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Heat acclimation performance

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https://www.readbyqxmd.com/read/27903515/passive-heat-acclimation-improves-skeletal-muscle-contractility-in-humans
#1
Sebastien Racinais, Mathew G Wilson, Julien D Périard
The aim of this study was to investigate the effect of repeated passive heat exposure (i.e. acclimation) on muscle contractility in humans. Fourteen non-heat acclimated males completed two trials including electrically evoked twitches and voluntary contractions in thermoneutral conditions (COOL: 24ºC, 40% RH) and hot ambient conditions in the hyperthermic state (HOT: 44-50ºC, 50% RH) on consecutive days in a counterbalanced order. Rectal temperature was ~36.5ºC in COOL and was maintained at ~39ºC throughout HOT...
November 30, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27894884/modulation-of-the-heat-shock-response-is-associated-with-acclimation-to-novel-temperatures-but-not-adaptation-to-climatic-variation-in-the-ants-aphaenogaster-picea-and-a-rudis
#2
Sara Helms Cahan, Andrew D Nguyen, John Stanton-Geddes, Clint A Penick, Yainna Hernáiz-Hernández, Bernice B DeMarco, Nicholas J Gotelli
Ecological diversification into thermally divergent habitats can push species toward their physiological limits, requiring them to accommodate temperature extremes through plastic or evolutionary changes that increase persistence under the local thermal regime. One way to withstand thermal stress is to increase production of heat shock proteins, either by maintaining higher baseline abundance within cells or by increasing the magnitude of induction in response to heat stress. We evaluated whether environmental variation was associated with expression of three heat shock protein genes in two closely-related species of woodland ant, Aphaenogaster picea and A...
November 25, 2016: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
https://www.readbyqxmd.com/read/27882829/the-effects-of-heat-stress-on-a-number-of-hematological-parameters-and-levels-of-thyroid-hormones-in-foundry-workers
#3
Sahar Norloei, Mohammad Javad Jafari, Leila Omidi, Soheila Khodakarim, Davood Bashash, Mohammad Bagher Abdollahi, Mina Jafari
The objective of this research was to determine the effects of heat stress on some hematological parameters and thyroid hormones among foundry workers. This study was performed on 25 heat-acclimated subjects while 10 office workers were selected as the control group. Wet bulb globe temperature (WBGT) was determined to estimate the heat stress. Blood sampling was conducted before and after the daily work shift. The mean value of the WBGT index was 35 °C. The levels of plasma osmolality (p = 0.04) and white blood cells (p = 0...
November 24, 2016: International Journal of Occupational Safety and Ergonomics: JOSE
https://www.readbyqxmd.com/read/27881668/restoration-of-thermoregulation-after-exercise
#4
Glen P Kenny, Ryan McGinn
Performing exercise, especially in the hot conditions, can heat the body causing significant increases in internal body temperature. To offset this increase, powerful and highly developed autonomic thermoregulatory responses (i.e., skin blood flow and sweating) are activated to enhance whole-body heat loss; a response mediated by temperature sensitive receptors in both the skin and the internal core regions of the body. Independent of thermal control of heat loss, nonthermal factors can have profound consequences on the body's ability to dissipate heat during exercise...
November 23, 2016: Journal of Applied Physiology
https://www.readbyqxmd.com/read/27571045/a-comparison-of-2-practical-cooling-methods-on-cycling-capacity-in-the-heat
#5
Saul A Cuttell, Victor Kiri, Christopher Tyler
CONTEXT: Cooling the torso and neck can improve exercise performance and capacity in a hot environment; however, the proposed mechanisms for the improvements often differ. OBJECTIVE: To directly compare the effects of cooling the neck and torso region using commercially available devices on exercise capacity in a hot environment (temperature = 35°C ± 0.1°C, relative humidity = 50.1% ± 0.7%). DESIGN: Crossover study. SETTING: Laboratory...
July 2016: Journal of Athletic Training
https://www.readbyqxmd.com/read/27524970/acclimation-training-improves-endurance-cycling-performance-in-the-heat-without-inducing-endotoxemia
#6
Joshua H Guy, David B Pyne, Glen B Deakin, Catherine M Miller, Andrew M Edwards
PURPOSE: While the intention of endurance athletes undertaking short term heat training protocols is to rapidly gain meaningful physical adaption prior to competition in the heat, it is currently unclear whether or not this process also presents an overt, acute challenge to the immune system. The aim of this study was therefore to examine the effects of heat training on both endurance performance and biomarkers associated with inflammatory and immune system responses. METHODS: Moderately-actively males (n = 24) were allocated randomly to either HOT (n = 8, 35°C, and 70% RH; NEUTRAL (n = 8, 20°C, and 45% RH); or a non-exercising control group, (CON, n = 8)...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27511024/hsp72-and-hsp90%C3%AE-mrna-transcription-is-characterised-by-large-sustained-changes-in-core-temperature-during-heat-acclimation
#7
Oliver R Gibson, James A Tuttle, Peter W Watt, Neil S Maxwell, Lee Taylor
Increased intracellular heat shock protein-72 (Hsp72) and heat shock protein-90α (Hsp90α) have been implicated as important components of acquired thermotolerance, providing cytoprotection during stress. This experiment determined the physiological responses characterising increases in Hsp72 and Hsp90α mRNA on the first and tenth day of 90-min heat acclimation (in 40.2 °C, 41.0 % relative humidity (RH)) or equivalent normothermic training (in 20 °C, 29 % RH). Pearson's product-moment correlation and stepwise multiple regression were performed to determine relationships between physiological [e...
November 2016: Cell Stress & Chaperones
https://www.readbyqxmd.com/read/27467216/local-versus-whole-body-sweating-adaptations-following-14-days-of-traditional-heat-acclimation
#8
Martin P Poirier, Daniel Gagnon, Glen P Kenny
The purpose of this study was to examine if local changes in sweat rate following 14 days of heat acclimation reflect those that occur at the whole-body level. Both prior to and following a 14-day traditional heat acclimation protocol, 10 males exercised in the heat (35 °C, ∼20% relative humidity) at increasing rates of heat production equal to 300 (Ex1), 350 (Ex2), and 400 (Ex3) W·m(-2). A 10-min recovery period followed Ex1, while a 20-min recovery period separated Ex2 and Ex3. The exercise protocol was performed in a direct calorimeter to measure whole-body sweat rate and, on a separate day, in a thermal chamber to measure local sweat rate (LSR), sweat gland activation (SGA), and sweat gland output (SGO) on the upper back, chest, and mid-anterior forearm...
August 2016: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
https://www.readbyqxmd.com/read/27446126/proteomic-and-physiological-analysis-of-the-response-of-oat-avena-sativa-seeds-to-heat-stress-under-different-moisture-conditions
#9
Lingling Chen, Quanzhu Chen, Lingqi Kong, Fangshan Xia, Huifang Yan, Yanqiao Zhu, Peisheng Mao
Seeds lose their viability when they are exposed to high temperature and moisture content (MC) during storage. The expression and metabolism of proteins plays a critical role in seed resistance to heat stress. However, the proteome response to heat stress in oat (Avena sativa) seeds during storage has not been revealed. To understand mechanisms of heat stress acclimation and tolerance in oat seeds, an integrated physiological and comparative proteomic analysis was performed on oat seeds with different MC during heat stress...
2016: Frontiers in Plant Science
https://www.readbyqxmd.com/read/27401764/cardiac-reflexes-in-a-warming-world-thermal-plasticity-of-barostatic-control-and-autonomic-tones-in-a-temperate-fish
#10
E Sandblom, A Ekström, J Brijs, L F Sundström, F Jutfelt, T D Clark, A Adill, T Aho, A Gräns
Thermal plasticity of cardiorespiratory function allows ectotherms like fish to cope with seasonal temperature changes and is critical for resilience to climate change. Yet, the chronic thermal effects on cardiovascular homeostatic reflexes in fish are little understood although this may have important implications for physiological performance and overall resilience to climate warming. We compared cardiac autonomic control and baroreflex regulation of heart rate in perch (Perca fluviatilis L.) from a reference area in the Baltic Sea at 18-19°C with conspecifics from the 'Biotest enclosure', a chronically heated ecosystem receiving warmed effluent water (24-25°C) from a nuclear power plant...
July 8, 2016: Journal of Experimental Biology
https://www.readbyqxmd.com/read/27359208/power-relative-to-body-mass-best-predicts-change-in-core-temperature-during-exercise-heat-stress
#11
O R Gibson, A G B Willmott, C James, M Hayes, N S Maxwell
Controlling internal temperature is crucial when prescribing exercise-heat stress, particularly during interventions designed to induce thermoregulatory adaptations. This study aimed to determine the relationship between the rate of rectal temperature (Trec) increase, and various methods for prescribing exercise-heat stress, to identify the most efficient method of prescribing isothermic heat acclimation (HA) training.Thirty-five males cycled in hot conditions (40°C, 39%R.H.) for 29±2 min. Subjects exercised at 60±9%V[Combining Dot Above]O2peak, with methods for prescribing exercise retrospectively observed for each participant...
June 29, 2016: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/27330883/combined-active-and-passive-heat-exposure-induced-heat-acclimation-in-a-soccer-referee-before-2014-fifa-world-cup
#12
A D Ruddock, S W Thompson, S A Hudson, C A James, O R Gibson, J A Mee
INTRODUCTION: The 2014 FIFA World Cup was held in Brazil, where the climatic conditions presented a significant thermoregulatory and perceptual challenge to those unfamiliar with the heat and humidity. CASE PRESENTATION: This case report documents the adaptation induced by a novel mixed methods (isothermic and passive) heat acclimation (HA) regime for a northern European professional soccer match official prior to the tournament. The intervention involved 13 HA sessions over an 18 day period comprising five isothermic HA sessions whereby intermittent running was used to target and maintain tympanic temperature (Tytemp) at 38 °C for 90 min, and seven passive HA sessions of 48 °C water bathing for 30 min...
2016: SpringerPlus
https://www.readbyqxmd.com/read/27227084/the-effect-of-10%C3%A2-days-of-heat-acclimation-on-exercise-performance-in-acute-hypobaric-hypoxia-4350%C3%A2-m
#13
Ailish C White, Roy M Salgado, Todd A Astorino, Jack A Loeppky, Suzanne M Schneider, James J McCormick, Trisha A McLain, Len Kravitz, Christine M Mermier
To examine the effect ("cross-tolerance") of heat acclimation (HA) on exercise performance upon exposure to acute hypobaric hypoxia (4350 m). Eight male cyclists residing at 1600 m performed tests of maximal aerobic capacity (VO2max) at 1600 m and 4350 m, a 16 km time-trial at 4350 m, and a heat tolerance test at 1600 m before and after 10 d HA at 40°C, 20% RH. Resting blood samples were obtained pre-and post- HA to estimate changes in plasma volume (ΔPV). Successful HA was indicated by significantly lower exercise heart rate and rectal temperature on day 10 vs...
January 2016: Temperature: Multidisciplinary Biomedical Journal
https://www.readbyqxmd.com/read/27174711/effects-of-elevated-temperature-on-the-shell-density-of-the-large-benthic-foraminifera-amphistegina-lobifera
#14
Martina Prazeres, John M Pandolfi
This study investigated the effects of elevated temperature on shell density and Mg-ATPase activity of Amphistegina lobifera. This species is abundant in shallow reef habitats, and can be vulnerable to daily physicochemical fluctuations. To assess potential responses and acclimation mechanisms of A. lobifera to changing temperature conditions, we performed a blocked-design experiment exposing specimens collected from different reef sites (inshore and offshore) to three temperature treatments (Control: 24 °C, +2 °C: 26 °C and +5 °C: 29 °C) for 30 days...
May 13, 2016: Journal of Eukaryotic Microbiology
https://www.readbyqxmd.com/read/27157334/the-effect-of-high-versus-low-intensity-heat-acclimation-on-performance-and-neuromuscular-responses
#15
Georgia L Wingfield, Rachel Gale, Geoffrey M Minett, Frank E Marino, Melissa Skein
This study examined the effect of exercise intensity and duration during 5-day heat acclimation (HA) on cycling performance and neuromuscular responses. 20 recreationally trained males completed a 'baseline' trial followed by 5 consecutive days HA, and a 'post-acclimation' trial. Baseline and post-acclimation trials consisted of maximal voluntary contractions (MVC), a single and repeated countermovement jump protocol, 20km cycling time trial (TT) and 5×6s maximal sprints (SPR). Cycling trials were undertaken in 33...
May 2016: Journal of Thermal Biology
https://www.readbyqxmd.com/read/27157329/changes-of-brain-monoamine-levels-and-physiological-indexes-during-heat-acclimation-in-rats
#16
Hikaru Nakagawa, Takeru Matsumura, Kota Suzuki, Chisa Ninomiya, Takayuki Ishiwata
Brain monoamines, such as noradrenaline (NA), dopamine (DA), and serotonin (5-HT), regulate many important physiological functions including thermoregulation. The purpose of this study was to clarify changes in NA, DA, and 5-HT levels in several brain regions in response to heat acclimation while also recording body temperature (Tb), heart rate (HR), and locomotor activity (Act). Rats were exposed to a heated environment (32°C) for 3h (3H), 1 day (1D), 7 days, 14 days (14D), 21 days, or 28 days (28D). After heat exposure, each of the following brain regions were immediately extracted and homogenized: the caudate putamen (CPu), preoptic area (PO), dorsomedial hypothalamus (DMH), frontal cortex (FC), and hippocampus (Hip)...
May 2016: Journal of Thermal Biology
https://www.readbyqxmd.com/read/27062348/ocean-warming-alters-cellular-metabolism-and-induces-mortality-in-fish-early-life-stages-a-proteomic-approach
#17
D Madeira, J E Araújo, R Vitorino, J L Capelo, C Vinagre, M S Diniz
Climate change has pervasive effects on marine ecosystems, altering biodiversity patterns, abundance and distribution of species, biological interactions, phenology, and organisms' physiology, performance and fitness. Fish early life stages have narrow thermal windows and are thus more vulnerable to further changes in water temperature. The aim of this study was to address the sensitivity and underlying molecular changes of larvae of a key fisheries species, the sea bream Sparus aurata, towards ocean warming...
July 2016: Environmental Research
https://www.readbyqxmd.com/read/27014080/cross-acclimation-between-heat-and-hypoxia-heat-acclimation-improves-cellular-tolerance-and-exercise-performance-in-acute-normobaric-hypoxia
#18
Ben J Lee, Amanda Miller, Rob S James, Charles D Thake
BACKGROUND: The potential for cross acclimation between environmental stressors is not well understood. Thus, the aim of this investigation was to determine the effect of fixed-workload heat or hypoxic acclimation on cellular, physiological, and performance responses during post acclimation hypoxic exercise in humans. METHOD: Twenty-one males (age 22 ± 5 years; stature 1.76 ± 0.07 m; mass 71.8 ± 7.9 kg; [Formula: see text]O2 peak 51 ± 7 mL(.)kg(-1.)min(-1)) completed a cycling hypoxic stress test (HST) and self-paced 16...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/26994185/effects-of-seasonal-acclimatization-on-temperature-dependence-of-cardiac-excitability-in-the-roach-rutilus-rutilus
#19
A Badr, M F El-Sayed, M Vornanen
Temperature sensitivity of electrical excitability is a potential limiting factor for performance level and thermal tolerance of excitable tissues in ectothermic animals. To test whether the rate and rhythm of the heart acclimatize to seasonal temperature changes, thermal sensitivity of cardiac excitation in a eurythermal teleost, the roach (Rutilus rutilus), was examined. Excitability of the heart was determined from in vivo electrocardiograms and in vitro microelectrode recordings of action potentials (APs) from winter and summer roach acclimatized to 4 and 18°C, respectively...
May 15, 2016: Journal of Experimental Biology
https://www.readbyqxmd.com/read/26972988/consequences-of-acclimation-on-the-resistance-to-acute-thermal-stress-proteomic-focus-on-mussels-from-pristine-site
#20
Romain Péden, Béatrice Rocher, Philippe Chan, David Vaudry, Agnès Poret, Stéphanie Olivier, Frank Le Foll, Florence Bultelle
Climate change constitutes an additional threat for intertidal species that already have to cope with a challenging environment. The present study focuses on the blue mussel Mytilus edulis and aims at investigating the importance of thermal acclimation in heat stress response. Microcosm exposures were performed with mussels submitted to an identical acute thermal stress following two thermal summer acclimations standing for present or future temperature conditions. Gill proteomes were analyzed by 2DE and 96 differentially expressed proteoforms were identified...
October 2016: Marine Environmental Research
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