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Heat acclimation performance

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https://www.readbyqxmd.com/read/28689718/long-term-and-acute-effects-of-temperature-and-oxygen-on-metabolism-food-intake-growth-and-heat-tolerance-in-a-freshwater-gastropod
#1
K Natan Hoefnagel, Wilco C E P Verberk
Temperature affects the physiology and life-history of ectothermic animals, often increasing metabolic rate and decreasing body size. Oxygen limitation has been put forward as a mechanism to explain thermal responses of body size and the ability to survive stress. However the time-scales involved in growth performance and heat tolerance differ radically. In order to increase our understanding of oxygen and temperature effects on body size and heat tolerance and the time scale involved, we reared Lymnaea stagnalis under six combinations of temperature and oxygen tension from hatching up to an age of 300 days and recorded shell length during this whole period...
August 2017: Journal of Thermal Biology
https://www.readbyqxmd.com/read/28683139/genome-wide-survey-of-heat-shock-factors-and-heat-shock-protein-70s-and-their-regulatory-network-under-abiotic-stresses-in-brachypodium-distachyon
#2
Feng Wen, Xiaozhu Wu, Tongjian Li, Mingliang Jia, Xinshen Liu, Peng Li, Xiaojian Zhou, Xinxin Ji, Xiaomin Yue
The heat shock protein 70s (Hsp70s) and heat shock factors (Hsfs) play key roles in protecting plant cells or tissues from various abiotic stresses. Brachypodium distachyon, recently developed an excellent model organism for functional genomics research, is related to the major cereal grain species. Although B. distachyon genome has been fully sequenced, the information of Hsf and Hsp70 genes and especially the regulatory network between Hsfs and Hsp70s remains incomplete. Here, a total of 24 BdHsfs and 29 BdHsp70s were identified in the genome by bioinformatics analysis and the regulatory network between Hsfs and Hsp70s were performed in this study...
2017: PloS One
https://www.readbyqxmd.com/read/28670286/short-term-low-volume-training-improves-heat-acclimatization-in-an-operational-context
#3
Keyne Charlot, Pierre-Emmanuel Tardo-Dino, Jean-François Buchet, Nathalie Koulmann, Stéphanie Bourdon, Benoit Lepetit, Martin Roslonski, Loïc Jousseaume, Alexandra Malgoyre
Personnel who travel to areas with a hot climate (WBGT > 27°C) may suffer from the heat (physiological strain, thermal discomfort, increased probability of heat illness), making them partially or fully inoperative. Performing physical activities during heat acclimatization is known to improve this process (i.e., improve measures of acclimatization for the same duration of acclimation). However, it is unknown whether such training would be efficient in an operative context, characterized by a high volume of work-related physical activity...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28662571/scaling-from-metabolism-to-population-growth-rate-to-understand-how-acclimation-temperature-alters-thermal-performance
#4
Thomas M Luhring, John P DeLong
The mean and variance of environmental temperature are changing as a consequence of human activities. Ectotherms are sensitive to these temperature changes in the short term, typically displaying a unimodal response of most biological rates to temperature (thermal performance curves; TPCs). Many organisms, however, may acclimate or evolve in response to new temperature regimes. In particular, population growth rate TPCs (r TPCs) reflect the ability to maintain positive growth under a range of temperatures, and therefore shifts in r TPCs due to acclimation are fundamental to our understanding of how ectotherms will respond to changes in climate...
June 28, 2017: Integrative and Comparative Biology
https://www.readbyqxmd.com/read/28652334/dissecting-and-modeling-zeaxanthin-and-lutein-dependent-nonphotochemical-quenching-in-arabidopsis-thaliana
#5
Michelle Leuenberger, Jonathan M Morris, Arnold M Chan, Lauriebeth Leonelli, Krishna K Niyogi, Graham R Fleming
Photosynthetic organisms use various photoprotective mechanisms to dissipate excess photoexcitation as heat in a process called nonphotochemical quenching (NPQ). Regulation of NPQ allows for a rapid response to changes in light intensity and in vascular plants, is primarily triggered by a pH gradient across the thylakoid membrane (∆pH). The response is mediated by the PsbS protein and various xanthophylls. Time-correlated single-photon counting (TCSPC) measurements were performed on Arabidopsis thaliana to quantify the dependence of the response of NPQ to changes in light intensity on the presence and accumulation of zeaxanthin and lutein...
June 26, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28605253/pre-cooling-with-crushed-ice-is-as-effective-as-heat-acclimation-at-improving-cycling-time-trial-performance-in-the-heat
#6
Matthew Zimmermann, Grant J Landers, Karen E Wallman, Georgina Kent
This study compared pre-cooling (ice ingestion) with heat acclimation training on cycling time trial (CTT) performance in the heat. Fifteen male cyclists/triathletes completed two 800 kJ cycle time trials in the heat, with a 12-day training program in between. Initially, all participants consumed 7 g·kg(-1) of water (22°C) in 30 min, prior to completing an 800 kJ CTT in hot, humid conditions (pre-CTT) (35°C, 50% relative humidity; RH). Participants were then split into two groups, pre-cooling (n=7): trained in thermoneutral conditions then underwent pre-cooling with ice ingestion (7 g·kg(-1),1°C) prior to the final CTT (post-CTT), heat acclimation (n=8): trained in hot conditions (35°C, 50% RH) and consumed water (7 g·kg(-1)) prior to post-CTT...
June 12, 2017: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/28592459/the-effects-of-10-days-of-separate-heat-and-hypoxic-exposure-on-heat-acclimation-and-temperate-exercise-performance
#7
Rebecca A Neal, Jamie Prout, Joseph Costello, Heather C Massey, Michael J Tipton, John S Young, Jo Corbett
Adaptations to heat and hypoxia are typically studied in isolation, but are often encountered in combination. Whether the adaptive response to multiple stressors affords the same response as when examined in isolation is unclear. We examined: i) the influence of overnight moderate normobaric hypoxia on the time course and magnitude of adaption to daily heat exposure; ii) whether heat acclimation (HA) was ergogenic and if this was influenced by an additional hypoxic-stimulus. Eight males (V̇O2max=58.5[8.3] mL·kg(-1)·min(-1)) undertook two 11-day HA programmes (balanced-crossover design), once with overnight normobaric hypoxia (8[1] h per night; 10 nights; FIO2=0...
June 7, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28542380/more-oxygen-during-development-enhanced-flight-performance-but-not-thermal-tolerance-of-drosophila-melanogaster
#8
Shayan Shiehzadegan, Jacqueline Le Vinh Thuy, Natalia Szabla, Michael J Angilletta, John M VandenBrooks
High temperatures can stress animals by raising the oxygen demand above the oxygen supply. Consequently, animals under hypoxia could be more sensitive to heating than those exposed to normoxia. Although support for this model has been limited to aquatic animals, oxygen supply might limit the heat tolerance of terrestrial animals during energetically demanding activities. We evaluated this model by studying the flight performance and heat tolerance of flies (Drosophila melanogaster) acclimated and tested at different concentrations of oxygen (12%, 21%, and 31%)...
2017: PloS One
https://www.readbyqxmd.com/read/28486332/short-term-heat-acclimation-and-precooling-independently-and-combined-improve-5-km-running-performance-in-the-heat
#9
C A James, A J Richardson, A G B Willmott, P W Watt, O R Gibson, N S Maxwell
Following heat acclimation (HA), endurance running performance remains impaired in hot vs temperate conditions. Combining HA with precooling demonstrates no additive benefit in intermittent sprint, or continuous cycling exercise protocols, during which heat strain may be less severe compared to endurance running. This study investigated the effect of short-term heat acclimation (STHA) combined with mixed-methods precooling, on endurance running performance and directly compared precooling and HA. Nine amateur trained runners completed 5 km treadmill time trials in the heat (32°C, 60% RH) under four conditions; no intervention (CON), precooling (PC), short-term heat acclimation (5 days - HA) and short-term heat acclimation with precooling (HA+PC)...
May 5, 2017: Journal of Strength and Conditioning Research
https://www.readbyqxmd.com/read/28482796/effects-of-cold-acclimation-on-gene-expression-in-fall-field-cricket-gryllus-pennsylvanicus-ionoregulatory-tissues
#10
Lauren E Des Marteaux, Alexander H McKinnon, Hiroko Udaka, Jantina Toxopeus, Brent J Sinclair
BACKGROUND: Cold tolerance is a key determinant of temperate insect distribution and performance. Chill-susceptible insects lose ion and water homeostasis during cold exposure, but prior cold acclimation improves both cold tolerance and defense of homeostasis. The mechanisms underlying these processes are mostly unknown; cold acclimation is thought to enhance ion transport in the cold and/or prevent leak of water and ions. To identify candidate mechanisms of cold tolerance plasticity we generated transcriptomes of ionoregulatory tissues (hindgut and Malpighian tubules) from Gryllus pennsylvanicus crickets and compared gene expression in warm- and cold-acclimated individuals...
May 8, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28462685/effect-of-heat-exposure-on-cognition-in-persons-with-tetraplegia
#11
John P Handrakis, Zhen Ni Guan, John W Nulty, Oriana Tascione, Dwindally Rosado-Rivera, Daniel White, Charlene Bang, Ann Spungen, William A Bauman
Individuals with cervical spinal cord injury (SCI) have impaired thermoregulatory mechanisms due to interruption of motor, sensory, and autonomic neuropathways. To determine the effects of heat exposure on core body temperature (Tcore) and cognitive performance in persons with tetraplegia, eight individuals with chronic tetraplegia (C3-C7, AIS A-B) and 9 able-bodied controls were acclimated to 27°C at baseline (BL) before being exposed to 35°C for up to 120 minutes (Heat Challenge). Rectal temperature (Tcore), distal skin temperatures (Tsk<sub>avg</sub>), sweat rate (QS<sub>avg</sub>), microvascular skin perfusion (LDF<sub>avg</sub>), and plasma norepinephrine (NE) were measured...
May 2, 2017: Journal of Neurotrauma
https://www.readbyqxmd.com/read/28424950/estimated-work-ability-in-warm-outdoor-environments-depends-on-the-chosen-heat-stress-assessment-metric
#12
Peter Bröde, Dusan Fiala, Bruno Lemke, Tord Kjellstrom
With a view to occupational effects of climate change, we performed a simulation study on the influence of different heat stress assessment metrics on estimated workability (WA) of labour in warm outdoor environments. Whole-day shifts with varying workloads were simulated using as input meteorological records for the hottest month from four cities with prevailing hot (Dallas, New Delhi) or warm-humid conditions (Managua, Osaka), respectively. In addition, we considered the effects of adaptive strategies like shielding against solar radiation and different work-rest schedules assuming an acclimated person wearing light work clothes (0...
April 19, 2017: International Journal of Biometeorology
https://www.readbyqxmd.com/read/28398156/a-simulated-heat-wave-has-diverse-effects-on-immune-function-and-oxidative-physiology-in-the-corn-snake-pantherophis-guttatus
#13
Z R Stahlschmidt, S S French, A Ahn, A Webb, M W Butler
Animals will continue to encounter increasingly warm environments, including more frequent and intense heat waves. Yet the physiological consequences of heat waves remain equivocal, potentially because of variation in adaptive plasticity (reversible acclimation) and/or aspects of experimental design. Thus, we measured a suite of physiological variables in the corn snake (Pantherophis guttatus) after exposure to field-parameterized, fluctuating temperature regimes (moderate temperature and heat wave treatments) to address two hypotheses: (1) a heat wave causes physiological stress, and (2) thermal performance of immune function exhibits adaptive plasticity in response to a heat wave...
July 2017: Physiological and Biochemical Zoology: PBZ
https://www.readbyqxmd.com/read/28389828/cross-adaptation-heat-and-cold-adaptation-to-improve-physiological-and-cellular-responses-to-hypoxia
#14
REVIEW
Oliver R Gibson, Lee Taylor, Peter W Watt, Neil S Maxwell
To prepare for extremes of heat, cold or low partial pressures of oxygen (O2), humans can undertake a period of acclimation or acclimatization to induce environment-specific adaptations, e.g. heat acclimation (HA), cold acclimation (CA), or altitude training. While these strategies are effective, they are not always feasible due to logistical impracticalities. Cross-adaptation is a term used to describe the phenomenon whereby alternative environmental interventions, e.g. HA or CA, may be a beneficial alternative to altitude interventions, providing physiological stress and inducing adaptations observable at altitude...
April 7, 2017: Sports Medicine
https://www.readbyqxmd.com/read/28343570/supplemental-intermittent-day-heat-training-and-the-lactate-threshold
#15
Stuart Gollan, Samuel Chalmers, Stephen Alderton, Kevin Norton
Heat acclimation over consecutive days has been shown to improve aerobic-based performance. Recently, it has been suggested that heat training can improve performance in a temperate environment. However, due to the multifactorial training demands of athletes, consecutive-day heat training may not be suitable. The current study aimed to investigate the effect of brief (8×30min) intermittent (every 3-4 days) supplemental heat training on the second lactate threshold point (LT2) in temperate and hot conditions...
April 2017: Journal of Thermal Biology
https://www.readbyqxmd.com/read/28177747/short-term-heat-acclimation-improves-the-determinants-of-endurance-performance-and-5-km-running-performance-in-the-heat
#16
Carl A 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 of controlled short-term 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 (GXTs) in cool (13 °C, 50% relative humidity (RH), pre-training) and hot conditions (32 °C, 60% RH, pre- and post-training), as well as 5-km time trials (TTs) in the heat, pre- and post-training...
March 2017: 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
#17
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
#18
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
#19
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...
August 2017: 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
#20
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
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