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Beever AT, Zhuang AY, Murias JM, Aboodarda SJ, MacInnis MJ. Effects of acute simulated altitude on the maximal lactate steady state in humans. Am J Physiol Regul Integr Comp Physiol 2024; 327:R195-R207. [PMID: 38842515 DOI: 10.1152/ajpregu.00065.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 05/03/2024] [Accepted: 05/17/2024] [Indexed: 06/07/2024]
Abstract
We sought to determine the effects of acute simulated altitude on the maximal lactate steady state (MLSS) and physiological responses to cycling at and 10 W above the MLSS-associated power output (PO) (MLSSp and MLSSp+10, respectively). Eleven (4 females) participants (means [SD]; 28 [4] yr; V̇o2max: 54.3 [6.9] mL·kg-1·min-1) acclimatized to ∼1,100 m performed 30-min constant PO trials in simulated altitudes of 0 m sea level (SL), 1,111 m mild altitude (MILD), and 2,222 m moderate altitude (MOD). MLSSp, defined as the highest PO with stable (<1 mM change) blood lactate concentration ([BLa]) between 10 and 30 min, was significantly lower in MOD (209 [54] W) compared with SL (230 [56] W; P < 0.001) and MILD (225 [58] W; P = 0.001), but MILD and SL were not different (P = 0.12). V̇o2 and V̇co2 decreased at higher simulated altitudes due to lower POs (P < 0.05), but other end-exercise physiological responses (e.g., [BLa], ventilation [V̇e], heart rate [HR]) were not different between conditions at MLSSp or MLSSp + 10 (P > 0.05). At the same absolute intensity (MLSSp for MILD), [BLa], HR, and V̇E and all perceptual variables were exacerbated in MOD compared with SL and MILD (P < 0.05). Maximum voluntary contraction, voluntary activation, and potentiated twitch forces were exacerbated at MLSSp + 10 relative to MLSSp within conditions (P < 0.05); however, condition did not affect performance fatiguability at the same relative or absolute intensity (P > 0.05). As MLSSp decreased in hypoxia, adjustments in PO are needed to ensure the same relative intensity across altitudes, but common indices of exercise intensity may facilitate exercise prescription and monitoring in hypoxia.NEW & NOTEWORTHY This study demonstrates the power output and metabolic rate associated with the maximal lactate steady-state (MLSS) decline in response to simulated altitude; however, common indices of exercise intensity remained unchanged when cycling was performed at the work rate associated with MLSS at each simulated altitude. These results support previous studies that investigated the effects of hypoxia on alternative measures of the critical intensity of exercise and will inform exercise prescription/monitoring across altitudes.
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Affiliation(s)
- Austin T Beever
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Andrea Y Zhuang
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Saied J Aboodarda
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Martin J MacInnis
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
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Absatirova V, Shandaulov A, Khamchiyev K, Shukurov F, Khalimova F. Changes in the pulmonary circulation due to gravitational loads in high altitude conditions. Clin Hemorheol Microcirc 2024; 86:419-432. [PMID: 38108346 DOI: 10.3233/ch-231910] [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] [Indexed: 12/19/2023]
Abstract
BACKGROUND The impact of gravity on the existence of all living things has long been of interest to scientists. The force of the Earth's gravity combined with hypoxia significantly affects blood circulation and blood accumulation in various parts of the human and animal body. To date, the relationship between body position and blood circulation in pulmonary circulation under hypobaric hypoxia has not been sufficiently studied. OBJECTIVES Therefore, the research aims to determine the possibility of changing the body position in space on the reactions in the pulmonary circulation in the plains and highlands. METHODS For this purpose, research was conducted on male Wistar rats, 44 of whom spent 150 days at an altitude of 3200 m above sea level, and 25 representatives of the control group - at an altitude of 164 m. RESULTS The study revealed that gravitational redistribution of blood in mountainous conditions is less pronounced compared to the control group. This is explained by the remodeling of the vascular wall and an increase in its stiffness. It was found that a change in pulmonary artery pressure at the time of a change in body position was recorded both on the plains and in the highlands. On the plains, when the body position of rats was changed to passive orthostatic, a decrease in systolic and diastolic pulmonary artery pressure was noted, and when the body position was changed to passive anti-orthostatic, an increase in pulmonary artery pressure was observed. The increase in pulmonary artery pressure was a compensatory mechanism due to the increased stiffness of the pulmonary vasculature. CONCLUSIONS The practical significance of this research is to expand the understanding of the pathogenesis of pulmonary hypertension in high-altitude hypoxia.
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Affiliation(s)
- Venera Absatirova
- Department of Normal Physiology, Astana Medical University, Astana, Kazakhstan
| | - Assylbek Shandaulov
- Department of Normal Physiology, Astana Medical University, Astana, Kazakhstan
| | - Kureysh Khamchiyev
- Department of Normal Physiology, Astana Medical University, Astana, Kazakhstan
| | - Firuz Shukurov
- Department of Normal Physiology, Avicenna Tajik State Medical University, Dushanbe, Tajikistan
| | - Fariza Khalimova
- Department of Normal Physiology, Avicenna Tajik State Medical University, Dushanbe, Tajikistan
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3
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Feng X, Zhao L, Chen Y, Wang Z, Lu H, Wang C. Optimal type and dose of hypoxic training for improving maximal aerobic capacity in athletes: a systematic review and Bayesian model-based network meta-analysis. Front Physiol 2023; 14:1223037. [PMID: 37745240 PMCID: PMC10513096 DOI: 10.3389/fphys.2023.1223037] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 08/17/2023] [Indexed: 09/26/2023] Open
Abstract
Objective: This study aimed to compare and rank the effect of hypoxic practices on maximum oxygen consumption (VO2max) in athletes and determine the hypoxic dose-response correlation using network meta-analysis. Methods: The Web of Science, PubMed, EMBASE, and EBSCO databases were systematically search for randomized controlled trials on the effect of hypoxc interventions on the VO2max of athletes published from inception until 21 February 2023. Studies that used live-high train-high (LHTH), live-high train-low (LHTL), live-high, train-high/low (HHL), intermittent hypoxic training (IHT), and intermittent hypoxic exposure (IHE) interventions were primarily included. LHTL was further defined according to the type of hypoxic environment (natural and simulated) and the altitude of the training site (low altitude and sea level). A meta-analysis was conducted to determine the standardized mean difference between the effects of various hypoxic interventions on VO2max and dose-response correlation. Furthermore, the hypoxic dosage of the different interventions were coordinated using the "kilometer hour" model. Results: From 2,072 originally identified titles, 59 studies were finally included in this study. After data pooling, LHTL, LHTH, and IHT outperformed normoxic training in improving the VO2max of athletes. According to the P-scores, LHTL combined with low altitude training was the most effective intervention for improving VO2max (natural: 0.92 and simulated: 0.86) and was better than LHTL combined with sea level training (0.56). A reasonable hypoxic dose range for LHTH (470-1,130 kmh) and HL (500-1,415 kmh) was reported with an inverted U-shaped curve relationship. Conclusion: Different types of hypoxic training compared with normoxic training serve as significant approaches for improving aerobic capacity in athletes. Regardless of the type of hypoxic training and the residential condition, LHTL with low altitude training was the most effective intervention. The characteristics of the dose-effect correlation of LHTH and LHTL may be associated with the negative effects of chronic hypoxia.
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Affiliation(s)
- Xinmiao Feng
- Sports Coaching College, Beijing Sports University, Beijing, China
| | - Linlin Zhao
- Sports Coaching College, Beijing Sports University, Beijing, China
| | | | - Zihao Wang
- Capital Institute of Physical Education and Sports, Beijing, Beijing, China
| | - Hongyuan Lu
- Sports Coaching College, Beijing Sports University, Beijing, China
| | - Chuangang Wang
- Sports Coaching College, Beijing Sports University, Beijing, China
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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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Rupp T, Saugy JJ, Bourdillon N, Millet GP. Brain-muscle interplay during endurance self-paced exercise in normobaric and hypobaric hypoxia. Front Physiol 2022; 13:893872. [PMID: 36091393 PMCID: PMC9453479 DOI: 10.3389/fphys.2022.893872] [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: 03/10/2022] [Accepted: 07/27/2022] [Indexed: 11/30/2022] Open
Abstract
Purpose: Hypoxia is one major environmental factor, supposed to mediate central motor command as well as afferent feedbacks at rest and during exercise. By using a comparison of normobaric (NH) and hypobaric (HH) hypoxia with the same ambient pressure in oxygen, we examined the potential differences on the cerebrovascular and muscular regulation interplay during a self-paced aerobic exercise. Methods: Sixteen healthy subjects performed three cycling time-trials (250 kJ) in three conditions: HH, NH and normobaric normoxia (NN) after 24 h of exposure. Cerebral and muscular oxygenation were assessed by near-infrared spectroscopy, cerebral blood flow by Doppler ultrasound system. Gas exchanges, peripheral oxygen saturation, power output and associated pacing strategies were also continuously assessed. Results: The cerebral oxygen delivery was lower in hypoxia than in NN but decreased similarly in both hypoxic conditions. Overall performance and pacing were significantly more down-regulated in HH versus NH, in conjunction with more impaired systemic (e.g. saturation and cerebral blood flow) and prefrontal cortex oxygenation during exercise. Conclusions: The difference in pacing was likely the consequence of a complex interplay between systemic alterations and cerebral oxygenation observed in HH compared to NH, aiming to maintain an equivalent cerebral oxygen delivery despite higher adaptive cost (lower absolute power output for the same relative exercise intensity) in HH compared to NH.
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Affiliation(s)
- Thomas Rupp
- LIBM, Inter-university Laboratory of Human Movement Science, University Savoie Mont Blanc, Chambéry, France
| | - Jonas J. Saugy
- ISSUL, Faculty of Biology and Medicine, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Bourdillon
- ISSUL, Faculty of Biology and Medicine, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Grégoire P. Millet
- ISSUL, Faculty of Biology and Medicine, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
- *Correspondence: Grégoire P. Millet,
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Saugy JJ, Schmoutz T, Botrè F. Altitude and Erythropoietin: Comparative Evaluation of Their Impact on Key Parameters of the Athlete Biological Passport: A Review. Front Sports Act Living 2022; 4:864532. [PMID: 35847455 PMCID: PMC9282833 DOI: 10.3389/fspor.2022.864532] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 05/30/2022] [Indexed: 11/13/2022] Open
Abstract
The hematological module of the Athlete's Biological Passport (ABP) identifies doping methods and/or substances used to increase the blood's capacity to transport or deliver oxygen to the tissues. Recombinant human erythropoietin (rhEPOs) are doping substances known to boost the production of red blood cells and might have an effect on the blood biomarkers of the ABP. However, hypoxic exposure influences these biomarkers similarly to rhEPOs. This analogous impact complicates the ABP profiles' interpretation by antidoping experts. The present study aimed to collect and identify, through a literature search, the physiological effects on ABP blood biomarkers induced by these external factors. A total of 43 studies were selected for this review. A positive correlation (R2 = 0.605, r = 0.778, p < 0.001) was identified between the hypoxic dose and the increase in hemoglobin concentration (HGB) percentage. In addition, the change in the reticulocyte percentage (RET%) has been identified as one of the most sensitive parameters to rhEPO use. The mean effects of rhEPO on blood parameters were greater than those induced by hypoxic exposure (1.7 times higher for HGB and RET% and 4 times higher for hemoglobin mass). However, rhEPO micro-doses have shown effects that are hardly distinguishable from those identified after hypoxic exposure. The results of the literature search allowed to identify temporal and quantitative evolution of blood parameters in connection with different hypoxic exposure doses, as well as different rhEPOs doses. This might be considered to provide justified and well-documented interpretations of physiological changes in blood parameters of the Athlete Biological Passport.
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Affiliation(s)
- Jonas J. Saugy
- Institute of Sport Sciences, University of Lausanne (ISSUL), Lausanne, Switzerland
- Research and Expertise in anti-Doping Sciences (REDs), University of Lausanne, Lausanne, Switzerland
- *Correspondence: Jonas J. Saugy
| | - Tania Schmoutz
- Institute of Sport Sciences, University of Lausanne (ISSUL), Lausanne, Switzerland
| | - Francesco Botrè
- Institute of Sport Sciences, University of Lausanne (ISSUL), Lausanne, Switzerland
- Research and Expertise in anti-Doping Sciences (REDs), University of Lausanne, Lausanne, Switzerland
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Płoszczyca K, Chalimoniuk M, Przybylska I, Czuba M. Effects of Short-Term Phosphate Loading on Aerobic Capacity under Acute Hypoxia in Cyclists: A Randomized, Placebo-Controlled, Crossover Study. Nutrients 2022; 14:236. [PMID: 35057416 PMCID: PMC8778537 DOI: 10.3390/nu14020236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 01/01/2022] [Accepted: 01/03/2022] [Indexed: 02/04/2023] Open
Abstract
The aim of this study was to evaluate the effects of sodium phosphate (SP) supplementation on aerobic capacity in hypoxia. Twenty-four trained male cyclists received SP (50 mg·kg-1 of FFM/day) or placebo for six days in a randomized, crossover study, with a three-week washout period between supplementation phases. Before and after each supplementation phase, the subjects performed an incremental exercise test to exhaustion in hypoxia (FiO2 = 16%). Additionally, the levels of 2,3-diphosphoglycerate (2,3-DPG), hypoxia-inducible factor 1 alpha (HIF-1α), inorganic phosphate (Pi), calcium (Ca), parathyroid hormone (PTH) and acid-base balance were determined. The results showed that phosphate loading significantly increased the Pi level by 9.0%, whereas 2,3-DPG levels, hemoglobin oxygen affinity, buffering capacity and myocardial efficiency remained unchanged. The aerobic capacity in hypoxia was not improved following SP. Additionally, our data revealed high inter-individual variability in response to SP. Therefore, the participants were grouped as Responders and Non-Responders. In the Responders, a significant increase in aerobic performance in the range of 3-5% was observed. In conclusion, SP supplementation is not an ergogenic aid for aerobic capacity in hypoxia. However, in certain individuals, some benefits can be expected, but mainly in athletes with less training-induced central and/or peripheral adaptation.
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Affiliation(s)
- Kamila Płoszczyca
- Department of Kinesiology, Institute of Sport, 01-982 Warsaw, Poland
| | - Małgorzata Chalimoniuk
- Department of Physiotherapy, Faculty of Physical Education and Health in Biala Podlaska, Jozef Pilsudski University of Physical Education in Warsaw, 21-500 Biala Podlaska, Poland
| | - Iwona Przybylska
- Department of Physiotherapy, Faculty of Physical Education and Health in Biala Podlaska, Jozef Pilsudski University of Physical Education in Warsaw, 21-500 Biala Podlaska, Poland
| | - Miłosz Czuba
- Department of Kinesiology, Institute of Sport, 01-982 Warsaw, Poland
- Faculty of Rehabilitation, Jozef Pilsudski University of Physical Education in Warsaw, 00-968 Warsaw, Poland
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8
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Bärtsch P. The Impact of Nocebo and Placebo Effects on Reported Incidence of Acute Mountain Sickness. High Alt Med Biol 2021; 23:8-17. [PMID: 34964659 DOI: 10.1089/ham.2021.0078] [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
Bärtsch Peter. The impact of nocebo and placebo effects on reported incidence of acute mountain sickness. High Alt Med Biol 00:000-000, 2021. Well comparable studies reporting acute mountain sickness (AMS) in nonacclimatized, acutely exposed individuals performed at 3,450-3,650 m (9 studies) and 4,559-4,675 m (18 studies) at real altitude or in hypobaric or in normobaric hypoxic chambers were analyzed with the hypothesis that the study design impacts occurrence of AMS. Individual symptoms and overall scores of AMS were not different between the three modalities of exposure to a comparable degree of hypoxia, indicating that hypobaria has, if at all, minimal influence on AMS. Studies not focusing versus those focusing on AMS report lower scores and prevalence of AMS at 3,500 m, but not at 4,559 m, while frequent assessment may be associated with more severe AMS. These data suggest that focusing on AMS creates expectations of getting AMS (nocebo effects) and increases its prevalence, while not paying attention reduces negative expectations and thus AMS. On the other hand, interventions promising improvement may cause positive expectations (placebo effect). Information about purpose and dangers of a study, repeated assessments for AMS, previous experiences of AMS, and observation of illness in other study participants are major factors contributing to negative expectations and thus nocebo effects increasing AMS. They should be considered when designing studies and subject information and be reported in detail in publications of studies on AMS.
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Affiliation(s)
- Peter Bärtsch
- Department of Internal Medicine, University Clinic, Heidelberg, Germany
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9
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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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10
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Płoszczyca K, Czuba M, Chalimoniuk M, Gajda R, Baranowski M. Red Blood Cell 2,3-Diphosphoglycerate Decreases in Response to a 30 km Time Trial Under Hypoxia in Cyclists. Front Physiol 2021; 12:670977. [PMID: 34211402 PMCID: PMC8239298 DOI: 10.3389/fphys.2021.670977] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/11/2021] [Indexed: 11/14/2022] Open
Abstract
Red blood cell 2,3-diphosphoglycerate (2,3-DPG) is one of the factors of rightward-shifted oxygen dissociation curves and decrease of Hb-O2 affinity. The reduction of Hb-O2 affinity is beneficial to O2 unloading at the tissue level. In the current literature, there are no studies about the changes in 2,3-DPG level following acute exercise in moderate hypoxia in athletes. For this reason, the aim of this study was to analyze the effect of prolonged intense exercise under normoxic and hypoxic conditions on 2,3-DPG level in cyclists. Fourteen male trained cyclists performed a simulation of a 30 km time trial (TT) in normoxia and normobaric hypoxia (FiO2 = 16.5%, ~2,000 m). During the TT, the following variables were measured: power, blood oxygen saturation (SpO2), and heart rate (HR). Before and immediately after exercise, the blood level of 2,3-DPG and acid–base equilibrium were determined. The results showed that the mean SpO2 during TT in hypoxia was 8% lower than in normoxia. The reduction of SpO2 in hypoxia resulted in a decrease of average power by 9.6% (p < 0.001) and an increase in the 30 km TT completion time by 3.8% (p < 0.01) compared to normoxia. The exercise in hypoxia caused a significant (p < 0.001) decrease in 2,3-DPG level by 17.6%. After exercise in normoxia, a downward trend of 2,3-DPG level was also observed, but this effect was not statistically significant. The analysis also revealed that changes of acid–base balance were significantly larger (p < 0.05) after exercise in hypoxia than in normoxia. In conclusion, intense exercise in hypoxic conditions leads to a decrease in 2,3-DPG concentration, primarily due to exercise-induced acidosis.
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Affiliation(s)
- Kamila Płoszczyca
- Department of Kinesiology, Institute of Sport - National Research Institute, Warsaw, Poland
| | - Miłosz Czuba
- Department of Kinesiology, Institute of Sport - National Research Institute, Warsaw, Poland
| | - Małgorzata Chalimoniuk
- Department of Physical Education and Health in Biala Podlaska, Józef Piłsudski University of Physical Education in Warsaw, Biala Podlaska, Poland
| | - Robert Gajda
- Center for Sports Cardiology, Gajda-Med Medical Center in Pułtusk, Pułtusk, Poland
| | - Marcin Baranowski
- Department of Physiology, Medical University of Bialystok, Bialystok, Poland
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11
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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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12
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Weng X, Chen H, Yu Q, Xu G, Meng Y, Yan X, McConell G, Lin W. Intermittent Hypoxia Exposure Can Prevent Reductions in Hemoglobin Concentration After Intense Exercise Training in Rats. Front Physiol 2021; 12:627708. [PMID: 33679440 PMCID: PMC7935520 DOI: 10.3389/fphys.2021.627708] [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: 11/10/2020] [Accepted: 02/01/2021] [Indexed: 11/21/2022] Open
Abstract
Intense exercise training can induce low concentrations of hemoglobin, which may be followed by maladaptation. Therefore, it is important for athletes to prevent low concentrations of hemoglobin during intense exercise training. In this study, we explored whether different protocols of intermittent hypoxic exposure (IHE, normobaric hypoxia, 14.5% O2) could prevent the exercise training-induced reduction in hemoglobin concentration in rats. Six-week-old male Sprague-Dawley rats were subjected to progressive intense treadmill exercise training over three weeks followed by three weeks of training with IHE after exercise. IHE lasted either 1 h, 2 h, or 1 h + 1 h (separated by a 3-h interval) after the exercise sessions. Hematological parameters, including hemoglobin concentration [(Hb)], red blood cells (RBCs), and hematocrit (Hct), and both renal and serum erythropoietin (EPO) were examined. We found that intense exercise training significantly reduced [Hb], RBCs, Hct, food intake and body weight (P < 0.01). Analysis of reticulocyte hemoglobin content (CHr) and reticulocyte counts in the serum of the rats suggested that this reduction was not due to iron deficiency or other cofounding factors. The addition of IHE after the intense exercise training sessions significantly alleviated the reduction in [Hb], RBCs, and Hct (P < 0.05) without an obvious impact on either food intake or body weight (P > 0.05). Increase in reticulocyte count in the rats from the IHE groups (P < 0.05 or P < 0.01) suggests that IHE promotes erythropoiesis to increase the hemoglobin concentration. Furthermore, the addition of IHE after the intense exercise training sessions also significantly increased the concentration of renal EPO (P < 0.05), although the increase of the serum EPO level was statistically insignificant (P > 0.05). The different IHE protocols were similarly effective at increasing renal EPO and preventing the training-induced decreases in [Hb], RBCs, and Hct. Collectively, this study suggests that IHE may be used as a new strategy to prevent intense exercise training-induced reductions in [Hb], and deserves future exploration in athletes.
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Affiliation(s)
- Xiquan Weng
- Department of Exercise Biochemistry, College of Exercise and Health, Guangzhou Sport University, Guangzhou, China
| | - Hao Chen
- Department of Exercise Biochemistry, College of Exercise and Health, Guangzhou Sport University, Guangzhou, China
| | - Qun Yu
- College of Sport, Yancheng Teachers University, Yancheng, China
| | - Guoqing Xu
- Department of Exercise Biochemistry, College of Exercise and Health, Guangzhou Sport University, Guangzhou, China
| | - Yan Meng
- Department of Exercise Biochemistry, College of Exercise and Health, Guangzhou Sport University, Guangzhou, China
| | - Xu Yan
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia.,Australia Institute for Musculoskeletal Sciences, Melbourne, VIC, Australia
| | - Glenn McConell
- Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia
| | - Wentao Lin
- Department of Exercise Biochemistry, College of Exercise and Health, Guangzhou Sport University, Guangzhou, China
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13
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Takezawa T, Dobashi S, Koyama K. Cardiorespiratory Response and Power Output During Submaximal Exercise in Normobaric Versus Hypobaric Hypoxia: A Pilot Study Using a Specific Chamber that Controls Environmental Factors. High Alt Med Biol 2021; 22:201-208. [PMID: 33599547 DOI: 10.1089/ham.2020.0142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Takezawa, Toshihiro, Shohei Dobashi, and Katsuhiro Koyama. Cardiorespiratory response and power output during submaximal exercise in normobaric versus hypobaric hypoxia: a pilot study using a specific chamber that controls environmental factors. High Alt Med Biol. 22: 201-208, 2021. Background: Many previous studies have examined hypoxia-induced physiological responses using various conditions, e.g., artificially reduced atmospheric oxygen concentration [normobaric hypoxia (NH) condition] or low barometric pressure at a mountain [hypobaric hypoxia (HH) condition]. However, when comparing the results from these previous studies conducted in artificial NH and HH including real high altitude, we must consider the possibility that environmental factors, such as temperature, humidity, and fraction of inspired carbon dioxide, might affect the physiological responses. Therefore, we examined cardiorespiratory responses and exercise performances during low- to high-intensity exercise at a fixed heart rate (HR) in both NH and HH using a specific chamber where atmospheric oxygen concentration and barometric pressure as well as the abovementioned environmental factors were precisely controlled. Methods: Ten well-trained university students (eight males and two females) performed the exercise test consisting of two 20-minute submaximal pedaling at the intensity corresponding to 50% (low) and 70% (high) of their HR reserve, under three conditions [NH (fraction of inspired oxygen, 0.135; barometric pressure, 754 mmHg), HH (fraction of inspired oxygen, 0.209; barometric pressure, 504 mmHg), and normobaric normoxia (NN; fraction of inspired oxygen, 0.209; barometric pressure, 754 mmHg)]. Peripheral oxygen saturation (SpO2) to estimate arterial oxygen saturation and partial pressure of end-tidal carbon dioxide (PETCO2) were monitored throughout the experiment. Results: SpO2, PETCO2, and power output at fixed HRs (i.e., pedaling efficiency) in NH and HH were all significantly lower than those in NN. Moreover, high-intensity exercise in HH induced greater decreases in SpO2 and power output than did high-intensity exercise in NH (NH vs. HH; SpO2, 78.2% ± 5.0% vs. 75.1% ± 7.1%; power output, 120.7 ± 24.9 W vs. 112.4 ± 23.2 W, both p < 0.05). However, high-intensity exercise in HH induced greater increases in PETCO2 than did high-intensity exercise in NH (NH vs. HH; 54.2 ± 5.9 mmHg vs. 57.2 ± 3.4 mmHg, p < 0.01). Conclusions: These results suggest that physiological responses and power output at a fixed HR during hypoxic exposure might depend on the method used to generate the hypoxic condition.
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Affiliation(s)
- Toshihiro Takezawa
- Faculty of Health and Sports Science, University of Juntendo, Inzai, Japan.,Graduate School Department of Medicine and Engineering Sciences, University of Yamanashi, Kofu, Japan
| | - Shohei Dobashi
- Graduate School Department of Medicine and Engineering Sciences, University of Yamanashi, Kofu, Japan.,Institute of Health and Sports Science and Medicine, Juntendo University, Inzai, Japan
| | - Katsuhiro Koyama
- Graduate School Department of Interdisciplinary Research, University of Yamanashi, Kofu, Japan
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14
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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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15
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Salgado RM, Coffman KE, Bradbury KE, Mitchell KM, Yurkevicius BR, Luippold AJ, Mayer TA, Charkoudian N, Alba BK, Fulco CS, Kenefick RW. Effect of 8 days of exercise-heat acclimation on aerobic exercise performance of men in hypobaric hypoxia. Am J Physiol Regul Integr Comp Physiol 2020; 319:R114-R122. [PMID: 32432914 DOI: 10.1152/ajpregu.00048.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exercise-heat acclimation (EHA) induces adaptations that improve tolerance to heat exposure. Whether adaptations from EHA can also alter responses to hypobaric hypoxia (HH) conditions remains unclear. This study assessed whether EHA can alter time-trial performance and/or incidence of acute mountain sickness (AMS) during HH exposure. Thirteen sea-level (SL) resident men [SL peak oxygen consumption (V̇o2peak) 3.19 ± 0.43 L/min] completed steady-state exercise, followed by a 15-min cycle time trial and assessment of AMS before (HH1; 3,500 m) and after (HH2) an 8-day EHA protocol [120 min; 5 km/h; 2% incline; 40°C and 40% relative humidity (RH)]. EHA induced lower heart rate (HR) and core temperature and plasma volume expansion. Time-trial performance was not different between HH1 and HH2 after 2 h (106.3 ± 23.8 vs. 101.4 ± 23.0 kJ, P = 0.71) or 24 h (107.3 ± 23.4 vs. 106.3 ± 20.8 kJ, P > 0.9). From HH1 to HH2, HR and oxygen saturation, at the end of steady-state exercise and time-trial tests at 2 h and 24 h, were not different (P > 0.05). Three of 13 volunteers developed AMS during HH1 but not during HH2, whereas a fourth volunteer only developed AMS during HH2. Heat shock protein 70 was not different from HH1 to HH2 at SL [1.9 ± 0.7 vs. 1.8 ± 0.6 normalized integrated intensities (NII), P = 0.97] or after 23 h (1.8 ± 0.4 vs. 1.7 ± 0.5 NII, P = 0.78) at HH. Our results indicate that this EHA protocol had little to no effect-neither beneficial nor detrimental-on exercise performance in HH. EHA may reduce AMS in those who initially developed AMS; however, studies at higher elevations, having higher incidence rates, are needed to confirm our findings.
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Affiliation(s)
- Roy M Salgado
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Kirsten E Coffman
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts.,Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee
| | - Karleigh E Bradbury
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Katherine M Mitchell
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Beau R Yurkevicius
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts.,Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee
| | - Adam J Luippold
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Thomas A Mayer
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts.,Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Billie K Alba
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts.,Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee
| | - Charles S Fulco
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts.,Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee
| | - Robert W Kenefick
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
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16
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Walsh JJ, Drouin PJ, King TJ, D'Urzo KA, Tschakovsky ME, Cheung SS, Day TA. Acute aerobic exercise impairs aspects of cognitive function at high altitude. Physiol Behav 2020; 223:112979. [PMID: 32479806 DOI: 10.1016/j.physbeh.2020.112979] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 11/28/2019] [Accepted: 05/20/2020] [Indexed: 12/24/2022]
Abstract
Hypoxia-mediated cognitive dysfunction can be transiently mitigated by exercise in a laboratory-based setting. Whether this effect holds true in the context of high altitude hypoxia has not been determined. We investigated the effect of acute aerobic exercise on cognitive function (CF) at low (1400m) and high altitude (4240m). Fifteen volunteers (24.1±3.5yrs; 9 females) exercised for 20-min at 40-60% of their heart rate reserve at low and high altitude. CF was assessed before and 10-min after exercise using a tablet-based battery of executive function tests. A sea-level control group (n=13; 24.2±2.4 years; 9 females) performed time-matched CF tests to assess the contribution of a learning effects due to repeated testing. Measures of resting CF were unaffected by ascent to high altitude. Following high altitude exercise, performance significantly worsened on the digit symbol substitution task - a test of processing speed, working memory, and visuospatial attention (z=0.01 vs. -0.59, p=0.02, η2=0.35). No effect was found on other measures of CF following exercise. There was no association between changes in peripheral oxygen saturation and changes in CF following high altitude exercise (r=0.22, p=0.44), but higher hemoglobin concentration at high altitude was associated with a decline in CF following exercise at high altitude (r=-0.65, p=0.02). Acute aerobic exercise performed at high altitude impairs some aspects of CF, whereas other CF tests remain unchanged. The strong ecological validity of this study warrants attention and follow-up investigations are needed to better characterize selective impairment of CF with high altitude exercise.
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Affiliation(s)
- Jeremy J Walsh
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada; School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada.
| | - Patrick J Drouin
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | - Trevor J King
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada; Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Katrina A D'Urzo
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | | | - Stephen S Cheung
- Department of Kinesiology, Brock University, St. Catherines, ON, Canada
| | - Trevor A Day
- Department of Biology, Mount Royal University, Calgary, AB, Canada
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17
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Millet GP, Debevec T. CrossTalk proposal: Barometric pressure, independent of , is the forgotten parameter in altitude physiology and mountain medicine. J Physiol 2020; 598:893-896. [DOI: 10.1113/jp278673] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
| | - Tadej Debevec
- Faculty of SportUniversity of Ljubljana Ljubljana Slovenia
- Department of AutomationBiocybernetics and RoboticsJozef Stefan Institute Ljubljana Slovenia
- School of Life sciencesFaculty of Medicine and Health SciencesNottingham University Nottingham UK
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18
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Degache F, Serain É, Roy S, Faiss R, Millet GP. The fatigue-induced alteration in postural control is larger in hypobaric than in normobaric hypoxia. Sci Rep 2020; 10:483. [PMID: 31949289 PMCID: PMC6965170 DOI: 10.1038/s41598-019-57166-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 12/18/2019] [Indexed: 11/09/2022] Open
Abstract
To test the hypothesis that postural control would be more affected by plantar flexors fatigue during acute exposure in hypobaric (HH) than in normobaric (NH) hypoxia or normobaric normoxia (NN). Twelve young male adults performed in a random order three experimental sessions (in HH and NH (FiO2 0.139) at an altitude of 2950 m, and in NN at 500 m) composed of a bipedal postural control with eyes open on a posturographic platform before and after a plantar flexors fatiguing protocol. Center of pressure (CoP) trajectory and stabilogramm diffusion analyses (SDA) parameters were assessed. A two-way repeated measures analysis of variance was used to identify differences by examination of the group and time interaction. Surface of CoP trajectory analysis, increased at POST in HH (p < 0.001) and in NH (p < 0.01) compared to NN. SDA confirmed that PC was more altered in HH than in NH (p < 0.001) and NN (p < 0.05) at POST. The plantar flexor fatigue-induced alteration in postural control increased to a larger extent in HH than in NH or NN, suggesting an alleviating influence of the decreased barometric pressure per se and a mechanical influence of the higher breathing frequency in HH.
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Affiliation(s)
- Francis Degache
- Therapeutic and Performance Sports Institute, MotionLab, Le Mont Sur Lausanne, Lausanne, Switzerland.
| | - Émilie Serain
- School of Health Sciences, University of Applied Sciences and Arts Western Switzerland, Lausanne, Switzerland
| | - Sophie Roy
- ISSUL Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Raphael Faiss
- ISSUL Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Grégoire P Millet
- ISSUL Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
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19
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Faulhaber M, Pramsohler S, Rausch L, Menz V. Cardiorespiratory and Metabolic Responses During Graded Exercise in Normobaric and Hypobaric Hypoxia. High Alt Med Biol 2020; 21:70-75. [PMID: 31923367 DOI: 10.1089/ham.2019.0094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background: The study investigated submaximal exercise responses during an acute exposure to normobaric hypoxia (NH) versus hypobaric hypoxia (HH) focusing on different exercise intensities. Methods: Eight recreationally trained male subjects (age 23 ± 3 years) performed submaximal cycling exercise at three different intensity levels (100, 150, and 200 W) in NH (simulated altitude 3150 m) and HH (terrestrial high altitude, 3150 m) in a cross-over study design. Cardiorespiratory parameter, blood lactate concentration, and ratings of perceived exertion were determined at each intensity level. Results: Cardiorespiratory parameters, arterial oxygen saturation, and ratings of perceived exertion did not differ between NH and HH except for the higher ventilatory equivalent for oxygen in HH compared to NH (25.9 ± 1.3 vs. 24.6 ± 1.0 at 100 W, 28.0 ± 1.6 vs. 27.1 ± 1.6 at 150 W, 32.1 ± 3.9 vs. 31.3 ± 3.6 at 200 W, p = 0.03). Blood lactate concentration tended to be higher in HH compared to NH (1.8 ± 0.9 mmol/L vs. 1.7 ± 0.8 mmol/L at 100 W, 3.2 ± 1.8 mmol/L vs. 2.8 ± 1.6 mmol/L at 150 W, 6.0 ± 3.1 mmol/L vs. 5.5 ± 3.0 mmol/L at 200 W, p = 0.08) with a significant interaction effect for exercise intensity (p = 0.02). Conclusions: Cycling during acute exposure to NH appears to result in equivalent cardiorespiratory responses to HH. The more pronounced lactate accumulation in HH should be a topic of future research.
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Affiliation(s)
- Martin Faulhaber
- Department of Sport Science, University Innsbruck, Innsbruck, Austria.,Austrian Society of Alpine and High Altitude Medicine, Mieming, Austria
| | - Stephan Pramsohler
- Hermann Buhl Institute for Hypoxia and Sleep Medicine Research, Bad Aibling, Germany
| | - Linda Rausch
- Hermann Buhl Institute for Hypoxia and Sleep Medicine Research, Bad Aibling, Germany
| | - Verena Menz
- Department of Sport Science, University Innsbruck, Innsbruck, Austria
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20
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Bradbury KE, Coffman KE, Mitchell KM, Luippold AJ, Fulco CS, Kenefick RW. Separate and combined influences of heat and hypobaric hypoxia on self-paced aerobic exercise performance. J Appl Physiol (1985) 2019; 127:513-519. [PMID: 31219777 DOI: 10.1152/japplphysiol.00023.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Heat and hypobaric hypoxia independently compromise exercise performance; however, their combined impact on exercise performance has yet to be quantified. This study examined the effects of heat, hypobaric hypoxia, and the combination of these environments on self-paced cycling time trial (TT) performance. Twelve subjects [2 female, 10 male; sea level (SL) peak oxygen consumption (V̇o2peak), 41.5 ± 4.4 mL·kg-1·min-1, mean ± SD] completed 30 min of steady-state cycling exercise (50% SL V̇o2peak), followed by a 15-min self-paced TT in four environmental conditions: SL thermoneutral [SLTN; 250 m, 20°C, 30-50% relative humidity (rh)], SL hot (SLH; 250 m, 35°C, 30% rh), hypobaric hypoxia thermoneutral (HTN; 3,000 m, 20°C, 30-50% rh), and hypobaric hypoxia hot (HH; 3,000 m, 35°C, 30% rh). Performance was assessed by the total work (kJ) completed. TT performance was lower (P < 0.05) in SLH, HTN, and HH relative to SLTN (-15.4 ± 9.7, -24.1 ± 16.2, and -33.1 ± 13.4 kJ, respectively). Additionally, the total work completed in HTN and HH was lower (P < 0.05) than that in SLH. In SLH, HTN, and HH, work rate was reduced versus SLTN (P < 0.05) within the first 3 min of exercise and was consistent for the remainder of the bout. No differences (P > 0.05) existed for heart rate or Ratings of Perceived Exertion at the end of exercise among conditions. The decrease in self-paced TT performance in the heat and/or hypobaric hypoxia conditions compared with SLTN conditions resulted from a nearly immediate reduction in work rate that may have been regulated by environmentally induced changes in physiological strain and perception of effort in response to TT exercise.NEW & NOTEWORTHY This is the first known study to examine the combined effects of heat and hypobaric hypoxia on short-duration self-paced cycling time trial performance. Regardless of environmental condition, subjects utilized an even work rate for the entire duration of the time trial. The presence of both environmental stressors led to a greater performance impairment than heat or hypobaric hypoxia alone, and the performance decrement stemmed from an early reduction of work rate.
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Affiliation(s)
- Karleigh E Bradbury
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Kirsten E Coffman
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Katherine M Mitchell
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Adam J Luippold
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Charles S Fulco
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Robert W Kenefick
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
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21
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Ogawa T, Fujii N, Kurimoto Y, Nishiyasu T. Effect of hypobaria on maximal ventilation, oxygen uptake, and exercise performance during running under hypobaric normoxic conditions. Physiol Rep 2019; 7:e14002. [PMID: 30756526 PMCID: PMC6372535 DOI: 10.14814/phy2.14002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/19/2019] [Accepted: 01/21/2019] [Indexed: 11/24/2022] Open
Abstract
During exposure to high altitude, hypoxia develops because of reductions in barometric pressure and partial pressure of O2 . Although several studies have examined the effects of hypoxia on exercise performance and physiological responses, such as maximal minute ventilation ( V · Emax ) and maximal oxygen uptake ( V · O2max ), how barometric pressure reduction (hypobaria) modulates them remains largely unknown. In this study, 11 young men performed incremental treadmill running tests to exhaustion under three conditions chosen at random: normobaric normoxia (NN; 763 ± 5 mmHg of barometric pressure, equivalent to sea level), hypobaric hypoxia (HH; 492 ± 1 mmHg of barometric pressure, equivalent to 3500 m above sea level (m a.s.l.)), and hypobaric normoxia (HN; 492 ± 1 mmHg of barometric pressure while breathing 32.2 ± 0.1% O2 to match the inspiratory O2 content under NN). V · Emax was higher in HN than in NN (160.9 ± 10.7 vs. 150.7 ± 10.0 L min-1 , P < 0.05). However, no differences in V · O2max and arterial oxyhemoglobin saturation were observed between NN and HN (all P > 0.05). Time to exhaustion was longer in HN than in NN (932 ± 83 vs. 910 ± 79 s, P < 0.05). These results suggest that reduced air density during exposure to an altitude of 3500 m a.s.l. increases maximal ventilation and extends time to exhaustion without affecting oxygen consumption or arterial oxygen saturation.
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Affiliation(s)
- Takeshi Ogawa
- Department of Physical EducationOsaka Kyoiku UniversityKashiwaraOsakaJapan
| | - Naoto Fujii
- Faculty of Health and Sports ScienceUniversity of TsukubaTsukubaJapan
| | - Yasuhiro Kurimoto
- Faculty of Health and Sports ScienceUniversity of TsukubaTsukubaJapan
| | - Takeshi Nishiyasu
- Faculty of Health and Sports ScienceUniversity of TsukubaTsukubaJapan
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22
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SHARMA AVISHP, SAUNDERS PHILOU, GARVICAN-LEWIS LAURAA, CLARK BRAD, GORE CHRISTOPHERJ, THOMPSON KEVING, PÉRIARD JULIEND. Normobaric Hypoxia Reduces V˙O2 at Different Intensities in Highly Trained Runners. Med Sci Sports Exerc 2019; 51:174-182. [DOI: 10.1249/mss.0000000000001745] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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23
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Mourot L, Millet GP. Is Maximal Heart Rate Decrease Similar Between Normobaric Versus Hypobaric Hypoxia in Trained and Untrained Subjects? High Alt Med Biol 2018; 20:94-98. [PMID: 30489174 DOI: 10.1089/ham.2018.0104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
We compared the decrease in maximal heart rate (HRmax) from normoxia to normobaric (NH) and hypobaric (HH) hypoxia, respectively, in trained and untrained subjects (n = 187). HRmax data in normoxia and NH (n = 55) or HH (n = 26) were collected from 81 publications. No study directly compared HRmax in NH and HH. Concomitant arterial oxygen saturation (SaO2) and HRmax data were found in 60 studies. Overall, the results showed that the higher the desaturation, the greater the decrease in HRmax. Since desaturation appeared to be slightly higher during HH versus NH and was higher in trained than in untrained subjects, the decrease in HRmax tended (p = 0.07) to be higher in trained subjects in HH than in NH (e.g., -12.7 bpm vs. -8.6 bpm at 4000 m), whereas in untrained subjects the difference was negligible (-9.9 bpm vs. -8.3 bpm). To conclude, when compared with normoxia, the decrease in HRmax was slightly higher in HH than in NH in trained subjects. However, this result has to be confirmed and from a practical point of view, one may question the significance of this difference as well as the relevance of using different HR values for prescribing training intensity during exercise performed in NH or in HH.
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Affiliation(s)
- Laurent Mourot
- 1 EA 3920 Prognostic Markers and Regulatory Factors of Cardiovascular Diseases and Exercise Performance, Health, Innovation Platform, University of Franche-Comté, Besançon, France.,2 Tomsk Polytechnic University, Tomsk, Russia
| | - Grégoire P Millet
- 3 Faculty of Biology and Medicine, ISSUL, Institute of Sport Sciences, University of Lausanne, Switzerland
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Mourot L. Limitation of Maximal Heart Rate in Hypoxia: Mechanisms and Clinical Importance. Front Physiol 2018; 9:972. [PMID: 30083108 PMCID: PMC6064954 DOI: 10.3389/fphys.2018.00972] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/02/2018] [Indexed: 12/17/2022] Open
Abstract
The use of exercise intervention in hypoxia has grown in popularity amongst patients, with encouraging results compared to similar intervention in normoxia. The prescription of exercise for patients largely rely on heart rate recordings (percentage of maximal heart rate (HRmax) or heart rate reserve). It is known that HRmax decreases with high altitude and the duration of the stay (acclimatization). At an altitude typically chosen for training (2,000-3,500 m) conflicting results have been found. Whether or not this decrease exists or not is of importance since the results of previous studies assessing hypoxic training based on HR may be biased due to improper intensity. By pooling the results of 86 studies, this literature review emphasizes that HRmax decreases progressively with increasing hypoxia. The dose–response is roughly linear and starts at a low altitude, but with large inter-study variabilities. Sex or age does not seem to be a major contributor in the HRmax decline with altitude. Rather, it seems that the greater the reduction in arterial oxygen saturation, the greater the reduction in HRmax, due to an over activity of the parasympathetic nervous system. Only a few studies reported HRmax at sea/low level and altitude with patients. Altogether, due to very different experimental design, it is difficult to draw firm conclusions in these different clinical categories of people. Hence, forthcoming studies in specific groups of patients are required to properly evaluate (1) the HRmax change during acute hypoxia and the contributing factors, and (2) the physiological and clinical effects of exercise training in hypoxia with adequate prescription of exercise training intensity if based on heart rate.
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Affiliation(s)
- Laurent Mourot
- EA 3920 Prognostic Markers and Regulatory Factors of Cardiovascular Diseases and Exercise Performance, Health, Innovation Platform, University of Franche-Comté, Besançon, France.,Tomsk Polytechnic University, Tomsk, Russia
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25
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DiPasquale DM. Moving the Debate Forward: Are Normobaric and Hypobaric Hypoxia Interchangeable in the Study of Altitude? Curr Sports Med Rep 2018; 16:68-70. [PMID: 28282350 DOI: 10.1249/jsr.0000000000000337] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Dana M DiPasquale
- Biomedical Department, Navy Experimental Diving Unit, Panama City, FL
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26
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Acute and chronic changes in baroreflex sensitivity in hypobaric vs. normobaric hypoxia. Eur J Appl Physiol 2017; 117:2401-2407. [PMID: 28956166 DOI: 10.1007/s00421-017-3726-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 09/21/2017] [Indexed: 12/21/2022]
Abstract
Normobaric hypoxia (NH) is used as a surrogate for hypobaric hypoxia (HH). Recent studies reported physiological differences between NH and HH. Baroreflex sensitivity (BRS) decreases at altitude or following intense training. However, until now no study compared the acute and chronic changes of BRS in NH vs. HH. First, BRS was assessed in 13 healthy male subjects prior and after 20 h of exposure at 3450 m (study 1), and second in 15 well-trained athletes prior and after 18 days of "live-high train-low" (LHTL) at 2250 m (study 2) in NH vs. HH. BRS decreased (p < 0.05) to the same extent in NH and HH after 20 h of hypoxia and after LHTL. These results confirm that altitude decreases BRS but the decrease is similar between HH and NH. The persistence of this decrease after the cessation of a chronic exposure is new and does not differ between HH and NH. The previously reported physiological differences between NH and HH do not appear strong enough to induce different BRS responses.
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Gasier HG, Reinhold AR, Loiselle AR, Soutiere SE, Fothergill DM. Effects of oral sodium nitrate on forearm blood flow, oxygenation and exercise performance during acute exposure to hypobaric hypoxia (4300 m). Nitric Oxide 2017; 69:1-9. [DOI: 10.1016/j.niox.2017.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 06/16/2017] [Accepted: 07/01/2017] [Indexed: 10/19/2022]
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28
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Hauser A, Troesch S, Saugy JJ, Schmitt L, Cejuela-Anta R, Faiss R, Steiner T, Robinson N, Millet GP, Wehrlin JP. Individual hemoglobin mass response to normobaric and hypobaric "live high-train low": A one-year crossover study. J Appl Physiol (1985) 2017; 123:387-393. [PMID: 28522767 DOI: 10.1152/japplphysiol.00932.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 05/12/2017] [Accepted: 05/12/2017] [Indexed: 11/22/2022] Open
Abstract
The purpose of this research was to compare individual hemoglobin mass (Hbmass) changes following a live high-train low (LHTL) altitude training camp under either normobaric hypoxia (NH) or hypobaric hypoxia (HH) conditions in endurance athletes. In a crossover design with a one-year washout, 15 male triathletes randomly performed two 18-day LHTL training camps in either HH or NH. All athletes slept at 2,250 meters and trained at altitudes <1,200 meters. Hbmass was measured in duplicate with the optimized carbon monoxide rebreathing method before (pre) and immediately after (post) each 18-day training camp. Hbmass increased similarly in HH (916-957 g, 4.5 ± 2.2%, P < 0.001) and in NH (918-953 g, 3.8 ± 2.6%, P < 0.001). Hbmass changes did not differ between HH and NH (P = 0.42). There was substantial interindividual variability among subjects to both interventions (i.e., individual responsiveness or the individual variation in the response to an intervention free of technical noise): 0.9% in HH and 1.7% in NH. However, a correlation between intraindividual ΔHbmass changes (%) in HH and in NH (r = 0.52, P = 0.048) was observed. HH and NH evoked similar mean Hbmass increases following LHTL. Among the mean Hbmass changes, there was a notable variation in individual Hbmass response that tended to be reproducible.NEW & NOTEWORTHY This is the first study to compare individual hemoglobin mass (Hbmass) response to normobaric and hypobaric live high-train low using a same-subject crossover design. The main findings indicate that hypobaric and normobaric hypoxia evoked a similar mean increase in Hbmass following 18 days of live high-train low. Notable variability and reproducibility in individual Hbmass responses between athletes was observed, indicating the importance of evaluating individual Hbmass response to altitude training.
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Affiliation(s)
- Anna Hauser
- Swiss Federal Institute of Sport, Section for Elite Sport, Magglingen, Switzerland; .,Faculty of Biology and Medicine, Department of Physiology, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Severin Troesch
- Swiss Federal Institute of Sport, Section for Elite Sport, Magglingen, Switzerland
| | - Jonas J Saugy
- Faculty of Biology and Medicine, Department of Physiology, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Laurent Schmitt
- National School of Mountain Sports/National Ski-Nordic Centre, Prémanon, France
| | - Roberto Cejuela-Anta
- Departmental Section of Physical Education and Sports, University of Alicante, Alicante, Spain; and
| | - Raphael Faiss
- Faculty of Biology and Medicine, Department of Physiology, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Thomas Steiner
- Swiss Federal Institute of Sport, Section for Elite Sport, Magglingen, Switzerland
| | - Neil Robinson
- Swiss Laboratory for Doping Analyses, University Center of Legal Medicine, Geneva & Lausanne, Center Hospitalier Universitaire Vaudois & University of Lausanne, Lausanne, Switzerland
| | - Grégoire P Millet
- Faculty of Biology and Medicine, Department of Physiology, Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Jon P Wehrlin
- Swiss Federal Institute of Sport, Section for Elite Sport, Magglingen, Switzerland
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Mansour RN, Enderami SE, Ardeshirylajimi A, Fooladsaz K, Fathi M, Ganji SM. Evaluation of hypoxia inducible factor-1 alpha gene expression in colorectal cancer stages of Iranian patients. J Cancer Res Ther 2017; 12:1313-1317. [PMID: 28169245 DOI: 10.4103/0973-1482.199542] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM OF STUDY Colorectal cancer (CRC) is the fourth most prevalent cancer globally. Several factors have roles in cancer establishment. One of the most important factors is hypoxia that induces hypoxia inducible factor-1 (HIF-1). The HIF-1 alpha overexpressed in hypoxia conditions and plays a pivotal role in carcinogenesis features. In this study, we aimed to examine the efficiency of HIF-1 alpha gene expression at mRNA and protein's level for CRC diagnosing and staging. MATERIALS AND METHODS In this study, the cases included into 75 cancer specimens in different stages (Group 2 = Stage 1, Group 3 = Stage 2, and Group 4 = Stage 3, 4) and ten normal specimens as control (Group 1). Real-time reverse transcription-polymerase chain reaction and immunohistochemistry (IHC) were performed for measuring gene expression at RNA and protein's level, respectively. The raw data were analyzed in the SPSS20 software. RESULTS HIF-1 alpha gene expression rate (2-ΔΔCT) and ΔCT values were significantly higher increased in Group 4 in compare to control (P < 0.001). Other cancer groups (2 and 3) had greater ΔCT values than control, but it was not statistically significant. Moreover, the rate of HIF-1 alpha gene expression (2-ΔΔCT) was increased with cancer stages. According to the IHC results, there was a positive relationship between CRC stages and HIF-1 alpha protein expression (P < 0.05). CONCLUSIONS HIF-1 alpha gene expression increased in earlier up to metastasis stages of CRC, but the assessment of HIF-1 alpha gene expression has not important role in the diagnosis of cancer in early stages and classification of carcinoma because the increasing of HIF-1 alpha gene expression is not significant in early cancer stages.
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Affiliation(s)
- Reyhaneh Nassiri Mansour
- Clinical Biochemistry and Nutrition Department, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Seyed Ehsan Enderami
- Medical Biotechnology Department, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Abdolreza Ardeshirylajimi
- Department of Tissue Engineering and Regenerative Medicine, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Koorosh Fooladsaz
- Clinical Biochemistry and Nutrition Department, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Mojtaba Fathi
- Clinical Biochemistry and Nutrition Department, Zanjan University of Medical Sciences, Zanjan, Iran
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Effect of acute hypoxia on cognition: A systematic review and meta-regression analysis. Neurosci Biobehav Rev 2017; 74:225-232. [PMID: 28111267 DOI: 10.1016/j.neubiorev.2017.01.019] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 01/12/2017] [Accepted: 01/16/2017] [Indexed: 12/20/2022]
Abstract
A systematic meta-regression analysis of the effects of acute hypoxia on the performance of central executive and non-executive tasks, and the effects of the moderating variables, arterial partial pressure of oxygen (PaO2) and hypobaric versus normobaric hypoxia, was undertaken. Studies were included if they were performed on healthy humans; within-subject design was used; data were reported giving the PaO2 or that allowed the PaO2 to be estimated (e.g. arterial oxygen saturation and/or altitude); and the duration of being in a hypoxic state prior to cognitive testing was ≤6days. Twenty-two experiments met the criteria for inclusion and demonstrated a moderate, negative mean effect size (g=-0.49, 95% CI -0.64 to -0.34, p<0.001). There were no significant differences between central executive and non-executive, perception/attention and short-term memory, tasks. Low (35-60mmHg) PaO2 was the key predictor of cognitive performance (R2=0.45, p<0.001) and this was independent of whether the exposure was in hypobaric hypoxic or normobaric hypoxic conditions.
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Heinzer R, Saugy JJ, Rupp T, Tobback N, Faiss R, Bourdillon N, Rubio JH, Millet GP. Comparison of Sleep Disorders between Real and Simulated 3,450-m Altitude. Sleep 2016; 39:1517-23. [PMID: 27166242 DOI: 10.5665/sleep.6010] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 04/12/2016] [Indexed: 02/05/2023] Open
Abstract
STUDY OBJECTIVES Hypoxia is known to generate sleep-disordered breathing but there is a debate about the pathophysiological responses to two different types of hypoxic exposure: normobaric hypoxia (NH) and hypobaric hypoxia (HH), which have never been directly compared. Our aim was to compare sleep disorders induced by these two types of altitude. METHODS Subjects were exposed to 26 h of simulated (NH) or real altitude (HH) corresponding to 3,450 m and a control condition (NN) in a randomized order. The sleep assessments were performed with nocturnal polysomnography (PSG) and questionnaires. Thirteen healthy trained males subjects volunteered for this study (mean ± SD; age 34 ± 9 y, body weight 76.2 ± 6.8 kg, height 179.7 ± 4.2 cm). RESULTS Mean nocturnal oxygen saturation was further decreased during HH than in NH (81.2 ± 3.1 versus 83.6 ± 1.9%; P < 0.01) when compared to NN (95.5 ± 0.9%; P < 0.001). Heart rate was higher in HH than in NH (61 ± 10 versus 55 ± 6 bpm; P < 0.05) and NN (48 ± 5 bpm; P < 0.001). Total sleep time was longer in HH than in NH (351 ± 63 versus 317 ± 65 min, P < 0.05), and both were shorter compared to NN (388 ± 50 min, P < 0.05). Breathing frequency did not differ between conditions. Apnea-hypopnea index was higher in HH than in NH (20.5 [15.8-57.4] versus 11.4 [5.0-65.4]; P < 0.01) and NN (8.2 [3.9-8.8]; P < 0.001). Subjective sleep quality was similar between hypoxic conditions but lower than in NN. CONCLUSIONS Our results suggest that HH has a greater effect on nocturnal breathing and sleep structure than NH. In HH, we observed more periodic breathing, which might arise from the lower saturation due to hypobaria, but needs to be confirmed.
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Affiliation(s)
- Raphaël Heinzer
- Center for Investigation and Research in Sleep, CHUV, Lausanne, Switzerland
| | - Jonas J Saugy
- ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Switzerland.,Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland
| | - Thomas Rupp
- Savoie Mont Blanc University, Exercise Physiology Laboratory, Chambery, France
| | - Nadia Tobback
- Center for Investigation and Research in Sleep, CHUV, Lausanne, Switzerland
| | - Raphael Faiss
- ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Switzerland.,Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland
| | - Nicolas Bourdillon
- ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Switzerland.,Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland
| | - José Haba Rubio
- Center for Investigation and Research in Sleep, CHUV, Lausanne, Switzerland
| | - Grégoire P Millet
- ISSUL, Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Switzerland.,Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Switzerland
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Saugy JJ, Schmitt L, Fallet S, Faiss R, Vesin JM, Bertschi M, Heinzer R, Millet GP. Sleep Disordered Breathing During Live High-Train Low in Normobaric Versus Hypobaric Hypoxia. High Alt Med Biol 2016; 17:233-238. [PMID: 27410774 DOI: 10.1089/ham.2016.0049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Saugy, Jonas J., Laurent Schmitt, Sibylle Fallet, Raphael Faiss, Jean-Marc Vesin, Mattia Bertschi, Raphaël Heinzer, and Grégoire P. Millet. Sleep disordered breathing during live high-train low in normobaric versus hypobaric hypoxia. High Alt Med Biol. 17:233-238, 2016.-The present study aimed to compare sleep disordered breathing during live high-train low (LHTL) altitude camp using normobaric hypoxia (NH) and hypobaric hypoxia (HH). Sixteen highly trained triathletes completed two 18-day LHTL camps in a crossover designed study. They trained at 1100-1200 m while they slept either in NH at a simulated altitude of 2250 m or in HH. Breathing frequency and oxygen saturation (SpO2) were recorded continuously during all nights and oxygen desaturation index (ODI 3%) calculated. Breathing frequency was lower for NH than HH during the camps (14.6 ± 3.1 breath × min-1 vs. 17.2 ± 3.4 breath × min-1, p < 0.001). SpO2 was lower for HH than NH (90.8 ± 0.3 vs. 91.9 ± 0.2, p < 0.001) and ODI 3% was higher for HH than NH (15.1 ± 3.5 vs. 9.9 ± 1.6, p < 0.001). Sleep in moderate HH is more altered than in NH during a LHTL camp.
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Affiliation(s)
- Jonas J Saugy
- 1 Faculty of Biology and Medicine, ISSUL, Institute of Sport Sciences, University of Lausanne , Switzerland .,2 Department of Physiology, Faculty of Biology and Medicine, University of Lausanne , Switzerland
| | - Laurent Schmitt
- 3 National School of Mountain Sports/National Ski-Nordic Centre , Prémanon, France
| | - Sibylle Fallet
- 4 Institute of Electrical Engineering, Swiss Federal Institute of Technology , Lausanne, Switzerland
| | - Raphael Faiss
- 1 Faculty of Biology and Medicine, ISSUL, Institute of Sport Sciences, University of Lausanne , Switzerland
| | - Jean-Marc Vesin
- 4 Institute of Electrical Engineering, Swiss Federal Institute of Technology , Lausanne, Switzerland
| | - Mattia Bertschi
- 5 Swiss Center for Electronics and Microtechnology , CSEM, Neuchâtel, Switzerland
| | - Raphaël Heinzer
- 6 Center for Investigation and Research in Sleep , CHUV, Lausanne, Switzerland
| | - Grégoire P Millet
- 1 Faculty of Biology and Medicine, ISSUL, Institute of Sport Sciences, University of Lausanne , Switzerland .,2 Department of Physiology, Faculty of Biology and Medicine, University of Lausanne , Switzerland
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Girard O, Bula S, Faiss R, Brocherie F, Millet GY, Millet GP. Does altitude level of a prior time-trial modify subsequent exercise performance in hypoxia and associated neuromuscular responses? Physiol Rep 2016. [PMCID: PMC4962066 DOI: 10.14814/phy2.12804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We examined the influence of prior time‐trials performed at different altitudes on subsequent exercise in moderate hypoxia and associated cardiometabolic and neuromuscular responses. In normobaric hypoxia (simulated altitude 2000 m; FiO2: 0.163), 10 healthy males performed (1) an incremental test to exhaustion (VO2max_2000) and (2) a test to exhaustion at 80% of the power output associated to VO2max_2000 for a reference time (947 ± 336 sec). Thereafter, two sessions were conducted in a randomized order: a cycle time‐trial corresponding to the reference time (TT1) followed 22 min later (passive rest at 2000 m) by a 6‐min cycle time‐trial (TT2). TT1 was either performed at 2000 or 3500 m (FiO2: 0.135), while TT2 was always performed at 2000 m. As expected, during TT1, the mean power output (247 ± 42 vs. 227 ± 37 W; P < 0.001) was higher at 2000 than 3500 m. During TT2, the mean power output (256 ± 42 vs. 252 ± 36 W) did not differ between conditions. Before and after TT1, maximal isometric voluntary contraction torque in knee extensors (pooled conditions: −7.9 ± 8.4%; P < 0.01), voluntary activation (−4.1 ± 3.1%; P < 0.05), and indices of muscle contractility (peak twitch torque: −39.1 ± 11.9%; doublet torques at 100 Hz: −15.4 ± 8.9%; 10/100 Hz ratio: −25.8 ± 7.7%; all P < 0.001) were equally reduced at 2000 m or 3500 m. Irrespective of the altitude of TT1, neuromuscular function remained similarly depressed after TT1 both before and after TT2 at 2000 m. A prior time‐trial performed at different altitude influenced to the same extent performance and associated cardiometabolic and neuromuscular responses during a subsequent exercise in moderate hypoxia.
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Affiliation(s)
- Olivier Girard
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Simone Bula
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Raphaël Faiss
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Franck Brocherie
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
| | - Guillaume Y. Millet
- Human Performance Laboratory; Faculty of Kinesiology; University of Calgary; Calgary AB Canada
| | - Grégoire P. Millet
- Department of Physiology; Faculty of Biology and Medicine; ISSUL; Institute of Sport Sciences; University of Lausanne; Lausanne Switzerland
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[Not Available]. High Alt Med Biol 2016; 17:57-60. [PMID: 27281470 DOI: 10.1089/ham.2016.29010.stg] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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