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Xie J, Xie S, Zhong Z, Dong H, Huang P, Zhou S, Tian H, Zhang J, Wu Y, Li P. Hypoxic preacclimatization combining intermittent hypoxia exposure with physical exercise significantly promotes the tolerance to acute hypoxia. Front Physiol 2024; 15:1367642. [PMID: 38633296 PMCID: PMC11021865 DOI: 10.3389/fphys.2024.1367642] [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: 01/11/2024] [Accepted: 03/19/2024] [Indexed: 04/19/2024] Open
Abstract
Background: Both hypoxia exposure and physical exercise before ascending have been proved to promote high altitude acclimatization, whether the combination of these two methods can bring about a better effect remains uncertain. Therefore, we designed this study to evaluate the effect of hypoxic preacclimatization combining intermittent hypoxia exposure (IHE) and physical exercise on the tolerance to acute hypoxia and screen the optimal preacclimatization scheme among the lowlanders. Methods: A total of 120 Han Chinese young men were enrolled and randomly assigned into four groups, including the control group and three experimental groups with hypoxic preacclimatization of 5-day rest, 5-day exercise, and 3-day exercise in a hypobaric chamber, respectively. Main physical parameters for hypoxia acclimatization, AMS incidence, physical and mental capacity were measured for each participant in the hypobaric chamber simulated to the altitude of 4500 m in the effect evaluation stage. The effect was compared between different schemes. Results: During the effect evaluation stage, SpO2 of the 5-day rest group and 5-day exercise group was significantly higher than that of the control group (p = 0.001 and p = 0.006, respectively). The participants with 5-day rest had significantly lower HR than the controls (p = 0.018). No significant differences of AMS incidence were found among the four groups, while the proportion of AMS headache symptom (moderate and severe vs. mild) was significantly lower in the 3-day exercise group than that in the control group (p = 0.002). The 5-day exercise group had significantly higher VO2max, than the other three groups (p = 0.033, p < 0.001, and p = 0.023, respectively). The 5-day exercise group also had significantly higher digital symbol and pursuit aiming test scores, while shorter color selection reaction time than the control group (p = 0.005, p = 0.005, and p = 0.004, respectively). Conclusion: Hypoxic preacclimatization combining IHE with physical exercise appears to be efficient in promoting the tolerance to acute hypoxia. Hypoxia duration and physical exercise of moderate intensity are helpful for improvement of SpO2 and HR, relief of AMS headache symptoms, and enhancement of mental and physical operation capacity.
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Affiliation(s)
- Jiaxin Xie
- Department of High Altitude Operational Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Shenwei Xie
- Department of Health Management, The 953rd Hospital of PLA, Shigatse, China
| | - Zhifeng Zhong
- Department of High Altitude Operational Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Huaping Dong
- Department of High Altitude Operational Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Pei Huang
- Department of High Altitude Operational Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Simin Zhou
- Department of High Altitude Operational Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Huaijun Tian
- Department of High Altitude Operational Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Jijian Zhang
- Department of High Altitude Operational Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Yu Wu
- Department of High Altitude Operational Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing, China
| | - Peng Li
- Department of High Altitude Operational Medicine, College of High Altitude Military Medicine, Army Medical University (Third Military Medical University), Chongqing, China
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Burtscher J, Swenson ER, Hackett PH, Millet GP, Burtscher M. Flying to high-altitude destinations: Is the risk of acute mountain sickness greater? J Travel Med 2023; 30:taad011. [PMID: 36694981 PMCID: PMC10289512 DOI: 10.1093/jtm/taad011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 12/31/2022] [Accepted: 01/17/2023] [Indexed: 01/26/2023]
Abstract
BACKGROUND Altitude sojourns increasingly attract individuals of all ages and different health statuses due to the appeal of high-altitude destinations worldwide and easy access to air travel. The risk of acute mountain sickness (AMS) when flying to high-altitude destinations remains underemphasized. Thus, this review aims to evaluate the altitude-dependent AMS incidence depending on the mode of ascending, e.g. by air vs terrestrial travel. METHODS A literature search was performed to identify the observational studies assessing AMS incidence after acute ascent of primarily healthy adults to real high altitude. In addition, placebo arms of interventional trials evaluating the prophylactic efficacy of various drugs have been separately analysed to confirm or refute the findings from the observational studies. Linear regression analyses were used to evaluate the altitude-dependent AMS incidence. RESULTS Findings of 12 observational studies, in which the AMS incidence in 11 021 individuals ascending to 19 different altitudes (2200-4559 m) was evaluated, revealed an impressive 4.5-fold steeper increase in the AMS incidence for air travel as compared with slower ascent modes, i.e. hiking or combined car and/or air travel and hiking. The higher AMS incidence following transportation by flight vs slower means was also confirmed in placebo-treated participants in 10 studies of drug prophylaxis against AMS. CONCLUSIONS Due to the short time span in going from low to high altitude, reduced acclimatization likely is the main reason for a higher AMS risk when travelling to high-altitude destinations by flight. To avoid frustrating travel experiences and health risks, appropriate and timely medical advice on how to prepare for air travel to high altitude is of vital importance. Effective preparation options include the use of modern pre-acclimatization strategies and pharmacological prophylaxis by acetazolamide or dexamethasone, or even considering alternate itineraries with more gradual ascent.
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Affiliation(s)
- Johannes Burtscher
- Institute of Sport Sciences, University of Lausanne, Lausanne 1015, Switzerland
- Department of Biomedical Sciences, University of Lausanne, Lausanne 1005, Switzerland
| | - Erik R Swenson
- VA Puget Health Care System, University of Washington, Seattle, WA, USA
| | - Peter H Hackett
- Altitude Research Center, Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne 1015, Switzerland
- Department of Biomedical Sciences, University of Lausanne, Lausanne 1005, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck A-6020, Austria
- Austrian Society for Alpine and High-Altitude Medicine, Innsbruck A-6020, Austria
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Mallet RT, Burtscher J, Pialoux V, Pasha Q, Ahmad Y, Millet GP, Burtscher M. Molecular Mechanisms of High-Altitude Acclimatization. Int J Mol Sci 2023; 24:ijms24021698. [PMID: 36675214 PMCID: PMC9866500 DOI: 10.3390/ijms24021698] [Citation(s) in RCA: 35] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/17/2023] Open
Abstract
High-altitude illnesses (HAIs) result from acute exposure to high altitude/hypoxia. Numerous molecular mechanisms affect appropriate acclimatization to hypobaric and/or normobaric hypoxia and curtail the development of HAIs. The understanding of these mechanisms is essential to optimize hypoxic acclimatization for efficient prophylaxis and treatment of HAIs. This review aims to link outcomes of molecular mechanisms to either adverse effects of acute high-altitude/hypoxia exposure or the developing tolerance with acclimatization. After summarizing systemic physiological responses to acute high-altitude exposure, the associated acclimatization, and the epidemiology and pathophysiology of various HAIs, the article focuses on molecular adjustments and maladjustments during acute exposure and acclimatization to high altitude/hypoxia. Pivotal modifying mechanisms include molecular responses orchestrated by transcription factors, most notably hypoxia inducible factors, and reciprocal effects on mitochondrial functions and REDOX homeostasis. In addition, discussed are genetic factors and the resultant proteomic profiles determining these hypoxia-modifying mechanisms culminating in successful high-altitude acclimatization. Lastly, the article discusses practical considerations related to the molecular aspects of acclimatization and altitude training strategies.
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Affiliation(s)
- Robert T. Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Johannes Burtscher
- Department of Biomedical Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
- Institute of Sport Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
| | - Vincent Pialoux
- Inter-University Laboratory of Human Movement Biology EA7424, University Claude Bernard Lyon 1, University of Lyon, FR-69008 Lyon, France
| | - Qadar Pasha
- Institute of Hypoxia Research, New Delhi 110067, India
| | - Yasmin Ahmad
- Defense Institute of Physiology & Allied Sciences (DIPAS), Defense Research & Development Organization(DRDO), New Delhi 110054, India
| | - Grégoire P. Millet
- Department of Biomedical Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
- Institute of Sport Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, A-6020 Innsbruck, Austria
- Austrian Society for Alpine and High-Altitude Medicine, A-6020 Innsbruck, Austria
- Correspondence:
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Furian M, Tannheimer M, Burtscher M. Effects of Acute Exposure and Acclimatization to High-Altitude on Oxygen Saturation and Related Cardiorespiratory Fitness in Health and Disease. J Clin Med 2022; 11:6699. [PMID: 36431176 PMCID: PMC9697047 DOI: 10.3390/jcm11226699] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 11/08/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022] Open
Abstract
Maximal values of aerobic power (VO2max) and peripheral oxygen saturation (SpO2max) decline in parallel with gain in altitude. Whereas this relationship has been well investigated when acutely exposed to high altitude, potential benefits of acclimatization on SpO2 and related VO2max in healthy and diseased individuals have been much less considered. Therefore, this narrative review was primarily aimed to identify relevant literature reporting altitude-dependent changes in determinants, in particular SpO2, of VO2max and effects of acclimatization in athletes, healthy non-athletes, and patients suffering from cardiovascular, respiratory and/or metabolic diseases. Moreover, focus was set on potential differences with regard to baseline exercise performance, age and sex. Main findings of this review emphasize the close association between individual SpO2 and VO2max, and demonstrate similar altitude effects (acute and during acclimatization) in healthy people and those suffering from cardiovascular and metabolic diseases. However, in patients with ventilatory constrains, i.e., chronic obstructive pulmonary disease, steep decline in SpO2 and V̇O2max and reduced potential to acclimatize stress the already low exercise performance. Finally, implications for prevention and therapy are briefly discussed.
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Affiliation(s)
- Michael Furian
- Pulmonary Division, University Hospital Zurich, 8092 Zurich, Switzerland
- Research Department, Swiss University of Traditional Chinese Medicine, 5330 Bad Zurzach, Switzerland
| | - Markus Tannheimer
- Department of Sport and Rehabilitation Medicine, University of Ulm, 89075 Ulm, Germany
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, 6020 Innsbruck, Austria
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Zafren K, Shlim DR, Basnyat B, Visser J. Advancing the evidence in altitude and wilderness medicine. J Travel Med 2020; 27:5881392. [PMID: 32761151 DOI: 10.1093/jtm/taaa129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 07/30/2020] [Indexed: 11/14/2022]
Abstract
The themes of this special issue of the Journal of Travel Medicine are wilderness and adventure travel. We hope that the wilderness medicine and travel medicine communities can work together on these areas of mutual interest.
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Affiliation(s)
- Ken Zafren
- Department of Emergency Medicine, Alaska Native Medical Center, Anchorage, AK, USA.,Department of Emergency Medicine, Stanford University Medical Center, Palo Alto, CA, USA.,Himalayan Rescue Association, Kathmandu, Nepal
| | - David R Shlim
- Jackson Hole Travel and Tropical Medicine, Jackson Hole, WY, USA
| | - Buddha Basnyat
- Himalayan Rescue Association, Kathmandu, Nepal.,Oxford University Clinical Research Unit-Nepal, Kathmandu Nepal.,Travel and Mountain Medicine Center, Kathmandu Nepal
| | - Jenny Visser
- Wellington School of Medicine, Wellington New Zealand.,The Travel Doctor, Wellington, New Zealand
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