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Heat acclimation performance

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
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
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...
August 11, 2016: Cell Stress & Chaperones
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
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
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
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
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
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
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
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
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
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
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
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
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
D Narinç, S Erdoğan, E Tahtabiçen, T Aksoy
Stress based on high temperature and humidity reduces the production performance of fast-growing broilers and causes high mortality. Temperatures higher than optimum have been applied to broilers in the embryonic period in order to overcome thermal stress. This study was conducted to investigate the effects of exposure to two long-term high-thermal environments on the developmental stability of embryonic growth, hatchability and chick quality. For this purpose, 600 broiler eggs were incubated. Treatments consisted of eggs incubated at 37...
August 2016: Animal: An International Journal of Animal Bioscience
A G B Willmott, O R Gibson, M Hayes, N S Maxwell
Endurance performances are impaired under conditions of elevated heat stress. Short term heat acclimation (STHA) over 4-6 days can evoke rapid adaptation, which mitigate decrements in performance and alleviate heat strain. This study investigated the efficacy of twice daily heat acclimation (TDHA) compared to single session per day heat acclimation (SDHA) and normothermic training, at inducing heat acclimation phenotype and its impact upon running performance in hot, humid conditions. Twenty one, moderately trained males were matched and assigned to three groups; SDHA (mean±SD) (peak oxygen consumption [V̇O2peak] 45...
February 2016: Journal of Thermal Biology
T Esperk, A Kjaersgaard, R J Walters, D Berger, W U Blanckenhorn
Extreme weather events such as heat waves are becoming more frequent and intense. Populations can cope with elevated heat stress by evolving higher basal heat tolerance (evolutionary response) and/or stronger induced heat tolerance (plastic response). However, there is ongoing debate about whether basal and induced heat tolerance are negatively correlated and whether adaptive potential in heat tolerance is sufficient under ongoing climate warming. To evaluate the evolutionary potential of basal and induced heat tolerance, we performed experimental evolution on a temperate source population of the dung fly Sepsis punctum...
May 2016: Journal of Evolutionary Biology
Shu-Hui Yu, Pu Yang, Tao Sun, Qian Qi, Xue-Qing Wang, Xiao-Ming Chen, Ying Feng, Bo-Wen Liu
The Chinese white wax scale insect, Ericerus pela, can survive at extremely low temperatures, and some overwintering individuals exhibit supercooling at temperatures below -30°C. To investigate the deep supercooling ability of E. pela, transcriptomic and proteomic analyses were performed to delineate the major gene and protein families responsible for the deep supercooling ability of overwintering females. Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that genes involved in the mitogen-activated protein kinase, calcium, and PI3K-Akt signaling pathways and pathways associated with the biosynthesis of soluble sugars, sugar alcohols and free amino acids were dominant...
June 2016: Insect Science
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