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acclimatization to high altitude

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https://www.readbyqxmd.com/read/28239483/soldiers-load-carriage-performance-in-high-mountains-a-physiological-study
#1
Tirthankar Chatterjee, Debojyoti Bhattacharyya, Anilendu Pramanik, Madhusudan Pal, Deepti Majumdar, Dhurjati Majumdar
BACKGROUND: The present study was designed to evaluate load carriage performance at extremely high altitudes with different loads and walking speeds in terms of physiological evaluation. The degree of maximum oxygen consumption changes at high altitudes was also examined. METHODS: Twelve Indian Army soldiers were acclimatized at altitudes of 3,505 m and 4,300 m. They walked for 10 minutes on a motorized treadmill at 2.5 km/h and 3.5 km/h speeds during carrying no loads and three magnitudes of load (10...
2017: Military Medical Research
https://www.readbyqxmd.com/read/28169986/erythrocytes-retain-hypoxic-adenosine-response-for-faster-acclimatization-upon-re-ascent
#2
Anren Song, Yujin Zhang, Leng Han, Gennady G Yegutkin, Hong Liu, Kaiqi Sun, Angelo D'Alessandro, Jessica Li, Harry Karmouty-Quintana, Takayuki Iriyama, Tingting Weng, Shushan Zhao, Wei Wang, Hongyu Wu, Travis Nemkov, Andrew W Subudhi, Sonja Jameson-Van Houten, Colleen G Julian, Andrew T Lovering, Kirk C Hansen, Hong Zhang, Mikhail Bogdanov, William Dowhan, Jianping Jin, Rodney E Kellems, Holger K Eltzschig, Michael Blackburn, Robert C Roach, Yang Xia
Faster acclimatization to high altitude upon re-ascent is seen in humans; however, the molecular basis for this enhanced adaptive response is unknown. We report that in healthy lowlanders, plasma adenosine levels are rapidly induced by initial ascent to high altitude and achieved even higher levels upon re-ascent, a feature that is positively associated with quicker acclimatization. Erythrocyte equilibrative nucleoside transporter 1 (eENT1) levels are reduced in humans at high altitude and in mice under hypoxia...
February 7, 2017: Nature Communications
https://www.readbyqxmd.com/read/28149350/the-influence-of-high-altitude-acclimatization-on-ventilatory-and-blood-oxygen-saturation-responses-during-normoxic-and-hypoxic-testing
#3
Anton Ušaj, Stojan Burnik
We investigated how acclimatization effects achieved during a high-altitude alpinist expedition influence endurance performance, ventilation ([Formula: see text]) and blood oxygen saturation (SaO2) in normoxic (NOR) and hypoxic conditions (HYP). An incremental testing protocol on a cycle ergometer was used to determine the power output corresponding to the Lactate (PLT) and Ventilatory Threshold (PVT) in NOR and HYP (FiO2=0.13) as indirect characteristics of endurance performance in both conditions. Furthermore, changes in [Formula: see text], SaO2, blood pH and Pco2 were measured at a similar absolute exercise intensity of 180 W in NOR and HYP conditions...
April 1, 2016: Journal of Human Kinetics
https://www.readbyqxmd.com/read/28032333/the-effect-of-%C3%AE-1-adrenergic-blockade-on-post-exercise-brachial-artery-flow-mediated-dilatation-at-sea-level-and-high-altitude
#4
Michael M Tymko, Joshua C Tremblay, Alex B Hansen, Connor A Howe, Chris K Willie, Mike Stembridge, Daniel J Green, Ryan L Hoiland, Prajan Subedi, James D Anholm, Philip N Ainslie
KEY POINTS: Our objective was to quantify endothelial function (via brachial artery flow-mediated dilatation) at sea level (344 m) and high altitude (3800 m) at rest and following both maximal exercise and 30 min of moderate-intensity cycling exercise with and without administration of an α1 -adrenergic blockade. Brachial endothelial function did not differ between sea level and high altitude at rest, nor following maximal exercise. At sea level, endothelial function decreased following 30 min of moderate-intensity exercise, and this decrease was abolished with α1 -adrenergic blockade...
March 1, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28006436/professor-bengt-saltin-symposium-environmental-challenges-to-human-performance
#5
REVIEW
Philip N Ainslie
This short review is from a presentation made at the Bengt Saltin Symposium, October 15-17, at the 2015 Canadian Society for Exercise Physiology conference, Hamilton, Canada. The review provides context of the important work of the late Dr. Saltin's contributions to environmental physiology. In addition to well-controlled laboratory experiments to better understand the influence of hypoxia or temperature, or both, Dr. Saltin also led several field expeditions to the North Greenland, Kenya, Himalayas, and the Andes, where he studied several aspects of human adaptation to environment...
January 2017: Applied Physiology, Nutrition, and Metabolism, Physiologie Appliquée, Nutrition et Métabolisme
https://www.readbyqxmd.com/read/27994555/physiological-adjustments-and-circulating-microrna-reprogramming-are-involved-in-early-acclimatization-to-high-altitude-in-chinese-han-males
#6
Bao Liu, He Huang, Shou-Xian Wang, Gang Wu, Gang Xu, Bing-Da Sun, Er-Long Zhang, Yu-Qi Gao
Background: Altitude acclimatization is a physiological process that restores oxygen delivery to the tissues and promotes oxygen use under high altitude hypoxia. High altitude sickness occurs in individuals without acclimatization. Unraveling the molecular underpinnings of altitude acclimatization could help understand the beneficial body responses to high altitude hypoxia as well as the altered biological events in un-acclimatized individuals. This study assessed physiological adjustments and circulating microRNA (cmiRNA) profiles in individuals exposed to high altitude, aiming to explore altitude acclimatization in humans...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27888818/high-altitude-illness
#7
REVIEW
Anna Hartman-Ksycińska, Jolanta Kluz-Zawadzka, Bogumił Lewandowski
High-altitude illness is a result of prolonged high-altitude exposure of unacclimatized individuals. The illness is seen in the form of acute mountain sickness (AMS) which if not treated leads to potentially life-threatening high altitude pulmonary oedema and high-altitude cerebral oedema. Medical problems are caused by hypobaric hypoxia stimulating hypoxia-inducible factor (HIF) release. As a result, the central nervous system, circulation and respiratory system function impairment occurs. The most important factor in AMS treatment is acclimatization, withdrawing further ascent and rest or beginning to descent; oxygen supplementation, and pharmacological intervention, and, if available, a portable hyperbaric chamber...
2016: Przegla̧d Epidemiologiczny
https://www.readbyqxmd.com/read/27793615/seasonal-variation-of-metabolism-in-lizard-phrynocephalus-vlangalii-at-high-altitude
#8
Shiwei Liang, Weixin Li, Yang Zhang, Xiaolong Tang, Jianzheng He, Yucheng Bai, Dongqin Li, Yan Wang, Qiang Chen
Seasonal acclimatization is important for animals to live optimally in the varying environment. Phrynocephalus vlangalii, a species of lizard endemic in China, distributes on Qinghai-Tibet Plateau ranging from 2000 to 4600m above sea level. To dissect how this lizard mediate metabolism to adapt various season, the preferred body temperature (Tb), standard metabolic rate (SMR), mitochondrial respiration rates and activities of four metabolic enzymes in this species were tested in different seasons (spring, summer, and autumn)...
January 2017: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
https://www.readbyqxmd.com/read/27754698/effect-of-increased-blood-flow-on-pulmonary-circulation-before-and-during-high-altitude-acclimatization
#9
Matthias Peter Hilty, Andrea Müller, Daniela Flück, Christoph Siebenmann, Peter Rasmussen, Stefanie Keiser, Katja Auinger, Carsten Lundby, Marco Maggiorini
Matthias Peter Hilty, Andrea Mueller, Daniela Flück, Christoph Siebenmann, Peter Rasmussen, Stefanie Keiser, Katja Auinger, Carsten Lundby, and Marco Maggiorini. Effect of increased blood flow on the pulmonary circulation before and during high altitude acclimatization. High Alt Med Biol. 17:305-314, 2016.-Introduction and Methods: Acute exposure to high altitude increases pulmonary artery pressure (Ppa) and pulmonary vascular resistance (PVR). The evolution of Ppa and PVR with continuous hypoxic exposure remains, however, elusive...
December 2016: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/27688941/long-term-acclimatization-to-high-altitude-hypoxia-modifies-interhemispheric-functional-and-structural-connectivity-in-the-adult-brain
#10
Ji Chen, Jinqiang Li, Qiaoqing Han, Jianzhong Lin, Tianhe Yang, Ziqian Chen, Jiaxing Zhang
BACKGROUND: Structural and functional networks can be reorganized to adjust to environmental pressures and physiologic changes in the adult brain, but such processes remain unclear in prolonged adaptation to high-altitude (HA) hypoxia. This study aimed to characterize the interhemispheric functionally and structurally coupled modifications in the brains of adult HA immigrants. METHODS: We performed resting-state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) in 16 adults who had immigrated to the Qinghai-Tibet Plateau (2300-4400 m) for 2 years and in 16 age-matched sea-level (SL) controls...
September 2016: Brain and Behavior
https://www.readbyqxmd.com/read/27643447/the-adrenocortical-response-to-synthetic-acth-following-a-trek-to-high-altitude
#11
J Mackey, A Mellor, J Watchorn, A Burnett, C Boot, D Woods
Gradual ascent to high altitude is typically associated with reduced resting aldosterone and unchanged cortisol, features that may facilitate acclimatization but are poorly understood. The aim of the study was to investigate the cortisol and aldosterone response to adrenocorticotrophic hormone at altitude. Eleven subjects underwent a 250 μg short synacthen test at sea-level and again after trekking to 3 600 m in Nepal. Cortisol and aldosterone were measured by conventional assay from blood samples taken immediately prior to the administration of synacthen (T0) and then 30 (T30) and 60 (T60) min later...
September 2016: Hormone and Metabolic Research, Hormon- und Stoffwechselforschung, Hormones et Métabolisme
https://www.readbyqxmd.com/read/27622961/yoga-practice-improves-physiological-and-biochemical-status-at-high-altitudes-a-prospective-case-control-study
#12
RANDOMIZED CONTROLLED TRIAL
Gidugu Himashree, Latika Mohan, Yogesh Singh
UNLABELLED: Context • High altitude (HA) is a psychophysiological stressor for natives of lower altitudes. Reducing the morbidity and optimizing the performance of individuals deployed in an HA region has been attempted and reported with varied results. Objective • The present study intended to explore the effects of comprehensive yogic practices on the health and performance of Indian soldiers deployed at HAs. Design • The research team designed a prospective, randomized, case-control study...
September 2016: Alternative Therapies in Health and Medicine
https://www.readbyqxmd.com/read/27601532/fulminant-high-altitude-blindness
#13
Evgeny Mashkovskiy, Piotr Szawarski, Pavel Ryzhkov, Tomaz Goslar, Irena Mrak
Prolonged altitude exposure even with acclimatization continues to present a physiological challenge to all organ systems including the central nervous system. We describe a case of a 41-year-old Caucasian female climber who suffered severe visual loss that was due to possible optic nerve pathology occurring during a high altitude expedition in the Himalayas. This case is atypical of classic high altitude cerebral oedema and highlights yet another danger of prolonged sojourn at extreme altitudes.
June 2016: Journal of Travel Medicine
https://www.readbyqxmd.com/read/27575244/high-altitude-pulmonary-edema-without-appropriate-action-progresses-to-right-ventricular-strain-a-case-study
#14
Logan Mills, Chris Harper, Sophie Rozwadowski, Chris Imray
Mills, Logan, Chris Harper, Sophie Rozwadowski, and Chris Imray. High altitude pulmonary edema without appropriate action progresses to right ventricular strain: A case study. High Alt Med Biol. 17:228-232, 2016.-A 24-year-old male developed high altitude pulmonary edema (HAPE) after three ascents to 4061 m over 3 days, sleeping each night at 2735 m. He complained of exertional dyspnea, dry cough, chest pain, fever, nausea, vertigo, and a severe frontal headache. Inappropriate continuation of ascent despite symptoms led to functional impairment and forced a return to the valley, but dyspnea persisted in addition to new orthopnea...
September 2016: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/27548274/brief-working-memory-and-physiological-monitoring-during-a-high-altitude-expedition
#15
Carine Malle, Benoît Ginon, Cyprien Bourrilhon
Malle, Carine, Benoît Ginon, and Cyprien Bourrilhon. Brief working memory and physiological monitoring during a high-altitude expedition. High Alt Med Biol. 17:359-364, 2016.-Background: Various studies have shown the deleterious effects of high-altitude hypoxia on cognitive functions, including attention and memory. Since optimal cognitive abilities may be crucial for mountain safety, this study was aimed to assess the relevance of a brief working memory test to quickly assess cognition at high altitude. METHODS: A set of physiological and cognitive measurements were collected from four professional climbers at various time points during the course of an expedition to Shishapangma (8043 m)...
December 2016: High Altitude Medicine & Biology
https://www.readbyqxmd.com/read/27421182/characteristics-of-eeg-activity-during-high-altitude-hypoxia-and-lowland-reoxygenation
#16
Jin-Ping Zhao, Ran Zhang, Qian Yu, Jia-Xing Zhang
The aim of the present study was to determine the effect of high altitude (HA) immigration on cerebral electrical activity. Electro-EncephaloGraphic (EEG) activity were recorded from 25 lowland soldiers during eyes-closed resting conditions under the following conditions: 7 days at lowland before ascending to altitude (Test 1), during the first 7 days (Test 2) and 30 days (Test 3) at 3800m altitude, and 7 days after return to lowland (Test 4). The EEG was Fourier transformed to provide absolute and relative power estimates for the alpha, beta, delta, and theta bands...
October 1, 2016: Brain Research
https://www.readbyqxmd.com/read/27418686/physiological-impact-of-patent-foramen-ovale-on-pulmonary-gas-exchange-ventilatory-acclimatization-and-thermoregulation
#17
REVIEW
Andrew T Lovering, Jonathan E Elliott, James T Davis
The foramen ovale, which is part of the normal fetal cardiopulmonary circulation, fails to close after birth in ∼35% of the population and represents a potential source of right-to-left shunt. Despite the prevalence of patent foramen ovale (PFO) in the general population, cardiopulmonary, exercise, thermoregulatory, and altitude physiologists may have underestimated the potential effect of this shunted blood flow on normal physiological processes in otherwise healthy humans. Because this shunted blood bypasses the respiratory system, it would not participate in either gas exchange or respiratory system cooling and may have impacts on other physiological processes that remain undetermined...
August 1, 2016: Journal of Applied Physiology
https://www.readbyqxmd.com/read/27414687/seven-passive-1-h-hypoxia-exposures-do-not-prevent-ams-in-susceptible-individuals
#18
Martin Faulhaber, Elena Pocecco, Hannes Gatterer, Martin Niedermeier, Maike Huth, Tobias Dünnwald, Verena Menz, Luciano Bernardi, Martin Burtscher
PURPOSE: The present study evaluated the effects of a pre-acclimatization program comprising 7 passive 1-hour exposures to 4,500 m normobaric hypoxia on the prevalence and severity of acute mountain sickness (AMS) during a subsequent exposure to real high altitude in persons susceptible to AMS. METHODS: The project was designed as a randomized controlled trial including 32 healthy female and male participants with known susceptibility to AMS symptoms. After baseline measurements participants were randomly assigned to the hypoxia or the control group to receive the pre-acclimatization program (7 passive 1-hour exposures within 7 days to normobaric hypoxia or sham hypoxia)...
July 12, 2016: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/27343109/does-the-sympathetic-nervous-system-adapt-to-chronic-altitude-exposure
#19
Mikael Sander
During continued exposure to hypobaric hypoxia in acclimatizing lowlanders increasing norepinephrine levels indirectly indicate sympathoexcitation, and in a few subjects serial measurements have suggested some adaptation over time. A few studies have provided direct microneurographic evidence for markedly increased muscle sympathetic nervous activity (MSNA) after 1-50 days of exposure of lowlanders to altitudes of 4100-5260 m above sea level. Only one study has provided two MSNA-measurements over time (10 and 50 days) in altitude (4100 m above sea level) and continued robust sympathoexcitation without adaptation was found in acclimatizing lowlanders...
2016: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/27343108/hemoglobin-mass-and-aerobic-performance-at-moderate-altitude-in-elite-athletes
#20
Jon Peter Wehrlin, Bernard Marti, Jostein Hallén
Fore more than a decade, the live high-train low (LHTL) approach, developed by Levine and Stray-Gundersen, has been widely used by elite endurance athletes. Originally, it was pointed out, that by living at moderate altitude, athletes should benefit from an increased red cell volume (RCV) and hemoglobin mass (Hbmass), while the training at low altitudes should prevent the disadvantage of reduced training intensity at moderate altitude. VO2max is reduced linearly by about 6-8 % per 1000 m increasing altitude in elite athletes from sea level to 3000 m, with corresponding higher relative training intensities for the same absolute work load...
2016: Advances in Experimental Medicine and Biology
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