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Hiroshi Nagahisa, Kazutaka Mukai, Hajime Ohmura, Toshiyuki Takahashi, Hirofumi Miyata
Hypoxic training is believed to increase endurance capacity in association with hypoxia inducible factor-1α (HIF-1α), a modulator of vascular endothelial growth factor-A (VEGF-A), and to influence activation of satellite cells (SCs). However, the effect of hypoxic training on SC activation and its relation to angiogenesis has not been thoroughly investigated. Eight Thoroughbred horses were subjected to normoxic (FIO2 = 21%) or hypoxic (FIO2 = 15%) training for 3 days/week (100%  [Formula: see text]) for 4 weeks...
2016: Oxidative Medicine and Cellular Longevity
Alex J Wadley, Ida S Svendsen, Michael Gleeson
Altitude exposure can exaggerate the transient increase in markers of oxidative stress observed following acute exercise. However, these responses have not been monitored in endurance-trained cyclists at altitudes typically experienced whilst training. Endurance trained males (n=12; mean (±SD) age: 28 ± 4 years, V̇O2max 63.7 ± 5.3 ml/kg/min) undertook two 75-min exercise trials at 70% relative V̇O2max; once in normoxia and once in hypobaric hypoxia, equivalent to 2000m above sea level (hypoxia). Blood samples were collected before, immediately after and 2 h post-exercise to assess plasma parameters of oxidative stress (protein carbonylation (PC), thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC) and catalase activity (CAT))...
October 6, 2016: International Journal of Sport Nutrition and Exercise Metabolism
Eduardo V Lemes, Eduardo Colombari, Daniel B Zoccal
Abdominal expiratory activity is absent at rest and is evoked during metabolic challenges, such as hypercapnia and hypoxia, or after the exposure to intermittent hypoxia (IH). The mechanisms engaged during this process are not completely understood. In this study, we hypothesized that serotonin (5-HT), acting in the retrotrapezoid nucleus/parafacial respiratory group (RTN/pFRG), is able to generate active expiration. In anesthetized (urethane, i.p.), tracheostomized, spontaneously-breathing adult male Holtzman rats we microinjected a serotoninergic agonist and antagonist bilaterally in the RTN/pFRG and recorded diaphragm and abdominal muscle activities...
September 22, 2016: Journal of Applied Physiology
Samuel Helfer, Joseph Quackenbush, Michael Fletcher, David R Pendergast
BACKGROUND: Climbing and trekking at altitude are common recreational and military activities. Physiological effects of altitude are hypoxia and hyperventilation. The hyperventilatory response to altitude may cause respiratory muscle fatigue and reduce sustained submaximal exercise. Voluntary isocapnic hyperpnea respiratory muscle training (VIHT) improves exercise endurance at sea level and at depth. The purpose of this study was to test the hypothesis that VIHT would improve exercise time at altitude [3600 m (11,811 ft)] compared to control and placebo groups...
August 2016: Aerospace Medicine and Human Performance
Vered Domankevich, Yarden Opatowsky, Assaf Malik, Abraham B Korol, Zeev Frenkel, Irena Manov, Aaron Avivi, Imad Shams
BACKGROUND: The subterranean blind mole rat, Spalax (genus Nannospalax) endures extreme hypoxic conditions and fluctuations in oxygen levels that threaten DNA integrity. Nevertheless, Spalax is long-lived, does not develop spontaneous cancer, and exhibits an outstanding resistance to carcinogenesis in vivo, as well as anti-cancer capabilities in vitro. We hypothesized that adaptations to similar extreme environmental conditions involve common mechanisms for overcoming stress-induced DNA damage...
2016: BMC Evolutionary Biology
Billy Sperlich, Christoph Zinner, Anna Hauser, Hans-Christer Holmberg, Jennifer Wegrzyk
Hyperoxia results from the inhalation of mixtures of gas containing higher partial pressures of oxygen (O2) than normal air at sea level. Exercise in hyperoxia affects the cardiorespiratory, neural and hormonal systems, as well as energy metabolism in humans. In contrast to short-term exposure to hypoxia (i.e. a reduced partial pressure of oxygen), acute hyperoxia may enhance endurance and sprint interval performance by accelerating recovery processes. This narrative literature review, covering 89 studies published between 1975 and 2016, identifies the acute ergogenic effects and health concerns associated with hyperoxia during exercise; however, long-term adaptation to hyperoxia and exercise remain inconclusive...
July 30, 2016: Sports Medicine
Fiona B McDonald, Eugene M Dempsey, Ken D O'Halloran
Alterations to the supply of oxygen during early life presents a profound stressor to physiological systems with aberrant remodeling that is often long-lasting. Chronic intermittent hypoxia (CIH) is a feature of apnea of prematurity, chronic lung disease, and sleep apnea. CIH affects respiratory control but there is a dearth of information concerning the effects of CIH on respiratory muscles, including the diaphragm-the major pump muscle of breathing. We investigated the effects of exposure to gestational CIH (gCIH) and postnatal CIH (pCIH) on diaphragm muscle function in male and female rats...
2016: Frontiers in Physiology
Carl A James, Ashley G B Willmott, Alan J Richardson, Peter W Watt, Neil S Maxwell
PURPOSE: Ischaemic preconditioning (IP) has been shown to be ergogenic for endurance performance in normothermic conditions and alleviate physiological strain under hypoxia, potentially through haemodynamic and/or metabolic mechanisms. Exertional hyperthermia is characterised by competition for blood flow between the muscles and skin, an enhanced metabolic strain and impaired endurance performance. This study investigated the effect of IP on the determinants of endurance performance, through an incremental exercise test in the heat...
September 2016: European Journal of Applied Physiology
Aki Nunomiya, Junchul Shin, Yasuo Kitajima, Takashi Dan, Toshio Miyata, Ryoichi Nagatomi
AIMS: Hypoxic response mediated by hypoxia-inducible factor (HIF) seems to contribute to the benefit of endurance training. To verify the direct contribution of HIF activation to running training without exposure to atmospheric hypoxia, we used prolyl hydroxylase domain 2 (PHD2) conditional knockout mice (cKO), which exhibit HIF activation independent of oxygen concentration, and we examined their maximal exercise capacity before and after 4 weeks of treadmill exercise training. METHODS: Phd2(f/f) mice (n = 26) and Phd2 cKO mice (n = 24) were randomly divided into two groups, trained and untrained, and were subjected to maximal running test before and after a 4-week treadmill-training regimen...
July 9, 2016: Acta Physiologica
Stefan De Smet, Ruud Van Thienen, Louise Deldicque, Ruth James, Craig Sale, David J Bishop, Peter Hespel
PURPOSE: We investigated the effect of sprint interval training (SIT) in normoxia, vs. SIT in hypoxia alone or in conjunction with oral nitrate intake, on buffering capacity of homogenized muscle (βhm) and fiber type distribution, as well as on sprint and endurance performance. METHODS: Twenty-seven moderately-trained participants were allocated to one of three experimental groups: SIT in normoxia (20.9% FiO2) + placebo (N), SIT in hypoxia (15% FiO2) + placebo (H), or SIT in hypoxia + nitrate supplementation (HN)...
2016: Frontiers in Physiology
Simona Delle Monache, Alessia Calgani, Patrizia Sanità, Francesca Zazzeroni, Emilio Gentile Warschauer, Antonio Giuliani, Gianfranco Amicucci, Adriano Angelucci
Recent studies suggest that adipose-derived stem cells (ASCs) play a role in tissue remodeling through the release of cytokines and growth factors. We compared the secreted cytokine profile of hypoxia-conditioned ASCs (hASCs) with normoxic ASCs (nASCs) and we analyzed the effect of ASCs conditioned medium (CM) on endothelial cells. We found that hypoxia induced a transient upregulation of VEGF in ASCs and a notable and enduring upregulation of leptin mRNA expression 30-fold greater than control after 24 h and up to 60-fold greater than control at day 7...
August 2016: Growth Factors
Daichi Sumi, Chihiro Kojima, Kazushige Goto
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
Markus Amann, Jerome A Dempsey
We recently hypothesized that across the range of normoxia to severe hypoxia the major determinant of central motor drive (CMD) during endurance exercise switches from a predominantly peripheral origin to a hypoxic-sensitive central component of fatigue. We found that peripheral locomotor muscle fatigue (pLMF) is the prevailing factor limiting central motor drive and therefore exercise performance from normoxia to moderate hypoxia (SaO2 > 75 %). In these levels of arterial hypoxemia, the development of pLMF is confined to a certain limit which varies between humans-pLMF does not develop to this limit in more severe hypoxia (SaO2 < 70 %) and exercise is prematurely terminated presumably to protect the brain from insufficient O2 supply...
2016: Advances in Experimental Medicine and Biology
Angela Navarrete-Opazo, Julio Alcayaga, Oscar Sepulveda, Enrique Rojas, Carolina Astudillo
Incomplete spinal cord injuries (iSCI) leave spared synaptic pathways below the level of injury. Intermittent hypoxia (IH) elicits plasticity in the spinal cord and strengthens spared synaptic pathways, expressed as respiratory and somatic functional recovery in experimental animals and humans with iSCI. This study corresponds to a randomized, triple-blind, two-arm parallel clinical trial performed in Santiago, Chile. We compared the effects of a 4-week protocol of IH combined with body weight-supported treadmill training (BWSTT), with continuous normoxia (Nx) and BWSTT on 10-meter walk test (10MWT), 6-minute walk test (6MWT), and timed up and go (TUG) test in ASIA C and D individuals with iSCI...
June 21, 2016: Journal of Neurotrauma
Steven Pennock, Leo A Kim, Andrius Kazlauskas
Vascular endothelial cell growth factor A (VEGF) is a biologically and therapeutically important growth factor because it promotes angiogenesis in response to hypoxia, which underlies a wide variety of both physiological and pathological settings. We report here that both VEGF receptor 2 (VEGFR2)-positive and -negative cells depended on VEGF to endure hypoxia. VEGF enhanced the viability of platelet-derived growth factor receptor α (PDGFRα)-positive and VEGFR2-negative cells by enabling indirect activation of PDGFRα, thereby reducing the level of p53...
September 15, 2016: Molecular and Cellular Biology
S Drozdovska, B Gavenauskas, T Drevytska, V Nosar, V Nagibin, I Mankovska, V Dosenko
Molecular mechanisms of adaptation to exercise despite a large number of studies remain unclear. One of the crucial factors in this process is hypoxia inducible factor (HIF) that regulates transcription of many target genes encoding proteins that are implicated in molecular adaptation to hypoxia. Experiments were conducted on 24 adult male Fisher rats. Real-time PCR analysis was performed for quantitative evaluation of Hif3α, Igf1, Glut-4 and Pdk-1 in m. gastrocnemius, m. soleus, in lung and heart tissues...
June 2016: Biology of Sport
Jonas J Saugy, Laurent Schmitt, Anna Hauser, Guillaume Constantin, Roberto Cejuela, Raphael Faiss, Jon P Wehrlin, Jérémie Rosset, Neil Robinson, Grégoire P Millet
PURPOSE: We investigated the changes in physiological and performance parameters after a Live High-Train Low (LHTL) altitude camp in normobaric (NH) or hypobaric hypoxia (HH) to reproduce the actual training practices of endurance athletes using a crossover-designed study. METHODS: Well-trained triathletes (n = 16) were split into two groups and completed two 18-day LTHL camps during which they trained at 1100-1200 m and lived at 2250 m (P i O2 = 111.9 ± 0.6 vs...
2016: Frontiers in Physiology
David Montero, Carsten Lundby
PURPOSE: Few recent studies indicate that short-term repeated sprint training in hypoxia (RSH) improves repeated sprint (RS) performance compared with identical training under normoxic conditions (RSN) in endurance-trained subjects. Herein, we sought to determine the effects of RSH against RSN on RS performance under normoxic and moderate hypoxic conditions, using a randomized, double-blind and cross-over experimental design. METHODS: Fifteen endurance-trained male subjects (age=25±4 years) performed 4 weeks of RS training (3 sessions/week) in normobaric hypoxia (RSH, FiO2=13...
May 3, 2016: International Journal of Sports Physiology and Performance
Ida S Svendsen, Erlend Hem, Michael Gleeson
PURPOSE: To determine how immune markers are affected by acute hypoxic exercise at the same relative intensity. METHODS: Twelve endurance-trained males (age: 28 ± 4 years, [Formula: see text]O2max: 63.7 ± 5.3 mL/kg/min) cycled for 75 min at 70 % of altitude-specific [Formula: see text]O2max, once in normoxia (N) and once in hypobaric hypoxia equivalent to 2000 m above sea-level (H). Blood and saliva samples were collected pre-, post- and 2 h post-exercise...
June 2016: European Journal of Applied Physiology
Junichi Suzuki
This study was designed to (1) investigate the effects of acute short-duration intermittent hypoxia on musclemRNAand microRNAexpression levels; and (2) clarify the mechanisms by which short-duration intermittent hypoxia improves endurance capacity. Experiment-1: Male mice were subjected to either acute 1-h hypoxia (12% O2), acute short-duration intermittent hypoxia (12% O2for 15 min, room air for 10 min, 4 times, Int-Hypo), or acute endurance exercise (Ex). The expression of vascular endothelial growth factor-AmRNAwas significantly greater than the control at 0 h post Ex and 6 h post Int-Hypo in the deep red region of the gastrocnemius muscle...
April 2016: Physiological Reports
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