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Hypoxia and exercise

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https://www.readbyqxmd.com/read/28323585/feasibility-of-hypoxic-challenge-testing-in-children-and-adolescents-with-congenital-heart-and-lung-disease
#1
Mandy E Spoorenberg, Erik H J Hulzebos, Tim Takken
BACKGROUND: This is a cross-sectional observational study to investigate the safety and feasibility of integrating changing body positions and physical activity in a hypoxic challenge test (HCT). The secondary objective was to compare oxygen saturation (Spo2) in two different locations (forehead and finger). METHODS: Included were 12 pediatric to young adult patients with congenital heart (N = 7) or lung disease (N = 5). An HCT was performed using breathing room air (21% oxygen) while sitting and breathing a normobaric hypoxic gas mixture (15% oxygen) through a facemask while seated, lying supine, standing, walking 3 km/h, and walking 5 km/h in a nonrandomized order...
December 1, 2016: Aerospace Medicine and Human Performance
https://www.readbyqxmd.com/read/28302708/thermoregulatory-responses-to-exercise-at-a-fixed-rate-of-heat-production-are-not-altered-by-acute-hypoxia
#2
Geoff B Coombs, Matthew N Cramer, Nicholas Ravanelli, Pascal Imbeault, Ollie Jay
This study sought to assess the within-subject influence of acute hypoxia on exercise-induced changes in core temperature and sweating. Eight participants [1.75 (0.06) m, 70.2 (6.8) kg, 25 (4) y, 54 (8) mL(.)kg(-1)(.)min(-1)] completed 45 min of cycling, once in normoxia (NORM; FiO2=0.21) and twice in hypoxia (HYP1/HYP2; FiO2=0.13) at 34.4(0.2)°C, 46(3)% RH. These trials were designed to elicit a) two distinctly different %VO2peak [NORM:45(8)% and HYP1:62(7)%] at the same heat production (Hprod) [NORM:6.7(0...
March 16, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28299447/markers-of-physiological-stress-during-exercise-under-conditions-of-normoxia-normobaric-hypoxia-hypobaric-hypoxia-and-genuine-high-altitude
#3
David Richard Woods, John Paul O'Hara, Christopher John Boos, Peter David Hodkinson, Costas Tsakirides, Neil Edward Hill, Darren Jose, Amanda Hawkins, Kelly Phillipson, Antonia Hazlerigg, Nicola Arjomandkhah, Liam Gallagher, David Holdsworth, Mark Cooke, Nicholas Donald Charles Green, Adrian Mellor
PURPOSE: To investigate whether there is a differential response at rest and following exercise to conditions of genuine high altitude (GHA), normobaric hypoxia (NH), hypobaric hypoxia (HH), and normobaric normoxia (NN). METHOD: Markers of sympathoadrenal and adrenocortical function [plasma normetanephrine (PNORMET), metanephrine (PMET), cortisol], myocardial injury [highly sensitive cardiac troponin T (hscTnT)], and function [N-terminal brain natriuretic peptide (NT-proBNP)] were evaluated at rest and with exercise under NN, at 3375 m in the Alps (GHA) and at equivalent simulated altitude under NH and HH...
March 15, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28292884/vascular-conductance-and-muscle-blood-flow-during-exercise-are-altered-by-inspired-oxygen-fraction-and-arterial-perfusion-pressure
#4
Rodrigo Villar, Richard L Hughson
We tested the hypothesis during the combined challenges of altered inspired O2 fraction (FIO2) and posture changes at lower power output regardless of body position that the vascular conductance (VC) recruitment to the exercising muscle would not limit muscle perfusion and estimated O2 delivery (DO2est ). However, in head-down tilt at the higher power output exercise in hypoxia, the recruitment of VC would have a functional limitation which would restrict muscle blood flow (MBF) leading to a limitation in DO2est with consequent increases in metabolic stress...
March 2017: Physiological Reports
https://www.readbyqxmd.com/read/28292879/%C3%AE-gpa-treatment-leads-to-elevated-basal-metabolic-rate-and-enhanced-hypoxic-exercise-tolerance-in-mice
#5
Trenton T Ross, Jeffrey D Overton, Katelyn F Houmard, Stephen T Kinsey
Treatments that increase basal metabolic rate (BMR) and enhance exercise capacity may be useful therapeutic approaches for treating conditions such as type 2 diabetes, obesity, and associated circulatory problems. β-guanidinopropionic acid (β-GPA) supplementation decreases high-energy phosphate concentrations, such as ATP and phosphocreatine (PCr) resulting in an energetic challenge that is similar to both exercise programs and hypoxic conditions. In this study, we administered β-GPA to mice for 2 or 6 weeks, and investigated the effect on muscle energetic status, body and muscle mass, muscle capillarity, BMR, and normoxic and hypoxic exercise tolerance (NET and HET, respectively)...
March 2017: Physiological Reports
https://www.readbyqxmd.com/read/28291666/risk-and-protective-factors-for-sudden-cardiac-death-during-leisure-activities-in-the-mountains-an-update
#6
REVIEW
Martin Burtscher
INTRODUCTION: Annually, more than 100 million tourists with widely varying health and fitness status are attracted by the mountainous areas around the world. Whereas mountaineering activities may contribute to the well established beneficial effects of regular exercise, for certain individuals these activities are also associated with a relatively high risk of death. METHODS: This manuscript presents an updated overview of risk and protective factors for sudden cardiac death during leisure activities in the mountains...
February 28, 2017: Heart, Lung & Circulation
https://www.readbyqxmd.com/read/28291256/exercise-rescues-obese-mothers-insulin-sensitivity-placental-hypoxia-and-male-offspring-insulin-sensitivity
#7
Denise S Fernandez-Twinn, Geraldine Gascoin, Barbara Musial, Sarah Carr, Daniella Duque-Guimaraes, Heather L Blackmore, Maria Z Alfaradhi, Elena Loche, Amanda N Sferruzzi-Perri, Abigail L Fowden, Susan E Ozanne
The prevalence of obesity during pregnancy continues to increase at alarming rates. This is concerning as in addition to immediate impacts on maternal wellbeing, obesity during pregnancy has detrimental effects on the long-term health of the offspring through non-genetic mechanisms. A major knowledge gap limiting our capacity to develop intervention strategies is the lack of understanding of the factors in the obese mother that mediate these epigenetic effects on the offspring. We used a mouse model of maternal-diet induced obesity to define predictive correlations between maternal factors and offspring insulin resistance...
March 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28290159/the-unexplored-crossroads-of-the-female-athlete-triad-and-iron-deficiency-a-narrative-review
#8
REVIEW
Dylan L Petkus, Laura E Murray-Kolb, Mary Jane De Souza
Despite the severity and prevalence of iron deficiency in exercising women, few published reports have explored how iron deficiency interacts with another prevalent and severe condition in exercising women: the 'female athlete triad.' This review aims to describe how iron deficiency may interact with each component of the female athlete triad, that is, energy status, reproductive function, and bone health. The effects of iron deficiency on energy status are discussed in regards to thyroid function, metabolic fuel availability, eating behaviors, and energy expenditure...
March 13, 2017: Sports Medicine
https://www.readbyqxmd.com/read/28280973/determinants-of-curvature-constant-w-of-the-power-duration-relationship-under-normoxia-and-hypoxia-the-effect-of-pre-exercise-alkalosis
#9
Sanjoy K Deb, Lewis A Gough, S Andy Sparks, Lars R McNaughton
PURPOSE: This study investigated the effect of induced alkalosis on the curvature constant (W') of the power-duration relationship under normoxic and hypoxic conditions. METHODS: Eleven trained cyclists (mean ± SD) Age: 32 ± 7.2 years; body mass (bm): 77.0 ± 9.2 kg; VO2peak: 59.2 ± 6.8 ml·kg(-1)·min(-1) completed seven laboratory visits which involved the determination of individual time to peak alkalosis following sodium bicarbonate (NaHCO3) ingestion, an environment specific ramp test (e...
March 9, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28277320/subcellular-energetics-and-metabolism-potential-therapeutic-applications
#10
Robert H Thiele
Part I of this review discussed the similarities between embryogenesis, mammalian adaptions to hypoxia (primarily driven by hypoxia-inducible factor-1 [HIF-1]), ischemia-reperfusion injury (and its relationship with reactive oxygen species), hibernation, diving animals, cancer, and sepsis, and it focused on the common characteristics that allow cells and organisms to survive in these states. Part II of this review describes techniques by which researchers gain insight into subcellular energetics and identify potential future tools for clinicians...
March 8, 2017: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/28270770/maximal-oxygen-uptake-is-achieved-in-hypoxia-but-not-normoxia-during-an-exhaustive-severe-intensity-run
#11
Matthew I Black, Christopher R Potter, Jo Corbett, Cain C T Clark, Stephen B Draper
Highly aerobically trained individuals are unable to achieve maximal oxygen uptake ([Formula: see text]) during exhaustive running lasting ~2 min, instead [Formula: see text] plateaus below [Formula: see text] after ~1 min. Hypoxia offers the opportunity to study the ([Formula: see text]) response to an exhaustive run relative to a hypoxia induced reduction in [Formula: see text]. The aim of this study was to explore whether there is a difference in the percentage of [Formula: see text] achieved (during a 2 min exhaustive run) in normoxia and hypoxia...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28261888/endurance-performance-in-well-trained-mice-is-enhanced-by-short-duration-intermittent-hypoxia-via-improved-muscle-fatty-acid-metabolism
#12
Junichi Suzuki
The author previously reported that short-duration intermittent hypoxia had additive effects on improvements in endurance capacity by enhancing fatty acid metabolism. The present study was designed to investigate the effects of short-duration intermittent hypoxia on endurance capacity in well-trained mice. Mice in the training group were housed in a cage with a wheel activity device for 7 weeks from 5 weeks old. Voluntary running markedly increased maximal exercise capacity (by 5.9-fold). Trained mice were then subjected to either normoxic treadmill training (Tr) or training with short-duration intermittent hypoxia (12% O2 for 15 min, 20...
March 5, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28260202/biochemical-responses-and-physical-performance-during-high-intensity-resistance-circuit-training-in-hypoxia-and-normoxia
#13
Domingo J Ramos-Campo, Jacobo A Rubio-Arias, Stéphane Dufour, Linda Chung, Vicente Ávila-Gandía, Pedro E Alcaraz
PURPOSE: The aim of this study was to analyze the effect of hypoxia on metabolic and acid-base balance, blood oxygenation, electrolyte, and half-squat performance variables during high-resistance circuit (HRC) training. METHODS: Twelve resistance-trained subjects participated in this study. After a 6RM testing session, participants performed three randomized trials of HRC: normoxia (NORM: FiO2 = 0.21), moderate hypoxia (MH: FiO2 = 0.16), or high hypoxia (HH: FiO2 = 0...
March 4, 2017: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/28255159/high-intensity-aerobic-exercise-training-improves-chronic-intermittent-hypoxia-induced-insulin-resistance-without-basal-autophagy-modulation
#14
Marion Pauly, Allan Assense, Aurélie Rondon, Amandine Thomas, Hervé Dubouchaud, Damien Freyssenet, Henri Benoit, Josiane Castells, Patrice Flore
Chronic intermittent hypoxia (IH) associated with obstructive sleep apnea (OSA) is a major risk factor for cardiovascular and metabolic diseases (insulin resistance: IR). Autophagy is involved in the pathophysiology of IR and high intensity training (HIT) has recently emerged as a potential therapy. We aimed to confirm IH-induced IR in a tissue-dependent way and to explore the preventive effect of HIT on IR-induced by IH. Thirty Swiss 129 male mice were randomly assigned to Normoxia (N), Intermittent Hypoxia (IH: 21-5% FiO2, 30 s cycle, 8 h/day) or IH associated with high intensity training (IH HIT)...
March 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28243207/hypoxia-induced-oxidative-stress-modulation-with-physical-activity
#15
REVIEW
Tadej Debevec, Grégoire P Millet, Vincent Pialoux
Increased oxidative stress, defined as an imbalance between prooxidants and antioxidants, resulting in molecular damage and disruption of redox signaling, is associated with numerous pathophysiological processes and known to exacerbate chronic diseases. Prolonged systemic hypoxia, induced either by exposure to terrestrial altitude or a reduction in ambient O2 availability is known to elicit oxidative stress and thereby alter redox balance in healthy humans. The redox balance modulation is also highly dependent on the level of physical activity...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28243206/spo2-and-heart-rate-during-a-real-hike-at-altitude-are-significantly-different-than-at-its-simulation-in-normobaric-hypoxia
#16
Nikolaus C Netzer, Linda Rausch, Arn H Eliasson, Hannes Gatterer, Matthias Friess, Martin Burtscher, Stephan Pramsohler
Rationale: Exposures to simulated altitude (normobaric hypoxia, NH) are frequently used in preparation for mountaineering activities at real altitude (hypobaric hypoxia, HH). However, physiological responses to exercise in NH and HH may differ. Unfortunately clinically useful information on such differences is largely lacking. This study therefore compared exercise responses between a simulated hike on a treadmill in NH and a similar field hike in HH. Methods: Six subjects (four men) participated in two trials, one in a NH chamber and a second in HH at an altitude of 4,205 m on the mountain Mauna Kea...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28236850/intermittent-hypoxia-as-a-means-to-improve-aerobic-capacity-in-type-2-diabetes
#17
R J Leone, S Lalande
Physical inactivity and a low maximal aerobic capacity (VO2max) strongly predict morbidity and mortality in patients with type 2 diabetes (T2D). Patients with T2D have a reduced VO2max when compared with healthy individuals of similar age, weight, and physical activity levels, and this lower aerobic capacity is usually attributed to a reduced oxygen delivery to the working muscles. The oxygen carrying capacity of the blood, as well as increases in cardiac output and blood flow, contribute to the delivery of oxygen to the active muscles during exercise...
March 2017: Medical Hypotheses
https://www.readbyqxmd.com/read/28229643/vestpd-as-a-measure-of-ventilatory-acclimatization-to-hypobaric-hypoxia
#18
J A Loeppky, A C Sheard, R M Salgado, C M Mermier
This study compared the ventilation response to an incremental ergometer exercise at two altitudes: 633 mmHg (resident altitude = 1,600 m) and following acute decompression to 455 mmHg (≈4,350 m altitude) in eight male cyclists and runners. At 455 mmHg, the VESTPD at RER <1.0 was significantly lower and the VEBTPS was higher because of higher breathing frequency; at VO2max, both VESTPD and VEBTPS were not significantly different. As percent of VO2max, the VEBTPS was nearly identical and VESTPD was 30% lower throughout the exercise at 455 mmHg...
September 2016: Physiol Int
https://www.readbyqxmd.com/read/28209739/myocardial-ischemic-tolerance-in-rats-subjected-to-endurance-exercise-training-during-adaptation-to-chronic-hypoxia
#19
Petra Alánová, Anna Chytilová, Jan Neckář, Jaroslav Hrdlička, Petra Míčová, Kristýna Holzerová, Markéta Hlaváčková, Kristýna Macháčková, František Papoušek, Jana Vašinová, Daniel Benák, Olga Nováková, František Kolář
Chronic hypoxia and exercise are natural stimuli that confer sustainable cardioprotection against ischemia/reperfusion (I/R) injury but it is unknown whether they can act in synergy to enhance ischemic resistance. Inflammatory response mediated by tumor necrosis factor-α (TNF-α) plays a role in the infarct size-limitation by continuous normobaric hypoxia (CNH) whereas exercise is associated with anti-inflammatory effects. This study was conducted to determine whether exercise training performed under conditions of CNH (12% O2) affects myocardial ischemic resistance with respect to inflammatory and redox status...
February 16, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28194720/effects-of-repeated-sprint-training-in-hypoxia-on-sea-level-performance-a-meta-analysis
#20
REVIEW
Franck Brocherie, Olivier Girard, Raphaël Faiss, Grégoire P Millet
BACKGROUND: Repeated-sprint training in hypoxia (RSH) is a recent intervention regarding which numerous studies have reported effects on sea-level physical performance outcomes that are debated. No previous study has performed a meta-analysis of the effects of RSH. OBJECTIVE: We systematically reviewed the literature and meta-analyzed the effects of RSH versus repeated-sprint training in normoxia (RSN) on key components of sea-level physical performance, i.e., best and mean (all sprint) performance during repeated-sprint exercise and aerobic capacity (i...
February 13, 2017: Sports Medicine
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