101
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Keramidas ME, Stavrou NAM, Kounalakis SN, Eiken O, Mekjavic IB. Severe hypoxia during incremental exercise to exhaustion provokes negative post-exercise affects. Physiol Behav 2016; 156:171-6. [PMID: 26802281 DOI: 10.1016/j.physbeh.2016.01.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 11/09/2015] [Accepted: 01/19/2016] [Indexed: 10/22/2022]
Abstract
The post-exercise emotional response is mainly dependent on the intensity of the exercise performed; moderate exercise causes positive feelings, whereas maximal exercise may prompt negative affects. Acute hypoxia impairs peak O2 uptake (V̇O2peak), resulting in a shift to a lower absolute intensity at the point of exhaustion. Hence, the purpose of the study was to examine whether a severe hypoxic stimulus would influence the post-exercise affective state in healthy lowlanders performing an incremental exercise to exhaustion. Thirty-six male lowlanders performed, in a counter-balanced order and separated by a 48-h interval, two incremental exercise trials to exhaustion to determine their V̇O2peak, while they were breathing either room air (AIR; FiO2: 0.21), or a hypoxic gas mixture (HYPO; FiO2: 0.12). Before and immediately after each trial, subjects were requested to complete two questionnaires, based on how they felt at that particular moment: (i) the Profile of Mood States-Short Form, and (ii) the Activation Deactivation Adjective Check List. During the post-exercise phase, they also completed the Multidimensional Fatigue Inventory. V̇O2peak was significantly lower in the HYPO than the AIR trial (~15%; p<0.001). Still, after the HYPO trial, energy, calmness and motivation were markedly impaired, whereas tension, confusion, and perception of physical and general fatigue were exaggerated (p≤0.05). Accordingly, present findings suggest that an incremental exercise to exhaustion performed in severe hypoxia provokes negative post-exercise emotions, induces higher levels of perceived fatigue and decreases motivation; the affective responses coincide with the comparatively lower V̇O2peak than that achieved in normoxic conditions.
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Affiliation(s)
- Michail E Keramidas
- Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology, Stockholm, Sweden; Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.
| | - Nektarios A M Stavrou
- Exercise and Sport Science Department, ASPETAR Orthopaedic and Sports Medicine Hospital, Doha, Qatar; Faculty of Physical Education and Sport Science, University of Athens, Athens, Greece
| | - Stylianos N Kounalakis
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Center, School of Technology and Health, Royal Institute of Technology, Stockholm, Sweden
| | - Igor B Mekjavic
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
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102
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Taylor L, Watkins SL, Marshall H, Dascombe BJ, Foster J. The Impact of Different Environmental Conditions on Cognitive Function: A Focused Review. Front Physiol 2016; 6:372. [PMID: 26779029 PMCID: PMC4701920 DOI: 10.3389/fphys.2015.00372] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 11/20/2015] [Indexed: 01/08/2023] Open
Abstract
Cognitive function defines performance in objective tasks that require conscious mental effort. Extreme environments, namely heat, hypoxia, and cold can all alter human cognitive function due to a variety of psychological and/or biological processes. The aims of this Focused Review were to discuss; (1) the current state of knowledge on the effects of heat, hypoxic and cold stress on cognitive function, (2) the potential mechanisms underpinning these alterations, and (3) plausible interventions that may maintain cognitive function upon exposure to each of these environmental stressors. The available evidence suggests that the effects of heat, hypoxia, and cold stress on cognitive function are both task and severity dependent. Complex tasks are particularly vulnerable to extreme heat stress, whereas both simple and complex task performance appear to be vulnerable at even at moderate altitudes. Cold stress also appears to negatively impact both simple and complex task performance, however, the research in this area is sparse in comparison to heat and hypoxia. In summary, this focused review provides updated knowledge regarding the effects of extreme environmental stressors on cognitive function and their biological underpinnings. Tyrosine supplementation may help individuals maintain cognitive function in very hot, hypoxic, and/or cold conditions. However, more research is needed to clarify these and other postulated interventions.
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Affiliation(s)
- Lee Taylor
- ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research CentreDoha, Qatar
- Applied Sport and Exercise Physiology Research Group, Department of Sport Science and Physical Activity, Institute for Sport and Physical Activity Research, University of BedfordshireBedford, UK
| | - Samuel L. Watkins
- Applied Sport and Exercise Physiology Research Group, Department of Sport Science and Physical Activity, Institute for Sport and Physical Activity Research, University of BedfordshireBedford, UK
| | - Hannah Marshall
- Applied Sport and Exercise Physiology Research Group, Department of Sport Science and Physical Activity, Institute for Sport and Physical Activity Research, University of BedfordshireBedford, UK
| | - Ben J. Dascombe
- Applied Sport Science and Exercise Testing Laboratory, Faculty of Science and Information Technology, University of NewcastleOurimbah, NSW, Australia
| | - Josh Foster
- Applied Sport and Exercise Physiology Research Group, Department of Sport Science and Physical Activity, Institute for Sport and Physical Activity Research, University of BedfordshireBedford, UK
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103
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Bian SZ, Jin J, Zhang JH, Li QN, Yu J, Yu SY, Chen JF, Yu XJ, Qin J, Huang L. Principal Component Analysis and Risk Factors for Acute Mountain Sickness upon Acute Exposure at 3700 m. PLoS One 2015; 10:e0142375. [PMID: 26554385 PMCID: PMC4640520 DOI: 10.1371/journal.pone.0142375] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 10/21/2015] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE We aimed to describe the heterogeneity in the clinical presentation of acute mountain sickness (AMS) and to identify its primary risk factors. METHODS The participants (n = 163) received case report form questionnaires, and their heart rate (HR), oxygen saturation (SpO2), echocardiographic and transcranial Doppler variables, ability to perform mental and physical work, mood and psychological factors were assessed within 18 to 22 hours after arriving at 3700 m from sea level (500 m) by plane. First, we examined the differences in all variables between the AMS-positive and the AMS-negative groups. Second, an adjusted regression analysis was performed after correlation and principal component analyses. RESULTS The AMS patients had a higher diastolic vertebral artery velocity (Vd; p = 0.018), a higher HR (p = 0.006) and a lower SpO2. The AMS subjects also experienced poorer sleep quality, as quantified using the Athens Insomnia Scale (AIS). Moreover, the AMS population exhibited more negative mood states, including anxiety, depression, hostility, fatigue and confusion. Five principal components focused on diverse aspects were also found to be significant. Additionally, more advanced age (p = 0.007), a higher HR (p = 0.034), a higher Vd (p = 0.014), a higher AIS score (p = 0.030), a decreased pursuit aiming capacity (p = 0.035) and decreased vigor (p = 0.015) were risk factors for AMS. CONCLUSIONS Mood states play critical roles in the development of AMS. Furthermore, an elevated HR and Vd, advanced age, elevated AIS sores, insufficient vigor and decreased mental work capacity are independent risk factors for AMS.
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Affiliation(s)
- Shi-Zhu Bian
- Institute of Cardiovascular Diseases of PLA; Xinqiao Hospital, Third Military Medical University, Chongqing, China
- Department of Cardiology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Jun Jin
- Institute of Cardiovascular Diseases of PLA; Xinqiao Hospital, Third Military Medical University, Chongqing, China
- Department of Cardiology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Ji-Hang Zhang
- Institute of Cardiovascular Diseases of PLA; Xinqiao Hospital, Third Military Medical University, Chongqing, China
- Department of Cardiology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Qian-Ning Li
- Department of Neurology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Jie Yu
- Institute of Cardiovascular Diseases of PLA; Xinqiao Hospital, Third Military Medical University, Chongqing, China
- Department of Cardiology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Shi-Yong Yu
- Institute of Cardiovascular Diseases of PLA; Xinqiao Hospital, Third Military Medical University, Chongqing, China
- Department of Cardiology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Jian-Fei Chen
- Institute of Cardiovascular Diseases of PLA; Xinqiao Hospital, Third Military Medical University, Chongqing, China
- Department of Cardiology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Xue-Jun Yu
- Institute of Cardiovascular Diseases of PLA; Xinqiao Hospital, Third Military Medical University, Chongqing, China
- Department of Cardiology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Jun Qin
- Institute of Cardiovascular Diseases of PLA; Xinqiao Hospital, Third Military Medical University, Chongqing, China
- Department of Cardiology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Lan Huang
- Institute of Cardiovascular Diseases of PLA; Xinqiao Hospital, Third Military Medical University, Chongqing, China
- Department of Cardiology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
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104
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Cross TJ, Keller-Ross M, Issa A, Wentz R, Taylor B, Johnson B. The Impact of Averaging Window Length on the"Desaturation Indexes during Overnight Pulse Oximetry at High-Altitude". Sleep 2015; 38:1331-4. [PMID: 25581919 DOI: 10.5665/sleep.4920] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 11/26/2014] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES To determine the impact of averaging window-length on the "desaturation" indexes (DIs) obtained via overnight pulse oximetry (SpO2) at high altitude. DESIGN Overnight SpO2 data were collected during a 10-day sojourn at high altitude. SpO2 was obtained using a commercial wrist-worn finger oximeter whose firmware was modified to store unaveraged beat-to-beat data. Simple moving averages of window lengths spanning 2 to 20 cardiac beats were retrospectively applied to beat-to-beat SpO2 datasets. After SpO2 artifacts were removed, the following DIs were then calculated for each of the averaged datasets: oxygen desaturation index (ODI); total sleep time with SpO2 < 80% (TST < 80), and the lowest SpO2 observed during sleep (SpO2 low). SETTING South Base Camp, Mt. Everest (5,364 m elevation). PARTICIPANTS Five healthy, adult males (35 ± 5 y; 180 ± 1 cm; 85 ± 4 kg). INTERVENTIONS N/A. MEASUREMENTS AND RESULTS 49 datasets were obtained from the 5 participants, totalling 239 hours of data. For all window lengths ≥ 2 beats, ODI and TST < 80 were lower, and SpO2 low was higher than those values obtained from the beat-to-beat SpO2 time series data (P < 0.05). CONCLUSIONS Our findings indicate that increasing oximeter averaging window length progressively underestimates the frequency and magnitude of sleep disordered breathing events at high altitude, as indirectly assessed via the desaturation indexes.
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Affiliation(s)
- Troy J Cross
- Heart Foundation Research Centre, Griffith Health Institute, Griffith University, Queensland, Australia.,Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | | | - Amine Issa
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - Robert Wentz
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - Bryan Taylor
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - Bruce Johnson
- Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
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105
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West JB. Barcroft's bold assertion: All dwellers at high altitudes are persons of impaired physical and mental powers. J Physiol 2015; 594:1127-34. [PMID: 25962370 DOI: 10.1113/jp270284] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 05/04/2015] [Indexed: 11/08/2022] Open
Abstract
Barcroft's bold assertion that everyone at high altitude has physical and mental impairment compared with sea level was very provocative. It was a result of the expedition that he led to Cerro de Pasco in Peru, altitude 4300 m. Although it is clear that newcomers to high altitude have reduced physical powers, some people believe that this does not apply to permanent residents who have been at high altitude for generations. The best evidence supports Barcroft's contention, although permanent residents often perform better than acclimatized lowlanders. Turning to neuropsychological function, newcomers to high altitude certainly have some impairment, and there is evidence that the same applies to highlanders. However the notion that permanent residents are impaired is anathema to many people. For example the eminent Peruvian physician Carlos Monge took great exception to Barcroft's remark and even attributed it to the fact that Barcroft was suffering from acute mountain sickness when he made it! Monge referred to 'climatic aggression', by which he meant the negative consequences of the inevitable hypoxia of high altitude. Recent technological advances such as oxygen enrichment of room air can overcome this 'aggression'. This might be useful in some settings at high altitude such as a nursery where newborn babies are cared for, and possibly operating rooms where the surgeon's dexterity may be enhanced. Other situations might be dormitories, conference rooms, and perhaps some school rooms. These constitute possible ways by which the effects of Barcroft's assertion might be countered.
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Affiliation(s)
- John B West
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093-0623, USA
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106
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Souza JFTD, Giampá SQDC, Lemos VDA, Santos SAD, Silva ETD, De Mello MT, Tufik S, Santos RVTD, Antunes HKM. Exercise performed at hypoxia influences mood state and anxiety symptoms. MOTRIZ: REVISTA DE EDUCACAO FISICA 2015. [DOI: 10.1590/s1980-65742015000200008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During hypoxia conditions, psychological states can be worsened. However, little information is available regarding the effect of physical exercise performed in hypoxia conditions on mood state and anxiety symptoms. The aim of the present study was to elucidate the acute effect of moderate physical exercise performed at hypoxia on mood states and anxiety symptoms in healthy young subjects. Ten volunteers were subjected to the following conditions: a normoxic condition (NC) and a hypoxic condition (HC). They performed 45 min of physical exercise. Their anxiety symptoms and mood states were evaluated at the initial time point as well as immediately following and 30 and 60 min after the exercise session. Our results showed a significant increase in post-exercise anxiety symptoms and a significant decrease in mood scores immediately after and 30 min after exercise performed in the HC. Moderate physical activity performed at hypoxia condition increased post-exercise anxiety and worsened mood state.
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107
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Creatine supplementation enhances corticomotor excitability and cognitive performance during oxygen deprivation. J Neurosci 2015; 35:1773-80. [PMID: 25632150 DOI: 10.1523/jneurosci.3113-14.2015] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Impairment or interruption of oxygen supply compromises brain function and plays a role in neurological and neurodegenerative conditions. Creatine is a naturally occurring compound involved in the buffering, transport, and regulation of cellular energy, with the potential to replenish cellular adenosine triphosphate without oxygen. Creatine is also neuroprotective in vitro against anoxic/hypoxic damage. Dietary creatine supplementation has been associated with improved symptoms in neurological disorders defined by impaired neural energy provision. Here we investigate, for the first time in humans, the utility of creatine as a dietary supplement to protect against energetic insult. The aim of this study was to assess the influence of oral creatine supplementation on the neurophysiological and neuropsychological function of healthy young adults during acute oxygen deprivation. Fifteen healthy adults were supplemented with creatine and placebo treatments for 7 d, which increased brain creatine on average by 9.2%. A hypoxic gas mixture (10% oxygen) was administered for 90 min, causing global oxygen deficit and impairing a range of neuropsychological processes. Hypoxia-induced decrements in cognitive performance, specifically attentional capacity, were restored when participants were creatine supplemented, and corticomotor excitability increased. A neuromodulatory effect of creatine via increased energy availability is presumed to be a contributing factor of the restoration, perhaps by supporting the maintenance of appropriate neuronal membrane potentials. Dietary creatine monohydrate supplementation augments neural creatine, increases corticomotor excitability, and prevents the decline in attention that occurs during severe oxygen deficit. This is the first demonstration of creatine's utility as a neuroprotective supplement when cellular energy provision is compromised.
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108
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Acute hypoxic gas breathing severely impairs cognition and task learning in humans. Physiol Behav 2015; 142:104-10. [DOI: 10.1016/j.physbeh.2015.02.006] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 11/23/2022]
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109
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Abstract
Problems at altitude are most often thought of in trained athletes summiting extremes of elevation. A more common group that needs consideration is the average person with obstructive sleep apnea who must travel to high altitudes for business or pleasure. While the altitudes involved are not likely to be as extreme as for those athletes climbing peaks like Mt. Everest, the increases in elevation may present difficulties for patients, especially if overnight stay is expected. The pathophysiology of altitude-related CNS, respiratory, and sleep disorders is discussed along with treatment options.
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Affiliation(s)
- Terry Rolan
- Department of Neurology, University of Missouri, Columbia
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110
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Cameron TA, Lucas SJE, Machado L. Near-infrared spectroscopy reveals link between chronic physical activity and anterior frontal oxygenated hemoglobin in healthy young women. Psychophysiology 2014; 52:609-17. [DOI: 10.1111/psyp.12394] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 11/07/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Tracy A. Cameron
- Department of Psychology and Brain Health Research Centre; University of Otago; Dunedin New Zealand
| | - Samuel J. E. Lucas
- School of Sport, Exercise and Rehabilitation Sciences; University of Birmingham; Birmingham UK
| | - Liana Machado
- Department of Psychology and Brain Health Research Centre; University of Otago; Dunedin New Zealand
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111
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Komiyama T, Sudo M, Higaki Y, Kiyonaga A, Tanaka H, Ando S. Does moderate hypoxia alter working memory and executive function during prolonged exercise? Physiol Behav 2014; 139:290-6. [PMID: 25460539 DOI: 10.1016/j.physbeh.2014.11.057] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 11/15/2014] [Accepted: 11/17/2014] [Indexed: 12/31/2022]
Abstract
It has been suggested that acute exercise improves cognitive function. However, little is known about how exercise under hypoxia affects cognitive function. The purpose of this study was to determine if hypoxia alters working memory and executive function during prolonged exercise. Sixteen participants performed cognitive tasks at rest and during exercise under normoxia and hypoxia [fraction of inspired oxygen (FIO2)=0.15, corresponding to an altitude of approximately 2600 m]. The level of hypoxia was moderate. We used a combination of Spatial Delayed Response (Spatial DR) task and Go/No-Go (GNG) task, where spatial working memory and executive function are required. Working memory was assessed by the accuracy of the Spatial DR task, and executive function was assessed by the accuracy and reaction time in the GNG task. The participants cycled an ergometer for 30 min under normoxia and moderate hypoxia while keeping their heart rate (HR) at 140 beats/min. They performed the cognitive tasks 5 min and 23 min after their HR reached 140 beats/min. Moderate hypoxia did not alter the accuracy of the Spatial DR (P=0.38) and GNG tasks (P=0.14). In contrast, reaction time in the GNG task significantly decreased during exercise relative to rest under normoxia and moderate hypoxia (P=0.02). These results suggest that moderate hypoxia and resultant biological processes did not provide sufficient stress to impair working memory and executive function during prolonged exercise. The beneficial effects on speed of response appear to persist during prolonged exercise under moderate hypoxia.
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Affiliation(s)
- Takaaki Komiyama
- Graduate School of Sports and Health Science, Fukuoka University, Japan
| | - Mizuki Sudo
- Physical Fitness Research Institute, Meiji Yasuda Life Foundation of Health and Welfare, Tokyo, Japan; Fukuoka University Institute for Physical Activity, Fukuoka University, Japan
| | - Yasuki Higaki
- Fukuoka University Institute for Physical Activity, Fukuoka University, Japan; Faculty of Sports and Health Science, Fukuoka University, Japan
| | - Akira Kiyonaga
- Fukuoka University Institute for Physical Activity, Fukuoka University, Japan; Faculty of Sports and Health Science, Fukuoka University, Japan
| | - Hiroaki Tanaka
- Fukuoka University Institute for Physical Activity, Fukuoka University, Japan; Faculty of Sports and Health Science, Fukuoka University, Japan
| | - Soichi Ando
- Faculty of Sports and Health Science, Fukuoka University, Japan; Graduate School of Informatics and Engineering, The University of Electro-communications, Japan.
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112
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Tang XG, Zhang JH, Qin J, Gao XB, Li QN, Yu J, Ding XH, Huang L. Age as a risk factor for acute mountain sickness upon rapid ascent to 3,700 m among young adult Chinese men. Clin Interv Aging 2014; 9:1287-94. [PMID: 25120358 PMCID: PMC4128797 DOI: 10.2147/cia.s67052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Background The aim of this study was to explore the relationship between age and acute mountain sickness (AMS) when subjects are exposed suddenly to high altitude. Methods A total of 856 young adult men were recruited. Before and after acute altitude exposure, the Athens Insomnia Scale score (AISS) was used to evaluate the subjective sleep quality of subjects. AMS was assessed using the Lake Louise scoring system. Heart rate (HR) and arterial oxygen saturation (SaO2) were measured. Results Results showed that, at 500 m, AISS and insomnia prevalence were higher in older individuals. After acute exposure to altitude, the HR, AISS, and insomnia prevalence increased sharply, and the increase in older individuals was more marked. The opposite trend was observed for SaO2. At 3,700 m, the prevalence of AMS increased with age, as did severe AMS, and AMS symptoms (except gastrointestinal symptoms). Multivariate logistic regression analysis showed that age was a risk factor for AMS (adjusted odds ratio [OR] 1.07, 95% confidence interval [CI] 1.01–1.13, P<0.05), as well as AISS (adjusted OR 1.39, 95% CI 1.28–1.51, P<0.001). Conclusion The present study is the first to demonstrate that older age is an independent risk factor for AMS upon rapid ascent to high altitude among young adult Chinese men, and pre-existing poor subjective sleep quality may be a contributor to increased AMS prevalence in older subjects.
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Affiliation(s)
- Xu-Gang Tang
- Institute of Cardiovascular Diseases, Chongqing, People's Republic of China
| | - Ji-hang Zhang
- Institute of Cardiovascular Diseases, Chongqing, People's Republic of China
| | - Jun Qin
- Institute of Cardiovascular Diseases, Chongqing, People's Republic of China
| | - Xu-bin Gao
- Institute of Cardiovascular Diseases, Chongqing, People's Republic of China
| | - Qian-ning Li
- Department of Neurology, Xinqiao Hospital, Third Military Medical University, Chongqing, People's Republic of China
| | - Jie Yu
- Institute of Cardiovascular Diseases, Chongqing, People's Republic of China
| | - Xiao-han Ding
- Institute of Cardiovascular Diseases, Chongqing, People's Republic of China
| | - Lan Huang
- Institute of Cardiovascular Diseases, Chongqing, People's Republic of China
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113
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Gao YX, Li P, Jiang CH, Liu C, Chen Y, Chen L, Ruan HZ, Gao YQ. Psychological and cognitive impairment of long-term migrators to high altitudes and the relationship to physiological and biochemical changes. Eur J Neurol 2014; 22:1363-9. [PMID: 25040466 DOI: 10.1111/ene.12507] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Accepted: 05/26/2014] [Indexed: 02/02/2023]
Abstract
BACKGROUND AND PURPOSE The present study aimed to examine how long-term migration to high-altitude regions affects mentality and cognition, and the correlation with various physiological and biochemical changes. METHODS The WHO Neurobehavioral Core Test Battery, Raven's Standard Progressive Matrices (RSPM) and Pittsburgh Sleep Quality Index questionnaire were used to assess 141 young male subjects who lived in plain regions and 217 young male subjects who had migrated to a 4500 m high-altitude region and lived there for 1-5 years. Arterial oxyhemoglobin saturation, cerebral tissue oxygenation indices (TOIs), serum S100B and brain-derived neurotrophic factor (BDNF) were also measured. RESULTS Long-term migrators to a high-altitude region exhibited exacerbated mood disorders, retarded color discrimination ability, decreased visual memory capacity, and impaired perceptual motor skill and motion stability. In addition, the migrators exhibited lower RSPM scores and lower sleep quality. Further analyses revealed significant correlations between sleep quality and cerebral TOIs, mood and sleep quality, mood and certain cognitive functions, mood and serum BDNF levels, and RSPM scores and serum S100B levels. CONCLUSIONS Long-term living at high altitudes causes significant impairment of psychological and cognitive function. Cerebral hypoxic extent, sleep quality and biochemical dysfunction are major influencing factors.
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Affiliation(s)
- Y-X Gao
- Department of Neurobiology, College of Basic Medical Science, Third Military Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing, China
| | - P Li
- Department of High Altitude Hygiene, College of High Altitude Medicine, Third Military Medical University, Chongqing, China.,Key Laboratory of High Altitude Medicine, Ministry of Education, Chongqing, China
| | - C-H Jiang
- Key Laboratory of High Altitude Medicine, Ministry of Education, Chongqing, China.,Department of Pathophysiology and High Altitude Physiology, College of High Altitude Medicine, Third Military Medical University, Chongqing, China
| | - C Liu
- Key Laboratory of High Altitude Medicine, Ministry of Education, Chongqing, China.,Department of Pathophysiology and High Altitude Physiology, College of High Altitude Medicine, Third Military Medical University, Chongqing, China
| | - Y Chen
- Key Laboratory of High Altitude Medicine, Ministry of Education, Chongqing, China.,Department of Pathophysiology and High Altitude Physiology, College of High Altitude Medicine, Third Military Medical University, Chongqing, China
| | - L Chen
- Key Laboratory of High Altitude Medicine, Ministry of Education, Chongqing, China.,Department of Pathophysiology and High Altitude Physiology, College of High Altitude Medicine, Third Military Medical University, Chongqing, China
| | - H-Z Ruan
- Department of Neurobiology, College of Basic Medical Science, Third Military Medical University, Chongqing, China.,Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing, China
| | - Y-Q Gao
- Key Laboratory of High Altitude Medicine, Ministry of Education, Chongqing, China.,Department of Pathophysiology and High Altitude Physiology, College of High Altitude Medicine, Third Military Medical University, Chongqing, China
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114
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The separate and combined effects of hypoxia and sustained recumbency/inactivity on sleep architecture. Eur J Appl Physiol 2014; 114:1973-81. [PMID: 24920550 DOI: 10.1007/s00421-014-2909-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 05/09/2014] [Indexed: 10/25/2022]
Abstract
PURPOSE The objective was to determine the separate and combined effects of hypoxia and inactivity/unloading on sleep architecture during a 10-day period of confinement. METHODS Ten subjects participated in three 10-day trials in random order: hypoxic ambulatory (HAMB), hypoxic bedrest (HBR), and normoxic bedrest (NBR). During the HAMB and HBR trials, subjects were confined to a hypoxic facility. The hypoxia profile was: simulated altitude of 2,990 m on day 1, 3,380 m on day 2, and 3,881 m on day 3. In the NBR and HBR trials, subjects maintained a horizontal position throughout the confinement period. During each trial, sleep polysomnography was conducted one night prior to (baseline; altitude of facility is 940 m) and on the first (NT1, altitude 2,990 m) and tenth (NT10, altitude 3,881 m) night of the 10-day intervention. RESULTS Average time in sleep stage 1 decreased from NT1 to NT10 irrespective of trial. Overall incidence and time spent in periodic breathing increased from NT1 to NT10 in both HAMB and HBR. During NT1, both HAMB and HBR reduced slow-wave sleep and increased light sleep, whereas NBR and HBR increased the number of awakenings/night. There were fewer awakenings during HAMB than NBR. CONCLUSIONS Acute exposure to both hypoxia and bedrest (HBR) results in greater sleep fragmentation due to more awakenings attributed to bedrest, and lighter sleep as a result of reduced slow wave sleep caused by the hypoxic environment.
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115
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Affiliation(s)
- Xiaodan Yan
- New York University School of Medicine, New York, New York
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116
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Patz DS, Patz MD, Hackett PH. Dead space mask eliminates central apnea at altitude. High Alt Med Biol 2014; 14:168-74. [PMID: 23795738 DOI: 10.1089/ham.2012.1111] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Travelers to high altitude may have disturbed sleep due to periodic breathing with frequent central apneas. We tested whether a mask with added dead space could reduce the central apneas of altitude. 16 subjects were recruited, age 18-35, residing at 4600 ft (1400 m). They each slept one night with full polysomnographic monitoring, including end tidal CO2, in a normobaric hypoxia tent simulating 12,000 ft. (3658 m) altitude. Those who had a central apnea index (CAI) >20/h returned for a night in the tent for dead space titration, during which they slept with increasing amounts of dead space, aiming for a CAI <5/h or <10% of baseline. Then each subject slept another night with the titrated amount of dead space. Of the 16 subjects, 5 had a central apnea index >20/h mean 49.1, range 21.4-131.5/hr. In each of the 5, the dead space mask reduced the CAI by at least 88% to a mean of 3.1, range 0.9-7.1/h, (p=0.04). Hypopnea index was unchanged. Three subjects required 500 cc of dead space or less. One subject required 860 cc, and one required 2.1 L. Morning symptoms and arousal index were not significantly affected by the dead space mask. Dead space did not appear to increase the CO2 reserve. At 12,000 ft., central apneas can be effectively reduced with a dead space mask, but clinical utility will require further evaluation.
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Affiliation(s)
- David S Patz
- St. Mary's Hospital, Grand Junction, CO 81507, USA.
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117
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Manickam M, Tulsawani R. Survival response of hippocampal neurons under low oxygen conditions induced by Hippophae rhamnoides is associated with JAK/STAT signaling. PLoS One 2014; 9:e87694. [PMID: 24516559 PMCID: PMC3916341 DOI: 10.1371/journal.pone.0087694] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 01/02/2014] [Indexed: 12/27/2022] Open
Abstract
Janus activated kinase/signal transducers and activators of transcription (JAK/STATs) pathway are associated with various neuronal functions including cell survival and inflammation. In the present study, it is hypothesized that protective action of aqueous extract of Hippophae rhamnoides in hippocampal neurons against hypoxia is mediated via JAK/STATs. Neuronal cells exposed to hypoxia (0.5% O2) display higher reactive oxygen species with compromised antioxidant status compared to unexposed control cells. Further, these cells had elevated levels of pro-inflammatory cytokines; tumor necrosis factor α and interleukin 6 and nuclear factor κappa B. Moreover, the expression of JAK1 was found to be highly expressed with phosphorylation of STAT3 and STAT5. Cells treated with JAK1, STAT3 and STAT5 specific inhibitors resulted in more cell death compared to hypoxic cells. Treatment of cells with extract prevented oxidative stress and inflammatory response associated with hypoxia. The extract treated cells had more cell survival than hypoxic cells with induction of JAK1 and STAT5b. Cells treated with extract having suppressed JAK1 or STAT3 or STAT5 expression showed reduced cell viability than the cell treated with extract alone. Overall, the findings from these studies indicate that the aqueous extract of Hippophae rhamnoides treatment inhibited hypoxia induced oxidative stress by altering cellular JAK1, STAT3 and STAT5 levels thereby enhancing cellular survival response to hypoxia and provide a basis for possible use of aqueous extract of Hippophae rhamnoides in facilitating tolerance to hypoxia.
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Affiliation(s)
- Manimaran Manickam
- Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Delhi, India
| | - Rajkumar Tulsawani
- Defence Institute of Physiology and Allied Sciences, Defence Research and Development Organization, Delhi, India
- * E-mail:
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118
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Tang XG, Zhang JH, Gao XB, Li QN, Li JB, Yu J, Qin J, Huang L. Sleep quality changes in insomniacs and non-insomniacs after acute altitude exposure and its relationship with acute mountain sickness. Neuropsychiatr Dis Treat 2014; 10:1423-32. [PMID: 25114534 PMCID: PMC4124070 DOI: 10.2147/ndt.s67218] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
OBJECTIVE We aimed to observe the changes in subjective sleep quality among insomniacs and non-insomniacs after acute ascending to 3,700 m and its possible relationship with acute mountain sickness (AMS). METHODS A total of 600 adult men were recruited. Subjects' subjective sleep quality was evaluated by the Athens Insomnia Scale. AMS was assessed using the Lake Louise scoring system. Arterial oxygen saturation was measured. RESULTS Despite insomnia resolution in only a few subjects, the prevalence of insomnia among insomniacs remained stable at 90% after rapid ascent to 3,700 m. However, among non-insomniacs, the prevalence of insomnia sharply increased to 32.13% in the first day of altitude exposure and progressively reduced to 4.26% by the 60th day of altitude stay. Moreover, the prevalences of insomnia symptoms decreased more markedly from day 1 to day 60 at 3,700 m among non-insomniacs than among insomniacs. At 3,700 m, the prevalence of AMS among insomniacs was 79.01%, 60.49%, and 32.10% on the first, third, and seventh days, respectively, which was significantly higher than that among non-insomniacs. Multivariate regression revealed that elevated Athens Insomnia Scale scores are an independent risk factor for AMS (adjusted odds ratio 1.388, 95% confidence interval: 1.314-1.464, P<0.001), whereas high arterial oxygen saturation and long duration of altitude exposure are protective factors against AMS. CONCLUSION Our results suggest that the effect of high-altitude exposure on subjective sleep quality is more marked, but disappears more quickly, among non-insomniacs than among insomniacs, whereas AMS is especially common among insomniacs. Moreover, poor subjective sleep quality is a risk factor for AMS.
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Affiliation(s)
- Xu-Gang Tang
- Institute of Cardiovascular Diseases, Third Military Medical University, Chongqing, People's Republic of China
| | - Ji-Hang Zhang
- Institute of Cardiovascular Diseases, Third Military Medical University, Chongqing, People's Republic of China
| | - Xu-Bin Gao
- Institute of Cardiovascular Diseases, Third Military Medical University, Chongqing, People's Republic of China
| | - Qian-Ning Li
- Department of Neurology, Xinqiao Hospital, Third Military Medical University, Chongqing, People's Republic of China
| | - Jia-Bei Li
- Institute of Cardiovascular Diseases, Third Military Medical University, Chongqing, People's Republic of China
| | - Jie Yu
- Institute of Cardiovascular Diseases, Third Military Medical University, Chongqing, People's Republic of China
| | - Jun Qin
- Institute of Cardiovascular Diseases, Third Military Medical University, Chongqing, People's Republic of China
| | - Lan Huang
- Institute of Cardiovascular Diseases, Third Military Medical University, Chongqing, People's Republic of China
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119
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Latshang TD, Lo Cascio CM, Stöwhas AC, Grimm M, Stadelmann K, Tesler N, Achermann P, Huber R, Kohler M, Bloch KE. Are nocturnal breathing, sleep, and cognitive performance impaired at moderate altitude (1,630-2,590 m)? Sleep 2013; 36:1969-76. [PMID: 24293773 PMCID: PMC3825448 DOI: 10.5665/sleep.3242] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Newcomers at high altitude (> 3,000 m) experience periodic breathing, sleep disturbances, and impaired cognitive performance. Whether similar adverse effects occur at lower elevations is uncertain, although numerous lowlanders travel to moderate altitude for professional or recreational activities. We evaluated the hypothesis that nocturnal breathing, sleep, and cognitive performance of lowlanders are impaired at moderate altitude. DESIGN Randomized crossover trial. SETTING University hospital at 490 m, Swiss mountain villages at 1,630 m and 2,590 m. PARTICIPANTS Fifty-one healthy men, median (quartiles) age 24 y (20-28 y), living below 800 m. INTERVENTIONS Studies at Zurich (490 m) and during 4 consecutive days at 1,630 m and 2,590 m, respectively, 2 days each. The order of altitude exposure was randomized. Polysomnography, psychomotor vigilance tests (PVT), the number back test, several other tests of cognitive performance, and questionnaires were evaluated. MEASUREMENTS AND RESULTS The median (quartiles) apnea-hypopnea index at 490 m was 4.6/h (2.3; 7.9), values at 1,630 and 2,590 m, day 1 and 2, respectively, were 7.0/h (4.1; 12.6), 5.4/h (3.5; 10.5), 13.1/h (6.7; 32.1), and 8.0/h (4.4; 23.1); corresponding values of mean nocturnal oxygen saturation were 96% (95; 96), 94% (93; 95), 94% (93; 95), 90% (89; 91), 91% (90; 92), P < 0.05 versus 490 m, all instances. Slow wave sleep on the first night at 2,590 m was 21% (18; 25) versus 24% (20; 27) at 490 m (P < 0.05). Psychomotor vigilance and various other measures of cognitive performance did not change significantly. CONCLUSIONS Healthy men acutely exposed during 4 days to hypoxemia at 1,630 m and 2,590 m reveal a considerable amount of periodic breathing and sleep disturbances. However, no significant effects on psychomotor reaction speed or cognitive performance were observed. CLINICAL TRIALS REGISTRATION Clinicaltrials.gov: NCT01130948.
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Affiliation(s)
| | | | | | - Mirjam Grimm
- Sleep Disorders Center and Pulmonary Division, University Hospital Zurich
| | | | - Noemi Tesler
- Child Development Center, Children's University Hospital Zurich
| | - Peter Achermann
- Institute of Pharmacology and Toxicology, University of Zurich
- Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
| | - Reto Huber
- Child Development Center, Children's University Hospital Zurich
- Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
| | - Malcolm Kohler
- Sleep Disorders Center and Pulmonary Division, University Hospital Zurich
- Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
| | - Konrad E. Bloch
- Sleep Disorders Center and Pulmonary Division, University Hospital Zurich
- Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
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Application of bioinformatics in chronobiology research. ScientificWorldJournal 2013; 2013:153839. [PMID: 24187519 PMCID: PMC3800665 DOI: 10.1155/2013/153839] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 08/18/2013] [Indexed: 01/17/2023] Open
Abstract
Bioinformatics and other well-established sciences, such as molecular biology, genetics, and biochemistry, provide a scientific approach for the analysis of data generated through “omics” projects that may be used in studies of chronobiology. The results of studies that apply these techniques demonstrate how they significantly aided the understanding of chronobiology. However, bioinformatics tools alone cannot eliminate the need for an understanding of the field of research or the data to be considered, nor can such tools replace analysts and researchers. It is often necessary to conduct an evaluation of the results of a data mining effort to determine the degree of reliability. To this end, familiarity with the field of investigation is necessary. It is evident that the knowledge that has been accumulated through chronobiology and the use of tools derived from bioinformatics has contributed to the recognition and understanding of the patterns and biological rhythms found in living organisms. The current work aims to develop new and important applications in the near future through chronobiology research.
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121
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Wilkes M, Simpson A, Knox M, Summers L. The Kilimanjaro score for assessing fitness to fly paragliders at high altitude. High Alt Med Biol 2013; 14:304-7. [PMID: 24067189 DOI: 10.1089/ham.2013.1035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Extreme sports such as paragliding are increasing in popularity, providing continued challenges for the development of safe practice techniques. In January and February 2013, the Wings of Kilimanjaro expedition aimed to launch 95 paragliders from the summit of Mount Kilimanjaro, 5790 m above sea level. A safe launch was paramount but risked being impaired by adverse environmental conditions, in particular the pathophysiological effects of high altitude. There are no existing scores to assess fitness for high-altitude paraglider launches present in the literature. A novel scoring system, the Kilimanjaro Score, was therefore developed to rapidly assess pilots pre-flight. The Kilimanjaro Score aimed to assess cognition, memory, and visual-spatial skill within the context of standard pre-flight checks. Further testing, including the Lake Louise Score, was to be performed if the pilot's Kilimanjaro Score was deemed unsatisfactory. We present the Kilimanjaro Score here for comment and refinement, and we invite other parties to consider its use in the field for high altitude paragliding activities.
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122
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Is there a role for "climatotherapy" in the sustainable development of mental health? Behav Brain Sci 2013; 36:487-8; discussion 503-11. [PMID: 23985163 DOI: 10.1017/s0140525x13000095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Climate, diet, lifestyle, and environmental settings have all been shown to modulate mood, play a role in mental disorders, and even pose a mental health risk. Can climatotherapy, in its adaptive approach aiming to restore balance among the economic, social, and ecological realms of human societies, situate itself as a therapeutic avenue for the promotion of sustainable mental health?
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123
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Gozal D. CrossTalk proposal: the intermittent hypoxia attending severe obstructive sleep apnoea does lead to alterations in brain structure and function. J Physiol 2013; 591:379-81. [PMID: 23322286 DOI: 10.1113/jphysiol.2012.241216] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- David Gozal
- Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL, USA.
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124
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Effects of high altitude on sleep and respiratory system and theirs adaptations. ScientificWorldJournal 2013; 2013:241569. [PMID: 23690739 PMCID: PMC3654241 DOI: 10.1155/2013/241569] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Accepted: 03/20/2013] [Indexed: 11/17/2022] Open
Abstract
High-altitude (HA) environments have adverse effects on the normal functioning body of people accustomed to living at low altitudes because of the change in barometric pressure which causes decrease in the amount of oxygen leading to hypobaric hypoxia. Sustained exposure to hypoxia has adverse effects on body weight, muscle structure and exercise capacity, mental functioning, and sleep quality. The most important step of acclimatization is the hyperventilation which is achieved by hypoxic ventilatory response of the peripheral chemoreceptors. Hyperventilation results in increase in arterial carbon-dioxide concentration. Altitude also affects sleep and cardiac output, which is the other determinant of oxygen delivery. Upon initial exposure to HA, the resting pulse rate increases rapidly, but with acclimatization, heart rate and cardiac output tend to fall. Another important component that leads to decrease in cardiac output is the reduction in the stroke volume with acclimatization. During sleep at HA, the levels of CO2 in the blood can drop very low and this can switch off the drive to breathe. Only after the body senses a further drop in O2 levels breathing is started again. Periodic breathing is thought to result from instability in the control system through the hypoxic drive or the response to CO2.
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125
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Can high altitude influence cytokines and sleep? Mediators Inflamm 2013; 2013:279365. [PMID: 23690660 PMCID: PMC3649750 DOI: 10.1155/2013/279365] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 02/27/2013] [Accepted: 03/21/2013] [Indexed: 11/18/2022] Open
Abstract
The number of persons who relocate to regions of high altitude for work, pleasure, sport, or residence increases every year. It is known that the reduced supply of oxygen (O2) induced by acute or chronic increases in altitude stimulates the body to adapt to new metabolic challenges imposed by hypoxia. Sleep can suffer partial fragmentation because of the exposure to high altitudes, and these changes have been described as one of the responsible factors for the many consequences at high altitudes. We conducted a review of the literature during the period from 1987 to 2012. This work explored the relationships among inflammation, hypoxia and sleep in the period of adaptation and examined a novel mechanism that might explain the harmful effects of altitude on sleep, involving increased Interleukin-1 beta (IL-1β), Interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) production from several tissues and cells, such as leukocytes and cells from skeletal muscle and brain.
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