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Baur DA, Baur KG, Buchanan BK, Ortiz MJ, Doody AG. Load carriage physiology in normoxia and hypoxia. Eur J Appl Physiol 2024; 124:925-943. [PMID: 37740748 PMCID: PMC10879375 DOI: 10.1007/s00421-023-05320-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 09/08/2023] [Indexed: 09/25/2023]
Abstract
PURPOSE To determine the effects of load carriage in normoxia and normobaric hypoxia on ventilatory responses, hemodynamics, tissue oxygenation, and metabolism. METHODS Healthy males (n = 12) completed 3 randomly ordered baseline graded exercise tests in the following conditions: (1) unloaded normoxic (U: FIO2 = 20.93%), (2) loaded (~ 30 kg) normoxic (LN), and (3) loaded hypoxic simulating ~ 3650 m (LH: FIO2 = ~ 13%). Thereafter, experimental exercise trials were completed in quasi-randomized order (i.e., U completed first) consisting of 3 × 10 min of walking (separated by 5 min seated rest) with stages matched with the U condition (in ascending order) for relative intensity, absolute oxygen consumption ([VO2]; 1.7 L min-1), and walking speed (1.45 ± 0.15 m s-1). RESULTS Load carriage increased perceived exertion and reduced VO2max (LN: - 7%; LH: - 32%; p < 0.05). At matched VO2, stroke volume and tidal volume were reduced and maintained with LN and LH vs. U, respectively (p < 0.05). Increases in cardiac output and minute ventilation at matched VO2 (with LH) and speed (with LN and LH), were primarily accomplished via increases in heart rate and breathing frequency (p < 0.05). Cerebral oxygenated hemoglobin (O2HHb) was increased at all intensities with LN, but deoxygenated hemoglobin and total hemoglobin were increased with LH (p < 0.05). Muscle oxygen kinetics and substrate utilization were similar between LN and U, but LH increased CHO dependence and reduced muscle O2HHb at matched speed (p < 0.05). CONCLUSION Load carriage reduces cardiorespiratory efficiency and increases physiological strain, particularly in hypoxic environments. Potential load carriage-induced alterations in cerebral blood flow may increase the risk for altitude illnesses and requires further study.
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Affiliation(s)
- Daniel A Baur
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA.
| | - Katherine G Baur
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
| | - Beverley K Buchanan
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
| | - Miles J Ortiz
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
| | - Abaigeal G Doody
- Department of Human Performance and Wellness, Virginia Military Institute, 208 Cormack Hall, Lexington, VA, 24450, USA
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2
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Souchet J, Josserand A, Darnet E, Le Chevalier H, Trochet A, Bertrand R, Calvez O, Martinez-Silvestre A, Guillaume O, Mossoll-Torres M, Pottier G, Philippe H, Aubret F, Gangloff EJ. Embryonic and juvenile snakes (Natrix maura, Linnaeus 1758) compensate for high elevation hypoxia via shifts in cardiovascular physiology and metabolism. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:1102-1115. [PMID: 37723946 DOI: 10.1002/jez.2756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 07/30/2023] [Accepted: 08/30/2023] [Indexed: 09/20/2023]
Abstract
The colonization of novel environments requires a favorable response to conditions never, or rarely, encountered in recent evolutionary history. For example, populations colonizing upslope habitats must cope with lower atmospheric pressure at elevation, and thus reduced oxygen availability. The embryo stage in oviparous organisms is particularly susceptible, given its lack of mobility and limited gas exchange via diffusion through the eggshell and membranes. Especially little is known about responses of Lepidosaurian reptiles to reduced oxygen availability. To test the role of physiological plasticity during early development in response to high elevation hypoxia, we performed a transplant experiment with the viperine snake (Natrix maura, Linnaeus 1758). We maintained gravid females originating from low elevation populations (432 m above sea level [ASL]-normoxia) at both the elevation of origin and high elevation (2877 m ASL-extreme high elevation hypoxia; approximately 72% oxygen availability relative to sea level), then incubated egg clutches at both low and high elevation. Regardless of maternal exposure to hypoxia during gestation, embryos incubated at extreme high elevation exhibited altered developmental trajectories of cardiovascular function and metabolism across the incubation period, including a reduction in late-development egg mass. This physiological response may have contributed to the maintenance of similar incubation duration, hatching success, and hatchling body size compared to embryos incubated at low elevation. Nevertheless, after being maintained in hypoxia, juveniles exhibit reduced carbon dioxide production relative to oxygen consumption, suggesting altered energy pathways compared to juveniles maintained in normoxia. These findings highlight the role of physiological plasticity in maintaining rates of survival and fitness-relevant phenotypes in novel environments.
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Affiliation(s)
- Jérémie Souchet
- Station d'Ecologie Théorique et Expérimentale (UAR CNRS 2029), Moulis, France
| | - Alicia Josserand
- Station d'Ecologie Théorique et Expérimentale (UAR CNRS 2029), Moulis, France
| | - Elodie Darnet
- Station d'Ecologie Théorique et Expérimentale (UAR CNRS 2029), Moulis, France
| | - Hugo Le Chevalier
- Station d'Ecologie Théorique et Expérimentale (UAR CNRS 2029), Moulis, France
| | - Audrey Trochet
- Société Herpétologique de France, Muséum National d'Histoire Naturelle, Paris, France
| | - Romain Bertrand
- Laboratoire Évolution et Diversité Biologique (UMR CNRS 5174), Université de Toulouse III Paul Sabatier, IRD, Toulouse, France
| | - Olivier Calvez
- Station d'Ecologie Théorique et Expérimentale (UAR CNRS 2029), Moulis, France
| | | | - Olivier Guillaume
- Station d'Ecologie Théorique et Expérimentale (UAR CNRS 2029), Moulis, France
| | | | | | - Hervé Philippe
- Station d'Ecologie Théorique et Expérimentale (UAR CNRS 2029), Moulis, France
| | - Fabien Aubret
- Station d'Ecologie Théorique et Expérimentale (UAR CNRS 2029), Moulis, France
- School of Molecular and Life Sciences, Curtin University, Perth, Australia
| | - Eric J Gangloff
- Station d'Ecologie Théorique et Expérimentale (UAR CNRS 2029), Moulis, France
- Department of Biological Sciences, Ohio Wesleyan University, Delaware, Ohio, USA
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3
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Bourdillon N, Aebi MR, Kayser B, Bron D, Millet GP. Both Hypoxia and Hypobaria Impair Baroreflex Sensitivity but through Different Mechanisms. Int J Sports Med 2022; 44:177-183. [PMID: 36455595 PMCID: PMC9977572 DOI: 10.1055/a-1960-3407] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Baroreflex sensitivity (BRS) is a measure of cardiovagal baroreflex and is lower in normobaric and hypobaric hypoxia compared to normobaric normoxia. The aim of this study was to assess the effects of hypobaria on BRS in normoxia and hypoxia. Continuous blood pressure and ventilation were recorded in eighteen seated participants in normobaric normoxia (NNx), hypobaric normoxia (HNx), normobaric hypoxia (NHx) and hypobaric hypoxia (HHx). Barometric pressure was matched between NNx vs. NHx (723±4 mmHg) and HNx vs. HHx (406±4 vs. 403±5 mmHg). Inspired oxygen pressure (PiO2) was matched between NNx vs. HNx (141.2±0.8 vs. 141.5±1.5 mmHg) and NHx vs. HHx (75.7±0.4 vs. 74.3±1.0 mmHg). BRS was assessed using the sequence method. BRS significantly decreased in HNx, NHx and HHx compared to NNx. Heart rate, mean systolic and diastolic blood pressures did not differ between conditions. There was the specific effect of hypobaria on BRS in normoxia (BRS was lower in HNx than in NNx). The hypoxic and hypobaric effects do not add to each other resulting in comparable BRS decreases in HNx, NHx and HHx. BRS decrease under low barometric pressure requires future studies independently controlling O2 and CO2 to identify central and peripheral chemoreceptors' roles.
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Affiliation(s)
- Nicolas Bourdillon
- ISSUL, institute of sports sciences, Université de Lausanne,
Lausanne, Switzerland,Correspondence Dr. Nicolas
Bourdillon Institute of Sport
ScienceISSULUniversity of
Lausanne1015
LausanneSwitzerland+ 33603370729
| | - Mathias Rolland Aebi
- ISSUL, institute of sports sciences, Université de Lausanne,
Lausanne, Switzerland,Wissenschaft & Technologie, armasuisse, Thun,
Switzerland
| | - Bengt Kayser
- ISSUL, institute of sports sciences, Université de Lausanne,
Lausanne, Switzerland
| | - Denis Bron
- ISSUL, institute of sports sciences, Université de Lausanne,
Lausanne, Switzerland
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Independent effects of acute normobaric hypoxia and hypobaric hypoxia on human physiology. Sci Rep 2022; 12:19570. [PMID: 36379983 PMCID: PMC9666440 DOI: 10.1038/s41598-022-23698-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 11/03/2022] [Indexed: 11/16/2022] Open
Abstract
The purpose of this study was to examine the effects of acute normobaric (NH, decreased FiO2) and hypobaric (HH, 4200 m ascent) hypoxia exposures compared to sea level (normobaric normoxia, NN). Tissue oxygenation, cardiovascular, and body fluid variables measured during rest and a 3-min step-test following 90-min exposures (NH, HH, NN). Muscle oxygenated hemoglobin (O2Hb) decreased, and muscle deoxygenated hemoglobin (HHb) increased environmentally independent from rest to exercise (p < 0.001). During exercise, brain O2Hb was lower at HH compared to NN (p = 0.007), trending similarly with NH (p = 0.066), but no difference between NN and NH (p = 0.158). During exercise, HR at NH (141 ± 4 beats·min-1) and HH (141 ± 3 beats·min-1) were higher than NN (127 ± 44 beats·min-1, p = 0.002), but not each other (p = 0.208). During exercise, stroke volume at HH (109.6 ± 4.1 mL·beat-1) was higher than NH (97.8 ± 3.3 mL·beat-1) and NN (99.8 ± 3.9 mL·beat-1, p ≤ 0.010) with no difference between NH and NN (p = 0.481). During exercise, cardiac output at NH (13.8 ± 0.6 L) and HH (15.5 ± 0.7 L) were higher than NN (12.6 ± 0.5 L, p ≤ 0.006) with HH also higher than NH (p = 0.001). During acute hypoxic stimuli, skeletal muscle maintains oxygenation whereas the brain does not. These differences may be mediated by environmentally specific cardiovascular compensation. Thus, caution is advised when equating NH and HH.
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5
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The effects of normobaric and hypobaric hypoxia on cognitive performance and physiological responses: A crossover study. PLoS One 2022; 17:e0277364. [DOI: 10.1371/journal.pone.0277364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 10/25/2022] [Indexed: 11/12/2022] Open
Abstract
This partially randomised controlled, crossover study sought to investigate the effects of normobaric hypoxia (NH) and hypobaric hypoxia (HH) on cognitive performance, the physiological response at rest and after a 3-min step-test. Twenty healthy participants (10 females and 10 males, 27.6±6.2yrs, 73.6±13.7kg, 175.3±8.9cm) completed a cognitive performance test, followed by the modified Harvard-step protocol, in four environments: normobaric normoxia (NN; PiO2: 146.0±1.5mmHg), NH (PiO2: 100.9±1.3mmHg), HH at the first day of ascent (HH1: PiO2 = 105.6±0.4mmHg) and HH after an overnight stay (HH2: PiO2 = 106.0±0.5mmHg). At rest and/or exercise, SpO2, NIRS, and cardiovascular and perceptual data were collected. The cerebral tissue oxygenation index and the cognitive performance (throughput, accuracy, and reaction time) were not different between the hypoxic conditions (all p>0.05). In NH, SpO2 was higher compared to HH1 (ΔSpO2 NH vs HH1: 1.7±0.5%, p = 0.003) whilst heart rate (ΔHR NH vs HH2: 5.8±2.6 bpm, p = 0.03) and sympathetic activation (ΔSNSi NH vs HH2: 0.8±0.4, p = 0.03) were lower in NH compared to HH2. Heart rate (ΔHR HH1 vs HH2: 6.9±2.6 bpm, p = 0.01) and sympathetic action (ΔSNSi HH1 vs HH2: 0.9±0.4, p = 0.02) were both lower in HH1 compared to HH2. In conclusion, cognitive performance and cerebral oxygenation didn’t differ between the hypoxic conditions. SpO2 was only higher in NH compared to HH1. In HH2, heart rate and sympathetic activation were higher compared to both NH and HH1. These conclusions account for a PiO2 between 100–106 mmHg.
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Burtscher J, Mallet RT, Pialoux V, Millet GP, Burtscher M. Adaptive Responses to Hypoxia and/or Hyperoxia in Humans. Antioxid Redox Signal 2022; 37:887-912. [PMID: 35102747 DOI: 10.1089/ars.2021.0280] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Significance: Oxygen is indispensable for aerobic life, but its utilization exposes cells and tissues to oxidative stress; thus, tight regulation of cellular, tissue, and systemic oxygen concentrations is crucial. Here, we review the current understanding of how the human organism (mal-)adapts to low (hypoxia) and high (hyperoxia) oxygen levels and how these adaptations may be harnessed as therapeutic or performance enhancing strategies at the systemic level. Recent Advances: Hyperbaric oxygen therapy is already a cornerstone of modern medicine, and the application of mild hypoxia, that is, hypoxia conditioning (HC), to strengthen the resilience of organs or the whole body to severe hypoxic insults is an important preparation for high-altitude sojourns or to protect the cardiovascular system from hypoxic/ischemic damage. Many other applications of adaptations to hypo- and/or hyperoxia are only just emerging. HC-sometimes in combination with hyperoxic interventions-is gaining traction for the treatment of chronic diseases, including numerous neurological disorders, and for performance enhancement. Critical Issues: The dose- and intensity-dependent effects of varying oxygen concentrations render hypoxia- and/or hyperoxia-based interventions potentially highly beneficial, yet hazardous, although the risks versus benefits are as yet ill-defined. Future Directions: The field of low and high oxygen conditioning is expanding rapidly, and novel applications are increasingly recognized, for example, the modulation of aging processes, mood disorders, or metabolic diseases. To advance hypoxia/hyperoxia conditioning to clinical applications, more research on the effects of the intensity, duration, and frequency of altered oxygen concentrations, as well as on individual vulnerabilities to such interventions, is paramount. Antioxid. Redox Signal. 37, 887-912.
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Affiliation(s)
- Johannes Burtscher
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.,Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Robert T Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Vincent Pialoux
- Inter-University Laboratory of Human Movement Biology EA7424, University Claude Bernard Lyon 1, University of Lyon, Lyon, France
| | - Grégoire P Millet
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.,Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
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7
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Hohenauer E, Taube W, Freitag L, Clijsen R. Sex differences during a cold-stress test in normobaric and hypobaric hypoxia: A randomized controlled crossover study. Front Physiol 2022; 13:998665. [PMID: 36225301 PMCID: PMC9549379 DOI: 10.3389/fphys.2022.998665] [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: 07/20/2022] [Accepted: 09/05/2022] [Indexed: 11/13/2022] Open
Abstract
Cold and hypoxia are two stressors that are frequently combined and investigated in the scientific literature. Despite the growing literature regarding normobaric hypoxia (NH) and hypobaric hypoxia (HH), responses between females and males are less often evaluated. Therefore, this study aims to investigate the physiological sex differences following a cold-stress test under normoxia, normobaric- and hypobaric hypoxia. A total of n = 10 females (24.8 ± 5.1 years) and n = 10 males (30.3 ± 6.3 years) from a university population volunteered for this study. The cold-stress test (CST) of the right hand (15°C for 2 min) was performed using a randomised crossover design in normobaric normoxia, NH and HH. The change (∆) from baseline to post-CST up to 15 min was analysed for cutaneous vascular conductance (CVC) and the hands’ skin temperature, whilst the mean values across time (post-CST up to 15 min) were assessed for peripheral oxygen saturation (SpO2), thermal sensation- and comfort. Pressure pain threshold (PPT) was assessed after the post-CST 15 min period. The hands’ skin temperature drop was higher (p = 0.01) in the female group (∆3.3 ± 1.5°C) compared to the male group (∆1.9 ± 0.9°C) only in NH. Females (−0.9 ± 0.5) rated this temperature drop in NH to feel significantly colder (p = 0.02) compared to the males (−0.2 ± 0.7). No differences were observed between sexes in NN, NH, and HH for ∆CVC, SpO2, thermal comfort and PPT. In conclusion, females and males show similar reactions after a CST under normoxia and hypoxia. Sex differences were observed in the local skin temperature response and thermal sensation only in NH.
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Affiliation(s)
- Erich Hohenauer
- Rehabilitation and Exercise Science Laboratory (RES lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
- Department of Physiotherapy, International University of Applied Sciences THIM, Landquart, Switzerland
- Department of Neurosciences and Movement Science, University of Fribourg, Fribourg, Switzerland
- Department of Movement and Sport Sciences, Vrije Universiteit Brussel, Brussels, Belgium
- *Correspondence: Erich Hohenauer,
| | - Wolfgang Taube
- Department of Neurosciences and Movement Science, University of Fribourg, Fribourg, Switzerland
| | - Livia Freitag
- Rehabilitation and Exercise Science Laboratory (RES lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
| | - Ron Clijsen
- Rehabilitation and Exercise Science Laboratory (RES lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
- Department of Physiotherapy, International University of Applied Sciences THIM, Landquart, Switzerland
- Department of Movement and Sport Sciences, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Health, Bern University of Applied Sciences, Berne, Switzerland
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Hohenauer E, Freitag L, Herten M, Siallagan J, Pollock E, Taube W, Clijsen R. The Methodological Quality of Studies Investigating the Acute Effects of Exercise During Hypoxia Over the Past 40 years: A Systematic Review. Front Physiol 2022; 13:919359. [PMID: 35784889 PMCID: PMC9243659 DOI: 10.3389/fphys.2022.919359] [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: 04/13/2022] [Accepted: 05/09/2022] [Indexed: 11/25/2022] Open
Abstract
Exercise under hypoxia and the physiological impact compared to normoxia or hypoxia has gained attention in the last decades. However, methodological quality assessment of articles in this area is lacking in the literature. Therefore, this article aimed to evaluate the methodologic quality of trials studying exercise under hypoxia. An electronic search was conducted until December 2021. The search was conducted in PubMed, CENTRAL, and PEDro using the PICO model. (P) Participants had to be healthy, (I) exercise under normobaric or hypobaric hypoxia had to be (C) compared to exercise in normoxia or hypoxia on (O) any physiological outcome. The 11-item PEDro scale was used to assess the methodological quality (internal validity) of the studies. A linear regression model was used to evaluate the evolution of trials in this area, using the total PEDro score of the rated trials. A total of n = 81 studies met the inclusion criteria and were processed in this study. With a mean score of 5.1 ± 0.9 between the years 1982 and 2021, the mean methodological quality can be described as “fair.” Only one study reached the highest score of 8/10, and n = 2 studies reached the lowest observed value of 3/10. The linear regression showed an increase of the PEDro score of 0.1 points per decade. A positive and small tendency toward increased methodologic quality was observed. The current results demonstrate that a positive and small tendency can be seen for the increase in the methodological quality in the field of exercise science under hypoxia. A “good” methodological quality, reaching a PEDro score of 6 points can be expected in the year 2063, using a linear regression model analysis. To accelerate this process, future research should ensure that methodological quality criteria are already included during the planning phase of a study.
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Affiliation(s)
- Erich Hohenauer
- Rehabilitation and Exercise Science Laboratory (RES Lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
- International University of Applied Sciences THIM, Landquart, Switzerland
- Department of Neurosciences and Movement Science, University of Fribourg, Fribourg, Switzerland
- Department of Movement and Sport Sciences, Vrije Universiteit Brussel, Brussels, Belgium
- *Correspondence: Erich Hohenauer,
| | - Livia Freitag
- Rehabilitation and Exercise Science Laboratory (RES Lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
| | - Miriam Herten
- Rehabilitation and Exercise Science Laboratory (RES Lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
| | - Julia Siallagan
- Rehabilitation and Exercise Science Laboratory (RES Lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
| | - Elke Pollock
- Department of Physiotherapy, Zurich University of Applied Sciences, Zurich, Switzerland
| | - Wolfgang Taube
- Department of Neurosciences and Movement Science, University of Fribourg, Fribourg, Switzerland
| | - Ron Clijsen
- Rehabilitation and Exercise Science Laboratory (RES Lab), Department of Business Economics, Health and Social Care, University of Applied Sciences and Arts of Southern Switzerland, Landquart, Switzerland
- International University of Applied Sciences THIM, Landquart, Switzerland
- Department of Movement and Sport Sciences, Vrije Universiteit Brussel, Brussels, Belgium
- Department of Health, Bern University of Applied Sciences, Berne, Switzerland
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Behrendt T, Bielitzki R, Behrens M, Herold F, Schega L. Effects of Intermittent Hypoxia-Hyperoxia on Performance- and Health-Related Outcomes in Humans: A Systematic Review. SPORTS MEDICINE - OPEN 2022; 8:70. [PMID: 35639211 PMCID: PMC9156652 DOI: 10.1186/s40798-022-00450-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 04/17/2022] [Indexed: 02/07/2023]
Abstract
BACKGROUND Intermittent hypoxia applied at rest or in combination with exercise promotes multiple beneficial adaptations with regard to performance and health in humans. It was hypothesized that replacing normoxia by moderate hyperoxia can increase the adaptive response to the intermittent hypoxic stimulus. OBJECTIVE Our objective was to systematically review the current state of the literature on the effects of chronic intermittent hypoxia-hyperoxia (IHH) on performance- and health-related outcomes in humans. METHODS PubMed, Web of Science™, Scopus, and Cochrane Library databases were searched in accordance with PRISMA guidelines (January 2000 to September 2021) using the following inclusion criteria: (1) original research articles involving humans, (2) investigation of the chronic effect of IHH, (3) inclusion of a control group being not exposed to IHH, and (4) articles published in peer-reviewed journals written in English. RESULTS Of 1085 articles initially found, eight studies were included. IHH was solely performed at rest in different populations including geriatric patients (n = 1), older patients with cardiovascular (n = 3) and metabolic disease (n = 2) or cognitive impairment (n = 1), and young athletes with overtraining syndrome (n = 1). The included studies confirmed the beneficial effects of chronic exposure to IHH, showing improvements in exercise tolerance, peak oxygen uptake, and global cognitive functions, as well as lowered blood glucose levels. A trend was discernible that chronic exposure to IHH can trigger a reduction in systolic and diastolic blood pressure. The evidence of whether IHH exerts beneficial effects on blood lipid levels and haematological parameters is currently inconclusive. A meta-analysis was not possible because the reviewed studies had a considerable heterogeneity concerning the investigated populations and outcome parameters. CONCLUSION Based on the published literature, it can be suggested that chronic exposure to IHH might be a promising non-pharmacological intervention strategy for improving peak oxygen consumption, exercise tolerance, and cognitive performance as well as reducing blood glucose levels, and systolic and diastolic blood pressure in older patients with cardiovascular and metabolic diseases or cognitive impairment. However, further randomized controlled trials with adequate sample sizes are needed to confirm and extend the evidence. This systematic review was registered on the international prospective register of systematic reviews (PROSPERO-ID: CRD42021281248) ( https://www.crd.york.ac.uk/prospero/ ).
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Affiliation(s)
- Tom Behrendt
- Department of Sport Science, Chair for Health and Physical Activity, Otto-von-Guericke University Magdeburg, Universitätsplatz 2, 39104 Magdeburg, Germany
| | - Robert Bielitzki
- Department of Sport Science, Chair for Health and Physical Activity, Otto-von-Guericke University Magdeburg, Universitätsplatz 2, 39104 Magdeburg, Germany
| | - Martin Behrens
- Department of Sport Science, Chair for Health and Physical Activity, Otto-von-Guericke University Magdeburg, Universitätsplatz 2, 39104 Magdeburg, Germany
- Department of Orthopaedics, Rostock University Medical Center, Doberaner Str. 142, 18057 Rostock, Germany
| | - Fabian Herold
- Research Group Degenerative and Chronic Disease, Movement, Faculty of Health Sciences, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Lutz Schega
- Department of Sport Science, Chair for Health and Physical Activity, Otto-von-Guericke University Magdeburg, Universitätsplatz 2, 39104 Magdeburg, Germany
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10
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Hypoxia and hemorheological properties in older individuals. Ageing Res Rev 2022; 79:101650. [PMID: 35597435 DOI: 10.1016/j.arr.2022.101650] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/20/2022] [Accepted: 05/13/2022] [Indexed: 12/17/2022]
Abstract
Hypoxia is caused by insufficient oxygen availability for the organism leading to reduced oxygen delivery to tissues and cells. It has been regarded as a severe threat to human health and it is indeed implicated in pathophysiological mechanisms involved in the development and progression of many diseases. Nevertheless, the potential of controlled hypoxia interventions (i.e. hypoxia conditioning) for improving cardio-vascular health is gaining increased attention. However, blood rheology is often a forgotten factor for vascular health while aging and hypoxia exposure are both suspected to alter hemorheological properties. These changes in blood rheology may influence the benefits-risks balance of hypoxia exposure in older individuals. The benefits of hypoxia exposure for vascular health are mainly reported for healthy populations and the combined impact of aging and hypoxia on blood rheology could therefore be deleterious in older individuals. This review discusses evidence of hypoxia-related and aging-related changes in blood viscosity and its determinants. It draws upon an extensive literature search on the effects of hypoxia/altitude and aging on blood rheology. Aging increases blood viscosity mainly through a rise in plasma viscosity, red blood cell (RBC) aggregation and a decrease in RBC deformability. Hypoxia also causes an increase in RBC aggregation and plasma viscosity. In addition, hypoxia exposure may increase hematocrit and modulate RBC deformability, depending on the hypoxic dose, i.e, beneficial effect of intermittent hypoxia with moderate dose vs deleterious effect of chronic continuous or intermittent hypoxia or if the hypoxic dose is too high. Special attention is directed toward the risks vs. benefits of hemorheological changes during hypoxia exposure in older individuals, and its clinical relevance for vascular disorders.
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11
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Tanner V, Faiss R, Saugy J, Bourdillon N, Schmitt L, Millet GP. Similar Supine Heart Rate Variability Changes During 24-h Exposure to Normobaric vs. Hypobaric Hypoxia. Front Neurosci 2021; 15:777800. [PMID: 34955728 PMCID: PMC8695977 DOI: 10.3389/fnins.2021.777800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 11/22/2021] [Indexed: 01/22/2023] Open
Abstract
Purpose: This study aimed to investigate the differences between normobaric (NH) and hypobaric hypoxia (HH) on supine heart rate variability (HRV) during a 24-h exposure. We hypothesized a greater decrease in parasympathetic-related parameters in HH than in NH. Methods: A pooling of original data from forty-one healthy lowland trained men was analyzed. They were exposed to altitude either in NH (FIO2 = 15.7 ± 2.0%; PB = 698 ± 25 mmHg) or HH (FIO2 = 20.9%; PB = 534 ± 42 mmHg) in a randomized order. Pulse oximeter oxygen saturation (SpO2), heart rate (HR), and supine HRV were measured during a 7-min rest period three times: before (in normobaric normoxia, NN), after 12 (H12), and 24 h (H24) of either NH or HH exposure. HRV parameters were analyzed for time- and frequency-domains. Results: SpO2 was lower in both hypoxic conditions than in NN and was higher in NH than HH at H24. Subjects showed similarly higher HR during both hypoxic conditions than in NN. No difference in HRV parameters was found between NH and HH at any time. The natural logarithm of root mean square of the successive differences (LnRMSSD) and the high frequency spectral power (HF), which reflect parasympathetic activity, decreased similarly in NH and HH when compared to NN. Conclusion: Despite SpO2 differences, changes in supine HRV parameters during 24-h exposure were similar between NH and HH conditions indicating a similar decrease in parasympathetic activity. Therefore, HRV can be analyzed similarly in NH and HH conditions.
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Affiliation(s)
- Valérian Tanner
- Medicine School, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Raphael Faiss
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.,REDs, Research and Expertise in Anti-Doping Sciences, University of Lausanne, Lausanne, Switzerland
| | - Jonas Saugy
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.,REDs, Research and Expertise in Anti-Doping Sciences, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Bourdillon
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Laurent Schmitt
- National Centre of Nordic-Ski, Research and Performance, Prémanon, France
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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12
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Debevec T, Poussel M, Osredkar D, Willis SJ, Sartori C, Millet GP. Post-exercise accumulation of interstitial lung water is greater in hypobaric than normobaric hypoxia in adults born prematurely. Respir Physiol Neurobiol 2021; 297:103828. [PMID: 34890833 DOI: 10.1016/j.resp.2021.103828] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 11/24/2021] [Accepted: 12/05/2021] [Indexed: 10/19/2022]
Abstract
We aimed to gauge the interstitial lung water accumulation following moderate-intensity exercise under normobaric and hypobaric hypoxic conditions in a group of preterm born but otherwise healthy young adults. Sixteen pre-term-born individuals (age = 21±2yrs.; gestational age = 29±3wk.; birth weight = 1160±273 g) underwent two 8 -h hypoxic/altitude exposures in a cross-over manner: 1) Normobaric hypoxic exposure (NH; FIO2 = 0.142±0.001; PIO2 = 90.6±0.9 mmHg) 2) Hypobaric hypoxic exposure (HH; terrestrial high-altitude 3840 m; PIO2 = 90.2±0.5 mmHg). Interstitial lung water was assessed via quantification of B-Lines (using lung ultrasound) before (normoxia) and after 4-h and 8-h of respective exposures. At each time point, B-Lines were quantified before (Pre) and immediately after (Post) a 6-min moderate-intensity exercise. The baseline B-lines count were comparable between both conditions (P = 0.191). A higher B-lines count was noted at Pre-H4 in HH versus NH (P = 0.0420). At Post-H8 B-lines score was significantly higher in HH (4.6 ± 1.6) than in NH (3.1 ± 1.4; P = 0.0073). Furthermore, at this time point, a significantly higher number of individuals with B-line scores ≥5 was observed in HH (n = 7) than in NH (n = 3; P = 0.0420). These findings suggest that short moderate-intensity exercise provokes a significant increase in the interstitial lung water accumulation after 8 h of exposure to terrestrial but not simulated altitude (≈3840 m) in prematurely born adults. Further work is needed to elucidate the exact mechanisms of (moderate-intensity) exercise-induced interstitial lung water accumulation in this population and directly compare the obtained data to full-term born adults.
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Affiliation(s)
- Tadej Debevec
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia; Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.
| | - Mathias Poussel
- Department of Pulmonary Function Testing and Exercise Physiology, CHRU de Nancy, Nancy, France; Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Damjan Osredkar
- Department of Pediatric Neurology, University Children's Hospital Ljubljana, Ljubljana, Slovenia
| | - Sarah J Willis
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Claudio Sartori
- Department of Internal Medicine and the Botnar Center for Extreme Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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13
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Doutreleau S. [Physiological and pathological responses to altitude]. Rev Mal Respir 2021; 38:1013-1024. [PMID: 34782179 DOI: 10.1016/j.rmr.2020.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 12/28/2020] [Indexed: 11/27/2022]
Abstract
Hypobaric hypoxia, the hallmark of a high altitude environment, has important physiological effects on both the cardiovascular and respiratory systems in order to maintain a balance between oxygen demand and supply. This dynamic of acclimatization is influenced both by the level of altitude and the speed of progression, but is also very individual with a wide spectrum of responses and sensitivities. This wide range of responses is associated with nonspecific symptoms characterising acute mountain sickness and high-altitude cerebral or pulmonary oedema. This article reviews the current knowledge about both the acclimatization processes and specific diseases of high-altitude.
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Affiliation(s)
- S Doutreleau
- Inserm, UM sports et pathologies, laboratoire HP2, CHU Grenoble-Alpes, université Grenoble Alpes, EXALT - centre d'expertise sur l'altitude, 38000 Grenoble, France.
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14
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Lemieux P, Birot O. Altitude, Exercise, and Skeletal Muscle Angio-Adaptive Responses to Hypoxia: A Complex Story. Front Physiol 2021; 12:735557. [PMID: 34552509 PMCID: PMC8450406 DOI: 10.3389/fphys.2021.735557] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 08/16/2021] [Indexed: 12/18/2022] Open
Abstract
Hypoxia, defined as a reduced oxygen availability, can be observed in many tissues in response to various physiological and pathological conditions. As a hallmark of the altitude environment, ambient hypoxia results from a drop in the oxygen pressure in the atmosphere with elevation. A hypoxic stress can also occur at the cellular level when the oxygen supply through the local microcirculation cannot match the cells’ metabolic needs. This has been suggested in contracting skeletal myofibers during physical exercise. Regardless of its origin, ambient or exercise-induced, muscle hypoxia triggers complex angio-adaptive responses in the skeletal muscle tissue. These can result in the expression of a plethora of angio-adaptive molecules, ultimately leading to the growth, stabilization, or regression of muscle capillaries. This remarkable plasticity of the capillary network is referred to as angio-adaptation. It can alter the capillary-to-myofiber interface, which represent an important determinant of skeletal muscle function. These angio-adaptive molecules can also be released in the circulation as myokines to act on distant tissues. This review addresses the respective and combined potency of ambient hypoxia and exercise to generate a cellular hypoxic stress in skeletal muscle. The major skeletal muscle angio-adaptive responses to hypoxia so far described in this context will be discussed, including existing controversies in the field. Finally, this review will highlight the molecular complexity of the skeletal muscle angio-adaptive response to hypoxia and identify current gaps of knowledges in this field of exercise and environmental physiology.
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Affiliation(s)
- Pierre Lemieux
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
| | - Olivier Birot
- Muscle Health Research Centre, School of Kinesiology and Health Science, York University, Toronto, ON, Canada
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15
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Sharma HS, Lafuente JV, Feng L, Muresanu DF, Menon PK, Castellani RJ, Nozari A, Sahib S, Tian ZR, Buzoianu AD, Sjöquist PO, Patnaik R, Wiklund L, Sharma A. Methamphetamine exacerbates pathophysiology of traumatic brain injury at high altitude. Neuroprotective effects of nanodelivery of a potent antioxidant compound H-290/51. PROGRESS IN BRAIN RESEARCH 2021; 266:123-193. [PMID: 34689858 DOI: 10.1016/bs.pbr.2021.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Military personnel are often exposed to high altitude (HA, ca. 4500-5000m) for combat operations associated with neurological dysfunctions. HA is a severe stressful situation and people frequently use methamphetamine (METH) or other psychostimulants to cope stress. Since military personnel are prone to different kinds of traumatic brain injury (TBI), in this review we discuss possible effects of METH on concussive head injury (CHI) at HA based on our own observations. METH exposure at HA exacerbates pathophysiology of CHI as compared to normobaric laboratory environment comparable to sea level. Increased blood-brain barrier (BBB) breakdown, edema formation and reductions in the cerebral blood flow (CBF) following CHI were exacerbated by METH intoxication at HA. Damage to cerebral microvasculature and expression of beta catenin was also exacerbated following CHI in METH treated group at HA. TiO2-nanowired delivery of H-290/51 (150mg/kg, i.p.), a potent chain-breaking antioxidant significantly enhanced CBF and reduced BBB breakdown, edema formation, beta catenin expression and brain pathology in METH exposed rats after CHI at HA. These observations are the first to point out that METH exposure in CHI exacerbated brain pathology at HA and this appears to be related with greater production of oxidative stress induced brain pathology, not reported earlier.
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Affiliation(s)
- Hari Shanker Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden.
| | - José Vicente Lafuente
- LaNCE, Department of Neuroscience, University of the Basque Country (UPV/EHU), Leioa, Bizkaia, Spain
| | - Lianyuan Feng
- Department of Neurology, Bethune International Peace Hospital, Shijiazhuang, Hebei Province, China
| | - Dafin F Muresanu
- Department of Clinical Neurosciences, University of Medicine & Pharmacy, Cluj-Napoca, Romania; "RoNeuro" Institute for Neurological Research and Diagnostic, Cluj-Napoca, Romania
| | - Preeti K Menon
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Rudy J Castellani
- Department of Pathology, University of Maryland, Baltimore, MD, United States
| | - Ala Nozari
- Anesthesiology & Intensive Care, Massachusetts General Hospital, Boston, MA, United States
| | - Seaab Sahib
- Department of Chemistry & Biochemistry, University of Arkansas, Fayetteville, AR, United States
| | - Z Ryan Tian
- Department of Chemistry & Biochemistry, University of Arkansas, Fayetteville, AR, United States
| | - Anca D Buzoianu
- Department of Clinical Pharmacology and Toxicology, "Iuliu Hatieganu" University of Medicine and Pharmacy, Cluj-Napoca, Romania
| | - Per-Ove Sjöquist
- Division of Cardiology, Department of Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Ranjana Patnaik
- Department of Biomaterials, School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi, India
| | - Lars Wiklund
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Aruna Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden.
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16
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Mallet RT, Burtscher J, Richalet JP, Millet GP, Burtscher M. Impact of High Altitude on Cardiovascular Health: Current Perspectives. Vasc Health Risk Manag 2021; 17:317-335. [PMID: 34135590 PMCID: PMC8197622 DOI: 10.2147/vhrm.s294121] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 05/12/2021] [Indexed: 12/12/2022] Open
Abstract
Globally, about 400 million people reside at terrestrial altitudes above 1500 m, and more than 100 million lowlanders visit mountainous areas above 2500 m annually. The interactions between the low barometric pressure and partial pressure of O2, climate, individual genetic, lifestyle and socio-economic factors, as well as adaptation and acclimatization processes at high elevations are extremely complex. It is challenging to decipher the effects of these myriad factors on the cardiovascular health in high altitude residents, and even more so in those ascending to high altitudes with or without preexisting diseases. This review aims to interpret epidemiological observations in high-altitude populations; present and discuss cardiovascular responses to acute and subacute high-altitude exposure in general and more specifically in people with preexisting cardiovascular diseases; the relations between cardiovascular pathologies and neurodegenerative diseases at altitude; the effects of high-altitude exercise; and the putative cardioprotective mechanisms of hypobaric hypoxia.
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Affiliation(s)
- Robert T Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Johannes Burtscher
- Department of Biomedical Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
- Institute of Sport Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
| | - Jean-Paul Richalet
- Laboratoire Hypoxie & Poumon, UMR Inserm U1272, Université Sorbonne Paris Nord 13, Bobigny Cedex, F-93017, France
| | - Gregoire P Millet
- Department of Biomedical Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
- Institute of Sport Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, A-6020, Austria
- Austrian Society for Alpine and High-Altitude Medicine, Mieming, Austria
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17
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High-altitude illnesses: Old stories and new insights into the pathophysiology, treatment and prevention. SPORTS MEDICINE AND HEALTH SCIENCE 2021; 3:59-69. [PMID: 35782163 PMCID: PMC9219347 DOI: 10.1016/j.smhs.2021.04.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/11/2021] [Accepted: 04/11/2021] [Indexed: 01/19/2023] Open
Abstract
Areas at high-altitude, annually attract millions of tourists, skiers, trekkers, and climbers. If not adequately prepared and not considering certain ascent rules, a considerable proportion of those people will suffer from acute mountain sickness (AMS) or even from life-threatening high-altitude cerebral (HACE) or/and pulmonary edema (HAPE). Reduced inspired oxygen partial pressure with gain in altitude and consequently reduced oxygen availability is primarily responsible for getting sick in this setting. Appropriate acclimatization by slowly raising the hypoxic stimulus (e.g., slow ascent to high altitude) and/or repeated exposures to altitude or artificial, normobaric hypoxia will largely prevent those illnesses. Understanding physiological mechanisms of acclimatization and pathophysiological mechanisms of high-altitude diseases, knowledge of symptoms and signs, treatment and prevention strategies will largely contribute to the risk reduction and increased safety, success and enjoyment at high altitude. Thus, this review is intended to provide a sound basis for both physicians counseling high-altitude visitors and high-altitude visitors themselves.
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18
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[Into thin air - Altitude training and hypoxic conditioning: From athlete to patient]. Rev Mal Respir 2021; 38:404-417. [PMID: 33722445 DOI: 10.1016/j.rmr.2021.02.066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 10/15/2020] [Indexed: 11/20/2022]
Abstract
INTRODUCTION Hypoxic exposure should be considered as a continuum, the effects of which depend on the dose and individual response to hypoxia. Hypoxic conditioning (HC) represents an innovative and promising strategy, ranging from improved human performance to therapeutic applications. STATE OF THE ART With the aim of improving sports performance, the effectiveness of hypoxic exposure, whether natural or simulated, is difficult to demonstrate because of the large variability of the protocols used. In therapeutics, the benefits of HC are described in many pathological conditions such as obesity or cardiovascular pathologies. If the HC benefits from a strong preclinical rationale, its application to humans remains limited. PERSPECTIVES Advances in training and acclimation will require greater personalization and precise periodization of hypoxic exposures. For patients, the harmonization of HC protocols, the identification of biomarkers and the development and subsequent validation of devices allowing a precise control of the hypoxic stimulus are necessary steps for the development of HC. CONCLUSIONS From the athlete to the patient, HC represents an innovative and promising field of research, ranging from the improvement of human performance to the prevention and treatment of certain pathologies.
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19
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Keeling RF, Powell FL, Shaffer G, Robbins PA, Simonson TS. Impacts of Changes in Atmospheric O 2 on Human Physiology. Is There a Basis for Concern? Front Physiol 2021; 12:571137. [PMID: 33737880 PMCID: PMC7960674 DOI: 10.3389/fphys.2021.571137] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 01/11/2021] [Indexed: 12/01/2022] Open
Abstract
Concern is often voiced over the ongoing loss of atmospheric O2. This loss, which is caused by fossil-fuel burning but also influenced by other processes, is likely to continue at least for the next few centuries. We argue that this loss is quite well understood, and the eventual decrease is bounded by the fossil-fuel resource base. Because the atmospheric O2 reservoir is so large, the predicted relative drop in O2 is very small even for extreme scenarios of future fossil-fuel usage which produce increases in atmospheric CO2 sufficient to cause catastrophic climate changes. At sea level, the ultimate drop in oxygen partial pressure will be less than 2.5 mm Hg out of a baseline of 159 mmHg. The drop by year 2300 is likely to be between 0.5 and 1.3 mmHg. The implications for normal human health is negligible because respiratory O2 consumption in healthy individuals is only weakly dependent on ambient partial pressure, especially at sea level. The impacts on top athlete performance, on disease, on reproduction, and on cognition, will also be very small. For people living at higher elevations, the implications of this loss will be even smaller, because of a counteracting increase in barometric pressure at higher elevations due to global warming.
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Affiliation(s)
- Ralph F Keeling
- Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, United States
| | - Frank L Powell
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Gary Shaffer
- GAIA Antarctic Research Center, University of Magallanes, Punta Arenas, Chile.,Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Peter A Robbins
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - Tatum S Simonson
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of California, San Diego, La Jolla, CA, United States
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20
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García I, Drobnic F, Javierre C, Pons V, Viscor G. Severe Hypoxic Exercise Does Not Impair Lung Diffusion in Elite Swimmers. High Alt Med Biol 2021; 22:90-95. [PMID: 33605802 DOI: 10.1089/ham.2020.0178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
García, Iker, Franchek Drobnic, Casimiro Javierre, Victoria Pons, and Ginés Viscor. Severe hypoxic exercise does not impair lung diffusion in elite swimmers. High Alt Med Biol. 22:90-95, 2021. Background: Exercise performed at high altitude may cause a subclinical pulmonary interstitial edema that can worsen gas exchange function. This study aimed to evaluate whether there are changes in alveolar-capillary diffusion after exercise during a short-term exposure to hypobaric hypoxia in elite swimmers. Materials and Methods: Seven elite swimmers (age: 20.4 ± 1.4 years, height: 1.78 ± 10.8 m, body mass: 69.7 ± 11.1 kg) participated in the study. Diffusing capacity of the lungs for carbon monoxide (DLCO), transfer coefficient of carbon monoxide, pulse oximeter oxygen saturation (SpO2), and heart rate (HR) were measured at sea level at rest (SL-R), and after a short-term hypobaric hypoxia exposure (4,000 m), both at rest (HA-R) and at the end of moderate interval exercise (HA-E). Results: The combined exposure to high altitude and exercise did not change DLCO from SL-R to HA-R, or HA-E (43.8 ± 9.8 to 41.3 ± 10.5 to 42.4 ± 8.6 ml minutes-1 mmHg-1, p = 0.391). As expected, elite swimmers showed large decrease in SpO2 (72 ± 5; p < 0.001) and increase in HR (139 ± 9 beats minutes-1; p < 0.003) after HA-E. Conclusions: An acute high-altitude exposure combined with submaximal exercise does not change alveolar-capillary diffusion in elite swimmers.
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Affiliation(s)
- Iker García
- Secció de Fisiologia, Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Barcelona, Spain.,Departament de Fisiologia i Nutrició, Centre d'Alt Rendiment (CAR), Sant Cugat del Vallés, Barcelona, Spain
| | | | - Casimiro Javierre
- Departament de Ciències Fisiològiques, Facultat de Medicina, Universitat de Barcelona, Barcelona, Barcelona, Spain
| | - Victoria Pons
- Departament de Fisiologia i Nutrició, Centre d'Alt Rendiment (CAR), Sant Cugat del Vallés, Barcelona, Spain
| | - Ginés Viscor
- Secció de Fisiologia, Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Barcelona, Spain
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21
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Busch SA, van Diepen S, Roberts R, Steele AR, Berthelsen LF, Smorschok MP, Bourgoin C, Steinback CD. Short-term hypoxia does not promote arrhythmia during voluntary apnea. Physiol Rep 2021; 9:e14703. [PMID: 33426815 PMCID: PMC7797307 DOI: 10.14814/phy2.14703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 12/06/2020] [Indexed: 12/19/2022] Open
Abstract
The presence of bradycardic arrhythmias during volitional apnea at altitude may be caused by chemoreflex activation/sensitization. We investigated whether bradyarrhythmic episodes became prevalent in apnea following short‐term hypoxia exposure. Electrocardiograms (ECG; lead II) were collected from 22 low‐altitude residents (F = 12; age=25 ± 5 years) at 671 m. Participants were exposed to normobaric hypoxia (Spo2 ~79 ± 3%) over a 5‐h period. ECG rhythms were assessed during both free‐breathing and maximal volitional end‐expiratory and end‐inspiratory apnea at baseline during normoxia and hypoxia exposure (20 min [AHX]; 5 h [HX5]). Free‐breathing HR became elevated at AHX (78 ± 10 bpm; p < 0.0001) and HX5 (80 ± 12 bpm; p < 0.0001) compared to normoxia (68 ± 10 bpm), whereas apnea caused significant bradycardia at AHX (nadir end‐expiratory −17 ± 14 bpm; p < 0.001) and HX5 (nadir end‐expiratory −19 ± 15 bpm; p < 0.001), but not during normoxia (nadir end‐expiratory −4 ± 13 bpm), with no difference in bradycardia responses between apneas at AHX and HX5. Conduction abnormalities were noted in five participants during normoxia (Premature Ventricular Contraction, Sinus Pause, Junctional Rhythm, Atrial Foci), which remained unchanged during apnea at AHX and HX5 (Premature Ventricular Contraction, Premature Atrial Contraction, Sinus Pause). End‐inspiratory apneas were overall longer across conditions (normoxia p < 0.05; AHX p < 0.01; HX5 p < 0.001), with comparable HR responses to end‐expiratory and fewer occurrences of arrhythmia. While short‐term hypoxia is sufficient to elicit bradycardia during apnea, the occurrence of arrhythmias in response to apnea was not affected. These findings indicate that previously observed bradyarrhythmic events in untrained individuals at altitude only become prevalent following chronic hypoxia specificlly.
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Affiliation(s)
- Stephen A Busch
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Sean van Diepen
- Department of Critical Care and Divison of Cardiology, Department of Medicine, University of Alberta, Edmonton, Canada
| | - Richard Roberts
- Department of Physiology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Canada
| | - Andrew R Steele
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Lindsey F Berthelsen
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Megan P Smorschok
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Cody Bourgoin
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
| | - Craig D Steinback
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Canada
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22
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Souchet J, Bossu C, Darnet E, Le Chevalier H, Poignet M, Trochet A, Bertrand R, Calvez O, Martinez-Silvestre A, Mossoll-Torres M, Guillaume O, Clobert J, Barthe L, Pottier G, Philippe H, Gangloff EJ, Aubret F. High temperatures limit developmental resilience to high-elevation hypoxia in the snake Natrix maura (Squamata: Colubridae). Biol J Linn Soc Lond 2020. [DOI: 10.1093/biolinnean/blaa182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Abstract
Climate change is generating range shifts in many organisms, notably along the altitudinal gradient. However, moving up in altitude exposes organisms to lower oxygen availability, which may negatively affect development and fitness, especially at high temperatures. To test this possibility in a potentially upward-colonizing species, we artificially incubated developing embryos of the viperine snake Natrix maura Linnaeus 1758, using a split-clutch design, in conditions of extreme high elevation or low elevation at two ecologically-relevant incubation temperatures (24 and 32 °C). Embryos at low and extreme high elevations incubated at cool temperatures did not differ in development time, hatchling phenotype or locomotor performance. However, at the warmer incubation temperature and at extreme high elevation, hatching success was reduced. Further, embryonic heart rates were lower, incubation duration longer and juveniles born smaller. Nonetheless, snakes in this treatment were faster swimmers than siblings in other treatment groups, suggesting a developmental trade-off between size and performance. Constraints on development may be offset by the maintenance of important performance metrics, thus suggesting that early life-history stages will not prevent the successful colonization of high-elevation habitat even under the dual limitations of reduced oxygen and increased temperature.
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Affiliation(s)
- Jérémie Souchet
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
| | - Coralie Bossu
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
| | - Elodie Darnet
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
| | - Hugo Le Chevalier
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
| | - Manon Poignet
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
| | - Audrey Trochet
- Société Herpétologique de France, Muséum National d’Histoire Naturelle, CP41, 57 rue Cuvier, Paris, France
| | - Romain Bertrand
- Laboratoire Évolution et Diversité Biologique, UMR 5174 Université de Toulouse III Paul Sabatier, CNRS, IRD, Toulouse, France
| | - Olivier Calvez
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
| | | | - Marc Mossoll-Torres
- Bomosa, Pl. Parc de la Mola, 10 Torre Caldea 7º, Les Escaldes, Andorra
- Pirenalia, c/ de la rectoria, 2 Casa Cintet, Encamp, Andorra
| | - Olivier Guillaume
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
| | - Jean Clobert
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
| | - Laurent Barthe
- Société Herpétologique de France, Muséum National d’Histoire Naturelle, CP41, 57 rue Cuvier, Paris, France
- Nature En Occitanie, 14 rue de Tivoli, Toulouse, France
| | | | - Hervé Philippe
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
- Département de Biochimie, Centre Robert-Cedergren, Université de Montréal, Montréal, QC, Canada
| | - Eric J Gangloff
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
- Department of Zoology, Ohio Wesleyan University, 61 Sandusky Street, Delaware, Ohio, USA
| | - Fabien Aubret
- Station d’Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, UMR 5321 CNRS—Université Paul Sabatier, Moulis, France
- School of Molecular and Life Sciences, Curtin University, Brand Drive, Bentley, WA, Australia
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Aebi MR, Bourdillon N, Noser P, Millet GP, Bron D. Cognitive Impairment During Combined Normobaric vs. Hypobaric and Normoxic vs. Hypoxic Acute Exposure. Aerosp Med Hum Perform 2020; 91:845-851. [PMID: 33334404 DOI: 10.3357/amhp.5616.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
INTRODUCTION: Exposure to hypoxia has a deleterious effect on cognitive function; however, the putative effect of hypobaria remains unclear. The present study aimed to evaluate cognitive performance in pilot trainees who were exposed to acute normobaric (NH) and hypobaric hypoxia (HH). Of relevance for military pilots, we also aimed to assess cognitive performance in hypobaric normoxia (HN).METHODS: A total of 16 healthy pilot trainees were exposed to 4 randomized conditions (i.e., normobaric normoxia, NN, altitude level of 440 m; HH at 5500 m; NH, altitude simulation of 5500 m; and HN). Subjects performed a cognitive assessment (KLT-R test). Cerebral oxygen delivery (cDO₂) was estimated based middle cerebral artery blood flow velocity (MCAv) and pulse oxygen saturation (Spo₂) monitored during cognitive assessment.RESULTS: Percentage of errors increased in NH (14.3 9.1%) and HH (12.9 6.4%) when compared to NN (6.5 4.1%) and HN (6.0 4.0%). Number of calculations accomplished was lower only in HH than in NN and HN. When compared to NN, cDO₂ decreased in NH and HH.DISCUSSION: Cognitive performance was decreased similarly in acute NH and HH. The cDO₂ reduction in NH and HH implies insufficient MCAv increase to ensure cognitive performance maintenance. The present study suggests negligible hypobaric influence on cognitive performance in hypoxia and normoxia.Aebi MR, Bourdillon N, Noser P, Millet GP, Bron D. Cognitive impairment during combined normobaric vs. hypobaric and normoxic vs. hypoxic acute exposure. Aerosp Med Hum Perform. 2020; 91(11):845851.
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Aebi MR, Bourdillon N, Bron D, Millet GP. Minimal Influence of Hypobaria on Heart Rate Variability in Hypoxia and Normoxia. Front Physiol 2020; 11:1072. [PMID: 32973566 PMCID: PMC7472461 DOI: 10.3389/fphys.2020.01072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/04/2020] [Indexed: 11/24/2022] Open
Abstract
Introduction The present study evaluated the putative effect of hypobaria on resting HRV in normoxia and hypoxia. Methods Fifteen young pilot trainees were exposed to five different conditions in a randomized order: normobaric normoxia (NN, PB = 726 ± 5 mmHg, FIO2 = 20.9%), hypobaric normoxia (HN, PB = 380 ± 6 mmHg, FIO2≅40%), normobaric hypoxia (NH, PB = 725 ± 4 mmHg, FIO2≅11%); and hypobaric hypoxia (HH at 3000 and 5500 m, HH3000 and HH5500, PB = 525 ± 6 and 380 ± 8 mmHg, respectively, FIO2 = 20.9%). HRV and pulse arterial oxygen saturation (SpO2) were measured at rest seated during a 6 min period in each condition. HRV parameters were analyzed (Kubios HVR Standard, V 3.0) for time (RMSSD) and frequency (LF, HF, LF/HF ratio, and total power). Gas exchanges were collected at rest for 10 min following HRV recording. Results SpO2 decreased in HH3000 (95 ± 3) and HH5500 (81 ± 5), when compared to NN (99 ± 0). SpO2 was higher in NH (86 ± 4) than HH5500 but similar between HN (98 ± 2) and NN. Participants showed lower RMSSD and total power values in NH and HH5500 when compared to NN. In hypoxia, LF/HF ratio was greater in HH5500 than NH, whereas in normoxia, LF/HF ratio was lower in HN than NN. Minute ventilation was higher in HH5500 than in all other conditions. Discussion The present study reports a slight hypobaric effect either in normoxia or in hypoxia on some HRV parameters. In hypoxia, with a more prominent sympathetic activation, the hypobaric effect is likely due to the greater ventilation stimulus and larger desaturation. In normoxia, the HRV differences may come from the hyperoxic breathing and slight breathing pattern change due to hypobaria in HN.
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Affiliation(s)
- Mathias Roland Aebi
- Swiss Aeromedical Center, Swiss Air Force, Dübendorf, Switzerland
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
- Armasuisse, Wissenschaft and Technologie, Thun, Switzerland
- *Correspondence: Mathias Roland Aebi,
| | - Nicolas Bourdillon
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
- Be.care SA, Renens, Switzerland
| | - Denis Bron
- Swiss Aeromedical Center, Swiss Air Force, Dübendorf, Switzerland
| | - Grégoire P. Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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25
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Souchet J, Gangloff EJ, Micheli G, Bossu C, Trochet A, Bertrand R, Clobert J, Calvez O, Martinez-Silvestre A, Darnet E, LE Chevalier H, Guillaume O, Mossoll-Torres M, Barthe L, Pottier G, Philippe H, Aubret F. High-elevation hypoxia impacts perinatal physiology and performance in a potential montane colonizer. Integr Zool 2020; 15:544-557. [PMID: 32649806 PMCID: PMC7689776 DOI: 10.1111/1749-4877.12468] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Climate change is generating range shifts in many organisms, notably along the elevational gradient in mountainous environments. However, moving up in elevation exposes organisms to lower oxygen availability, which may reduce the successful reproduction and development of oviparous organisms. To test this possibility in an upward‐colonizing species, we artificially incubated developing embryos of the viperine snake (Natrix maura) using a split‐clutch design, in conditions of extreme high elevation (hypoxia at 2877 m above sea level; 72% sea‐level equivalent O2 availability) or low elevation (control group; i.e. normoxia at 436 m above sea level). Hatching success did not differ between the two treatments. Embryos developing at extreme high elevation had higher heart rates and hatched earlier, resulting in hatchlings that were smaller in body size and slower swimmers compared to their siblings incubated at lower elevation. Furthermore, post‐hatching reciprocal transplant of juveniles showed that snakes which developed at extreme high elevation, when transferred back to low elevation, did not recover full performance compared to their siblings from the low elevation incubation treatment. These results suggest that incubation at extreme high elevation, including the effects of hypoxia, will not prevent oviparous ectotherms from producing viable young, but may pose significant physiological challenges on developing offspring in ovo. These early‐life performance limitations imposed by extreme high elevation could have negative consequences on adult phenotypes, including on fitness‐related traits.
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Affiliation(s)
- Jérémie Souchet
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | - Eric J Gangloff
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France.,Department of Zoology, Ohio Wesleyan University, Delaware, Ohio, USA
| | - Gaëlle Micheli
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | - Coralie Bossu
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | - Audrey Trochet
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | - Romain Bertrand
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | - Jean Clobert
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | - Olivier Calvez
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | | | - Elodie Darnet
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | - Hugo LE Chevalier
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | - Olivier Guillaume
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
| | - Marc Mossoll-Torres
- Bomosa, Pl. Parc de la Mola, Les Escaldes, Andorra.,Pirenalia, Encamp, Andorra
| | | | | | - Hervé Philippe
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France.,Département de Biochimie, Centre Robert-Cedergren, Université de Montréal, Montréal, Canada
| | - Fabien Aubret
- Station d'Ecologie Théorique et Expérimentale du Centre National de la Recherche Scientifique, Moulis, France
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26
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A Focused Review on the Maximal Exercise Responses in Hypo- and Normobaric Hypoxia: Divergent Oxygen Uptake and Ventilation Responses. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17145239. [PMID: 32698542 PMCID: PMC7400084 DOI: 10.3390/ijerph17145239] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 12/26/2022]
Abstract
The literature suggests that acute hypobaric (HH) and normobaric (NH) hypoxia exposure elicits different physiological responses. Only limited information is available on whether maximal cardiorespiratory exercise test outcomes, performed on either the treadmill or the cycle ergometer, are affected differently by NH and HH. A focused literature review was performed to identify relevant studies reporting cardiorespiratory responses in well-trained male athletes (individuals with a maximal oxygen uptake, VO2max > 50 mL/min/kg at sea level) to cycling or treadmill running in simulated acute HH or NH. Twenty-one studies were selected. The exercise tests in these studies were performed in HH (n = 90) or NH (n = 151) conditions, on a bicycle ergometer (n = 178) or on a treadmill (n = 63). Altitudes (simulated and terrestrial) varied between 2182 and 5400 m. Analyses (based on weighted group means) revealed that the decline in VO2max per 1000 m gain in altitude was more pronounced in acute NH vs. HH (-7.0 ± 1.4% vs. -5.6 ± 0.9%). Maximal minute ventilation (VEmax) increased in acute HH but decreased in NH with increasing simulated altitude (+1.9 ± 0.9% vs. -1.4 ± 1.8% per 1000 m gain in altitude). Treadmill running in HH caused larger decreases in arterial oxygen saturation and heart rate than ergometer cycling in acute HH, which was not the case in NH. These results indicate distinct differences between maximal cardiorespiratory responses to cycling and treadmill running in acute NH or HH. Such differences should be considered when interpreting exercise test results and/or monitoring athletic training.
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Patrician A, Carr J, Ainslie PN. Response to Millet and Debevec re: "The Effect of an Expiratory Resistance Mask With Dead Space on Sleep, Acute Mountain Sickness, Cognition, and Ventilatory Acclimatization in Normobaric Hypoxia," by Patrician et al. and "Global REACH 2018: The Effect of an Expiratory Resistance Mask with Dead Space on Sleep and Acute Mountain Sickness During Acute Exposure to Hypobaric Hypoxia" by Carr et al. High Alt Med Biol 2020; 21:436. [PMID: 32667827 DOI: 10.1089/ham.2020.0111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Alexander Patrician
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan Campus, Kelowna, Canada
| | - Jay Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan Campus, Kelowna, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia-Okanagan Campus, Kelowna, Canada
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Affiliation(s)
- Jean-Paul Richalet
- Université Paris 13, INSERM 1272 Hypoxie et poumon, Bobigny, France.,INSEP, Pôle medical, Paris, France
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Millet GP, Debevec T. Rebuttal from Grégoire P. Millet and Tadej Debevec. J Physiol 2020; 598:901-902. [PMID: 32053210 DOI: 10.1113/jp279425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Tadej Debevec
- Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia.,Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.,School of Life sciences, Faculty of Medicine and Health Sciences, Nottingham University, Nottingham, UK
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