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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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Simim MADM, Souza HDS, Cardoso Filho CA, Gianoni RLDS, Bezerra RR, Affonso HDO, Amadio AC, D’Almeida V, Serrão JC, Claudino JG. Sleep quality monitoring in individual sports athletes: parameters and definitions by systematic review. Sleep Sci 2020; 13:267-285. [PMID: 33564374 PMCID: PMC7856669 DOI: 10.5935/1984-0063.20200032] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Accepted: 06/22/2020] [Indexed: 12/26/2022] Open
Abstract
In the present review, we identify which instruments and parameters are used for sleep quality monitoring in individual sport athletes and which definitions were used for sleep quality parameters in this literature field. Systematic searches for articles reporting the qualitative markers related to sleep in team sport athletes were conducted in PubMed, Scopus and Web of Science online databases. The systematic review followed the Preferred Reporting Items for Systematic Reviews. The initial search returned 3316 articles. After the removal of duplicate articles, eligibility assessment, 75 studies were included in this systematic review. Our main findings were that the most widely used measurement instruments were Actigraphy (25%), Rating Likert Scales (16%) and Sleep Diary (13%). On sleep quality parameters (Sleep duration = 14%; Wake after sleep onset = 14%; Sleep Quality = 12%; Sleep Effciency = 11% and Sleep Latency = 9%), the main point is that there are different definitions for the same parameters in many cases reported in the literature. We conclude that the most widely used instruments for monitoring sleep quality were Actigraphy, Likert scales and Sleep diary. Moreover, the definitions of sleep parameters are inconsistent in the literature, hindering the understanding of the sleep-sport performance relationship.
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Affiliation(s)
- Mário Antônio de Moura Simim
- Federal University of Ceará, Institute of Physical Education and Sports - Fortaleza - Ceará - Brazil
- Federal University of Ceará, Master Program in Physioterapy and Functioning - Fortaleza - Ceará - Brazil
| | - Helton de Sá Souza
- Universidade Federal de São Paulo, Departamento de Psicobiologia - São Paulo -Brazil
- Centro Universitário de Volta Redonda - UniFOA, Curso de Educação Física - Volta Redonda - Rio de Janeiro - Brazil
| | | | - Rodrigo Luiz da Silva Gianoni
- Paulista University - UNIP
- LOAD CONTROL, Research and Development Department - Contagem - Minas Gerais - Brazil
- Peruíbe College - FPbe - UNISEPE
| | | | - Helvio de Oliveira Affonso
- Appto Physiology, Laboratory of Exercise, Nutrition and Sports Training, Espirito Santo - Vitoria - Espírito Santo - Brazil
- Vila Velha University, Pharmaceutical Sciences Graduate Program - Vila Velha - Espírito Santo - Brazil
| | - Alberto Carlos Amadio
- Universidade de São Paulo, School of Physical Education and Sport - Laboratory of Biomechanics- Brazil
| | - Vânia D’Almeida
- Universidade Federal de São Paulo, Departamento de Psicobiologia - São Paulo -Brazil
| | - Júlio Cerca Serrão
- Universidade de São Paulo, School of Physical Education and Sport - Laboratory of Biomechanics- Brazil
| | - João Gustavo Claudino
- Universidade de São Paulo, School of Physical Education and Sport - Laboratory of Biomechanics- Brazil
- LOAD CONTROL, Research and Development Department - Contagem - Minas Gerais - Brazil
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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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Jacobs RA. Con: Live high-train low does not improve sea-level performance beyond that achieved with the equivalent living and training at sea level. High Alt Med Biol 2014; 14:328-30. [PMID: 24377336 DOI: 10.1089/ham.2013.1040] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Robert A Jacobs
- 1 Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich , Zurich, Switzerland
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Aughey RJ, Buchheit M, Garvican-Lewis LA, Roach GD, Sargent C, Billaut F, Varley MC, Bourdon PC, Gore CJ. Yin and yang, or peas in a pod? Individual-sport versus team-sport athletes and altitude training. Br J Sports Med 2013; 47:1150-4. [PMID: 24255910 PMCID: PMC3841751 DOI: 10.1136/bjsports-2013-092764] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2013] [Indexed: 11/04/2022]
Abstract
The question of whether altitude training can enhance subsequent sea-level performance has been well investigated over many decades. However, research on this topic has focused on athletes from individual or endurance sports, with scant number of studies on team-sport athletes. Questions that need to be answered include whether this type of training may enhance team-sport athlete performance, when success in team-sport is often more based on technical and tactical ability rather than physical capacity per se. This review will contrast and compare athletes from two sports representative of endurance (cycling) and team-sports (soccer). Specifically, we draw on the respective competition schedules, physiological capacities, activity profiles and energetics of each sport to compare the similarities between athletes from these sports and discuss the relative merits of altitude training for these athletes. The application of conventional live-high, train-high; live-high, train-low; and intermittent hypoxic training for team-sport athletes in the context of the above will be presented. When the above points are considered, we will conclude that dependent on resources and training objectives, altitude training can be seen as an attractive proposition to enhance the physical performance of team-sport athletes without the need for an obvious increase in training load.
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Affiliation(s)
- Robert J Aughey
- Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria, Australia
- Western Bulldogs Football Club, Melbourne, Victoria, Australia
| | - Martin Buchheit
- Sport Science Department, Physiology Unit, ASPIRE Academy for Sports Excellence, Doha, Qatar
| | - Laura A Garvican-Lewis
- Department of Physiology, Australian Institute of Sport, Canberra, Australian Capital Territory, Australia
- National Institute of Sports Studies, University of Canberra, Canberra, Australian Capital Territory, Australia
| | - Gregory D Roach
- Appleton Institute for Behavioural Science, Central Queensland University, Adelaide, South Australia, Australia
| | - Charli Sargent
- Appleton Institute for Behavioural Science, Central Queensland University, Adelaide, South Australia, Australia
| | | | - Matthew C Varley
- Institute of Sport, Exercise and Active Living, Victoria University, Melbourne, Victoria, Australia
| | - Pitre C Bourdon
- Sport Science Department, Physiology Unit, ASPIRE Academy for Sports Excellence, Doha, Qatar
| | - Christopher J Gore
- Department of Physiology, Australian Institute of Sport, Canberra, Australian Capital Territory, Australia
- Exercise Physiology Laboratory, Flinders University, Adelaide, South Australia, Australia
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6
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Stadelmann K, Latshang TD, Lo Cascio CM, Tesler N, Stoewhas AC, Kohler M, Bloch KE, Huber R, Achermann P. Quantitative changes in the sleep EEG at moderate altitude (1630 m and 2590 m). PLoS One 2013; 8:e76945. [PMID: 24167552 PMCID: PMC3805553 DOI: 10.1371/journal.pone.0076945] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 08/28/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Previous studies have observed an altitude-dependent increase in central apneas and a shift towards lighter sleep at altitudes >4000 m. Whether altitude-dependent changes in the sleep EEG are also prevalent at moderate altitudes of 1600 m and 2600 m remains largely unknown. Furthermore, the relationship between sleep EEG variables and central apneas and oxygen saturation are of great interest to understand the impact of hypoxia at moderate altitude on sleep. METHODS Fourty-four healthy men (mean age 25.0 ± 5.5 years) underwent polysomnographic recordings during a baseline night at 490 m and four consecutive nights at 1630 m and 2590 m (two nights each) in a randomized cross-over design. RESULTS Comparison of sleep EEG power density spectra of frontal (F3A2) and central (C3A2) derivations at altitudes compared to baseline revealed that slow-wave activity (SWA, 0.8-4.6 Hz) in non-REM sleep was reduced in an altitude-dependent manner (~4% at 1630 m and 15% at 2590 m), while theta activity (4.6-8 Hz) was reduced only at the highest altitude (10% at 2590 m). In addition, spindle peak height and frequency showed a modest increase in the second night at 2590 m. SWA and theta activity were also reduced in REM sleep. Correlations between spectral power and central apnea/hypopnea index (AHI), oxygen desaturation index (ODI), and oxygen saturation revealed that distinct frequency bands were correlated with oxygen saturation (6.4-8 Hz and 13-14.4 Hz) and breathing variables (AHI, ODI; 0.8-4.6 Hz). CONCLUSIONS The correlation between SWA and AHI/ODI suggests that respiratory disturbances contribute to the reduction in SWA at altitude. Since SWA is a marker of sleep homeostasis, this might be indicative of an inability to efficiently dissipate sleep pressure.
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Affiliation(s)
- Katrin Stadelmann
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | | | | | - Noemi Tesler
- University Children's Hospital Zurich, Zurich, Switzerland
| | | | - Malcolm Kohler
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Pulmonary Division, University Hospital Zurich, Zurich, Switzerland
| | - Konrad E. Bloch
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- Pulmonary Division, University Hospital Zurich, Zurich, Switzerland
| | - Reto Huber
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
- University Children's Hospital Zurich, Zurich, Switzerland
| | - Peter Achermann
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
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Abstract
Sleep is now considered as a new frontier in performance enhancement. This article presents background content on sleep function, sleep needs and methods of sleep investigation along with data on the potential effects of Ramadan fasting on sleep in normal individuals and athletes. Accumulated sleep loss has negative impacts on cognitive function, mood, daytime sleepiness and performance. Sleep studies in athletes fasting during Ramadan are very rare. Most of them have demonstrated that during this month, sleep duration decreased and sleep timing shifted. But the direct relation between sleep changes and performance during Ramadan is not yet elucidated. Objective sleep patterns can be investigated using polysomnography, actigraphy, and standardised questionnaires and recorded in daily journals or sleep logs. The available data on sleep indicate that team doctors and coaches should consider planning sleep schedule and napping; implementing educational programmes focusing on the need for healthy sleep; and consider routine screening for sleep loss in athletes of all age groups and genders.
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Affiliation(s)
- Rachida Roky
- University of Hassan II Ain Chock, Laboratory of Physiology and Molecular Genetics, Km 8 Route d'El Jadida, B.P 5366 Maarif, Casablanca, 20100, Morocco.
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Hoshikawa M, Uchida S, Ganeko M, Sumitomo J, Totoki M, Kojima T, Nakamura Y, Kawahara T. Sleep quality under mild hypoxia in men with low hypoxic ventilatory response. Eur J Sport Sci 2012; 14 Suppl 1:S205-12. [DOI: 10.1080/17461391.2012.681805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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9
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Prevalence of Cheyne–Stokes respiration in modern treated congestive heart failure. Sleep Breath 2008; 13:181-5. [DOI: 10.1007/s11325-008-0218-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2008] [Revised: 08/05/2008] [Accepted: 08/11/2008] [Indexed: 11/24/2022]
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Abstract
At the Olympic level, differences in performance are typically less than 0.5%. This helps explain why many contemporary elite endurance athletes in summer and winter sport incorporate some form of altitude/hypoxic training within their year-round training plan, believing that it will provide the "competitive edge" to succeed at the Olympic level. The purpose of this paper is to describe the practical application of altitude/hypoxic training as used by elite athletes. Within the general framework of the paper, both anecdotal and scientific evidence will be presented relative to the efficacy of several contemporary altitude/hypoxic training models and devices currently used by Olympic-level athletes for the purpose of legally enhancing performance. These include the three primary altitude/hypoxic training models: 1) live high+train high (LH+TH), 2) live high+train low (LH+TL), and 3) live low+train high (LL+TH). The LH+TL model will be examined in detail and will include its various modifications: natural/terrestrial altitude, simulated altitude via nitrogen dilution or oxygen filtration, and hypobaric normoxia via supplemental oxygen. A somewhat opposite approach to LH+TL is the altitude/hypoxic training strategy of LL+TH, and data regarding its efficacy will be presented. Recently, several of these altitude/hypoxic training strategies and devices underwent critical review by the World Anti-Doping Agency (WADA) for the purpose of potentially banning them as illegal performance-enhancing substances/methods. This paper will conclude with an update on the most recent statement from WADA regarding the use of simulated altitude devices.
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Affiliation(s)
- Randall L Wilber
- Athlete Performance Laboratory, United States Olympic Committee, Colorado Springs, CO 80909, USA.
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Legault S, Lanfranchi P, Montplaisir J, Nielsen T, Dore A, Khairy P, Marcotte F, Mercier LA. Nocturnal breathing in cyanotic congenital heart disease. Int J Cardiol 2007; 128:197-200. [PMID: 17643525 DOI: 10.1016/j.ijcard.2007.06.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Revised: 05/10/2007] [Accepted: 06/15/2007] [Indexed: 10/23/2022]
Abstract
BACKGROUND Sleep disordered breathing is frequently observed in patients with cardiovascular disease. Even in the absence of heart disease, acute and chronic hypoxia have been shown to promote sleep-related periodic breathing with central apnea characterized by a repetitive reduction or lack of respiratory activity. Cyanotic congenital heart disease (CCHD) is associated with chronic hypoxia, regardless of whether an increase in pulmonary artery pressures coexists. Sleep aggravated hypoxia has been observed in many such patients, but it remains to be determined whether sleep disordered breathing is contributory. We, therefore, sought to assess sleep-related breathing pattern in patients with CCHD. METHODS Adults with CCHD, resting arterial oxygen saturation <90%, and systemic ejection fraction >40% were prospectively enrolled in a cross-sectional study. To assess sleep and respiratory indices, subjects underwent a standardized clinical appraisal that included arterial blood gas analysis and a comprehensive sleep study with an ambulatory device. An apnea-hypopnea index (AHI) >or=5/h was considered to indicate sleep apnea. RESULTS Ten adults with CCHD, aged 38+/-11 years, completed the study. Seven patients had elevated pulmonary artery pressures, with a mean systolic pressure of 86.3+/-18.1 mm Hg. All patients demonstrated normal sleep parameters. Oxygen saturation further declined in 5 patients during sleep. However, no associated alteration in respiratory parameters was observed and no significant arrhythmia. The mean AHI was 1.1+/-1.0/h. No subject met the pre-defined criterion for sleep apnea. CONCLUSION Although further oxygen desaturation may be observed during sleep in patients with CCHD, it occurs in the absence of sleep disordered breathing.
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Affiliation(s)
- Sylvie Legault
- Adult Congenital Heart Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada
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13
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Yun AJ. Environmental discontinuity hypothesis: Buffer dysfunctions as a source of human disease. Med Hypotheses 2007; 68:434-8. [PMID: 16759813 DOI: 10.1016/j.mehy.2005.11.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Revised: 11/02/2005] [Accepted: 11/04/2005] [Indexed: 11/17/2022]
Abstract
Adaptive physiologic buffers enable organisms to respond to environmental variation with appropriate plasticity. Modern humans have substantially remodeled their environment such that many interactions with the environment have become relatively discontinuous functions compared to the past. Examples include sunlight, temperature, and altitude. We propose that environmental discontinuity represents a Darwinian maladaptation and may promote disease by inducing buffer dysfunctions. Skin pigmentation is an adaptive, dynamic buffer that normalizes sunlight exposure to balance the potential harm of damaging rays with the importance of sunlight in driving systemic biologic functions such as melatonin and vitamin D. Due to lifestyle characteristics such as indoor-outdoor living, well-intended sun-avoidance campaigns, and inhomogeneous use of apparel and sunblock techniques, modern humans increasingly experience sunlight variation as a discontinuous function. The resulting skin pigmentation buffer dysfunction may promote diseases associated with over- or under-exposure to sunlight, the most striking example being melanoma. In addition to promoting discontinuity of sunlight exposure, sun-avoidance campaigns may undermine sun-dependent biologic pathways such as melatonin and vitamin D that appear to protect against cancer. These issues may partly explain the rise in melanoma rates despite the implementation of sun-avoidance campaigns. Also discussed is the potential role that discontinuous temperature variation associated with modern lifestyles plays in diseases such as viral infection, heart failure, and acute coronary syndromes. Acute discontinuous changes in pressure and oxygen levels related to air travel may contribute to autonomic dysfunction, venous thromboembolism, and viral infections. Therapeutic implications are discussed.
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Affiliation(s)
- Anthony J Yun
- Radiology, Stanford University, 470 University Avenue, Palo Alto, CA 94301, USA.
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