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Guo C, Lan L, Yan Y, Kang M. Effects of acute exposure to hypoxia on sleep structure in healthy adults: A systematic review. Sleep Med Rev 2024; 75:101928. [PMID: 38614049 DOI: 10.1016/j.smrv.2024.101928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/14/2024] [Accepted: 03/21/2024] [Indexed: 04/15/2024]
Abstract
The sleep quality of lowlanders in hypoxic environments has become increasingly important with an increase in highland and alpine activities. This study aimed to identify the effects of acute exposure to hypoxia on the sleep structure of lowlanders and to analyze the changes in sleep indicators at varying levels of hypoxia. This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Twenty-three studies were screened and included in the quantitative analysis. The results showed that acute exposure to hypoxia reduced sleep quality in lowlanders. Post-sleep arousal events and the percentage of N1 were significantly increased, whereas total sleep time, sleep efficiency, and the percentage of N3 and rapid eye movement sleep were significantly decreased in hypoxic environments. Acute exposure to hypoxia had the greatest negative impact on wakefulness after sleep onset (WASO). In addition, a larger decrease in sleep efficiency and higher increase in the percentages of N1 and WASO were observed when lowlanders were exposed to higher levels of hypoxia. This study clarifies the quantitative effects of acute hypoxic exposure on sleep in lowlanders based on original studies and explains the sleep disorders faced by lowlanders in hypoxic environments.
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Affiliation(s)
- Chao Guo
- Department of Architecture, School of Design, Shanghai Jiao Tong University, Shanghai, China
| | - Li Lan
- Department of Architecture, School of Design, Shanghai Jiao Tong University, Shanghai, China.
| | - Yan Yan
- Department of Architecture, School of Design, Shanghai Jiao Tong University, Shanghai, China
| | - Mengyuan Kang
- Department of Architecture, School of Design, Shanghai Jiao Tong University, Shanghai, China
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2
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Bonato G, Goodman S, Tjh L. Physiological and performance effects of live high train low altitude training for elite endurance athletes: A narrative review. Curr Res Physiol 2023; 6:100113. [PMID: 38107789 PMCID: PMC10724230 DOI: 10.1016/j.crphys.2023.100113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 11/10/2023] [Accepted: 11/21/2023] [Indexed: 12/19/2023] Open
Abstract
Altitude training has become an important training application for athletes due its potential for altering physiology and enhancing performance. This practice is commonly used by athletes, with a popular choice being the live high - train low approach. This model recommends that athletes live at high altitude (1250-3000 m), but train at low altitude or sea-level (0-1200 m). Exposure to altitude often leads to hypoxic stress and in turn stimulates changes in total haemoglobin mass, erythropoietin, and soluble transferrin receptors, which alter further underlying physiology. Through enhanced physiology, improved exercise performance may arise through enhancement of the oxygen transport system which is important for endurance events. Previous investigations into the effects of altitude training on exercise performance have been completed in a range of contexts, including running, cycling, swimming, and triathlon. Often following a LHTL altitude intervention, athletes realise improvements in maximal oxygen consumption capacity, time trial performance and peak power outputs. Although heterogeneity exists among LHTL methodologies, i.e., exposure durations and altitude ranges, we synthesised this data into kilometre hours, and found that the most common hypoxic doses used in LHTL interventions ranged from ∼578-687 km h. As this narrative review demonstrates, there are potential advantages to using altitude training to enhance physiology and improve performance for endurance athletes.
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Affiliation(s)
- G. Bonato
- Exercise and Sports Science, School of Science and Technology, The University of New England, Armidale, 2350, Australia
- College of Arts, Society and Education, James Cook University, Townsville, 4811, Australia
| | - S.P.J Goodman
- Exercise and Sports Science, School of Science and Technology, The University of New England, Armidale, 2350, Australia
| | - Lathlean Tjh
- Exercise and Sports Science, School of Science and Technology, The University of New England, Armidale, 2350, Australia
- The Adelaide Medical School, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, 5000, Australia
- South Australian Health and Medical Research Institute (SAHMRI), Adelaide, 5000, Australia
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3
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Zhang L, Jin Y, Zhang Q, Liu H, Chen C, Song L, Li X, Ma Z, Yang Q. Transcutaneous Vagus Nerve Stimulation for Insomnia in People Living in Places or Cities with High Altitudes: A Randomized Controlled Trial. Brain Sci 2023; 13:985. [PMID: 37508917 PMCID: PMC10377398 DOI: 10.3390/brainsci13070985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND The purpose of this study was to investigate the effectiveness and safety of transcutaneous vagus nerve stimulation (tVNS) to improve insomnia in the special environment of a plateau. METHODS This study was a single-center, single-blind, randomized controlled trial. A total of 100 patients with insomnia at high altitude were randomized into three groups receiving either transcutaneous vagus nerve stimulation intervention in the left ear tragus (treatment group), pseudo-stimulation intervention (sham group), or cognitive behavioral therapy for insomnia (CBTI group). The primary measure was the Pittsburgh Sleep Quality Index (PSQI) score. In addition, we assessed the patients' objective sleep status with polysomnography and evaluated changes in the Insomnia Severity Index Scale (ISI) and Generalized Anxiety Disorder-7 (GAD-7) scores. We used one-way ANOVA and repeated-measures ANOVA for analysis. RESULTS Patients' PSQI, ISI, and GAD-7 scale scores significantly decreased after 4 weeks of tVNS treatment and were greater than those of the control group. Polysomnographic data also demonstrated shortened sleep latency and longer deep sleep in the patients. CONCLUSION tVNS is effective in improving sleep quality and reducing anxiety levels in high-altitude insomnia patients but should be confirmed in future adequate and prolonged trials to guide clinical promotion.
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Affiliation(s)
- Liang Zhang
- Department of Military Medical Psychology, Air Force Military Medical University, Xi'an 710032, China
| | - Yinchuan Jin
- Department of Military Medical Psychology, Air Force Military Medical University, Xi'an 710032, China
| | - Qintao Zhang
- Department of Military Medical Psychology, Air Force Military Medical University, Xi'an 710032, China
| | - Hongyao Liu
- Department of Military Medical Psychology, Air Force Military Medical University, Xi'an 710032, China
| | - Chen Chen
- Department of Military Medical Psychology, Air Force Military Medical University, Xi'an 710032, China
| | - Lei Song
- Department of Military Medical Psychology, Air Force Military Medical University, Xi'an 710032, China
| | - Xiao Li
- Department of Military Medical Psychology, Air Force Military Medical University, Xi'an 710032, China
| | - Zhujing Ma
- Department of Military Medical Psychology, Air Force Military Medical University, Xi'an 710032, China
| | - Qun Yang
- Department of Military Medical Psychology, Air Force Military Medical University, Xi'an 710032, China
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Van Cutsem J, Pattyn N. Primum non nocere; It's time to consider altitude training as the medical intervention it actually is! Front Psychol 2022; 13:1028294. [PMID: 36582343 PMCID: PMC9792969 DOI: 10.3389/fpsyg.2022.1028294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 11/23/2022] [Indexed: 12/15/2022] Open
Abstract
Sleep is one of the most important aspects of recovery, and is known to be severely affected by hypoxia. The present position paper focuses on sleep as a strong moderator of the altitude training-response. Indeed, the response to altitude training is highly variable, it is not a fixed and classifiable trait, rather it is a state that is determined by multiple factors (e.g., iron status, altitude dose, pre-intervention hemoglobin mass, training load, and recovery). We present an overview of evidence showing that sleep, and more specifically the prolonged negative impact of altitude on the nocturnal breathing pattern, affecting mainly deep sleep and thus the core of physiological recovery during sleep, could play an important role in intra- and interindividual variability in the altitude training-associated responses in professional and recreational athletes. We conclude our paper with a set of suggested recommendations to customize the application of altitude training to the specific needs and vulnerabilities of each athlete (i.e., primum non nocere). Several factors have been identified (e.g., sex, polymorphisms in the TASK2/KCNK5, NOTCH4 and CAT genes and pre-term birth) to predict individual vulnerabilities to hypoxia-related sleep-disordered breathing. Currently, polysomnography should be the first choice to evaluate an individual's predisposition to a decrease in deep sleep related to hypoxia. Further interventions, both pharmacological and non-pharmacological, might alleviate the effects of nocturnal hypoxia in those athletes that show most vulnerable.
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Affiliation(s)
- Jeroen Van Cutsem
- Vital Signs and Performance Monitoring (VIPER) Research Unit, Royal Military Academy, Brussels, Belgium,Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium,*Correspondence: Jeroen Van Cutsem,
| | - Nathalie Pattyn
- Vital Signs and Performance Monitoring (VIPER) Research Unit, Royal Military Academy, Brussels, Belgium,Human Physiology and Sports Physiotherapy Research Group, Vrije Universiteit Brussel, Brussels, Belgium
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5
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Hrozanova M, Talsnes R, Karlsson Ø, McGawley K, Moen F. An observational study of sleep characteristics in elite endurance athletes during an altitude training camp at 1800 m. Sleep Health 2021; 7:691-698. [PMID: 34635445 DOI: 10.1016/j.sleh.2021.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 08/05/2021] [Accepted: 08/23/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To observe changes in sleep from baseline and during an altitude training camp in elite endurance athletes. DESIGN Prospective, observational. SETTING Baseline monitoring at <500 m for 2 weeks and altitude monitoring at 1800 m for 17-22 days. PARTICIPANTS Thirty-three senior national-team endurance athletes (mean age 25.8 ± S.D. 2.8 years, 16 women). MEASUREMENTS Daily measurements of sleep (using a microwave Doppler radar at baseline and altitude), oxygen saturation (SpO2), training load and subjective recovery (at altitude). RESULTS At altitude vs. baseline, sleep duration (P = .036) and light sleep (P < .001) decreased, while deep sleep (P < .001) and respiration rate (P = .020) increased. During the first altitude week vs. baseline, deep sleep increased (P = .001). During the first vs. the second and third altitude weeks, time in bed (P = .005), sleep duration (P = .001), and light sleep (P < .001) decreased. Generally, increased SpO2 was associated with increased deep sleep while increased training load was associated with increased respiration rate. CONCLUSION This is the first study to document changes in sleep from near-sea-level baseline and during a training camp at 1800 m in elite endurance athletes. Ascending to altitude reduced total sleep time and light sleep, while deep sleep and respiration rate increased. SpO2 and training load at altitude were associated with these responses. This research informs our understanding of the changes in sleep occurring in elite endurance athletes attending training camps at competition altitudes.
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Affiliation(s)
- Maria Hrozanova
- Center for Elite Sports Research, Faculty of Medicine and Health Sciences, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway.
| | - Rune Talsnes
- Meråker High School, Trøndelag County Council, Meråker, Norway; Department of Sports Science and Physical Education, Nord University, Bodø, Norway
| | - Øyvind Karlsson
- Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Kerry McGawley
- Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Frode Moen
- Faculty of Social and Educational Sciences, Department of Education and Lifelong Learning, Norwegian University of Science and Technology, Trondheim, Norway
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Vlahoyiannis A, Aphamis G, Bogdanis GC, Sakkas GK, Andreou E, Giannaki CD. Deconstructing athletes' sleep: A systematic review of the influence of age, sex, athletic expertise, sport type, and season on sleep characteristics. J Sport Health Sci 2021; 10:387-402. [PMID: 32325024 PMCID: PMC8343120 DOI: 10.1016/j.jshs.2020.03.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/19/2019] [Accepted: 02/14/2020] [Indexed: 05/11/2023]
Abstract
PURPOSE This systematic review aimed to describe objective sleep parameters for athletes under different conditions and address potential sleep issues in this specific population. METHODS PubMed and Scopus were searched from inception to April 2019. Included studies measured sleep only via objective evaluation tools such as polysomnography or actigraphy. The modified version of the Newcastle-Ottawa Scale was used for the quality assessment of the studies. RESULTS Eighty-one studies were included, of which 56 were classified as medium quality, 5 studies as low quality, and 20 studies as high quality. A total of 1830 athletes were monitored over 18,958 nights. Average values for sleep-related parameters were calculated for all athletes according to sex, age, athletic expertise level, training season, and type of sport. Athletes slept on average 7.2 ± 1.1 h/night (mean ± SD), with 86.3% ± 6.8% sleep efficiency (SE). In all datasets, the athletes' mean total sleep time was <8 h. SE was low for young athletes (80.3% ± 8.8%). Reduced SE was attributed to high wake after sleep onset rather than sleep onset latency. During heavy training periods, sleep duration and SE were on average 36 min and 0.8% less compared to pre-season and 42 min and 3.0% less compared to in-season training periods, respectively. CONCLUSION Athletes' sleep duration was found to be short with low SE, in comparison to the general consensus for non-athlete healthy adults. Notable sleep issues were revealed in young athletes. Sleep quality and architecture tend to change across different training periods.
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Affiliation(s)
- Angelos Vlahoyiannis
- Department of Life and Health Sciences, University of Nicosia, Nicosia 1700, Cyprus
| | - George Aphamis
- Department of Life and Health Sciences, University of Nicosia, Nicosia 1700, Cyprus
| | - Gregory C Bogdanis
- School of Physical Education and Sport Science, National and Kapodistrian University of Athens, Athens 17237, Greece
| | - Giorgos K Sakkas
- Department of Physical Education and Sport Science, University of Thessaly, Trikala 42100, Greece; School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff CF5 2YB, UK
| | - Eleni Andreou
- Department of Life and Health Sciences, University of Nicosia, Nicosia 1700, Cyprus
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7
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Vlahoyiannis A, Sakkas GK, Manconi M, Aphamis G, Giannaki CD. A critical review on sleep assessment methodologies in athletic populations: factors to be considered. Sleep Med 2020; 74:211-223. [PMID: 32861013 DOI: 10.1016/j.sleep.2020.07.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/18/2020] [Accepted: 07/27/2020] [Indexed: 12/13/2022]
Abstract
A growing body of research focus on athletes' sleep in order to investigate the effects of sleep in sports performance and recovery or the prevalence of sleep disorders in athletes. At the same time, several sleep monitoring tools have been developed and used in athletic populations for fulfilling these purposes. This review aimed to provide critical assessment to the most used by athletes' methodological approaches and compared them with the gold standard approach. Advantages and disadvantages of the various sleep monitoring tools were critically discussed. Literature related to aspects of athletes' sleep was reviewed. From the shortlisted studies, several factors that seem to affect sleep in athletes were identified using objective methods such as polysomnography/electroencephalography and actigraphy. These factors were associated to sleep (eg such as sleep environment, familiarization procedures and napping) and daily habits (eg nutrition, fluid consumption, alcohol and caffeine intake, tobacco use). The selected studies that evaluated sleep objectively were screened according the reporting rates of these variables. The majority of the screened studies were found to underreport these variables. Practical issues were addressed and recommendations about reporting sleep-related factors were made in order to improve studies' quality assessment and allow for more robust comparisons between studies.
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Affiliation(s)
| | - Giorgos K Sakkas
- Department of Physical Education and Sport Science, University of Thessaly, Trikala, Greece; School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Mauro Manconi
- Sleep and Epilepsy Center, Neurocenter of Southern Switzerland, Civic Hospital (EOC) of Lugano, Lugano, Switzerland
| | - George Aphamis
- Department of Life and Health Sciences, University of Nicosia, Nicosia, Cyprus
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8
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Li QF, Wang H, Zheng L, Yang F, Li HZ, Li JX, Cheng D, Lu K, Liu Y. Effects of Modest Hypoxia and Exercise on Cardiac Function, Sleep-Activity, Negative Geotaxis Behavior of Aged Female Drosophila. Front Physiol 2020; 10:1610. [PMID: 32038290 PMCID: PMC6985434 DOI: 10.3389/fphys.2019.01610] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 12/23/2019] [Indexed: 12/13/2022] Open
Abstract
Mild normobaric hypoxia (NH) and modest exercise have multiple beneficial effects on health, but the changes in physiological function induced by NH and/or exercise remain unclear. The purpose of this investigation was to examine the specific effects of NH and/or exercise on cardiac function and myocardial structure and behavior including sleep-activity and negative geotaxis in aged Drosophila. We also assessed the survival rate of flies after hypoxia and/or exercise. One-thousand wild-type w1118 virgin female flies were randomly divided into four groups and treated with NH and/or exercise from ages 3-6 weeks. We found that exercise remarkably delayed the decline of actin and myosin and the age-related changes in cardiac structure, improved abnormal cardiac contraction, and enhanced the cardiac pumping force by inducing cardiac hypertrophy and delaying deterioration of cardiac contractility and diastolic compliance, and improved abnormal heart contraction. NH also increased the content of actin and myosin, but induced a decrease in heart diameter and heart rate, as well as an increase in the number of mitochondria and deeper sleep, which may be the manifestation of energy saving under long-term hypoxia. Both NH and exercise improved sleep quality and climbing ability of aged flies, as well as extended the maximum life span, which shows the benefits of hypoxia and exercise. Finally, the superposition of NH and exercise did not impart any obvious physiological and behavior improvement. Therefore, it is necessary to further explore the appropriate combination of hypoxia and exercise.
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Affiliation(s)
- Qiu Fang Li
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Changsha, China
| | - Hui Wang
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Changsha, China
| | - Lan Zheng
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Changsha, China
| | - Fan Yang
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Changsha, China
| | - Han Zhe Li
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Changsha, China
| | - Jin Xiu Li
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Changsha, China
| | - Dan Cheng
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Changsha, China
| | - Kai Lu
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Changsha, China
| | - Yang Liu
- Key Laboratory of Physical Fitness and Exercise Rehabilitation of Hunan Province, Hunan Normal University, Changsha, China
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Li C, Kee YH, Lam LS. Effect of Brief Mindfulness Induction on University Athletes' Sleep Quality Following Night Training. Front Psychol 2018; 9:508. [PMID: 29706914 PMCID: PMC5907683 DOI: 10.3389/fpsyg.2018.00508] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 03/26/2018] [Indexed: 12/15/2022] Open
Abstract
Given the need to alleviate sleep problems confronting athletes, the present experiment, conducted as much as possible in a naturalistic fashion that mimics daily life, seeks to examine whether a brief mindfulness induction immediately prior to sleep following night training can improve athletes' sleep. A sample of university athletes (n = 80) was recruited and 63 of them were eligible to participate in this experiment. They were then randomly assigned into experimental group (n = 32) and control group (n = 31). Following night training and just prior to sleep, those in the experimental group received a self-administered brief 6-min mindfulness induction via a video clip, whereas the control group participants viewed a similar 6-min video devoid of mindfulness induction passively. Questionnaire-based measures of training intensity, pre-sleep arousal, state mindfulness, and sleep diary (i.e., level of rest, sleep duration, and overall sleep quality) were administered. Results showed that brief mindfulness induction reduced pre-sleep arousal, and improved level of rest and overall sleep quality, but not sleep duration. Pre-sleep arousal was also found to be a partial mediator in the relationship between the brief mindfulness induction and reported level of rest during sleep. These findings suggest that the brief mindfulness induction may be an effective approach for decreasing pre-sleep arousal and improving sleep quality after night training among athletes.
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Affiliation(s)
- Chunxiao Li
- Department of Health and Physical Education, The Education University of Hong Kong, Ting Kok, Hong Kong
| | - Ying Hwa Kee
- National Institute of Education, Nanyang Technological University, Singapore, Singapore
| | - Lok Shan Lam
- Department of Health and Physical Education, The Education University of Hong Kong, Ting Kok, Hong Kong
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10
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Simpson NS, Gibbs EL, Matheson GO. Optimizing sleep to maximize performance: implications and recommendations for elite athletes. Scand J Med Sci Sports 2016; 27:266-274. [PMID: 27367265 DOI: 10.1111/sms.12703] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/27/2016] [Indexed: 01/07/2023]
Abstract
Despite a growing body of literature demonstrating a positive relationship between sleep and optimal performance, athletes often have low sleep quality and quantity. Insufficient sleep among athletes may be due to scheduling constraints and the low priority of sleep relative to other training demands, as well as a lack of awareness of the role of sleep in optimizing athletic performance. Domains of athletic performance (e.g., speed and endurance), neurocognitive function (e.g., attention and memory), and physical health (e.g., illness and injury risk, and weight maintenance) have all been shown to be negatively affected by insufficient sleep or experimentally modeled sleep restriction. However, healthy adults are notoriously poor at self-assessing the magnitude of the impact of sleep loss, underscoring the need for increased awareness of the importance of sleep among both elite athletes and practitioners managing their care. Strategies to optimize sleep quality and quantity in athletes include approaches for expanding total sleep duration, improving sleep environment, and identifying potential sleep disorders.
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Affiliation(s)
- N S Simpson
- Department of Psychiatry, Stanford University School of Medicine, Stanford, CA, USA
| | - E L Gibbs
- PGSP-Stanford PsyD Consortium, Palo Alto, CA, USA
| | - G O Matheson
- Division of Sports Medicine & Human Performance Lab, Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA, USA
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12
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Hoshikawa M, Uchida S, Osawa T, Eguchi K, Arimitsu T, Suzuki Y, Kawahara T. Effects of Five Nights under Normobaric Hypoxia on Sleep Quality. Med Sci Sports Exerc 2016; 47:1512-8. [PMID: 25386712 DOI: 10.1249/mss.0000000000000569] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The purpose of this study was to evaluate the effects of five nights' sleep under normobaric hypoxia on ventilatory acclimatization and sleep quality. METHODS Seven men initially slept for six nights under normoxia and then for five nights under normobaric hypoxia equivalent to a 2000-m altitude. Nocturnal polysomnograms (PSGs), arterial blood oxygen saturation (SpO2), and respiratory events were recorded on the first and fifth nights under both conditions. RESULTS The hypoxic ventilatory response (HVR), hypercapnic ventilatory response (HCVR), and resting end-tidal CO2 (resting PETCO2) were measured three times during the experimental period. The duration of slow-wave sleep (SWS: stage N3) and the whole-night delta (1-3 Hz) power of nonrapid eye movement (NREM) sleep EEG decreased on the first night under hypoxia. This hypoxia-induced sleep quality deterioration on the first night was accompanied by a lower mean and minimum SpO2, a longer time spent with SpO2 below 90% (<90% SpO2 time), and more episodes of respiratory disturbance. On the fifth night, the SWS duration and whole-night delta power did not differ between the conditions. Although the mean SpO2 under hypoxia was still lower than under normoxia, the minimum SpO2 increased, and the <90% SpO2 time and number of episodes of respiratory disturbance decreased during the five nights under hypoxia. The HVR increased and resting PETCO2 decreased after five nights under hypoxia. CONCLUSIONS The results suggest that five nights under hypoxia improves the sleep quality. This may be derived from improvements of respiratory disturbances, the minimum SpO2, and <90% SpO2 time.
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Affiliation(s)
- Masako Hoshikawa
- 1Department of Sports Sciences, Japan Institute of Sports Sciences, Nishigaoka, Kita-ku, Tokyo, JAPAN; 2Faculty of Sport Sciences, Waseda University, Mitakajima, Tokorozawa, Saitama, JAPAN; 3Director General, Japan Institute of Sports Sciences, Nishigaoka, Kita-ku, Tokyo, JAPAN
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Álvarez-herms J, Julià-sánchez S, Hamlin M, Corbi F, Pagès T, Viscor G. Popularity of hypoxic training methods for endurance-based professional and amateur athletes. Physiol Behav 2015; 143:35-8. [DOI: 10.1016/j.physbeh.2015.02.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 02/03/2015] [Accepted: 02/11/2015] [Indexed: 11/24/2022]
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Sargent C, Schmidt WF, Aughey RJ, Bourdon PC, Soria R, Claros JCJ, Garvican-Lewis LA, Buchheit M, Simpson BM, Hammond K, Kley M, Wachsmuth N, Gore CJ, Roach GD. The impact of altitude on the sleep of young elite soccer players (ISA3600). Br J Sports Med 2014; 47 Suppl 1:i86-92. [PMID: 24282215 PMCID: PMC3903148 DOI: 10.1136/bjsports-2013-092829] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Background Altitude training is used by elite athletes to improve sports performance, but it may also disrupt sleep. The aim of this study was to examine the effects of 2 weeks at high altitude on the sleep of young elite athletes. Methods Participants (n=10) were members of the Australian under-17 soccer team on an 18-day (19-night) training camp in Bolivia, with six nights at near sea level in Santa Cruz (430 m) and 13 nights at high altitude in La Paz (3600 m). Sleep was monitored using polysomnography during a baseline night at 430 m and three nights at 3600 m (immediately after ascent, 1 week after ascent and 2 weeks after ascent). Data were analysed using effect size statistics. Results All results are reported as comparisons with baseline. Rapid eye movement (REM) sleep was likely lower immediately upon ascent to altitude, possibly lower after 1 week and similar after 2 weeks. On all three nights at altitude, hypopneas and desaturations were almost certainly higher; oxygen saturation was almost certainly lower; and central apnoeas, respiratory arousals and periodic breathing were very likely higher. The effects on REM sleep were common to all but one participant, but the effects on breathing were specific to only half the participants. Conclusions The immediate effects of terrestrial altitude of 3600 m are to reduce the amount of REM sleep obtained by young elite athletes, and to cause 50% of them to have impaired breathing during sleep. REM sleep returns to normal after 2 weeks at altitude, but impaired breathing does not improve.
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Affiliation(s)
- Charli Sargent
- Appleton Institute for Behavioural Science, Central Queensland University, , Adelaide, Australia
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Roach GD, Schmidt WF, Aughey RJ, Bourdon PC, Soria R, Claros JCJ, Garvican-Lewis LA, Buchheit M, Simpson BM, Hammond K, Kley M, Wachsmuth N, Gore CJ, Sargent C. The sleep of elite athletes at sea level and high altitude: a comparison of sea-level natives and high-altitude natives (ISA3600). Br J Sports Med 2014; 47 Suppl 1:i114-20. [PMID: 24282197 PMCID: PMC3903309 DOI: 10.1136/bjsports-2013-092843] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Altitude exposure causes acute sleep disruption in non-athletes, but little is known about its effects in elite athletes. The aim of this study was to examine the effects of altitude on two groups of elite athletes, that is, sea-level natives and high-altitude natives. METHODS Sea-level natives were members of the Australian under-17 soccer team (n=14). High-altitude natives were members of a Bolivian under-20 club team (n=12). Teams participated in an 18-day (19 nights) training camp in Bolivia, with 6 nights at near sea level in Santa Cruz (430 m) and 13 nights at high altitude in La Paz (3600 m). Sleep was assessed on every day/night using activity monitors. RESULTS The Australians' sleep was shorter, and of poorer quality, on the first night at altitude compared with sea level. Sleep quality returned to normal by the end of the first week at altitude, but sleep quantity had still not stabilised at its normal level after 2 weeks. The quantity and quality of sleep obtained by the Bolivians was similar, or greater, on all nights at altitude compared with sea level. The Australians tended to obtain more sleep than the Bolivians at sea level and altitude, but the quality of the Bolivians' sleep tended to be better than that of the Australians at altitude. CONCLUSIONS Exposure to high altitude causes acute and chronic disruption to the sleep of elite athletes who are sea-level natives, but it does not affect the sleep of elite athletes who are high-altitude natives.
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Affiliation(s)
- Gregory D Roach
- Appleton Institute for Behavioural Science, Central Queensland University, , Adelaide, Australia
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Girard O, Amann M, Aughey R, Billaut F, Bishop DJ, Bourdon P, Buchheit M, Chapman R, D'Hooghe M, Garvican-Lewis LA, Gore CJ, Millet GP, Roach GD, Sargent C, Saunders PU, Schmidt W, Schumacher YO. Position statement--altitude training for improving team-sport players' performance: current knowledge and unresolved issues. Br J Sports Med 2013; 47 Suppl 1:i8-16. [PMID: 24282213 PMCID: PMC3903313 DOI: 10.1136/bjsports-2013-093109] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2013] [Indexed: 01/09/2023]
Abstract
Despite the limited research on the effects of altitude (or hypoxic) training interventions on team-sport performance, players from all around the world engaged in these sports are now using altitude training more than ever before. In March 2013, an Altitude Training and Team Sports conference was held in Doha, Qatar, to establish a forum of research and practical insights into this rapidly growing field. A round-table meeting in which the panellists engaged in focused discussions concluded this conference. This has resulted in the present position statement, designed to highlight some key issues raised during the debates and to integrate the ideas into a shared conceptual framework. The present signposting document has been developed for use by support teams (coaches, performance scientists, physicians, strength and conditioning staff) and other professionals who have an interest in the practical application of altitude training for team sports. After more than four decades of research, there is still no consensus on the optimal strategies to elicit the best results from altitude training in a team-sport population. However, there are some recommended strategies discussed in this position statement to adopt for improving the acclimatisation process when training/competing at altitude and for potentially enhancing sea-level performance. It is our hope that this information will be intriguing, balanced and, more importantly, stimulating to the point that it promotes constructive discussion and serves as a guide for future research aimed at advancing the bourgeoning body of knowledge in the area of altitude training for team sports.
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Affiliation(s)
- Olivier Girard
- Research and Education Centre, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
| | - Markus Amann
- Department of Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Robert Aughey
- Exercise and Active Living, Institute of Sport, Victoria University, Melbourne, Australia
- Western Bulldogs Football Club, Melbourne, Australia
| | | | - David J Bishop
- Exercise and Active Living, Institute of Sport, Victoria University, Melbourne, Australia
| | | | | | - Robert Chapman
- Department of Kinesiology, Indiana University, High Performance Department, USA Track & Field, Indianapolis, Indiana, USA
| | - Michel D'Hooghe
- Fédération Internationale de Football Association (FIFA) Medical Commission and FIFA Medical Assessment and Research Centre (F-MARC), Langerei, 71, 8000 Brugge, Belgium
| | - Laura A Garvican-Lewis
- Department of Physiology, Australian Institute of Sport, Canberra, Australia
- University of Canberra, Canberra, Australia
| | - Christopher J Gore
- Department of Physiology, Australian Institute of Sport, Canberra, Australia
- Exercise Physiology Laboratory, Flinders University, Adelaide, Australia
| | - Grégoire P Millet
- Department of Physiology—Faculty of Biology and Medicine, ISSUL—Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Gregory D Roach
- Appleton Institute for Behavioural Science, Central Queensland University, Adelaide, Australia
| | - Charli Sargent
- Appleton Institute for Behavioural Science, Central Queensland University, Adelaide, Australia
| | - Philo U Saunders
- Department of Physiology, Australian Institute of Sport, Canberra, Australia
- University of Canberra, Canberra, Australia
| | - Walter Schmidt
- Department of Sports Medicine/Sports Physiology, University of Bayreuth, Bayreuth, Germany
| | - Yorck O Schumacher
- Research and Education Centre, ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Doha, Qatar
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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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] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Hoshikawa M, Uchida S, Sugo T, Kumai Y, Hanai Y, Kawahara T. Sleep quality in athletes under normobaric hypoxia equivalent to 1500 m altitude: A polysomnographic study. Eur J Sport Sci 2010. [DOI: 10.1080/17461390903470020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Abstract
The increase in oxygen transport elicited by several weeks of exposure to moderate to high altitude is used to increase physical performance when returning to sea level. However, many studies have shown that aerobic performance may not increase at sea level after a training block at high altitude. Subsequently, the concept of living high and training low was introduced in the early 1990s and was further modified to include simulated altitude using hypobaric or normobaric hypoxia. Review is given of the main studies that have used this procedure. Hematological changes are limited to insignificant or moderate increase in red cell mass, depending on the "dose" of hypoxia. Maximal aerobic performance is increased when the exposure to hypoxia is at least over 18 days. Submaximal performance and running economy have been found increased in several, but not all, studies. The tolerance (fatigue, sleep, immunological status, cardiac function) is good when the altitude or simulated altitude is not higher than 3000 m. Virtually no data are available about the effect of this procedure upon anaerobic performance. The wide spread of these techniques deserves further investigations.
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Affiliation(s)
- J-P Richalet
- Université Paris 13, Laboratoire Réponses Cellulaires et Fonctionnelles à l'Hypoxie, EA2363, ARPE, Bobigny, France.
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Gore CJ, McSharry PE, Hewitt AJ, Saunders PU. Preparation for football competition at moderate to high altitude. Scand J Med Sci Sports 2008; 18 Suppl 1:85-95. [DOI: 10.1111/j.1600-0838.2008.00836.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Hoshikawa M, Uchida S, Sugo T, Kumai Y, Hanai Y, Kawahara T. Changes in sleep quality of athletes under normobaric hypoxia equivalent to 2,000-m altitude: a polysomnographic study. J Appl Physiol (1985) 2007; 103:2005-11. [PMID: 17690200 DOI: 10.1152/japplphysiol.00315.2007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study evaluated the sleep quality of athletes in normobaric hypoxia at a simulated altitude of 2,000 m. Eight male athletes slept in normoxic condition (NC) and hypoxic conditions equivalent to those at 2,000-m altitude (HC). Polysomnographic recordings of sleep included the electroencephalogram (EEG), electrooculogram, chin surface electromyogram, and electrocardiogram. Thoracic and abdominal motion, nasal and oral airflow, and arterial blood oxygen saturation (SaO2) were also recorded. Standard visual sleep stage scoring and fast Fourier transformation analyses of the EEG were performed on 30-s epochs. Subjective sleepiness and urinary catecholamines were also monitored. Mean SaO2 decreased and respiratory disturbances increased with HC. The increase in respiratory disturbances was significant, but the increase was small and subclinical. The duration of slow-wave sleep (stage 3 and 4) and total delta power (<3 Hz) of the all-night non-rapid eye movement sleep EEG decreased for HC compared with NC. Subjective sleepiness and amounts of urinary catecholamines did not differ between the conditions. These results indicate that acute exposure to normobaric hypoxia equivalent to that at 2,000-m altitude decreased slow-wave sleep in athletes, but it did not change subjective sleepiness or amounts of urinary catecholamines.
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Affiliation(s)
- Masako Hoshikawa
- Department of Sports Science, Japan Institute of Sports Sciences, Tokyo, Japan.
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Abstract
Rapid deployment of unacclimatized soldiers to high mountainous environments causes debilitating effects on operational capabilities (physical work performance), and force health (altitude sickness). Most of these altitude-induced debilitations can be prevented or ameliorated by a wide range of physiological responses collectively referred to as altitude acclimatization. Acclimatization to a target altitude can be induced by slow progressive ascents or continuous sojourns at intermediate altitudes. However, this "altitude residency" requirement reduces their utilization in rapid response military missions that exploit the air mobility capability of modern military forces to quickly deploy to an area of operations on short notice. A more recent approach to induce altitude acclimatization is the use of daily intermittent hypoxic exposures (IHE) in lieu of continuous residence at high altitudes. IHE treatments consist of three elements: 1) IHE simulated altitude (inspired oxygen partial pressure: PIO2), 2) IHE session duration, and 3) total number of IHE sessions over the treatment period. This paper reviews and summarizes the results of 25 published IHE studies. This review finds that an IHE altitude>or=4000 m, and daily exposure duration of at least 1.5 h repeated over a week or more are required to have a high probability of developing altitude acclimatization. The efficacy of shorter duration (<1.5 h) hypoxic exposures at >or=4000 m simulated altitudes, and longer exposures (>4 h) at moderate altitudes (2500-3500 m) is not well documented. The predominate IHE-induced altitude acclimatization response appears to be increased arterial oxygen content through ventilatory acclimatization. Thus, IHE is a promising approach to provide the benefits of altitude acclimatization to low-altitude-based soldiers before their deployment to high mountainous regions.
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Affiliation(s)
- Stephen R Muza
- U.S. Army Research Institute of Environmental Medicine, Natick, MA 02053, USA.
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Abstract
Altitude training has been used regularly for the past five decades by elite endurance athletes, with the goal of improving performance at sea level. The dominant paradigm is that the improved performance at sea level is due primarily to an accelerated erythropoietic response due to the reduced oxygen available at altitude, leading to an increase in red cell mass, maximal oxygen uptake, and competitive performance. Blood doping and exogenous use of erythropoietin demonstrate the unequivocal performance benefits of more red blood cells to an athlete, but it is perhaps revealing that long-term residence at high altitude does not increase hemoglobin concentration in Tibetans and Ethiopians compared with the polycythemia commonly observed in Andeans. This review also explores evidence of factors other than accelerated erythropoiesis that can contribute to improved athletic performance at sea level after living and/or training in natural or artificial hypoxia. We describe a range of studies that have demonstrated performance improvements after various forms of altitude exposures despite no increase in red cell mass. In addition, the multifactor cascade of responses induced by hypoxia includes angiogenesis, glucose transport, glycolysis, and pH regulation, each of which may partially explain improved endurance performance independent of a larger number of red blood cells. Specific beneficial nonhematological factors include improved muscle efficiency probably at a mitochondrial level, greater muscle buffering, and the ability to tolerate lactic acid production. Future research should examine both hematological and nonhematological mechanisms of adaptation to hypoxia that might enhance the performance of elite athletes at sea level.
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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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