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Cognition and Neuropsychological Changes at Altitude-A Systematic Review of Literature. Brain Sci 2022; 12:brainsci12121736. [PMID: 36552195 PMCID: PMC9775937 DOI: 10.3390/brainsci12121736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/05/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
High-altitude (HA) exposure affects cognitive functions, but studies have found inconsistent results. The aim of this systematic review was to evaluate the effects of HA exposure on cognitive functions in healthy subjects. A structural overview of the applied neuropsychological tests was provided with a classification of superordinate cognitive domains. A literature search was performed using PubMed up to October 2021 according to PRISMA guidelines. Eligibility criteria included a healthy human cohort exposed to altitude in the field (at minimum 2440 m [8000 ft]) or in a hypoxic environment in a laboratory, and an assessment of cognitive domains. The literature search identified 52 studies (29 of these were field studies; altitude range: 2440 m-8848 m [8000-29,029 ft]). Researchers applied 112 different neuropsychological tests. Attentional capacity, concentration, and executive functions were the most frequently studied. In the laboratory, the ratio of altitude-induced impairments (64.7%) was twice as high compared to results showing no change or improved results (35.3%), but altitudes studied were similar in the chamber compared to field studies. In the field, the opposite results were found (66.4 % no change or improvements, 33.6% impairments). Since better acclimatization can be assumed in the field studies, the findings support the hypothesis that sufficient acclimatization has beneficial effects on cognitive functions at HA. However, it also becomes apparent that research in this area would benefit most if a consensus could be reached on a standardized framework of freely available neurocognitive tests.
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2
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Vento KA, Borden CK, Blacker KJ. Sex comparisons in physiological and cognitive performance during hypoxic challenge. Front Physiol 2022; 13:1062397. [PMID: 36505049 PMCID: PMC9727089 DOI: 10.3389/fphys.2022.1062397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 11/11/2022] [Indexed: 11/24/2022] Open
Abstract
Within the tactical aviation community, human performance research lags in considering potential psychophysiological differences between male and female aviators due to little inclusion of females during the design and development of aircraft systems. A poor understanding of how male and female aviators differ with respect to human performance results in unknown potential sex differences on aeromedically relevant environmental stressors, perchance leading to suboptimal performance, safety, and health guidelines. For example, previous hypoxia studies have excluded female participants or lacked a sizeable sample to examine sex comparisons. As such, progress toward sensor development and improving hypoxia familiarization training are stunted due to limited knowledge of how individual differences, including sex, may or may not underlie hypoxia symptoms and performance impairment. Investigating sex differences bridges the gap between aerospace medicine and operational health, and addressing hypoxia is one of many facets yet to be studied. In the current study, we retrospectively examined N = 6 hypoxia studies with male-female participant samples (total, N = 189; male, n = 118; female, n = 71). We explored sex as a predictor of physiological response, sensory deficits, the severity of cognitive performance declines, and symptom manifestation via linear and binary logistic regression models. We found that the female sex predicted lower peripheral oxygen saturation and the likelihood of headache reporting in response to hypoxic challenge, yet explained little variance when combined with age and body mass index. The sensory and cognitive performance models did not converge, suggesting high intra-individual variability. Together, sex, age, and body mass index were not the most robust predictors in responses to hypoxic challenge; we cannot infer this for sensory deficits and cognitive performance within an experimentally induced hypoxic environment. The findings have implications for improving hypoxia familiarization training, monitoring sensor development, and emergency response and recovery protocols in case of a hypoxia occurrence suitable for all aircrew. We recommend continuing to elucidate the impact of sex and intrapersonal differences in hypoxia and other aeromedically relevant stressors in tactical aviation.
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Affiliation(s)
- Kaila A. Vento
- Naval Medical Research Unit-Dayton Wright-Patterson Air Force Base, Dayton, OH, United States,Oak Ridge Institute for Science and Education, Oak Ridge, TN, United States
| | - Cammi K. Borden
- Naval Medical Research Unit-Dayton Wright-Patterson Air Force Base, Dayton, OH, United States,Oak Ridge Institute for Science and Education, Oak Ridge, TN, United States
| | - Kara J. Blacker
- Naval Medical Research Unit-Dayton Wright-Patterson Air Force Base, Dayton, OH, United States,*Correspondence: Kara J. Blacker,
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3
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Pighin S, Bonini N, Hadjichristidis C, Schena F, Modena R, Savadori L. Hypoxia and risk preferences: Mild hypoxia impacts choices for low-probability high-payoff bets. Front Physiol 2022; 13:960773. [PMID: 36105278 PMCID: PMC9465039 DOI: 10.3389/fphys.2022.960773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/27/2022] [Indexed: 11/13/2022] Open
Abstract
Mild degrees of hypoxia are known to exert a detrimental effect on cognitive functions. In a lab study, we assessed the effect of mild hypoxia on risk-taking behavior. Participants (N = 25) were presented with pairs of bets of equal expected monetary value, one having a higher probability of winning/losing a lower payoff (safer bet) and one having a lower probability of winning/losing a higher payoff (riskier bet). We systematically varied the ratio of the probabilities (and corresponding payoffs) of the two bets and examined how this affected participants’ choice between them. Following a familiarization session, participants performed the task twice: once in a normoxic environment (20.9% oxygen concentration) and once in a mildly hypoxic environment (14.1% oxygen concentration). Participants were not told and could not guess which environment they were in. We found a higher preference for the riskier bet in the mild hypoxic than normoxic environment but only in the loss domain. Furthermore, as the probability ratio increased, mild hypoxia increased the preference for the riskier bet in the domain of losses but decreased it for gains. The present findings support that mild hypoxia promotes riskier choices in the loss domain and provide new insights into the impact of mild hypoxia in moderating the effect of probability ratio on risky choices.
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Affiliation(s)
- Stefania Pighin
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto, Italy
- *Correspondence: Stefania Pighin,
| | - Nicolao Bonini
- Department of Economics and Management, University of Trento, Trento, Italy
| | | | - Federico Schena
- Research Center Sport, Mountain and Health (CERISM), University of Verona, Rovereto, Italy
| | - Roberto Modena
- Research Center Sport, Mountain and Health (CERISM), University of Verona, Rovereto, Italy
| | - Lucia Savadori
- Department of Economics and Management, University of Trento, Trento, Italy
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4
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Blacker KJ, McHail DG. Time course of recovery from acute hypoxia exposure as measured by vigilance and event-related potentials. Physiol Behav 2021; 239:113508. [PMID: 34175363 DOI: 10.1016/j.physbeh.2021.113508] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/02/2021] [Accepted: 06/22/2021] [Indexed: 11/24/2022]
Abstract
Exposure to reduced levels of breathable oxygen is known to cause a number of deleterious effects on human performance. Previous work has demonstrated that in healthy adults, hypoxia results in decrements on a wide range of sensory, cognitive, and motor tasks. However, very little is known about the time course of recovery of cognitive functions following a hypoxic exposure. While previous studies have shown that physiological responses like heart rate and oxygen saturation rebound almost immediately, one previous study has shown a delayed recovery for response time (RT) measures following hypoxia. In the current study, we assessed the time course of neurocognitive recovery following a hypoxic exposure in healthy adults using the psychomotor vigilance task (PVT), passively elicited event-related potentials (ERPs) that assess auditory processing, and physiological measures. We also compared whether speed of recovery differed when participants were provided with 21% or 100% oxygen immediately following hypoxic exposure. Participants underwent a baseline testing session and two separate recovery sessions where they were assessed during a hypoxic exposure and at regular intervals for up to four hours post-exposure. Results demonstrated that RT, as measured by the PVT, significantly slowed during hypoxia compared to baseline and continued to be impaired until 60 min post-exposure. We assessed the mismatch negativity (MMN) and P3a ERP components in response to an auditory oddball paradigm and found a significant reduction in the amplitude of the MMN during hypoxia compared to baseline and that attenuation in amplitude persisted for up to 120 min post-exposure. Together, these results indicate that both RT and auditory processing showed a delayed recovery following hypoxia. We found no strong evidence for differential recovery speed based on recovery gas administered (21% versus 100% oxygen). These results have implications for guidance regarding return-to-duty status for military aviators following a hypoxic exposure.
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Affiliation(s)
- Kara J Blacker
- Naval Medical Research Unit-Dayton, Wright-Patterson AFB, OH, USA.
| | - Daniel G McHail
- Naval Medical Research Unit-Dayton, Wright-Patterson AFB, OH, USA.
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5
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Pun M, Guadagni V, Drogos LL, Pon C, Hartmann SE, Furian M, Lichtblau M, Muralt L, Bader PR, Moraga FA, Soza D, Lopez I, Rawling JM, Ulrich S, Bloch KE, Giesbrecht B, Poulin MJ. Cognitive Effects of Repeated Acute Exposure to Very High Altitude Among Altitude-Experienced Workers at 5050 m. High Alt Med Biol 2019; 20:361-374. [DOI: 10.1089/ham.2019.0012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Matiram Pun
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Veronica Guadagni
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Department of Clinical Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, Canada
- O'Brien Institute for Public Health, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Lauren L. Drogos
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Charlotte Pon
- Safety Group, Atacama Large Millimeter Submillimeter Array, Calama, Chile
| | - Sara E. Hartmann
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Michael Furian
- Department of Respiratory Medicine, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Mona Lichtblau
- Department of Respiratory Medicine, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Lara Muralt
- Department of Respiratory Medicine, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Patrick R. Bader
- Department of Respiratory Medicine, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Fernando A. Moraga
- Laboratorio de Fisiología, Hipoxia y Función Vascular, Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
| | - Daniel Soza
- Safety Group, Atacama Large Millimeter Submillimeter Array, Calama, Chile
| | - Ivan Lopez
- Safety Group, Atacama Large Millimeter Submillimeter Array, Calama, Chile
| | - Jean M. Rawling
- Department of Family Medicine, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Silvia Ulrich
- Department of Respiratory Medicine, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Konrad E. Bloch
- Department of Respiratory Medicine, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Barry Giesbrecht
- Department of Psychological and Brain Sciences, and Institute for Collaborative Biotechnologies, University of California Santa Barbara, Santa Barbara, California
| | - Marc J. Poulin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Department of Clinical Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, Canada
- O'Brien Institute for Public Health, Cumming School of Medicine, University of Calgary, Calgary, Canada
- Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, Canada
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6
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Ando S, Komiyama T, Sudo M, Higaki Y, Ishida K, Costello JT, Katayama K. The interactive effects of acute exercise and hypoxia on cognitive performance: A narrative review. Scand J Med Sci Sports 2019; 30:384-398. [PMID: 31605635 DOI: 10.1111/sms.13573] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 09/09/2019] [Accepted: 10/04/2019] [Indexed: 12/13/2022]
Abstract
Acute moderate intensity exercise has been shown to improve cognitive performance. In contrast, hypoxia is believed to impair cognitive performance. The detrimental effects of hypoxia on cognitive performance are primarily dependent on the severity and duration of exposure. In this review, we describe how acute exercise under hypoxia alters cognitive performance, and propose that the combined effects of acute exercise and hypoxia on cognitive performance are mainly determined by interaction among exercise intensity and duration, the severity of hypoxia, and duration of exposure to hypoxia. We discuss the physiological mechanism(s) of the interaction and suggest that alterations in neurotransmitter function, cerebral blood flow, and possibly cerebral metabolism are the primary candidates that determine cognitive performance when acute exercise is combined with hypoxia. Furthermore, acclimatization appears to counteract impaired cognitive performance during prolonged exposure to hypoxia although the precise physiological mechanism(s) responsible for this amelioration remain to be elucidated. This review has implications for sporting, occupational, and recreational activities at terrestrial high altitude where cognitive performance is essential. Further studies are required to understand physiological mechanisms that determine cognitive performance when acute exercise is performed in hypoxia.
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Affiliation(s)
- Soichi Ando
- Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan
| | - Takaaki Komiyama
- Center for Education in Liberal Arts and Sciences, Osaka University, Osaka, Japan
| | - Mizuki Sudo
- Meiji Yasuda Life Foundation of Health and Welfare, Tokyo, Japan
| | - Yasuki Higaki
- Faculty of Sports Science, Fukuoka University, Fukuoka, Japan
| | - Koji Ishida
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
| | - Joseph T Costello
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Keisho Katayama
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
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7
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Zimorski V, Mentel M, Tielens AGM, Martin WF. Energy metabolism in anaerobic eukaryotes and Earth's late oxygenation. Free Radic Biol Med 2019; 140:279-294. [PMID: 30935869 PMCID: PMC6856725 DOI: 10.1016/j.freeradbiomed.2019.03.030] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 03/21/2019] [Accepted: 03/26/2019] [Indexed: 01/09/2023]
Abstract
Eukaryotes arose about 1.6 billion years ago, at a time when oxygen levels were still very low on Earth, both in the atmosphere and in the ocean. According to newer geochemical data, oxygen rose to approximately its present atmospheric levels very late in evolution, perhaps as late as the origin of land plants (only about 450 million years ago). It is therefore natural that many lineages of eukaryotes harbor, and use, enzymes for oxygen-independent energy metabolism. This paper provides a concise overview of anaerobic energy metabolism in eukaryotes with a focus on anaerobic energy metabolism in mitochondria. We also address the widespread assumption that oxygen improves the overall energetic state of a cell. While it is true that ATP yield from glucose or amino acids is increased in the presence of oxygen, it is also true that the synthesis of biomass costs thirteen times more energy per cell in the presence of oxygen than in anoxic conditions. This is because in the reaction of cellular biomass with O2, the equilibrium lies very far on the side of CO2. The absence of oxygen offers energetic benefits of the same magnitude as the presence of oxygen. Anaerobic and low oxygen environments are ancient. During evolution, some eukaryotes have specialized to life in permanently oxic environments (life on land), other eukaryotes have remained specialized to low oxygen habitats. We suggest that the Km of mitochondrial cytochrome c oxidase of 0.1-10 μM for O2, which corresponds to about 0.04%-4% (avg. 0.4%) of present atmospheric O2 levels, reflects environmental O2 concentrations that existed at the time that the eukaryotes arose.
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Affiliation(s)
- Verena Zimorski
- Institute of Molecular Evolution, Heinrich-Heine-University, 40225, Düsseldorf, Germany.
| | - Marek Mentel
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, 851 04, Bratislava, Slovakia.
| | - Aloysius G M Tielens
- Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center Rotterdam, The Netherlands; Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
| | - William F Martin
- Institute of Molecular Evolution, Heinrich-Heine-University, 40225, Düsseldorf, Germany.
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8
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Heinrich EC, Djokic MA, Gilbertson D, DeYoung PN, Bosompra NO, Wu L, Anza-Ramirez C, Orr JE, Powell FL, Malhotra A, Simonson TS. Cognitive function and mood at high altitude following acclimatization and use of supplemental oxygen and adaptive servoventilation sleep treatments. PLoS One 2019; 14:e0217089. [PMID: 31188839 PMCID: PMC6561544 DOI: 10.1371/journal.pone.0217089] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 05/03/2019] [Indexed: 11/19/2022] Open
Abstract
Impairments in cognitive function, mood, and sleep quality occur following ascent to high altitude. Low oxygen (hypoxia) and poor sleep quality are both linked to impaired cognitive performance, but their independent contributions at high altitude remain unknown. Adaptive servoventilation (ASV) improves sleep quality by stabilizing breathing and preventing central apneas without supplemental oxygen. We compared the efficacy of ASV and supplemental oxygen sleep treatments for improving daytime cognitive function and mood in high-altitude visitors (N = 18) during acclimatization to 3,800 m. Each night, subjects were randomly provided with ASV, supplemental oxygen (SpO2 > 95%), or no treatment. Each morning subjects completed a series of cognitive function tests and questionnaires to assess mood and multiple aspects of cognitive performance. We found that both ASV and supplemental oxygen (O2) improved daytime feelings of confusion (ASV: p < 0.01; O2: p < 0.05) and fatigue (ASV: p < 0.01; O2: p < 0.01) but did not improve other measures of cognitive performance at high altitude. However, performance improved on the trail making tests (TMT) A and B (p < 0.001), the balloon analog risk test (p < 0.0001), and the psychomotor vigilance test (p < 0.01) over the course of three days at altitude after controlling for effects of sleep treatments. Compared to sea level, subjects reported higher levels of confusion (p < 0.01) and performed worse on the TMT A (p < 0.05) and the emotion recognition test (p < 0.05) on nights when they received no treatment at high altitude. These results suggest that stabilizing breathing (ASV) or increasing oxygenation (supplemental oxygen) during sleep can reduce feelings of fatigue and confusion, but that daytime hypoxia may play a larger role in other cognitive impairments reported at high altitude. Furthermore, this study provides evidence that some aspects of cognition (executive control, risk inhibition, sustained attention) improve with acclimatization.
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Affiliation(s)
- Erica C. Heinrich
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Matea A. Djokic
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Dillon Gilbertson
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Pamela N. DeYoung
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Naa-Oye Bosompra
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Lu Wu
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Cecilia Anza-Ramirez
- Departamento de Ciencias Biológicas y Fisiológicas, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jeremy E. Orr
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Frank L. Powell
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Atul Malhotra
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Tatum S. Simonson
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California, United States of America
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9
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The effect of severe and moderate hypoxia on exercise at a fixed level of perceived exertion. Eur J Appl Physiol 2019; 119:1213-1224. [PMID: 30820661 PMCID: PMC6469630 DOI: 10.1007/s00421-019-04111-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 02/21/2019] [Indexed: 02/08/2023]
Abstract
Purpose The purpose of this study was to determine the primary cues regulating perceived effort and exercise performance using a fixed-RPE protocol in severe and moderate hypoxia. Methods Eight male participants (26 ± 6 years, 76.3 ± 8.6 kg, 178.5 ± 3.6 cm, 51.4 ± 8.0 mL kg− 1 min− 1\documentclass[12pt]{minimal}
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\begin{document}$$\dot {V}$$\end{document}V˙O2max) completed three exercise trials in environmental conditions of severe hypoxia (FIO2 0.114), moderate hypoxia (FIO2 0.152), and normoxia (FIO2 0.202). They were instructed to continually adjust their power output to maintain a perceived effort (RPE) of 16, exercising until power output declined to 80% of the peak 30-s power output achieved. Results Exercise time was reduced (severe hypoxia 428 ± 210 s; moderate hypoxia 1044 ± 384 s; normoxia 1550 ± 590 s) according to a reduction in FIO2 (P < 0.05). The rate of oxygen desaturation during the first 3 min of exercise was accelerated in severe hypoxia (− 5.3 ± 2.8% min− 1) relative to moderate hypoxia (− 2.5 ± 1.0% min− 1) and normoxia (− 0.7 ± 0.3% min− 1). Muscle tissue oxygenation did not differ between conditions (P > 0.05). Minute ventilation increased at a faster rate according to a decrease in FIO2 (severe hypoxia 27.6 ± 6.6; moderate hypoxia 21.8 ± 3.9; normoxia 17.3 ± 3.9 L min− 1). Moderate-to-strong correlations were identified between breathing frequency (r = − 0.718, P < 0.001), blood oxygen saturation (r = 0.611, P = 0.002), and exercise performance. Conclusions The primary cues for determining perceived effort relate to progressive arterial hypoxemia and increases in ventilation.
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10
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Brechbuhl C, Brocherie F, Millet GP, Schmitt L. Effects of Repeated-Sprint Training in Hypoxia on Tennis-Specific Performance in Well-Trained Players. Sports Med Int Open 2018; 2:E123-E132. [PMID: 30539129 PMCID: PMC6259464 DOI: 10.1055/a-0719-4797] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 08/02/2018] [Accepted: 08/12/2018] [Indexed: 11/28/2022] Open
Abstract
This study examined the physiological, physical and technical responses to repeated-sprint training in normobaric hypoxia [RSH, inspired fraction of oxygen (FiO
2
) 14.5%] vs. normoxia (RSN, FiO
2
20.9%). Within 12 days, eighteen well-trained tennis players (RSH, n=9 vs. RSN, n=9) completed five specific repeated-sprint sessions that consisted of four sets of 5 maximal shuttle-run sprints. Testing sessions included repeated-sprint ability and Test to Exhaustion Specific to Tennis (TEST). TEST’s maximal duration to exhaustion and time to attain the ‘onset of blood lactate accumulation’ at 4 mMol.L
−1
(OBLA) improvements were significantly higher in RSH compared to RSN. Change in time to attain OBLA was concomitant with observations similar in time to the second ventilatory threshold. Significant interaction (P=0.003) was found for ball accuracy with greater increase in RSH (+13.8%, P=0.013) vs. RSN (–4.6%, P=0.15). A correlation (r=0.59, P<0.001) was observed between change in ball accuracy and TEST’s time to exhaustion. Greater improvement in some tennis-specific physical and technical parameters was observed after only 5 sessions of RSH vs. RSN in well-trained tennis players.
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Affiliation(s)
- Cyril Brechbuhl
- French Tennis Federation, National Tennis Center, 4 Place de la Porte Molitor, Paris, France.,ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Franck Brocherie
- Laboratory Sport, Expertise and Performance (EA 7370), Research Unit, French Institute of Sport (INSEP), Paris, France
| | - Gregoire P Millet
- ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Laurent Schmitt
- ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.,National Ski-Nordic Center, Premanon, Les Rousses, France
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11
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Burtscher M, Niedermeier M, Burtscher J, Pesta D, Suchy J, Strasser B. Preparation for Endurance Competitions at Altitude: Physiological, Psychological, Dietary and Coaching Aspects. A Narrative Review. Front Physiol 2018; 9:1504. [PMID: 30425646 PMCID: PMC6218926 DOI: 10.3389/fphys.2018.01504] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/05/2018] [Indexed: 01/14/2023] Open
Abstract
It was the Summer Olympic Games 1968 held in Mexico City (2,300 m) that required scientists and coaches to cope with the expected decline of performance in endurance athletes and to establish optimal preparation programs for competing at altitude. From that period until now many different recommendations for altitude acclimatization in advance of an altitude competition were proposed, ranging from several hours to several weeks. Those recommendations are mostly based on the separate consideration of the physiology of acclimatization, psychological issues, performance changes, logistical or individual aspects, but there is no review considering all these aspects in their entirety. Therefore, the present work primarily focusses on the period of altitude sojourn prior to the competition at altitude based on physiological and psychological aspects complemented by nutritional and sports practical considerations.
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Affiliation(s)
- Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria.,Austrian Society for Alpine and Mountain Medicine, Innsbruck, Austria
| | - Martin Niedermeier
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Johannes Burtscher
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Dominik Pesta
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Institute for Diabetes Research at Heinrich Heine University, Düsseldorf, Germany.,German Center for Diabetes Research, München-Neuherberg, Germany
| | - Jiri Suchy
- Faculty of Physical Education and Sport, Charles University, Prague, Czechia
| | - Barbara Strasser
- Department of Epidemiology and Preventive Medicine, University of Regensburg, Regensburg, Germany.,Medical School, Sigmund Freud University, Vienna, Austria
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The influence of hypoxia and prolonged exercise on attentional performance at high and extreme altitudes: A pilot study. PLoS One 2018; 13:e0205285. [PMID: 30281651 PMCID: PMC6169942 DOI: 10.1371/journal.pone.0205285] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/21/2018] [Indexed: 12/13/2022] Open
Abstract
Introduction Exposure to hypoxic conditions is reported to impair cognitive performance. Further, moderate physical exercise improves cognitive function, but little is known about the influence of exercise on cognitive function in hypoxia. Therefore, the current study aimed to examine the influence of hypoxia (HYP) and prolonged exercise (EX) on attentional performance. Methods A total of 80 participants (female: n = 29; male: n = 51) were assigned to four groups: HYP + EX (n = 15), HYP (n = 25), EX (n = 21) and normoxia (NOR) (n = 21). The Frankfurt Attention Inventory—2 (FAIR-2) was performed at four testing points (day 1, 14, 16 and 18) to assess attentional performance. All groups completed a pretest (D1) and a follow-up test (D18). In HYP + EX conditions, the cognitive task was performed in a hypoxic state after prolonged exercise (D14: 3950 m, D16: 5739 m) during a mountain climb on Mt. Kilimanjaro. Participants in HYP were tested under intermittent hypoxia at rest in a hypoxic chamber (D14: 3500 m, D16: 5800 m), and those in EX were tested under normoxia after prolonged exercise during a 7-day backcountry ski hiking tour. NOR was a control group, and participants completed all tests under normoxia and at rest. Results Hypoxia impaired the attentional functions performance value (PV) and continuity value (CV) for the HYP + EX (p = 0.000) and HYP (L: p = 0.025; K: p = 0.043) groups at 5739 m and 5800 m, respectively, but not the function quality value (QV). In contrast, the EX group did not exhibit changes in attentional function. Conclusion The current results suggest that attentional performance is impaired during extreme normobaric and hypobaric hypoxic exposure. We further conclude that greater cognitive impairment under hypobaric hypoxia during a mountain climb compared with normobaric hypoxia at rest is not caused by prolonged exercise, but may be influenced by other factors (e.g. low temperatures, dehydration, or sleep deprivation) that remain to be verified.
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Treml B, Kleinsasser A, Stadlbauer KH, Steiner I, Pajk W, Pilch M, Burtscher M, Knotzer H. Cutaneous Microvascular Blood Flow and Reactivity in Hypoxia. Front Physiol 2018; 9:160. [PMID: 29559919 PMCID: PMC5845666 DOI: 10.3389/fphys.2018.00160] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 02/19/2018] [Indexed: 01/04/2023] Open
Abstract
As is known, hypoxia leads to an increase in microcirculatory blood flow of the skin in healthy volunteers. In this pilot study, we investigated microcirculatory blood flow and reactive hyperemia of the skin in healthy subjects in normobaric hypoxia. Furthermore, we examined differences in microcirculation between hypoxic subjects with and without short-term acclimatization, whether or not skin microvasculature can acclimatize. Fourty-six healthy persons were randomly allocated to either short-term acclimatization using intermittent hypoxia for 1 h over 7 days at an FiO2 0.126 (treatment, n = 23) or sham short-term acclimatization for 1 h over 7 days at an FiO2 0.209 (control, n = 23). Measurements were taken in normoxia and at 360 and 720 min during hypoxia (FiO2 0.126). Microcirculatory cutaneous blood flow was assessed with a laser Doppler flowmeter on the forearm. Reactive hyperemia was induced by an ischemic stimulus. Measurements included furthermore hemodynamics, blood gas analyses and blood lactate. Microcirculatory blood flow increased progressively during hypoxia (12.3 ± 7.1–19.0 ± 8.1 perfusion units; p = 0.0002) in all subjects. The magnitude of the reactive hyperemia was diminished during hypoxia (58.2 ± 14.5–40.3 ± 27.4 perfusion units; p = 0.0003). Short-term acclimatization had no effect on microcirculatory blood flow. When testing for a hyperemic response of the skin's microcirculation we found a diminished signal in hypoxia, indicative for a compromised auto-regulative circulatory capacity. Furthermore, hypoxic short-term acclimatization did not affect cutaneous microcirculatory blood flow. Seemingly, circulation of the skin was unable to acclimatize using a week-long short-term acclimatization protocol. A potential limitation of our study may be the 7 days between acclimatization and the experimental test run. However, there is evidence that the hypoxic ventilatory response, an indicator of acclimatization, is increased for 1 week after short-term acclimatization. Then again, 1 week is what one needs to get from home to a location at significant altitude.
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Affiliation(s)
- Benedikt Treml
- Department of General and Surgical Intensive Care, Medical University Innsbruck, Innsbruck, Austria
| | - Axel Kleinsasser
- Department of Anesthesiology and Critical Care Medicine, Medical University Innsbruck, Innsbruck, Austria
| | - Karl-Heinz Stadlbauer
- Department of Anesthesiology and Critical Care Medicine, Klinikum Vöcklabruck, Vöcklabruck, Austria
| | - Iris Steiner
- Department of Anesthesiology and Critical Care Medicine, Medical University Innsbruck, Innsbruck, Austria
| | - Werner Pajk
- Department of Anesthesiology and Critical Care Medicine, Medical University Innsbruck, Innsbruck, Austria
| | - Michael Pilch
- Department of Pediatrics, County Hospital Kufstein, Kufstein, Austria
| | - Martin Burtscher
- Department of Sport Science, Medical Section, University Innsbruck, Innsbruck, Austria
| | - Hans Knotzer
- Department of Anesthesiology and Critical Care Medicine II, Klinikum Wels-Grieskirchen, Wels, Austria
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