hypoxia disrupts the oxygen cascade and consequently aerobic energy production, whereas heat impacts the circulatory system’s ability to solely support exercise performance. Cold lowers efficiency and increases the metabolic cost of exercise, whereas air pollution negatively impacts the respiratory system. This review will examine the effects imposed by environmental conditions on CP and W′ and describe the key physiological mechanisms which are affected by the environment.
Graphical Abstract
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Travers G, Kippelen P, Trangmar SJ, González-Alonso J. Physiological Function during Exercise and Environmental Stress in Humans-An Integrative View of Body Systems and Homeostasis. Cells 2022; 11:383. [PMID: 35159193 PMCID: PMC8833916 DOI: 10.3390/cells11030383] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 11/26/2022] Open
Abstract
Claude Bernard's milieu intérieur (internal environment) and the associated concept of homeostasis are fundamental to the understanding of the physiological responses to exercise and environmental stress. Maintenance of cellular homeostasis is thought to happen during exercise through the precise matching of cellular energetic demand and supply, and the production and clearance of metabolic by-products. The mind-boggling number of molecular and cellular pathways and the host of tissues and organ systems involved in the processes sustaining locomotion, however, necessitate an integrative examination of the body's physiological systems. This integrative approach can be used to identify whether function and cellular homeostasis are maintained or compromised during exercise. In this review, we discuss the responses of the human brain, the lungs, the heart, and the skeletal muscles to the varying physiological demands of exercise and environmental stress. Multiple alterations in physiological function and differential homeostatic adjustments occur when people undertake strenuous exercise with and without thermal stress. These adjustments can include: hyperthermia; hyperventilation; cardiovascular strain with restrictions in brain, muscle, skin and visceral organs blood flow; greater reliance on muscle glycogen and cellular metabolism; alterations in neural activity; and, in some conditions, compromised muscle metabolism and aerobic capacity. Oxygen supply to the human brain is also blunted during intense exercise, but global cerebral metabolism and central neural drive are preserved or enhanced. In contrast to the strain seen during severe exercise and environmental stress, a steady state is maintained when humans exercise at intensities and in environmental conditions that require a small fraction of the functional capacity. The impact of exercise and environmental stress upon whole-body functions and homeostasis therefore depends on the functional needs and differs across organ systems.
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Affiliation(s)
- Gavin Travers
- The European Astronaut Centre, The European Space Agency, Linder Höhe, 51147 Cologne, Germany;
| | - Pascale Kippelen
- Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge UB8 3PH, UK;
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK
| | - Steven J. Trangmar
- School of Life and Health Sciences, University of Roehampton, London SW15 4JD, UK;
| | - José González-Alonso
- Centre for Human Performance, Exercise and Rehabilitation, Brunel University London, Uxbridge UB8 3PH, UK;
- Division of Sport, Health and Exercise Sciences, Department of Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK
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Oyanagi K, Tsubaki A. Effects of increased respiratory rate on cortical oxygenated hemoglobin during low-intensity exercise. Respir Physiol Neurobiol 2021; 291:103691. [PMID: 33992799 DOI: 10.1016/j.resp.2021.103691] [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: 12/13/2020] [Revised: 04/29/2021] [Accepted: 05/10/2021] [Indexed: 11/18/2022]
Abstract
This study aimed to examine whether the end-tidal partial pressure of CO2 (PEtCO2) affects the concentration of oxygenated hemoglobin (O2Hb) measured by near-infrared spectroscopy (NIRS). Participants were examined under the conditions of normal and increased ventilation. We measured O2Hb, mean blood pressure, skin blood flow, PEtCO2, respiratory rate, and minute volume at 30 % of the maximum oxygen uptake during exercise. ΔO2Hb and PEtCO2 during exercise were lower in the increased ventilation than in the normal ventilation condition. Pearson's product-moment correlation analysis showed a significant positive correlation between ΔO2Hb and ΔMAP, ΔSBF, and PEtCO2. Correlation coefficients were 0.249 (p < 0.001) for ΔMAP, 0.343 (p < 0.001) for ΔSBF, and 0.315 (p < 0.001) for PEtCO2. In conclusion, we identified increased ventilation during bicycle ergometer exercise as a significant factor associated with significantly low PEtCO2 and ΔO2Hb.
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Affiliation(s)
- Keiichi Oyanagi
- Department of Rehabilitation, Kobe City Medical Center General Hospital, Kobe, Japan.
| | - Atsuhiro Tsubaki
- Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
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Rivas E, Allie KN, Salvador PM, Schoech L, Martinez M. Sex difference in cerebral blood flow velocity during exercise hyperthermia. J Therm Biol 2020; 94:102741. [PMID: 33292982 DOI: 10.1016/j.jtherbio.2020.102741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Cerebral blood flow and thermal perception during physical exercise under hyperthermia conditions in females are poorly understood. Because sex differences exist for blood pressure control, resting middle cerebral artery velocity (MCAVmean), and pain, we tested the hypothesis that females would have greater reductions in MCAvmean and increased thermal perceptual strain during exercise hyperthermia compared to males. METHODS Twenty-two healthy active males and females completed 60 min of matched exercise metabolic heat production in a 1) control cool (24.0 ± 0.0 °C; 14.4 ± 3.4% Rh) and 2) hot (42.3 ± 0.3 °C; 28.4 ± 5.2% Rh) conditions in random order, separated by at least 3 days while MCAvmean, thermal comfort, and preference was obtained during the exercise. RESULTS Compared to 36 °C mean body temperature (Mbt), as hyperthermia increased to 39 °C Mbt, females had a greater reduction in absolute (MCAvmean), and relative change (%Δ MCAvmean) and conductance (%Δ MCAvmean conductance) in MCAVmean compared to males (Interaction: Temperature x Sex, P ≤ 0.002). During exercise in cool conditions, absolute and conductance MCAvmean was maintained from rest through exercise; however, females had greater MCAVmean compared to males (Main effect: Sex, P < 0.0008). We also found disparities in females' perceptual thermal comfort and thermal preference. These differences may be associated with a greater reduction in partial pressure of end-tidal CO2, and different cardiovascular and blood pressure control to exercise under hyperthermia. CONCLUSIONS In summary, females exercise cerebral blood flow velocity is reduced to a greater extent (25% vs 15%) and the initial reduction occurs at lower hyperthermia mean body temperatures (~38 °C vs ~39 °C) and are under greater thermal perceptual strain compared to males.
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Affiliation(s)
- Eric Rivas
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA; KBR, Human Physiology, Performance, Protection & Operations Laboratory, NASA Johnson Space Center, Houston, TX, USA.
| | - Kyleigh N Allie
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Paolo M Salvador
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA
| | - Lauren Schoech
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA
| | - Mauricio Martinez
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
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Douzi W, Dugué B, Theurot D, Vinches L, Hallé S, Dupuy O. Cooling During Exercise May Induce Benefits Linked to Improved Brain Perfusion. Int J Sports Med 2020; 42:122-131. [PMID: 32920802 DOI: 10.1055/a-1213-5960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The aim of this study was to evaluate the impact of using a cooling vest during physical exercise (per-cooling) in humid and temperate conditions (≈22°C, ≈80% relative humidity) on perceptual and physiological responses (tissue oxygenation and heart rate). 20 physically active men performed twice a 30-min cycling exercise at 70% of their theoretical maximum heart rate while using an activated (experimental condition) and a deactivated (control condition) cooling system in a randomized crossover study. Heart rate and tissue (cerebral and muscular) oxygenation were continuously measured during exercise and recovery, and skin temperature was measured every 10 min. Perception of temperature, humidity and comfort were assessed at the end of the recovery period. Results showed a decrease in trunk skin temperature (p<0.05), a faster heart rate recovery and an increase in the concentration of total hemoglobin at the brain level (p<0.05) compared with control condition. Moreover, an improved subjective rating of thermal sensations, wetness and comfort compared to control values (p<0.05) was noted. In conclusion, wearing a cooling vest during submaximal exercise improves perceptual and physiological responses in humid temperate conditions, which may be due to a better blood perfusion at the brain level and a better parasympathetic reactivation.
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Affiliation(s)
- Wafa Douzi
- Laboratoire "Mobilité, Vieillissement, Exercice (MOVE) - EA 6314" et Faculté des Sciences du Sport, Université de Poitiers, Poitiers, France
| | - Benoit Dugué
- Laboratoire "Mobilité, Vieillissement, Exercice (MOVE) - EA 6314" et Faculté des Sciences du Sport, Université de Poitiers, Poitiers, France
| | - Dimitri Theurot
- Laboratoire "Mobilité, Vieillissement, Exercice (MOVE) - EA 6314" et Faculté des Sciences du Sport, Université de Poitiers, Poitiers, France
| | - Ludwig Vinches
- École de santé publique - Département de Santé Environnementale et Santé au Travail, Université de Montréal, Montreal, Canada
| | - Stéphane Hallé
- Department of Mechanical Engineering, Ecole de Technologie Supérieure, Montreal, Canada
| | - Olivier Dupuy
- Laboratoire "Mobilité, Vieillissement, Exercice (MOVE) - EA 6314" et Faculté des Sciences du Sport, Université de Poitiers, Poitiers, France
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Abstract
People undertaking prolonged vigorous exercise experience substantial bodily fluid losses due to thermoregulatory sweating. If these fluid losses are not replaced, endurance capacity may be impaired in association with a myriad of alterations in physiological function, including hyperthermia, hyperventilation, cardiovascular strain with reductions in brain, skeletal muscle and skin blood perfusion, greater reliance on muscle glycogen and cellular metabolism, alterations in neural activity and, in some conditions, compromised muscle metabolism and aerobic capacity. The physiological strain accompanying progressive exercise-induced dehydration to a level of ~ 4% of body mass loss can be attenuated or even prevented by: (1) ingesting fluids during exercise, (2) exercising in cold environments, and/or (3) working at intensities that require a small fraction of the overall body functional capacity. The impact of dehydration upon physiological function therefore depends on the functional demand evoked by exercise and environmental stress, as cardiac output, limb blood perfusion and muscle metabolism are stable or increase during small muscle mass exercise or resting conditions, but are impaired during whole-body moderate to intense exercise. Progressive dehydration is also associated with an accelerated drop in perfusion and oxygen supply to the human brain during submaximal and maximal endurance exercise. Yet their consequences on aerobic metabolism are greater in the exercising muscles because of the much smaller functional oxygen extraction reserve. This review describes how dehydration differentially impacts physiological function during exercise requiring low compared to high functional demand, with an emphasis on the responses of the human brain, heart and skeletal muscles.
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Rivas E, Allie KN, Salvador PM. Progressive dry to humid hyperthermia alters exercise cerebral blood flow. J Therm Biol 2019; 84:398-406. [PMID: 31466779 DOI: 10.1016/j.jtherbio.2019.07.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/27/2019] [Accepted: 07/29/2019] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Exercising in hot conditions may increase the risk for exertional heat-related illness due to reduction in cerebral blood flow (CBF); however, the acute effect of exercise-induced changes on CBF during compensable and uncompensable heat stress remain unclear. We tested the hypothesis that exercising in hot dry and humid conditions would have different CBF responses. METHODS Nine healthy active males completed a 30 min baseline rest then 60 min of low intensity self-paced exercise (12 rating of perceived exertion) in a 1) control compensable neutral dry (CN; 23.7 ± 0.7 °C; 10.7 ± 0.8%Rh) and 2) compensable hot dry (CH; 42.3 ± 0.3 °C; 10.7 ± 1.8%Rh) that progressively increased to an uncompensable hot humid (UCH; 42.3 ± 0.3 °C; 55.2 ± 7.7%Rh) environment in random order separated by at least 4 days. RESULTS We observed that during CN environments from rest through 60 min of exercise, middle cerebral velocity (MCAvmean) and conductance (MCAvmean CVC) remained unchanged. In contrast, during CH, MCAvmean, MCAvmean CVC, and cardiac output (Q) increased and systemic vascular resistance (SVR) decreased. However, under UCH, MCAvmean, MCAvmean CVC, and Q was reduced. No difference in mean arterial pressure or ventilation was observed during any condition. Only during UCH, end-tidal PO2 increased and PCO2 decreased. The redistribution of blood to the skin for thermoregulation (heart rate, skin blood flow and sweat rate) remained higher during exercise in UCH environments. CONCLUSIONS Collectively, exercise cerebral blood flow is altered by an integrative physiological manner that differs in CN, CH, and UCH environments. The control of CBF may be secondary to thermoregulatory control which may provide an explanation for the cause of exertional heat illness.
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Affiliation(s)
- Eric Rivas
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA.
| | - Kyleigh N Allie
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Paolo M Salvador
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
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Périard JD, Houtkamp D, Bright F, Daanen HAM, Abbiss CR, Thompson KG, Clark B. Hyperoxia enhances self‐paced exercise performance to a greater extent in cool than hot conditions. Exp Physiol 2019; 104:1398-1407. [DOI: 10.1113/ep087864] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/02/2019] [Indexed: 11/08/2022]
Affiliation(s)
- J. D. Périard
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
| | - D. Houtkamp
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
- Department of Human Movement SciencesFaculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam Amsterdam The Netherlands
| | - F. Bright
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
| | - H. A. M. Daanen
- Department of Human Movement SciencesFaculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam Amsterdam The Netherlands
| | - C. R. Abbiss
- Centre for Exercise and Sports Science ResearchSchool of Medical and Health Sciences, Edith Cowan University Joondalup WA Australia
| | - K. G. Thompson
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
- New South Wales Institute of Sport Sydney NSW Australia
| | - B. Clark
- University of Canberra Research Institute for Sport and Exercise Bruce ACT Australia
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de Melo-Marins D, Souza-Silva AA, da Silva-Santos GLL, Freire-Júnior FDA, Lee JKW, Laitano O. Personalized Hydration Strategy Attenuates the Rise in Heart Rate and in Skin Temperature Without Altering Cycling Capacity in the Heat. Front Nutr 2018; 5:22. [PMID: 29707541 PMCID: PMC5907529 DOI: 10.3389/fnut.2018.00022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/22/2018] [Indexed: 11/13/2022] Open
Abstract
The optimal hydration plan [i.e., drink to thirst, ad libitum (ADL), or personalized plan] to be adopted during exercise in recreational athletes has recently been a matter of debate and, due to conflicting results, consensus does not exist. In the present investigation, we tested whether a personalized hydration strategy based on sweat rate would affect cardiovascular and thermoregulatory responses and exercise capacity in the heat. Eleven recreational male cyclists underwent two familiarization cycling sessions in the heat (34°C, 40% RH) where sweat rate was also determined. A fan was used to enhance sweat evaporation. Participants then performed three randomized time-to-exhaustion (TTE) trials in the heat with different hydration strategies: personalized volume (PVO), where water was consumed, based on individual sweat rate, every 10 min; ADL, where free access to water was allowed; and a control (CON) trial with no fluids. Blood osmolality and urine-specific gravity were measured before each trial. Heart rate (HR), rectal, and skin temperatures were monitored throughout trials. Time to exhaustion at 70% of maximal workload was used to define exercise capacity in the heat, which was similar in all trials (p = 0.801). Body mass decreased after ADL (p = 0.008) and CON (p < 0.001) and was maintained in PVO trials (p = 0.171). Participants consumed 0 ml in CON, 166 ± 167 ml in ADL, and 1,080 ± 166 ml in PVO trials. The increase in mean body temperature was similar among trials despite a lower increase in skin temperature during PVO trial in comparison with CON (2.1 ± 0.6 vs. 2.9 ± 0.5°C, p = 0.0038). HR was lower toward the end of TTE in PVO (162 ± 8 bpm) in comparison with ADL (168 ± 12 bpm) and CON (167 ± 10 bpm), p < 0.001. In conclusion, a personalized hydration strategy can reduce HR during a moderate to high intensity exercise session in the heat and halt the increase in skin temperature. Despite these advantages, cycling capacity in the heat remained unchanged.
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Affiliation(s)
- Denise de Melo-Marins
- College of Physical Education, Federal University of Vale do São Francisco (UNIVASF), Petrolina, Brazil
| | - Ana Angélica Souza-Silva
- College of Physical Education, Federal University of Vale do São Francisco (UNIVASF), Petrolina, Brazil
| | | | | | - Jason Kai Wei Lee
- Defence Medical and Environmental Research Institute, DSO National Laboratories, Singapore, Singapore.,Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Orlando Laitano
- College of Physical Education, Federal University of Vale do São Francisco (UNIVASF), Petrolina, Brazil
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MacRae BA, Annaheim S, Spengler CM, Rossi RM. Skin Temperature Measurement Using Contact Thermometry: A Systematic Review of Setup Variables and Their Effects on Measured Values. Front Physiol 2018. [PMID: 29441024 DOI: 10.3389/fphys.2018.00029, 10.3389/fpls.2018.00029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background: Skin temperature (Tskin) is commonly measured using Tskin sensors affixed directly to the skin surface, although the influence of setup variables on the measured outcome requires clarification. Objectives: The two distinct objectives of this systematic review were (1) to examine measurements from contact Tskin sensors considering equilibrium temperature and temperature disturbance, sensor attachments, pressure, environmental temperature, and sensor type, and (2) to characterise the contact Tskin sensors used, conditions of use, and subsequent reporting in studies investigating sports, exercise, and other physical activity. Data sources and study selection: For the measurement comparison objective, Ovid Medline and Scopus were used (1960 to July 2016) and studies comparing contact Tskin sensor measurements in vivo or using appropriate physical models were included. For the survey of use, Ovid Medline was used (2011 to July 2016) and studies using contact temperature sensors for the measurement of human Tskinin vivo during sport, exercise, and other physical activity were included. Study appraisal and synthesis methods: For measurement comparisons, assessments of risk of bias were made according to an adapted version of the Cochrane Collaboration's risk of bias tool. Comparisons of temperature measurements were expressed, where possible, as mean difference and 95% limits of agreement (LoA). Meta-analyses were not performed due to the lack of a common reference condition. For the survey of use, extracted information was summarised in text and tabular form. Results: For measurement comparisons, 21 studies were included. Results from these studies indicated minor (<0.5°C) to practically meaningful (>0.5°C) measurement bias within the subgroups of attachment type, applied pressure, environmental conditions, and sensor type. The 95% LoA were often within 1.0°C for in vivo studies and 0.5°C for physical models. For the survey of use, 172 studies were included. Details about Tskin sensor setup were often poorly reported and, from those reporting setup information, it was evident that setups widely varied in terms of type of sensors, attachments, and locations used. Conclusions: Setup variables and conditions of use can influence the measured temperature from contact Tskin sensors and thus key setup variables need to be appropriately considered and consistently reported.
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Affiliation(s)
- Braid A MacRae
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland.,Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Simon Annaheim
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
| | - Christina M Spengler
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - René M Rossi
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
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13
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MacRae BA, Annaheim S, Spengler CM, Rossi RM. Skin Temperature Measurement Using Contact Thermometry: A Systematic Review of Setup Variables and Their Effects on Measured Values. Front Physiol 2018; 9:29. [PMID: 29441024 PMCID: PMC5797625 DOI: 10.3389/fphys.2018.00029] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 01/09/2018] [Indexed: 11/13/2022] Open
Abstract
Background: Skin temperature (Tskin) is commonly measured using Tskin sensors affixed directly to the skin surface, although the influence of setup variables on the measured outcome requires clarification. Objectives: The two distinct objectives of this systematic review were (1) to examine measurements from contact Tskin sensors considering equilibrium temperature and temperature disturbance, sensor attachments, pressure, environmental temperature, and sensor type, and (2) to characterise the contact Tskin sensors used, conditions of use, and subsequent reporting in studies investigating sports, exercise, and other physical activity. Data sources and study selection: For the measurement comparison objective, Ovid Medline and Scopus were used (1960 to July 2016) and studies comparing contact Tskin sensor measurements in vivo or using appropriate physical models were included. For the survey of use, Ovid Medline was used (2011 to July 2016) and studies using contact temperature sensors for the measurement of human Tskinin vivo during sport, exercise, and other physical activity were included. Study appraisal and synthesis methods: For measurement comparisons, assessments of risk of bias were made according to an adapted version of the Cochrane Collaboration's risk of bias tool. Comparisons of temperature measurements were expressed, where possible, as mean difference and 95% limits of agreement (LoA). Meta-analyses were not performed due to the lack of a common reference condition. For the survey of use, extracted information was summarised in text and tabular form. Results: For measurement comparisons, 21 studies were included. Results from these studies indicated minor (<0.5°C) to practically meaningful (>0.5°C) measurement bias within the subgroups of attachment type, applied pressure, environmental conditions, and sensor type. The 95% LoA were often within 1.0°C for in vivo studies and 0.5°C for physical models. For the survey of use, 172 studies were included. Details about Tskin sensor setup were often poorly reported and, from those reporting setup information, it was evident that setups widely varied in terms of type of sensors, attachments, and locations used. Conclusions: Setup variables and conditions of use can influence the measured temperature from contact Tskin sensors and thus key setup variables need to be appropriately considered and consistently reported.
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Affiliation(s)
- Braid A. MacRae
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Simon Annaheim
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
| | - Christina M. Spengler
- Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - René M. Rossi
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, St. Gallen, Switzerland
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14
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Périard JD, De Pauw K, Zanow F, Racinais S. Cerebrocortical activity during self-paced exercise in temperate, hot and hypoxic conditions. Acta Physiol (Oxf) 2018; 222. [PMID: 28686002 DOI: 10.1111/apha.12916] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 06/02/2017] [Accepted: 07/03/2017] [Indexed: 12/14/2022]
Abstract
AIM Heat stress and hypoxia independently influence cerebrocortical activity and impair prolonged exercise performance. This study examined the relationship between electroencephalography (EEG) activity and self-paced exercise performance in control (CON, 18 °C, 40% RH), hot (HOT, 35 °C, 60% RH) and hypoxic (HYP, 18 °C, 40% RH FiO2 : 0.145) conditions. METHODS Eleven well-trained cyclists completed a 750 kJ cycling time trial in each condition on separate days in a counterbalanced order. EEG activity was recorded with α- and β-activity evaluated in the frontal (F3 and F4) and central (C3 and C4) areas. Standardized low-resolution brain electromagnetic tomography (sLORETA) was also utilized to localize changes in cerebrocortical activity. RESULTS Both α- and β-activity decreased in the frontal and central areas during exercise in HOT relative to CON (P < 0.05). α-activity was also lower in HYP compared with CON (P < 0.05), whereas β-activity remained similar. β-activity was higher in HYP than in HOT (P < 0.05). sLORETA revealed that α- and β-activity increased at the onset of exercise in the primary somatosensory and motor cortices in CON and HYP, while only β-activity increased in HOT. A decrease in α- and β-activity occurred thereafter in all conditions, with α-activity being lower in the somatosensory and somatosensory association cortices in HOT relative to CON. CONCLUSION High-intensity prolonged self-paced exercise induces cerebrocortical activity alterations in areas of the brain associated with the ability to inhibit conflicting attentional processing under hot and hypoxic conditions, along with the capacity to sustain mental readiness and arousal under heat stress.
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Affiliation(s)
- J. D. Périard
- Research Institute for Sport and Exercise; University of Canberra; Canberra ACT Australia
- Athlete Health and Performance Research Centre; Aspetar Orthopaedic and Sports Medicine Hospital; Doha Qatar
| | - K. De Pauw
- Research Group Human Physiology; Faculty of Physical Education and Physiotherapy; Vrije Universiteit Brussel; Brussels Belgium
| | - F. Zanow
- ANT Neuro bv; Enschede the Netherlands
| | - S. Racinais
- Athlete Health and Performance Research Centre; Aspetar Orthopaedic and Sports Medicine Hospital; Doha Qatar
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15
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Racinais S, Cocking S, Périard JD. Sports and environmental temperature: From warming-up to heating-up. Temperature (Austin) 2017; 4:227-257. [PMID: 28944269 DOI: 10.1080/23328940.2017.1356427] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/09/2017] [Accepted: 07/09/2017] [Indexed: 01/22/2023] Open
Abstract
Most professional and recreational athletes perform pre-conditioning exercises, often collectively termed a 'warm-up' to prepare for a competitive task. The main objective of warming-up is to induce both temperature and non-temperature related responses to optimize performance. These responses include increasing muscle temperature, initiating metabolic and circulatory adjustments, and preparing psychologically for the upcoming task. However, warming-up in hot and/or humid ambient conditions increases thermal and circulatory strain. As a result, this may precipitate neuromuscular and cardiovascular impairments limiting endurance capacity. Preparations for competing in the heat should include an acclimatization regimen. Athletes should also consider cooling interventions to curtail heat gain during the warm-up and minimize dehydration. Indeed, although it forms an important part of the pre-competition preparation in all environmental conditions, the rise in whole-body temperature should be limited in hot environments. This review provides recommendations on how to build an effective warm-up following a 3 stage RAMP model (Raise, Activate and Mobilize, Potentiate), including general and context specific exercises, along with dynamic flexibility work. In addition, this review provides suggestion to manipulate the warm-up to suit the demands of competition in hot environments, along with other strategies to avoid heating-up.
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Affiliation(s)
- Sébastien Racinais
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,French Institute of Sport (INSEP), Laboratory Sport, Expertise and Performance (EA 7370), Paris, France
| | - Scott Cocking
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,Research Institute for Sport and Exercise Science, Liverpool John Moores University, United Kingdom
| | - Julien D Périard
- Aspetar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Doha, Qatar.,University of Canberra, Research Institute for Sport and Exercise, Canberra, Australia
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16
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Middle cerebral artery blood flow velocity during a 4 km cycling time trial. Eur J Appl Physiol 2017; 117:1241-1248. [DOI: 10.1007/s00421-017-3612-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 04/10/2017] [Indexed: 11/26/2022]
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17
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Davies MJ, Clark B, Welvaert M, Skorski S, Garvican-Lewis LA, Saunders P, Thompson KG. Effect of Environmental and Feedback Interventions on Pacing Profiles in Cycling: A Meta-Analysis. Front Physiol 2016; 7:591. [PMID: 27994554 PMCID: PMC5136559 DOI: 10.3389/fphys.2016.00591] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 11/14/2016] [Indexed: 11/15/2022] Open
Abstract
In search of their optimal performance athletes will alter their pacing strategy according to intrinsic and extrinsic physiological, psychological and environmental factors. However, the effect of some of these variables on pacing and exercise performance remains somewhat unclear. Therefore, the aim of this meta-analysis was to provide an overview as to how manipulation of different extrinsic factors affects pacing strategy and exercise performance. Only self-paced exercise studies that provided control and intervention group(s), reported trial variance for power output, disclosed the type of feedback received or withheld, and where time-trial power output data could be segmented into start, middle and end sections; were included in the meta-analysis. Studies with similar themes were grouped together to determine the mean difference (MD) with 95% confidence intervals (CIs) between control and intervention trials for: hypoxia, hyperoxia, heat-stress, pre-cooling, and various forms of feedback. A total of 26 studies with cycling as the exercise modality were included in the meta-analysis. Of these, four studies manipulated oxygen availability, eleven manipulated heat-stress, four implemented pre-cooling interventions and seven studies manipulated various forms of feedback. Mean power output (MPO) was significantly reduced in the middle and end sections (p < 0.05), but not the start section of hypoxia and heat-stress trials compared to the control trials. In contrast, there was no significant change in trial or section MPO for hyperoxic or pre-cooling conditions compared to the control condition (p > 0.05). Negative feedback improved overall trial MPO and MPO in the middle section of trials (p < 0.05), while informed feedback improved overall trial MPO (p < 0.05). However, positive, neutral and no feedback had no significant effect on overall trial or section MPO (p > 0.05). The available data suggests exercise regulation in hypoxia and heat-stress is delayed in the start section of trials, before significant reductions in MPO occur in the middle and end of the trial. Additionally, negative feedback involving performance deception may afford an upward shift in MPO in the middle section of the trial improving overall performance. Finally, performance improvements can be retained when participants are informed of the deception.
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Affiliation(s)
- Michael J Davies
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Department of Physiology, Australian Institute of SportBruce, ACT, Australia
| | - Bradley Clark
- University of Canberra Research Institute for Sport and Exercise Bruce, ACT, Australia
| | - Marijke Welvaert
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Department of Physiology, Australian Institute of SportBruce, ACT, Australia
| | - Sabrina Skorski
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Institute of Sports and Preventive Medicine, Saarland UniversitySaarbrücken, Germany
| | - Laura A Garvican-Lewis
- University of Canberra Research Institute for Sport and ExerciseBruce, ACT, Australia; Department of Physiology, Australian Institute of SportBruce, ACT, Australia; Mary Mackillop Institute for Health Research, Australian Catholic UniversityMelbourne, VIC, Australia
| | - Philo Saunders
- Department of Physiology, Australian Institute of Sport Bruce, ACT, Australia
| | - Kevin G Thompson
- University of Canberra Research Institute for Sport and Exercise Bruce, ACT, Australia
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18
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Junge N, Jørgensen R, Flouris AD, Nybo L. Prolonged self-paced exercise in the heat - environmental factors affecting performance. Temperature (Austin) 2016; 3:539-548. [PMID: 28090557 PMCID: PMC5198812 DOI: 10.1080/23328940.2016.1216257] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Revised: 07/10/2016] [Accepted: 07/19/2016] [Indexed: 11/03/2022] Open
Abstract
In this review we examine how self-paced performance is affected by environmental heat stress factors during cycling time trial performance as well as considering the effects of exercise mode and heat acclimatization. Mean power output during prolonged cycling time trials in the heat (≥30°C) was on average reduced by 15% in the 14 studies that fulfilled the inclusion criteria. Ambient temperature per se was a poor predictor of the integrated environmental heat stress and 2 of the prevailing heat stress indices (WBGT and UTCI) failed to predict the environmental influence on performance. The weighing of wind speed appears to be too low for predicting the effect for cycling in trained acclimatized subjects, where performance may be maintained in outdoor time trials at ambient temperatures as high as 36°C (36°C UTCI; 28°C WBGT). Power output during indoor trials may also be maintained with temperatures up to at least 27°C when humidity is modest and wind speed matches the movement speed generated during outdoor cycling, whereas marked reductions are observed when air movement is minimal. For running, representing an exercise mode with lower movement speed and higher heat production for a given metabolic rate, it appears that endurance is affected even at much lower ambient temperatures. On this basis we conclude that environmental heat stress impacts self-paced endurance performance. However, the effect is markedly modified by acclimatization status and exercise mode, as the wind generated by the exercise (movement speed) or the environment (natural or fan air movement) exerts a strong influence.
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Affiliation(s)
- Nicklas Junge
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen , Denmark
| | - Rasmus Jørgensen
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen , Denmark
| | - Andreas D Flouris
- FAME Laboratory, Department of Exercise Science, University of Thessaly , Trikala, Greece
| | - Lars Nybo
- Department of Nutrition, Exercise and Sports, August Krogh Building, University of Copenhagen , Denmark
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19
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PÉRIARD JULIEND, RACINAIS SÉBASTIEN. Performance and Pacing during Cycle Exercise in Hyperthermic and Hypoxic Conditions. Med Sci Sports Exerc 2016; 48:845-53. [DOI: 10.1249/mss.0000000000000839] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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20
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Cramer MN, Thompson MW, Périard JD. Thermal and Cardiovascular Strain Mitigate the Potential Benefit of Carbohydrate Mouth Rinse During Self-Paced Exercise in the Heat. Front Physiol 2015; 6:354. [PMID: 26635634 PMCID: PMC4658580 DOI: 10.3389/fphys.2015.00354] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 11/10/2015] [Indexed: 11/23/2022] Open
Abstract
Purpose: To determine whether a carbohydrate mouth rinse can alter self-paced exercise performance independently of a high degree of thermal and cardiovascular strain. Methods: Eight endurance-trained males performed two 40-km cycling time trials in 35°C, 60% RH while swilling a 20-ml bolus of 6.5% maltodextrin (CHO) or a color- and taste-matched placebo (PLA) every 5 km. Heart rate, power output, rectal temperature (Tre), and mean skin temperature (Tsk) were recorded continuously; cardiac output, oxygen uptake (VO2), mean arterial pressure (MAP), and perceived exertion (RPE) were measured every 10 min. Results: Performance time and mean power output were similar between treatments, averaging 63.9 ± 3.2 and 64.3 ± 2.8 min, and 251 ± 23 and 242 ± 18 W in CHO and PLA, respectively. Power output, stroke volume, cardiac output, MAP, and VO2 decreased during both trials, increasing slightly or remaining stable during a final 2-km end-spurt. Tre, Tsk, heart rate, and RPE increased throughout exercise similarly with both treatments. Changes in RPE correlated with those in Tre (P < 0.005) and heart rate (P < 0.001). Conclusions: These findings suggest that carbohydrate mouth rinsing does not improve ~1-h time trial performance in hot-humid conditions, possibly due to a failure in down-regulating RPE, which may be influenced more by severe thermal and cardiovascular strain.
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Affiliation(s)
- Matthew N Cramer
- School of Human Kinetics, Faculty of Health Sciences, University of Ottawa Ottawa, ON, Canada ; Discipline of Exercise and Sport Science, Faculty of Health Sciences, University of Sydney Lidcombe, NSW, Australia
| | - Martin W Thompson
- Discipline of Exercise and Sport Science, Faculty of Health Sciences, University of Sydney Lidcombe, NSW, Australia
| | - Julien D Périard
- Discipline of Exercise and Sport Science, Faculty of Health Sciences, University of Sydney Lidcombe, NSW, Australia ; Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital Doha, Qatar
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21
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Trangmar SJ, Chiesa ST, Llodio I, Garcia B, Kalsi KK, Secher NH, González-Alonso J. Dehydration accelerates reductions in cerebral blood flow during prolonged exercise in the heat without compromising brain metabolism. Am J Physiol Heart Circ Physiol 2015; 309:H1598-607. [PMID: 26371170 PMCID: PMC4670459 DOI: 10.1152/ajpheart.00525.2015] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/03/2015] [Indexed: 11/23/2022]
Abstract
Reductions in cerebral blood flow and extracranial perfusion, induced by dehydration during prolonged exercise in the heat, may be coupled to fatigue. However, cerebral metabolism remains stable through enhanced O2 and glucose extraction. Thus, fatigue developed during prolonged exercise with dehydration is related to reductions in cerebral blood flow rather than to the cerebral metabolic rate for O2. Dehydration hastens the decline in cerebral blood flow (CBF) during incremental exercise, whereas the cerebral metabolic rate for O2 (CMRO2) is preserved. It remains unknown whether CMRO2 is also maintained during prolonged exercise in the heat and whether an eventual decline in CBF is coupled to fatigue. Two studies were undertaken. In study 1, 10 male cyclists cycled in the heat for ∼2 h with (control) and without fluid replacement (dehydration) while internal and external carotid artery blood flow and core and blood temperature were obtained. Arterial and internal jugular venous blood samples were assessed with dehydration to evaluate CMRO2. In study 2, in 8 male subjects, middle cerebral artery blood velocity was measured during prolonged exercise to exhaustion in both dehydrated and euhydrated states. After a rise at the onset of exercise, internal carotid artery flow declined to baseline with progressive dehydration (P < 0.05). However, cerebral metabolism remained stable through enhanced O2 and glucose extraction (P < 0.05). External carotid artery flow increased for 1 h but declined before exhaustion. Fluid ingestion maintained cerebral and extracranial perfusion throughout nonfatiguing exercise. During exhaustive exercise, however, euhydration delayed but did not prevent the decline in cerebral perfusion. In conclusion, during prolonged exercise in the heat, dehydration accelerates the decline in CBF without affecting CMRO2 and also restricts extracranial perfusion. Thus, fatigue is related to a reduction in CBF and extracranial perfusion rather than CMRO2.
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Affiliation(s)
- Steven J Trangmar
- Centre for Sports Medicine and Human Performance, Brunel University London, Uxbridge, United Kingdom; and
| | - Scott T Chiesa
- Centre for Sports Medicine and Human Performance, Brunel University London, Uxbridge, United Kingdom; and
| | - Iñaki Llodio
- Centre for Sports Medicine and Human Performance, Brunel University London, Uxbridge, United Kingdom; and
| | - Benjamin Garcia
- Centre for Sports Medicine and Human Performance, Brunel University London, Uxbridge, United Kingdom; and
| | - Kameljit K Kalsi
- Centre for Sports Medicine and Human Performance, Brunel University London, Uxbridge, United Kingdom; and
| | - Niels H Secher
- Centre for Sports Medicine and Human Performance, Brunel University London, Uxbridge, United Kingdom; and Department of Anaesthesia, The Copenhagen Muscle Research Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - José González-Alonso
- Centre for Sports Medicine and Human Performance, Brunel University London, Uxbridge, United Kingdom; and
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22
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González Henríquez JJ, Losa-Reyna J, Torres-Peralta R, Rådegran G, Koskolou M, Calbet JAL. A new equation to estimate temperature-corrected PaCO2 from PET CO2 during exercise in normoxia and hypoxia. Scand J Med Sci Sports 2015; 26:1045-51. [PMID: 26314285 DOI: 10.1111/sms.12545] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2015] [Indexed: 01/11/2023]
Abstract
End-tidal PCO2 (PET CO2 ) has been used to estimate arterial pressure CO2 (Pa CO2 ). However, the influence of blood temperature on the Pa CO2 has not been taken into account. Moreover, there is no equation validated to predict Pa CO2 during exercise in severe acute hypoxia. To develop a new equation to predict temperature-corrected Pa CO2 values during exercise in normoxia and severe acute hypoxia, 11 volunteers (21.2 ± 2.1 years) performed incremental exercise to exhaustion in normoxia (Nox, PI O2 : 143 mmHg) and hypoxia (Hyp, PI O2 : 73 mmHg), while arterial blood gases and temperature (ABT) were simultaneously measured together with end-tidal PCO2 (PET CO2 ). The Jones et al. equation tended to underestimate the temperature corrected (tc) Pa CO2 during exercise in hypoxia, with greater deviation the lower the Pa CO2 tc (r = 0.39, P < 0.05). The new equation has been developed using a random-effects regression analysis model, which allows predicting Pa CO2 tc both in normoxia and hypoxia: Pa CO2 tc = 8.607 + 0.716 × PET CO2 [R(2) = 0.91; intercept SE = 1.022 (P < 0.001) and slope SE = 0.027 (P < 0.001)]. This equation may prove useful in noninvasive studies of brain hemodynamics, where an accurate estimation of Pa CO2 is needed to calculate the end-tidal-to-arterial PCO2 difference, which can be used as an index of pulmonary gas exchange efficiency.
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Affiliation(s)
- J J González Henríquez
- Department of Mathematics, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
| | - J Losa-Reyna
- Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
| | - R Torres-Peralta
- Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
| | - G Rådegran
- Department of Clinical Sciences Lund, Cardiology, Lund University, Lund, Sweden.,The Haemodynamic Laboratory, The Section for Heart Failure and Valvular Disease, The Clinic for Heart and Lung Disease, Skåne University Hospital, Lund, Sweden
| | - M Koskolou
- Faculty of Physical Education and Sport Science, National and Kapodistrian University of Athens, Athens, Greece
| | - J A L Calbet
- Research Institute of Biomedical and Health Sciences (IUIBS), University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain.,Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Canary Islands, Spain
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23
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Périard JD, Racinais S. Self-paced exercise in hot and cool conditions is associated with the maintenance of %V̇O2peak within a narrow range. J Appl Physiol (1985) 2015; 118:1258-65. [PMID: 25814635 DOI: 10.1152/japplphysiol.00084.2015] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 03/23/2015] [Indexed: 11/22/2022] Open
Abstract
This study examined the time course and extent of decrease in peak oxygen uptake (V̇O2peak) during self-paced exercise in HOT (35°C and 60% relative humidity) and COOL (18°C and 40% relative humidity) laboratory conditions. Ten well-trained cyclists completed four consecutive 16.5-min time trials (15-min self-paced effort with 1.5-min maximal end-spurt to determine V̇O2peak) interspersed by 5 min of recovery on a cycle ergometer in each condition. Rectal temperature increased significantly more in HOT (39.4 ± 0.7°C) than COOL (38.6 ± 0.3°C; P < 0.001). Power output was lower throughout HOT compared with COOL (P < 0.001). The decrease in power output from trial 1 to 4 was ∼16% greater in HOT (P < 0.001). Oxygen uptake (V̇o2) was lower throughout HOT than COOL (P < 0.05), except at 5 min and during the end-spurt in trial 1. In HOT, V̇O2peak reached 97, 89, 85, and 85% of predetermined maximal V̇o2, whereas in COOL 97, 94, 93, and 92% were attained. Relative exercise intensity (%V̇O2peak) during trials 1 and 2 was lower in HOT (∼84%) than COOL (∼86%; P < 0.05), decreasing slightly during trials 3 and 4 (∼80 and ∼85%, respectively; P < 0.05). However, heart rate was higher throughout HOT (P = 0.002), and ratings of perceived exertion greater during trials 3 and 4 in HOT (P < 0.05). Consequently, the regulation of self-paced exercise appears to occur in conjunction with the maintenance of %V̇O2peak within a narrow range (80-85% V̇O2peak). This range widens under heat stress, however, when exercise becomes protracted and a disassociation develops between relative exercise intensity, heart rate, and ratings of perceived exertion.
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Affiliation(s)
- Julien D Périard
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Sébastien Racinais
- Athlete Health and Performance Research Centre, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
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