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Corbett J, Young JS, Tipton MJ, Costello JT, Williams TB, Walker EF, Lee BJ, Stevens CE. Molecular biomarkers for assessing the heat-adapted phenotype: a narrative scoping review. J Physiol Sci 2023; 73:26. [PMID: 37848829 DOI: 10.1186/s12576-023-00882-4] [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: 06/13/2023] [Accepted: 10/03/2023] [Indexed: 10/19/2023]
Abstract
Heat acclimation/acclimatisation (HA) mitigates heat-related decrements in physical capacity and heat-illness risk and is a widely advocated countermeasure for individuals operating in hot environments. The efficacy of HA is typically quantified by assessing the thermo-physiological responses to a standard heat acclimation state test (i.e. physiological biomarkers), but this can be logistically challenging, time consuming, and expensive. A valid molecular biomarker of HA would enable evaluation of the heat-adapted state through the sampling and assessment of a biological medium. This narrative review examines candidate molecular biomarkers of HA, highlighting the poor sensitivity and specificity of these candidates and identifying the current lack of a single 'standout' biomarker. It concludes by considering the potential of multivariable approaches that provide information about a range of physiological systems, identifying a number of challenges that must be overcome to develop a valid molecular biomarker of the heat-adapted state, and highlighting future research opportunities.
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Affiliation(s)
- J Corbett
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK.
| | - J S Young
- National Horizons Centre, Teesside University, Darlington, UK
| | - M J Tipton
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
| | - J T Costello
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
| | - T B Williams
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
| | - E F Walker
- Defence Science and Technology Laboratory, Porton Down, Salisbury, UK
| | - B J Lee
- Occupational and Environmental Physiology Group, Centre for Sport, Exercise and Life Sciences, Faculty of Health and Life Sciences, Coventry University, Coventry, UK
| | - C E Stevens
- Extreme Environments Laboratory, School of Sport Health and Exercise Sciences, University of Portsmouth, Portsmouth, UK
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Kane DA, Foo ACY, Noftall EB, Brebner K, Marangoni DG. Lactate shuttling as an allostatic means of thermoregulation in the brain. Front Neurosci 2023; 17:1144639. [PMID: 37250407 PMCID: PMC10217782 DOI: 10.3389/fnins.2023.1144639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 04/18/2023] [Indexed: 05/31/2023] Open
Abstract
Lactate, the redox-balanced end product of glycolysis, travels within and between cells to fulfill an array of physiologic functions. While evidence for the centrality of this lactate shuttling in mammalian metabolism continues to mount, its application to physical bioenergetics remains underexplored. Lactate represents a metabolic "cul-de-sac," as it can only re-enter metabolism by first being converted back to pyruvate by lactate dehydrogenase (LDH). Given the differential distribution of lactate producing/consuming tissues during metabolic stresses (e.g., exercise), we hypothesize that lactate shuttling vis-à-vis the exchange of extracellular lactate between tissues serves a thermoregulatory function, i.e., an allostatic strategy to mitigate the consequences of elevated metabolic heat. To explore this idea, the rates of heat and respiratory oxygen consumption in saponin-permeabilized rat cortical brain samples fed lactate or pyruvate were measured. Heat and respiratory oxygen consumption rates, and calorespirometric ratios were lower during lactate vs. pyruvate-linked respiration. These results support the hypothesis of allostatic thermoregulation in the brain with lactate.
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Affiliation(s)
- Daniel A. Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS, Canada
| | - Alexander C. Y. Foo
- Department of Chemistry, St. Francis Xavier University, Antigonish, NS, Canada
| | - Erin B. Noftall
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, NS, Canada
| | - Karen Brebner
- Department of Psychology, St. Francis Xavier University, Antigonish, NS, Canada
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Borg DN, O'Brien JL. Comment on "Effects of Heat Acclimation and Acclimatisation on Maximal Aerobic Capacity Compared to Exercise Alone in Both Thermoneutral and Hot Environments: A Meta-Analysis and Meta-Regression". Sports Med 2022; 52:1715-1718. [PMID: 34874545 DOI: 10.1007/s40279-021-01611-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2021] [Indexed: 11/26/2022]
Affiliation(s)
- David N Borg
- Menzies Health Institute Queensland, The Hopkins Centre, Griffith University, Brisbane, Australia.
- School of Health Sciences and Social Work, Griffith University, Brisbane, Australia.
| | - Julia L O'Brien
- School of Mathematical Sciences, Queensland University of Technology, Brisbane, Australia
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Effects of Heat Acclimation Following Heat Acclimatization on Whole Body Heat Exchange in Trained Endurance Athletes. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19116412. [PMID: 35681997 PMCID: PMC9180767 DOI: 10.3390/ijerph19116412] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/16/2022] [Accepted: 05/19/2022] [Indexed: 02/05/2023]
Abstract
The purpose of this study was to examine the changes in metabolic heat production (Hprod), evaporative heat loss (Hevap), and dry heat loss (Hdry), following heat acclimatization (HAz) and heat acclimation (HA). Twenty-two male endurance athletes (mean ± standard deviation; age, 37 ± 12 y; body mass, 73.4 ± 8.7 kg; height, 178.7 ± 6.8 cm; and VO2max, 57.1 ± 7.2 mL·kg−1·min−1) completed three trials (baseline; post-HAz; and post-HA), which consisted of 60 min steady state exercise at 59 ± 2% velocityVO2max in the heat (ambient temperature [Tamb], 35.2 ± 0.6 °C; relative humidity [%rh] 47.5 ± 0.4%). During the trial, VO2 and RER were collected to calculate Hprod, Hevap, and Hdry. Following the baseline trial, participants completed self-directed outdoor summer training followed by a post-HAz trial. Then, five days of HA were completed over eight days in the heat (Tamb, 38.7 ± 1.1 °C; %rh, 51.2 ± 2.3%). During the HA sessions, participants exercised to maintain hyperthermia (38.50 °C and 39.75 °C) for 60 min. Then, a post-HA trial was performed. There were no differences in Hprod between the baseline (459 ± 59 W·m−2), post-HAz (460 ± 61 W·m−2), and post-HA (464 ± 55 W·m−2, p = 0.866). However, Hevap was significantly increased post-HA (385 ± 84 W·m−2) compared to post-HAz (342 ± 86 W·m−2, p = 0.043) and the baseline (332 ± 77 W·m−2, p = 0.037). Additionally, Hdry was significantly lower at post-HAz (125 ± 8 W·m−2, p = 0.013) and post-HA (121 ± 10 W·m−2, p < 0.001) compared to the baseline (128 ± 7 W·m−2). Hdry at post-HA was also lower than post-HAz (p = 0.049). Hprod did not change following HAz and HA. While Hdry was decreased following HA, the decrease in Hdry was smaller than the increases in Hevap. Adaptations in body heat exchange can occur by HA following HAz.
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Bartolomé I, Siquier-Coll J, Pérez-Quintero M, Robles-Gil MC, Grijota FJ, Muñoz D, Maynar-Mariño M. 3-Week passive acclimation to extreme environmental heat (100± 3 °C) in dry sauna increases physical and physiological performance among young semi-professional football players. J Therm Biol 2021; 100:103048. [PMID: 34503795 DOI: 10.1016/j.jtherbio.2021.103048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 05/10/2021] [Accepted: 06/26/2021] [Indexed: 10/21/2022]
Abstract
This manuscript aims to evaluate the influence of a novel passive heat acclimation program among human participants in the physical performance, as well as in several physiological parameters. 36 male football players were acclimated using a dry sauna bath to extreme hot (100 ± 3 °C), performing a total of nine sauna sessions with a weekly frequency of three sessions. The players were randomly into the sauna group (SG; n = 18; age: 20.69 ± 2.09 years) and the control group (CG; n = 18; age: 20.23 ± 1.98 years). All participants performed maximal effort test until exhaustion as well as hamstring flexibility test before and after the acclimation program. Anthropometric, respiratory, circulatory, hematological and physiological variables were evaluated at the beginning and at the end of the survey. Statistical analysis consisted of a Mann-Whitney U test to determine differences between groups at the beginning and at the end of the survey and a Wilcoxon test for paired samples to compare the differences for each group separately. Additionally, size effects of the pre-post acclimation changes were calculated. After the acclimation program SG participants experienced a diminution in body weight (p < 0.01), body mass index (p < 0.01), body fat (p < 0.05) and fat percentage (p < 0.05) decreased. Hamstring flexibility (p < 0.05) and work capacity (p < 0.05) increased. External basal temperature decreased (p < 0.05) as well as post-exercise systolic and diastolic blood pressures (p < 0.05). Finally, maximal oxygen uptake (ml Kg-1 min-1) (p < 0.05), maximal minute ventilation (p < 0.05) and maximal breath frequency (p < 0.05) increased at the end of the intervention. There were no significant changes in the CG in any variable. Favorable adaptations have been observed in this survey, suggesting a beneficial effect of extreme heat acclimation on physical performance. Several of the observed responses seem interesting for sport performance and health promotion as well. However, this is a novel, extreme protocol which requires further research.
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Affiliation(s)
- I Bartolomé
- Sport Sciences Faculty, University of Extremadura, Avenida de la Universidad s/n, 10003, Cáceres, Spain
| | - J Siquier-Coll
- Movement, Brain and Health Research Group (MOBhE), Center of Higher Education Alberta Giménez (Comillas Pontifical University), Palma de Mallorca, Balearic Islands, Spain.
| | - M Pérez-Quintero
- Sport Sciences Faculty, University of Extremadura, Avenida de la Universidad s/n, 10003, Cáceres, Spain
| | - M C Robles-Gil
- Sport Sciences Faculty, University of Extremadura, Avenida de la Universidad s/n, 10003, Cáceres, Spain
| | - F J Grijota
- Faculty of Language and Education, University of Nebrija, Campus La Berzosa, Calle del Hostal, 28248, Hoyo de Manzanares, Madrid, Spain
| | - D Muñoz
- Sport Sciences Faculty, University of Extremadura, Avenida de la Universidad s/n, 10003, Cáceres, Spain
| | - M Maynar-Mariño
- Sport Sciences Faculty, University of Extremadura, Avenida de la Universidad s/n, 10003, Cáceres, Spain
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Benjamin CL, Sekiguchi Y, Morrissey MC, Butler CR, Filep EM, Stearns RL, Casa DJ. The effects of hydration status and ice-water dousing on physiological and performance indices during a simulated soccer match in the heat. J Sci Med Sport 2021; 24:723-728. [DOI: 10.1016/j.jsams.2021.05.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 04/30/2021] [Accepted: 05/17/2021] [Indexed: 12/27/2022]
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Effects of Heat Acclimation and Acclimatisation on Maximal Aerobic Capacity Compared to Exercise Alone in Both Thermoneutral and Hot Environments: A Meta-Analysis and Meta-Regression. Sports Med 2021; 51:1509-1525. [PMID: 33811616 PMCID: PMC8222027 DOI: 10.1007/s40279-021-01445-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2021] [Indexed: 11/25/2022]
Abstract
Background Heat acclimation and acclimatisation (HA) is typically used to enhance tolerance to the heat, thereby improving performance. HA might also confer a positive adaptation to maximal oxygen consumption (\documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max), although this has been historically debated and requires clarification via meta-analysis. Objectives (1) To meta-analyse all studies (with and without control groups) that have investigated the effect of HA on \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max adaptation in thermoneutral or hot environments; (2) Conduct meta-regressions to establish the moderating effect of selected variables on \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max adaptation following HA. Methods A search was performed using various databases in May 2020. The studies were screened using search criteria for eligibility. Twenty-eight peer-reviewed articles were identified for inclusion across four separate meta-analyses: (1) Thermoneutral \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max within-participants (pre-to-post HA); (2) Hot \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max within-participants (pre-to-post HA); (3) Thermoneutral \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max measurement; HA vs. control groups; (4) Hot \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max measurement, HA vs. control groups. Meta-regressions were performed for each meta-analysis based on: isothermal vs. iso-intensity programmes, days of heat exposure, HA ambient temperature (°C), heat index, HA session duration (min), ambient thermal load (HA session x ambient temperature), mean mechanical intensity (W) and the post-HA testing period (days). Results The meta-analysis of pre–post differences in thermoneutral \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max demonstrated small-to-moderate improvements in \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max (Hedges’ g = 0.42, 95% CI 0.24–0.59, P < 0.001), whereas moderate improvements were found for the equivalent analysis of hot \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max changes (Hedges’ g = 0.63, 95% CI 0.26–1.00, P < 0.001), which were positively moderated by the number of days post-testing (P = 0.033, β = 0.172). Meta-analysis of control vs. HA thermoneutral \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max demonstrated a small improvement in \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max in HA compared to control (Hedges’ g = 0.30, 95% CI 0.06–0.54, P = 0.014) and this effect was larger for the equivalent hot \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max analysis where a higher (moderate-to-large) improvement in \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max was found (Hedges’ g = 0.75, 95% CI 0.22–1.27, P = 0.005), with the number of HA days (P = 0.018; β = 0.291) and the ambient temperature during HA (P = 0.003; β = 0.650) positively moderating this effect. Conclusion HA can enhance \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max adaptation in thermoneutral or hot environments, with or without control group consideration, by at least a small and up to a moderate–large amount, with the larger improvements occurring in the heat. Ambient heat, number of induction days and post-testing days can explain some of the changes in hot \documentclass[12pt]{minimal}
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\begin{document}$$V{\text{O}}_{2\max }$$\end{document}VO2max adaptation.
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Roussey G, Bernard T, Fontanari P, Louis J. Heat acclimation training with intermittent and self-regulated intensity may be used as an alternative to traditional steady state and power-regulated intensity in endurance cyclists. J Therm Biol 2021; 98:102935. [PMID: 34016357 DOI: 10.1016/j.jtherbio.2021.102935] [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] [Received: 09/07/2020] [Revised: 03/01/2021] [Accepted: 03/29/2021] [Indexed: 11/26/2022]
Abstract
The study aimed to determine the effects of self-regulated and variable intensities sustained during short-term heat acclimation training on cycling performance. Seventeen competitive-level male athletes performed a 20-km cycling time trial before (TT-PRE), immediately after (TT-POST1) and one week after (TT-POST2) a 5-day acclimation training program, including either RPE-regulated intermittent (HA-HIT, N = 9) or fixed and low-intensity (HA-LOW, N = 8) training sessions in the heat (39 °C; 40% relative humidity). Total training volume was 23% lower in HA-HIT compared to HA-LOW. Physiological responses were evaluated during a 40-min fixed-RPE cycling exercise performed before (HST-PRE) and immediately after (HST-POST) heat acclimation. All participants in HA-LOW group tended to improve mean power output from TT-PRE to TT-POST1 (+8.1 ± 5.2%; ES = 0.55 ± 0.23), as well as eight of the nine athletes in HA-HIT group (+4.3 ± 2.0%; ES = 0.29 ± 0.31) without difference between groups, but TT-POST2 results showed that improvements were dissipated one week after. Similar improvements in thermal sensation and lower elevations of core temperature in HST-POST following HA-LOW and HA-HIT training protocols suggest that high intensity and RPE regulated bouts could be an efficient strategy for short term heat acclimation protocols, for example prior to the competition. Furthermore, the modest impact of lowered thermal sensation on cycling performance confirms that perceptual responses of acclimated athletes are dissociated from physiological stress when exercising in the heat.
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Affiliation(s)
- Gilles Roussey
- Laboratoire Motricité Humaine, Education, Sport, Santé (LAMHESS), Université Côte d'Azur, Nice, France
| | - Thierry Bernard
- Laboratoire Motricité Humaine, Education, Sport, Santé (LAMHESS), Université Côte d'Azur, Nice, France
| | - Pierre Fontanari
- Laboratoire Motricité Humaine, Education, Sport, Santé (LAMHESS), Université Côte d'Azur, Nice, France
| | - Julien Louis
- Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University, Liverpool, Byrom Street, L3 3AF, United Kingdom.
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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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Popovska-Perčinić F, Manojlović-Stojanoski M, Pendovski L, Dinevska Kjovkarovska S, Miova B, Grubin J, Milošević V, Ajdžanović V. A Moderate Increase in Ambient Temperature Influences The Structure and Hormonal Secretion of Adrenal Glands in Rats. CELL JOURNAL 2020; 22:415-424. [PMID: 32347034 PMCID: PMC7211272 DOI: 10.22074/cellj.2021.6827] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/22/2019] [Indexed: 12/13/2022]
Abstract
Objective As a consequence of global warming, the increase in the average annual temperature is observed, while the living organisms actively adapt to these changes. High environmental temperature initiates numerous physiological, autonomic, and behavioral responses, and activates the stress response. Thus, the aim of the study was to investigate effect of a moderate increase in ambient temperature on the activity of the hypothalamic-pituitary-adrenocortical (HPA) axis by determining histological changes in adrenal glands and hormonal levels in adult male rats. Materials and Methods In this experimental study, the morpho-functional state of adrenal glands was estimated by stereological evaluation of parameters, including the adrenal volume, adrenocortical cell/nuclear size and number, and the volume density of vascular tissues after four days of exposure to a moderate increase in ambient temperature of 35 ± 1˚C. Novelli histochemical and vascular endothelial growth factor (VEGF) immunohistochemical staining provided insight into the adrenal gland vascular network. Additionally, the adrenal levels of aldosterone, corticosterone, and pituitary adrenocorticotropic hormone (ACTH) were determined as crucial indicators of the hypothalamic-pituitaryadrenocortical (HPA) axis activity. Results Prolonged exposure to a moderate increase in ambient temperature for four days resulted in a significant increase in ACTH level up to 24%, which altered adrenal glands both structurally and functionally. The adrenocortical volume and number of cells in all cortical zones were markedly increased (P<0.05). A statistically significant increase was shown in the level of aldosterone (16%) and corticosterone (25%) in serum levels of individuals. Conclusion Increased activity of the HPA axis reflects the response to a moderate increase in ambient temperature during four days, showing the capacity of the HPA axis to adapt the organism to daily temperature changes.
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Affiliation(s)
- Florina Popovska-Perčinić
- Department of Functional Morphology, Institute of Reproduction and Biomedicine, Faculty of Veterinary Medicine, Ss Cyril and Methodius University in Skopje, Lazar Pop Trajkov 5-7, Skopje, Republic of Macedonia
| | - Milica Manojlović-Stojanoski
- Department of Cytology, Institute for Biological Research Siniša Stanković, University of Belgrade, 142 Despot Stefan Blvd., Belgrade, Republic of Serbia. Electronic Address:
| | - Lazo Pendovski
- Department of Functional Morphology, Institute of Reproduction and Biomedicine, Faculty of Veterinary Medicine, Ss Cyril and Methodius University in Skopje, Lazar Pop Trajkov 5-7, Skopje, Republic of Macedonia
| | - Suzana Dinevska Kjovkarovska
- Department of Physiology and Biochemistry, Institute of Biology, Faculty of Natural Sciences and Mathematics, Ss Cyril and Methodius University in Skopje, Arhimedova 3, Skopje, Republic of Macedonia
| | - Biljana Miova
- Department of Physiology and Biochemistry, Institute of Biology, Faculty of Natural Sciences and Mathematics, Ss Cyril and Methodius University in Skopje, Arhimedova 3, Skopje, Republic of Macedonia
| | - Jasmina Grubin
- Ministry of Education, Science and Technological Development of the Republic of Serbia, Njegoševa 12, Belgrade, Republic of Serbia
| | - Verica Milošević
- Department of Cytology, Institute for Biological Research Siniša Stanković, University of Belgrade, 142 Despot Stefan Blvd., Belgrade, Republic of Serbia
| | - Vladimir Ajdžanović
- Department of Cytology, Institute for Biological Research Siniša Stanković, University of Belgrade, 142 Despot Stefan Blvd., Belgrade, Republic of Serbia
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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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12
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Rivas E, Crandall CG, Suman OE, Moustaid-Moussa N, Ben-Ezra V. Exercise heat acclimation causes post-exercise hypotension and favorable improvements in lipid and immune profiles: A crossover randomized controlled trial. J Therm Biol 2019; 84:266-273. [PMID: 31466764 DOI: 10.1016/j.jtherbio.2019.07.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 06/17/2019] [Accepted: 07/11/2019] [Indexed: 01/24/2023]
Abstract
BACKGROUND Passive hyperthermic exposure causes an acute hypotensive response following the cessation of heat stress. Chronic heat stress is well documented in animal studies to instigate metabolic and lipid alterations. However, it is unknown if exercise-heat acclimation also causes favorable chronic blood pressure, lipid, and immune responses in humans. PURPOSE This project tested the hypothesis that 10-day exercise-heat acclimation (HA) would cause greater post-exercise reductions in arterial blood pressure and favorable metabolic, lipid, and immune responses compared to 10-day exercise under neutral conditions (CON). METHODS Thirteen healthy sedentary participants (8M/5F, 28 ± 6y, 78 ± 17 kg), completed a 10-day (90 min/day exercise bout) clamped hyperthermia HA (increase internal temperature 1.5 °C, in 42 °C, 28% Rh) and control (CON: 23 °C, 42% Rh) protocols in a counterbalanced design with a 2 month washout. Pre- and post-exercise HA/CON blood pressures were taken 1-h post-exercise on exercise days 1 and 10. Metabolic, lipid and immune panels were taken pre-post HA/CON. RESULTS Exercise under heat stress had greater post-exercise hypotension (systolic; -6 mmHg, diastolic; -8 mmHg; and mean arterial pressure; -7 mmHg) on both days 1 and 10 compared to exercise under neutral conditions (main effect for condition, P ≤ 0.004). Only from pre-to-post HA, total cholesterol (168 ± 19 to 157 ± 15; P < 0.03) and triglycerides (137 ± 45 to 111 ± 30; P < 0.03) were reduced, while absolute lymphocytes (-26%), monocytes (-22%), and basophils (-49%) significantly decreased (each P ≤ 0.04). Relative values of neutrophils increased (18%) and lymphocytes decreased (-20%) only after HA (P ≤ 0.04). CONCLUSION These data indicate that exercise in the heat (regardless of acclimation status) causes a profound post-exercise hypotensive response, while HA causes favorable lipid, and immune profile changes. Further examination of exercise-heat acclimation on vascular, metabolic, and immune responses will offer insight for benefits in other clinical populations with vascular, metabolic and immune dysfunction.
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Affiliation(s)
- Eric Rivas
- Exercise & Thermal Integrative Physiology Laboratory, Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA; Obesity Research Institute, Texas Tech University, Lubbock, TX, USA.
| | - Craig G Crandall
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital of Dallas, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Oscar E Suman
- Department of Surgery, University of Texas Medical Branch Galveston, TX, USA
| | - Naima Moustaid-Moussa
- Obesity Research Institute, Texas Tech University, Lubbock, TX, USA; Department of Nutritional Sciences, Texas Tech University, Lubbock, TX, USA
| | - Vic Ben-Ezra
- Department of Kinesiology, Texas Woman's University, Denton, TX, USA
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