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Heat acclimation performance

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https://www.readbyqxmd.com/read/28177747/short-term-heat-acclimation-improves-the-determinants-of-endurance-performance-and-5-000-m-running-performance-in-the-heat
#1
Carl Alexander James, Alan J Richardson, Peter W Watt, Ashley G B Willmott, Oliver R Gibson, Neil S Maxwell
This study investigated the effect of 5 days controlled hyperthermia heat acclimation (STHA) on the determinants of endurance performance and 5 km performance in runners, relative to the impairment afforded by moderate heat stress. A control group (CON), matched for total work and power output (2.7 W.kg-1), differentiated thermal and exercise contributions of STHA on exercise performance. Seventeen participants (10 STHA, 7 CON) completed graded exercise tests (GXT) in cool (13°C, 50% RH, pre training) and hot conditions (32°C, 60% RH, pre and post training), as well as 5 km time trials (TT) in the heat, pre and post training...
November 18, 2016: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
https://www.readbyqxmd.com/read/28177370/fermentation-products-as-feed-additives-mitigate-some-ill-effects-of-heat-stress-in-pigs
#2
S Kumar, B E Bass, M Bandrick, C L Loving, S L Brockmeier, T Looft, J Trachsel, D M Madson, M Thomas, T A Casey, J W Frank, T B Stanton, H K Allen
Heat stress (HS) may result in economic losses to pig producers across the USA and worldwide. Despite significant advancements in management practices, HS continues to be a challenge. In this study, an in-feed antibiotic (carbadox, CBX) and antibiotic alternatives ( [XPC], and [SGX] fermentation products) were evaluated in a standard pig starter diet as mitigations against the negative effects of HS in pigs. A total of 100 gilts were obtained at weaning (6.87 ± 0.82 kg BW, 19.36 ± 0.72 d of age) and randomly assigned to dietary treatments (2 rooms/treatment, 2 pens/room, 6 to 7 pigs/pen)...
January 2017: Journal of Animal Science
https://www.readbyqxmd.com/read/28052099/effects-of-thermal-regimes-starvation-and-age-on-heat-tolerance-of-the-parthenium-beetle-zygogramma-bicolorata-coleoptera-chrysomelidae-following-dynamic-and-static-protocols
#3
Frank Chidawanyika, Casper Nyamukondiwa, Lorraine Strathie, Klaus Fischer
Temperature and resource availability are key elements known to limit the occurrence and survival of arthropods in the wild. In the current era of climate change, critical thermal limits and the factors affecting these may be of particular importance. We therefore investigated the critical thermal maxima (CTmax) of adult Zygogramma bicolorata beetles, a biological control agent for the invasive plant Parthenium hysterophorus, in relation to thermal acclimation, hardening, age, and food availability using static (constant) and dynamic (ramping) protocols...
2017: PloS One
https://www.readbyqxmd.com/read/28035584/from-lab-to-real-world-heat-acclimation-considerations-for-elite-athletes
#4
Julia R Casadio, Andrew E Kilding, James D Cotter, Paul B Laursen
As major sporting events are often held in hot environments, increased interest in ways of optimally heat acclimating athletes to maximise performance has emerged. Heat acclimation involves repeated exercise sessions in hot conditions that induce physiological and thermoregulatory adaptations that attenuate heat-induced performance impairments. Current evidence-based guidelines for heat acclimation are clear, but the application of these recommendations is not always aligned with the time commitments and training priorities of elite athletes...
December 29, 2016: Sports Medicine
https://www.readbyqxmd.com/read/27935427/short-term-heat-acclimation-prior-to-a-multi-day-desert-ultra-marathon-improves-physiological-and-psychological-responses-without-compromising-immune-status
#5
Ashley G B Willmott, Mark Hayes, Kirsty A M Waldock, Rebecca L Relf, Emily R Watkins, Carl A James, Oliver R Gibson, Nicholas J Smeeton, Alan J Richardson, Peter W Watt, Neil S Maxwell
Multistage, ultra-endurance events in hot, humid conditions necessitate thermal adaptation, often achieved through short term heat acclimation (STHA), to improve performance by reducing thermoregulatory strain and perceptions of heat stress. This study investigated the physiological, perceptual and immunological responses to STHA prior to the Marathon des Sables. Eight athletes (age 42 ± 4 years and body mass 81.9 ± 15.0 kg) completed 4 days of controlled hyperthermia STHA (60 min·day(‒1), 45°C and 30% relative humidity)...
December 9, 2016: Journal of Sports Sciences
https://www.readbyqxmd.com/read/27932993/effect-of-permissive-dehydration-on-induction-and-decay-of-heat-acclimation-and-temperate-exercise-performance
#6
Rebecca A Neal, Heather C Massey, Michael J Tipton, John S Young, Jo Corbett
Purpose: It has been suggested that dehydration is an independent stimulus for heat acclimation (HA), possibly through influencing fluid-regulation mechanisms and increasing plasma volume (PV) expansion. There is also some evidence that HA may be ergogenic in temperate conditions and that this may be linked to PV expansion. We investigated: (i) the influence of dehydration on the time-course of acquisition and decay of HA; (ii) whether dehydration augmented any ergogenic benefits in temperate conditions, particularly those related to PV expansion...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27927623/metabolic-and-functional-characterization-of-effects-of-developmental-temperature-in-drosophila-melanogaster
#7
Mads F Schou, Torsten Nygaard Kristensen, Anders Pedersen, Goran B Karlsson, Volker Loeschcke, Anders Malmendal
The ability of ectotherms to respond to changes in their thermal environment through plastic mechanisms is central to their adaptive capability. However, we still lack knowledge on physiological and functional responses by which ectotherms acclimate to temperatures during development, and in particular, how physiological stress at extreme temperatures may counteract beneficial acclimation responses at benign temperatures. We exposed Drosophila melanogaster to ten developmental temperatures covering their entire permissible temperature range...
December 7, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27903515/passive-heat-acclimation-improves-skeletal-muscle-contractility-in-humans
#8
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
#9
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...
February 2017: 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
#10
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
#11
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
#12
COMPARATIVE STUDY
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
Oliver R Gibson, Ashley G B Willmott, Carl A James, Mark Hayes, Neil S Maxwell
Gibson, OR, Willmott, AGB, James, CA, Hayes, M, and Maxwell, NS. Power relative to body mass best predicts change in core temperature during exercise-heat stress. J Strength Cond Res 31(2): 403-414, 2017-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...
February 2017: 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
#19
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
#20
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
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