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Heat acclimation performance

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https://www.readbyqxmd.com/read/28992016/determining-the-effects-of-early-gestation-in-utero-heat-stress-on-postnatal-fasting-heat-production-and-circulating-biomarkers-associated-with-metabolism-in-growing-pigs
#1
N M Chapel, C J Byrd, D W Lugar, G M Morello, L H Baumgard, J W Ross, T J Safranski, M C Lucy, J S Johnson
The study objective was to characterize effects of early gestation in utero heat stress (IUHS) on postnatal fasting heat production (FHP) and blood biomarkers associated with metabolism in growing pigs. Based on previous observation of increased postnatal core body temperature set point in IUHS pigs, we hypothesized that FHP would be altered during postnatal life because of IUHS. Pregnant first-parity gilts were exposed to thermoneutral (TN; = 4; 17.8 ± 0.1°C) or heat stress (HS; = 4; cyclical 28 to 38°C) conditions from d 30 to 60 of gestation...
September 2017: Journal of Animal Science
https://www.readbyqxmd.com/read/28950696/effect-of-intensive-and-repetitive-heat-exposure-on-the-sudomotor-activity
#2
Jeong Beom Lee, Hyung Seok Seo, Young Oh Shin
The sweating response is modulated in two different ways depending on adaptation conditions. In this work, we examined sudomotor activities before and after intensive and repetitive heat exposure. Nine male volunteers were exposed to 30-min half-body immersion in hot water (42 ± 0.5°C) at the same time of day on alternate days for 3 weeks. All experiments were performed in an automated climate chamber. Tympanic (Tty) and skin (Ts) temperatures were measured. Mean body temperature (mTb) was calculated. Sudomotor activities, including sweat onset time, sweat rate and volume, activated sweat gland density (ASGD) and output (ASGO), were tested in four regions of the skin: chest, abdomen, upper back and thigh...
October 31, 2017: Chinese Journal of Physiology
https://www.readbyqxmd.com/read/28873320/influence-of-rhodiola-rosea-on-the-heat-acclimation-process-in-young-healthy-men
#3
Saima Timpmann, Anthony C Hackney, Maria Tamm, Kairi Kreegipuu, Eve Unt, Vahur Ööpik
The adaptogen <i>Rhodiola rosea</i> (RR) may mitigate stress responses and have beneficial effects on endurance capacity (EC) and mental performance. Heat acclimation (HA) improves EC in the heat, but the potential impact of RR on the HA process is unknown. Therefore, our intent was to determine would RR impact positively on the efficacy of the HA process. Twenty male subjects (age 22.5 ± 3.0 years) completed two EC tests involving walking (6 km·h <sup>-1</sup>) until volitional exhaustion in a climate chamber (air temperature, 42°C; relative humidity, 18%) before (H1) and after (H2) an 8-day HA period...
September 5, 2017: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
https://www.readbyqxmd.com/read/28872380/optimizing-heat-acclimation-for-endurance-athletes-high-vs-low-intensity-training
#4
Cyril Schmit, Rob Duffield, Christophe Hausswirth, Jeanick Brisswalter, Yann Le Meur
PURPOSE: We sought to determine the effect of high- vs. low-intensity training in the heat and ensuing taper period in the heat on endurance performance. METHODS: Nineteen well-trained triathletes undertook 5 days of normal training and a 1-week taper, including either low- (HA-L, n=10) or high-intensity (HA-H, n=9) training sessions in the heat (30°C, 50% of relative humidity). A control group (n=10) reproduced their usual training in thermoneutral conditions...
September 5, 2017: International Journal of Sports Physiology and Performance
https://www.readbyqxmd.com/read/28855321/the-role-of-stochastic-thermal-environments-in-modulating-the-thermal-physiology-of-an-intertidal-limpet-lottia-digitalis
#5
Madeline J Drake, Nathan A Miller, Anne E Todgham
Much of our understanding of the thermal physiology of intertidal organisms comes from experiments with animals acclimated under constant conditions and exposed to a single heat stress. In nature, however, the thermal environment is more complex. Aerial exposure and the unpredictable nature of thermal stress during low tides may be critical factors in defining the thermal physiology of intertidal organisms. In the fingered limpet, Lottia digitalis, we investigated whether upper temperature tolerance and thermal sensitivity were influenced by the pattern of fluctuation with which thermal stress was applied...
September 1, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28839273/infection-increases-vulnerability-to-climate-change-via-effects-on-host-thermal-tolerance
#6
Sasha E Greenspan, Deborah S Bower, Elizabeth A Roznik, David A Pike, Gerry Marantelli, Ross A Alford, Lin Schwarzkopf, Brett R Scheffers
Unprecedented global climate change and increasing rates of infectious disease emergence are occurring simultaneously. Infection with emerging pathogens may alter the thermal thresholds of hosts. However, the effects of fungal infection on host thermal limits have not been examined. Moreover, the influence of infections on the heat tolerance of hosts has rarely been investigated within the context of realistic thermal acclimation regimes and potential anthropogenic climate change. We tested for effects of fungal infection on host thermal tolerance in a model system: frogs infected with the chytrid Batrachochytrium dendrobatidis...
August 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28739443/sauna-exposure-immediately-prior-to-short-term-heat-acclimation-accelerates-phenotypic-adaptation-in-females
#7
Jessica A Mee, Sophie Peters, Jonathan H Doust, Neil S Maxwell
OBJECTIVES: Investigate whether a sauna exposure prior to short-term heat acclimation (HA) accelerates phenotypic adaptation in females. DESIGN: Randomised, repeated measures, cross-over trial. METHODS: Nine females performed two 5-d HA interventions (controlled hyperthermia Tre≥38.5°C), separated by 7-wk, during the follicular phase of the menstrual cycle confirmed by plasma concentrations of 17-β estradiol and progesterone. Prior to each 90-min HA session participants sat for 20-min in either a temperate environment (20°C, 40% RH; HAtemp) wearing shorts and sports bra or a hot environment (50°C, 30% RH) wearing a sauna suit to replicate sauna conditions (HAsauna)...
July 4, 2017: Journal of Science and Medicine in Sport
https://www.readbyqxmd.com/read/28729874/systematic-analysis-of-hsf-family-genes-in-the-brassica-napus-genome-reveals-novel-responses-to-heat-drought-and-high-co2-stresses
#8
Xiaoyi Zhu, Chunqian Huang, Liang Zhang, Hongfang Liu, Jinhui Yu, Zhiyong Hu, Wei Hua
Drought and heat stress are major causes of lost plant crop yield. In the future, high levels of CO2, in combination of other abiotic stress factors, will become a novel source of stress. Little is known of the mechanisms involved in the acclimation responses of plants to this combination of abiotic stress factors, though it has been demonstrated that heat shock transcription factors (Hsfs) are involved in plant response to various abiotic stresses. In this study, we performed a genome-wide identification and a systematic analysis of genes in the Hsf gene family in Brassica napus...
2017: Frontiers in Plant Science
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
#9
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
#10
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
#11
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
#12
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...
July 1, 2017: Integrative and Comparative Biology
https://www.readbyqxmd.com/read/28652334/dissecting-and-modeling-zeaxanthin-and-lutein-dependent-nonphotochemical-quenching-in-arabidopsis-thaliana
#13
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...
August 15, 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
#14
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/effects-of-10-days-of-separate-heat-and-hypoxic-exposure-on-heat-acclimation-and-temperate-exercise-performance
#15
Rebecca A Rendell, Jamie Prout, Joseph T 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 1) the influence of overnight moderate normobaric hypoxia on the time course and magnitude of adaptation to daily heat exposure and 2) whether heat acclimation (HA) was ergogenic and whether this was influenced by an additional hypoxic stimulus. Eight males [V̇o2max = 58...
September 1, 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
#16
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
#17
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
#18
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
#19
John P Handrakis, Zhen Ni Guan, John W Nulty, Oriana Tascione, Dwindally Rosado-Rivera, Daniel White, Charlene Bang, Ann M Spungen, William A Bauman
Individuals with cervical spinal cord injury (SCI) have impaired thermoregulatory mechanisms attributed 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, 8 individuals with chronic tetraplegia (C3-C7, American Spinal Cord Injury Association Impairment Scale 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 min (Heat Challenge)...
August 16, 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
#20
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
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