High Altitude Expedition Research Articles

ABSTRACTS 7th World Congress of Mountain & Wilderness Medicine A combined meeting of the International Society for Mountain Medicine and the Wilderness Medical Society July 30-August 4, 2016 Telluride, Colorado.

ABSTRACTS 7th World Congress of Mountain & Wilderness Medicine A combined meeting of the International Society for Mountain Medicine and the Wilderness Medical Society July 30-August 4, 2016 Telluride, Colorado.

Professor Bengt Saltin Symposium - Environmental challenges to human performance.

This short review is from a presentation made at the Bengt Saltin Symposium, October 15-17, at the 2015 Canadian Society for Exercise Physiology conference, Hamilton, Canada. The review provides context of the important work of the late Dr. Saltin's contributions to environmental physiology. In addition to well-controlled laboratory experiments to better understand the influence of hypoxia or temperature, or both, Dr. Saltin also led several field expeditions to the North Greenland, Kenya, Himalayas, and the Andes, where he studied several aspects of human adaptation to environment. The 1998 Danish High-Altitude Expedition to the Andes, in particular, resulted in many major contributions to the field of altitude physiology including, but not limited to, mechanisms of reductions in maximal oxygen uptake, the lactate paradox, acclimatization, muscle metabolism, gas exchange, cerebrovascular physiology, etc. Of note, many of these related studies were conducted in both Danish sojourners to altitude and Bolivian altitude natives of Aymara ancestry, thus providing some of the most mechanistic comparisons with high altitude natives to date. A framework of these physiological contributions in terrestrial extremes is provided in this review.

Brief Working Memory and Physiological Monitoring During a High-Altitude Expedition.

A set of physiological and cognitive measurements were collected from four professional climbers at various time points during the course of an expedition to Shishapangma (8043 m). Progressive high-altitude exposure induced a classical physiological response (i.e., decreased SpO2 and increased heart rate). Except for the final ascent, no participants suffered from acute mountain sickness and perceived exertion remained low. With the exception of an increased number of night awakenings, reported sleep quality was good. No working memory decline was observed in any of the participants, even at the highest altitudes. Altogether, these findings show that the participants were properly acclimatized to altitude. They also highlight the technical feasibility of assessing cognitive functions all along high-altitude expeditions. The direct access of such tools on a smartphone may improve mountain climbing safety.

Association of Cognitive Performance with Time at Altitude, Sleep Quality, and Acute Mountain Sickness Symptoms

It is well documented that cognitive performance may be altered with ascent to altitude, but the association of various cognitive performance tests with symptoms of acute mountain sickness (AMS) is not well understood. Our objective was to assess and compare cognitive performance during a high-altitude expedition using several tests and to report the association of each test with AMS, headache, and quality of sleep. During an expedition to Mount Everest, 3 cognitive tests (Stroop, Trail Making, and the real-time cognitive assessment tool, an in-house developed motor accuracy test) were used along with a questionnaire to assess health and AMS. Eight team members were assessed pre-expedition, postexpedition, and at several time points during the expedition. There were no significant differences (P >.05) found among scores taken at 3 time points at base camp and the postexpedition scores for all 3 tests. Changes in the Stroop test scores were significantly associated with the odds of AMS (P <.05). The logistic regression results show that the percent change from baseline for Stroop score (β = -5.637; P = .032) and Stroop attempts (β = -5.269; P = .049) are significantly associated with the odds of meeting the criteria for AMS. No significant changes were found in overall cognitive performance at altitude, but a significant relationship was found between symptoms of AMS and performance in certain cognitive tests. This research shows the need for more investigation of objective physiologic assessments to associate with self-perceived metrics of AMS to gauge effect on cognitive performance.

Increased endothelial microparticles and oxidative stress at extreme altitude.

Hypoxia and oxidative stress affect endothelial function. Endothelial microparticles (MP) are established measures of endothelial dysfunction and influence vascular reactivity. To evaluate the effects of hypoxia and antioxidant supplementation on endothelial MP profiles, a double-blind, placebo-controlled trial, during a high altitude expedition was performed. 29 participants were randomly assigned to a treatment group (n = 14), receiving vitamin E, C, A, and N-acetylcysteine daily, and a control group (n = 15), receiving placebo. Blood samples were obtained at 490 m (baseline), 3530, 4590, and 6210 m. A sensitive tandem mass spectrometry method was used to measure 8-iso-prostaglandin F2α and hydroxyoctadecadienoic acids as markers of oxidative stress. Assessment of MP profiles including endothelial activation markers (CD62+MP and CD144+MP) and cell apoptosis markers (phosphatidylserine+MP and CD31+MP) was performed using a standardized flow cytometry-based protocol. 15 subjects reached all altitudes and were included in the final analysis. Oxidative stress increased significantly at altitude. No statistically significant changes were observed comparing baseline to altitude measurements of phosphatidylserine expressing MP (p = 0.1718) and CD31+MP (p = 0.1305). Compared to baseline measurements, a significant increase in CD62+MP (p = 0.0079) and of CD144+MP was detected (p = 0.0315) at high altitudes. No significant difference in any MP level or oxidative stress markers were found between the treatment and the control group. Hypobaric hypoxia is associated with increased oxidative stress and induces a significant increase in CD62+ and CD144+MP, whereas phosphatidylserine+MP and CD31+MP remain unchanged. This indicates that endothelial activation rather than an apoptosis is the primary factor of hypoxia induced endothelial dysfunction.

Interdisciplinary Interprofessionalism at Mid-Century: Ancel Keys, Human Biology, and the Laboratory of Physiological Hygiene, 1940-1950.

In 1944, physiologist Ancel Keys and his University of Minnesota colleague, psychologist Josef Brozek published an article in Science titled General Aspects of Interdisciplinary Research in Experimental Human Biology.1 They wrote paper in part to promote synthetic and interdisciplinary style of research on health and performance conducted at Keys's Laboratory of Physiological Hygiene (LPH). A term coined by biologist Raymond Pearl during interwar period, human was a holistic science that encompassed research in physical anthropology, genetics, clinical medicine, physiology, biochemistry, and organismal and population biology, as researchers in field examined dynamic, ecological relationship between i ndividuals or populations and their adaptation to environmental stress.2 Keys embraced this interdisciplinary approach during his fellowship years (1933-36) at Harvard Fatigue Lab. There, physician and philosopher L.J. Henderson and psychologist Elton Mayo had extended science of biology to problems of industry and athletics in an effort to optimize performance.3 Keys pursued a similar goal in 1935, when he led Harvardbased International High Altitude Expedition to Chile. Over four months, an interdisciplinary scientific team measured their physiological and psychological acclimatization to great heights-a topic of interest to aviation and mining industries in Andes.4The Science essay also offered Keys and Brozek a pulpit to urge wholesale restructuring of undergraduate and graduate study in sciences. They wrote at a time when universities across nation were grappling with place of sciences in undergraduate general education, and when applied problems of World War II had brought investigators from different disciplines together, demonstrating power of collaborative scientific research-most notably in Manhattan Project but also in projects such as Keys's development of first compact, calorie-dense, lightweight meal for soldiers: K ration. Ruefully observing that the young scientist has a greater chance of advancement if he saws wood on his own wood pile . . . [and] does not participate in interdepartmental, collaborative projects, Keys and Brozek critiqued specialization that characterized graduate science education.5 Asserting that problems in biology (and many fields) demanded analysis and manipulation of a sector of reality, and . . . this reality is always multifarious,6 they offered example of LPH as a sort of interdisciplinary, interprofessional Camelot. There each scientist was familiar with language, problems, and research methods of other and biochemists and psychologists, together with technical assistants, worked as a team under coordinating effort of a directorcolleague. Under these circumstances, Keys and Brozek added, participants should engage one another as both active listeners and active talkers to attain an between dominance and submission.7Whether or not members of Ancel Keys's laboratory staff achieved such equilibrium is a subject for debate. Some recall Keys as a research director of old-school variety: a brilliant individual whose authority was as unquestioned as his scientific ability. Yet, there can be no doubt that he tried to promote social and intellectual equilibrium or that his laboratory boasted an extensive record of productive interprofessional collaborations among biochemists (including his wife Margaret Haney Keys), psychologists such as Brozek, and myriad physiologists, physicians, statisticians, dieticians, and nurses at LPH.8 The last two groups were employed as technicians, a term that masks their centrality to Keys's interdisciplinary scientific enterprise. This essay explores interdisciplinary science and interprofessional relations at LPH, with particular emphasis on two nutritional projects: K ration and Minnesota Starvation Experiment (MSE). …

Tolerance of Organ Transplant Recipients to Physical Activity during a High-Altitude Expedition: Climbing Mount Kilimanjaro.

BackgroundIt is generally unknown to what extent organ transplant recipients can be physically challenged. During an expedition to Mount Kilimanjaro, the tolerance for strenuous physical activity and high-altitude of organ transplant recipients after various types of transplantation was compared to non-transplanted controls.MethodsTwelve organ transplant recipients were selected to participate (2 heart-, 2 lung-, 2 kidney-, 4 liver-, 1 allogeneic stem cell- and 1 small bowel-transplantation). Controls comprised the members of the medical team and accompanying family members (n = 14). During the climb, cardiopulmonary parameters and symptoms of acute mountain sickness were recorded twice daily. Capillary blood analyses were performed three times during the climb and once following return.ResultsEleven of the transplant participants and all controls began the final ascent from 4700 meters and reached over 5000 meters. Eight transplant participants (73%) and thirteen controls (93%) reached the summit (5895m). Cardiopulmonary parameters and altitude sickness scores demonstrated no differences between transplant participants and controls. Signs of hyperventilation were more pronounced in transplant participants and adaptation to high-altitude was less effective, which was related to a decreased renal function. This resulted in reduced metabolic compensation.ConclusionOverall, tolerance to strenuous physical activity and feasibility of a high-altitude expedition in carefully selected organ transplant recipients is comparable to non-transplanted controls.

Energy Expenditure and Intensity Levels During a 6170-m Summit in the Karakoram Mountains

Although the majority of high altitude studies have used doubly labeled water to assess energy expenditure (EE), minimal research has examined variation in intensity levels while participating in such an expedition. The purpose of this study was to use ambulatory monitoring technology to assess EE and time spent in moderate (3.0-6.0 METS), vigorous (6.0-9.0 METS), and very vigorous (>9.0 METS) intensities during an expedition to summit a 6170-m peak in Northern Pakistan. Twelve men and 2 women were studied. Their EE was determined from galvanic skin response, heat flux, and biaxial accelerometry using a multisensor armband. Lake Louise Scores for altitude illness assessment were obtained each morning. Average daily total EE and number of steps taken was 4173 ± 848 kcal/d (range, 3332 to 4838 kcal/d) and 26,232 ± 7210 steps/d (range, 11,788 to 34,979 steps/d), respectively. On average, subjects spent approximately 7.7 h/d performing physical activity (>3.0 METS). Of this, subjects spent 399 ± 107, 61 ± 77, and 3 ± 10 min/d at moderate, vigorous, and very vigorous intensity levels, respectively, corresponding to 88%, 11%, and 1% of total physical activity time. During summit day, subjects climbed at an intensity equivalent to approximately 42% of their high altitude predicted maximal oxygen consumption at 5100 m). During a high altitude expedition, subjects predominantly exercise at a moderate intensity, with limited time spent at higher intensity levels. Use of accelerometer-based technology may provide more cost-effective and logistically easier means of assessing EE in extreme environments.

Oxidative Stress in Hypobaric Hypoxia and Influence on Vessel-Tone Modifying Mediators

Increased pulmonary artery pressure is a well-known phenomenon of hypoxia and is seen in patients with chronic pulmonary diseases, and also in mountaineers on high altitude expedition. Different mediators are known to regulate pulmonary artery vessel tone. However, exact mechanisms are not fully understood and a multimodal process consisting of a whole panel of mediators is supposed to cause pulmonary artery vasoconstriction. We hypothesized that increased hypoxemia is associated with an increase in vasoconstrictive mediators and decrease of vasodilatators leading to a vasoconstrictive net effect. Furthermore, we suggested oxidative stress being partly involved in changement of these parameters. Oxygen saturation (Sao2) and clinical parameters were assessed in 34 volunteers before and during a Swiss research expedition to Mount Muztagh Ata (7549 m) in Western China. Blood samples were taken at four different sites up to an altitude of 6865 m. A mass spectrometry-based targeted metabolomic platform was used to detect multiple parameters, and revealed functional impairment of enzymes that require oxidation-sensitive cofactors. Specifically, the tetrahydrobiopterin (BH4)-dependent enzyme nitric oxide synthase (NOS) showed significantly lower activities (citrulline-to-arginine ratio decreased from baseline median 0.21 to 0.14 at 6265 m), indicating lower NO availability resulting in less vasodilatative activity. Correspondingly, an increase in systemic oxidative stress was found with a significant increase of the percentage of methionine sulfoxide from a median 6% under normoxic condition to a median level of 30% (p<0.001) in camp 1 at 5533 m. Furthermore, significant increase in vasoconstrictive mediators (e.g., tryptophan, serotonin, and peroxidation-sensitive lipids) were found. During ascent up to 6865 m, significant altitude-dependent changes in multiple vessel-tone modifying mediators with excess in vasoconstrictive metabolites could be demonstrated. These changes, as well as highly significant increase in systemic oxidative stress, may be predictive for increase in acute mountain sickness score and changes in Sao2.

Effect of intermittent hypoxic training on cardiovascular responses to altitude (2800 m)

Introduction: Intermittent hypoxic exposure (IHE) prior to ascent to high altitude is postulated as a beneficial pre-conditioning strategy in the prevention of high altitude illness. Variations in arterial stiffness and endothelial function (vascular tone) may also be important in the pathogenesis of altitude related illness. The influence of IHE pre-conditioning on cardiovascular adaptations (notably arterial stiffness and vascular tone) to altitude is less clear. This study explored the impact of normobaric IHE pre-conditioning on acute cardiovascular adaptations to high altitude. Method: Participants were assigned to one of three intervention groups: control (no IHE), IHE at rest (IHE-rest) or IHE with training (IHE-training) matched for fitness, age and sex. In the 14- day period prior to a high altitude expedition IHE groups completed 10×2 hour hypoxic exposures in an environmental chamber (12.2% O2 equivalent to 4300 m), at rest (IHE-rest) or rest plus 20 minutes running at 80% heart rate reserve (calculated from individual predetermined VO2max at altitude). Arterial stiffness (SI) and vascular tone (RI) responses were recorded using a non-invasive finger photoplethysmography technique at sea-level (baseline), pre and post IHE intervention period, 12 and 72 hours post arrival at altitude (Lukla, Nepal, 2800 m). Results: Thirty apparently healthy participants (18 male, 12 female, age range 20-62 years) free from cardiovascular disease were recruited (n = 10 per condition). Two-way repeated measures (intervention x time) ANOVA revealed no main effect for intervention for SI (control_1.07±1.41 m.s-1, IHE-rest _0.50±0.65 m.s-1, IHE-training_1.07±0.81 m.s-1; P = 0.083) or RI (control_3.3±4.4%, IHE-rest_7.6±25.6%, IHE-training 7.2±18.1%; P = 0.174). There were no between-group interaction effects for any cardiovascular measurements (P = 0.059 for RI; P = 0.112 for SI) Conclusion: Intermittent hypoxic exposure prior to ascent to high altitude does not significantly alter vascular tone or arterial stiffness in apparently healthy adults. The impact of IHE preconditioning on endothelial function at higher altitudes and in the prevention of altitude related illness remains to be elucidated.

The Physiology of Extremes: Ancel Keys and the International High Altitude Expedition of 1935

This article examines the International High Altitude Expedition of 1935 and its significance in the life and science of Ancel Keys. Both the expedition and Keys's story afford excellent opportunities to explore the growing reach of interwar physiology into extreme climates-whether built or natural. As IHAE scientists assessed human performance and adaptation to hypoxia, low barometric pressure, and cold, they not only illuminated the physiological and psychological processes of high altitude acclimatization, but they also drew borderlines between the normal and the pathological, paved the way for the neocolonial exploitation of natural and human resources in Latin America, and pioneered field methods in physiology that were adapted and adopted by the Allied Forces during the Second World War. This case study in the physiology of place reveals the power and persistence of environmental determinism within biomedicine well into the twentieth century.

High‐altitude retinopathy

AbstractPurpose To report the clinical characteristics of 3 cases of high altitude retinopathy (HAR) and a review of the literature.Methods We report 3 cases of patients consulting for HAR after high trekking above 7000m.Results Patient 1 was a 27 years‐old man, high level sportsman, coming back from a GASNERBRUM expedition (7600m) and complaining of right eye central scotoma. Fundus examination revealed 2 haemorrhages : one next the fovea and one on the temporal arcade vessel. Patient 2 was a 52 years‐old man, high mountain guide, coming back from EVERSEST ascent (8000m) and complaining of left eye central scotoma and visual acuity deficit. Fundus examination found one parafoveal haemorrhage in the left eye and paramacular haemorrhages in the right eye. Patient 3 was a young 25 years‐old military doctor coming back from a high altitude expedition (7000m), he was complaining of right eye central scotoma during the descent and headache. Fundus examination found three macular haemorrhages and one on the inferior temporal arcade vessel. Only one of the three patients presented other symptomes of high altitude illness. All of us presented a positive outcome with complete functional and anatomical resolution of HAR, less than 2 month, without sequela.Conclusion The real incidence and physiopathology of HAR are not very well known. Retinal haemorrhages after a high trekking are an early manifestation of HAR and more generally high altitude illness. It usually occurs at altitudes above 4000m. While macular involvement or retinal vein occlusion may result in permanent visual acuity deficit, these haemorrhages are generally asymptomatic and spontaneous regressive.

Carbohydrate Supplementation and Exercise Performance at High Altitude: A Randomized Controlled Trial

Acute carbohydrate supplementation decreases effort perception and increases endurance exercise capacity at sea level. It also improves laboratory-based endurance performance at altitude. However, the effect of chronic carbohydrate supplementation at altitude, when acclimatization may attenuate carbohydrate effects, achieved doses are lower and metabolic effects may be different, is unknown and was therefore focused on in the present study. Forty-one members of a 22-day high altitude expedition were randomized in a double-blind design to receive either placebo or carbohydrate supplementation. Diet was manipulated with commercially available energy drinks consumed ad libitum throughout the expedition. Participants performed a mountaineering time trial at 5192 m, completed submaximal incremental exercise step tests to assess cardiovascular parameters before, during, and after the expedition, and recorded spontaneous physical activity by accelerometer on rest days. Compared to placebo, compliant individuals of the carbohydrate-supplemented group received daily an additional 3.5±1.4 g carbohydrate·kg body mass(-1). Compliant individuals of the carbohydrate supplemented group reported 18% lower ratings of perceived exertion during the time trial at altitude, and completed it 17% faster than the placebo group (both p<0.05 by t-test). However, cardiovascular parameters obtained during submaximal exercise and spontaneous physical activity on rest days were similar between the two groups (all p>0.05 by analysis of variance). This study utilized testing protocols of specific relevance to high altitude sojourners, including the highest mountaineering time trial completed to date at altitude. Chronic carbohydrate supplementation reduced ratings of perceived exertion and improved physical performance, especially during prolonged and higher intensity exercise tasks.

Centenary of the Anglo-American high-altitude expedition to Pikes Peak

This year (2011) marks the centenary of one of the most important early research expeditions to high altitude. The principal participants were J. S. Haldane and C. G. Douglas from Oxford, Y. Henderson from Yale and E. C. Schneider from Colorado College. Pikes Peak just outside Colorado Springs proved to be an excellent venue because of its substantial altitude of 4300 m, convenient access via a cog railway and comfortable living accommodation. The expedition had a classical design, with measurements made first at sea level, then on the summit for 5 weeks and then at sea level again. The extensive scientific programme included descriptions of acute mountain sickness, many measurements of partial pressures in alveolar gas and arterial blood, changes in ventilation, including periodic breathing, exercise measurements and a large number of blood studies. One error was the conclusion that the arterial P(O(2)) could considerably exceed the alveolar value, implying oxygen secretion by the lung, but this should not detract from the other important advances. Mabel FitzGerald was invited to be a member of the expedition but did not join the men on the summit. Instead, she visited various mining camps in Colorado at somewhat lower altitudes and carried out classical studies of alveolar gas partial pressures and haemoglobin values. Indeed, her results of alveolar P(O(2)) and P(CO(2)) are frequently cited today. The Pikes Peak expedition was a model and it had an extensive influence on later studies.

Changes of coagulation parameters during high altitude expedition.

Data on changes of haemostatic parameters at altitudes above 5000 m are very limited. So far it is unknown, whether altered coagulation could contribute to the development of acute mountain sickness. Thirty four healthy mountaineers were randomised to two acclimatisation protocols and undertook an expedition on Muztagh Ata (7549 m) in China. Tests were performed at five altitudes up to 6865 m. Haemostatic parameters, such as PT, aPTT, D-Dimer, APC-Resistance (APCR), von Willebrand Factor activity (RCo), ADAMTS-13 & C-Natriuretic Peptide (CNP) were assessed together with Lake Louise AMS score. D-Dimer significantly increased with increasing altitude (median 0.62 to 0.81 mcg/L, p <0.0001). During ascent, PT increased (83% to >100%) and APCR decreased significantly from 0.95 to 0.8 (p <0.01). Furthermore, a significant increase of aPTT (38 to 43 sec) was paralleled by significant changes of RCo (102% to 62%) (both p <0.001). There were no significant changes in ADAMTS-13 and CNP. No significant relationship between investigated parameters and AMS scores could be detected. When comparing the participants of the two acclimatisation protocols, there was an overall higher RCo in patients with a faster ascent protocol (p = 0.04). This was accompanied by lower ADAMTS-13 of the coagulation system in these patients (p = 0.04). Coagulation parameters change significantly during hypobaric hypoxia. Whereas we could detect no association between AMS scores and coagulation parameters, our results do show some parameters to be associated with an acclimatisation protocol and a successful ascent to the summit.

Changes of coagulation parameters during high altitude expedition.

Data on changes of haemostatic parameters at altitudes above 5000 m are very limited. So far it is unknown, whether altered coagulation could contribute to the development of acute mountain sickness. Thirty four healthy mountaineers were randomised to two acclimatisation protocols and undertook an expedition on Muztagh Ata (7549 m) in China. Tests were performed at five altitudes up to 6865 m. Haemostatic parameters, such as PT, aPTT, D-Dimer, APC-Resistance (APCR), von Willebrand Factor activity (RCo), ADAMTS-13 & C-Natriuretic Peptide (CNP) were assessed together with Lake Louise AMS score. D-Dimer significantly increased with increasing altitude (median 0.62 to 0.81 mcg/L, p <0.0001). During ascent, PT increased (83% to >100%) and APCR decreased significantly from 0.95 to 0.8 (p <0.01). Furthermore, a significant increase of aPTT (38 to 43 sec) was paralleled by significant changes of RCo (102% to 62%) (both p <0.001). There were no significant changes in ADAMTS-13 and CNP. No significant relationship between investigated parameters and AMS scores could be detected. When comparing the participants of the two acclimatisation protocols, there was an overall higher RCo in patients with a faster ascent protocol (p = 0.04). This was accompanied by lower ADAMTS-13 of the coagulation system in these patients (p = 0.04). Coagulation parameters change significantly during hypobaric hypoxia. Whereas we could detect no association between AMS scores and coagulation parameters, our results do show some parameters to be associated with an acclimatisation protocol and a successful ascent to the summit.

Body composition at high altitude: a randomized placebo-controlled trial of dietary carbohydrate supplementation

BackgroundBody mass loss is inevitable with chronic hypoxic exposure. However, the exact body-composition changes, their causes, and possible treatments remain unknown. ObjectiveThe objective was to investigate body composition during a high-altitude expedition by using non–empirically derived methods, experimentally manipulating energy intake, and investigating the influence of initial body composition. DesignForty-one participants completed a 21-d expedition in the Himalayas. Energy intake was manipulated with a double-blind, placebo-controlled, randomized trial of carbohydrate energy supplementation. Body composition was assessed before and after the expedition by using a 4-component model including fat mass, total body water, bone mineral mass, and residual mass (principally protein and glycogen). Data were analyzed by repeated-measures analysis of variance. ResultsParticipants allocated to receive carbohydrate were given an additional 15,058 ± 6211 kcal over the 21-d expedition (>6 kcal · kg−1 · d−1). Nevertheless, the functionally important residual mass decreased in both groups by 6% (main effect of time: P = 0.021), with no effect of allocation (interaction effect: P = 0.116). Similar decreases were observed for fat mass (11%) and total body water (3%), which were also unabated by allocation. Furthermore, high initial fat mass (by median split) did not preserve residual mass (high-fat compared with low-fat participants: residual loss = 5% compared with 8%; P = 0.990). ConclusionsHigh-altitude exposure decreased body mass, including the functionally important residual component. These losses were not abated by increasing energy intake or an initially high fat mass. Factors other than negative energy balance must contribute to body-composition changes with chronic hypoxia. This trial was registered at clinicaltrials.gov as NCT00731510.

Is There a Safer and More Successful Way to Climb Kilimanjaro?

High Altitude Medicine & BiologyVol. 10, No. 3 Letters to the EditorIs There a Safer and More Successful Way to Climb Kilimanjaro?Stephanie Mackie and Jeremy S. WindsorStephanie MackieUniversity of Glasgow Faculty of Medicine, Glasgow, United Kingdom.Search for more papers by this author and Jeremy S. WindsorUniversity College London, Centre for Altitude, Space and Extreme Environment Medicine, London, United Kingdom.Search for more papers by this authorPublished Online:23 Sep 2009https://doi.org/10.1089/ham.2009.1015AboutSectionsPDF/EPUB ToolsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail "Is There a Safer and More Successful Way to Climb Kilimanjaro?." , 10(3), pp. 301–302FiguresReferencesRelatedDetailsCited byIncidence and predictors of severe altitude illness symptoms in Mt. Kilimanjaro hikers: a prospective cohort study26 March 2022 | Journal of Travel Medicine, Vol. 29, No. 5Preliminary Evidence-Based Method of Medical Kit Design for Wilderness Expeditions Modeled by a High-Altitude Expedition to Mount KilimanjaroThe Journal of Emergency Medicine, Vol. 62, No. 6Risk Determinants of Acute Mountain Sickness and Summit Success on a 6-Day Ascent of Mount Kilimanjaro (5895 m)Wilderness & Environmental Medicine, Vol. 27, No. 1Twice-Daily Assessment of Trekkers on Kilimanjaro's Machame Route to Evaluate the Incidence and Time-Course of Acute Mountain Sickness Joel Meyer27 December 2012 | High Altitude Medicine & Biology, Vol. 13, No. 4Are UK Commercial Expeditions Complying with Wilderness Medical Society Guidelines on Ascent Rates to Altitude?: Table 11 May 2011 | Journal of Travel Medicine, Vol. 18, No. 3Expedition Medicine—the Risk of Illness and InjuryWilderness & Environmental Medicine, Vol. 21, No. 4 Volume 10Issue 3Sep 2009 InformationCopyright 2009, Mary Ann Liebert, Inc.To cite this article:Stephanie Mackie and Jeremy S. Windsor.Is There a Safer and More Successful Way to Climb Kilimanjaro?.High Altitude Medicine & Biology.Sep 2009.301-302.http://doi.org/10.1089/ham.2009.1015Published in Volume: 10 Issue 3: September 23, 2009PDF download

Decreased anaerobic performance and hormone adaptation after expedition to Peak Lenin

The change of anaerobic exercise abilities during and after a high-altitude expedition or hypoxic exposure is not well studied. To evaluate the effects of an extreme-altitude expedition on anaerobic performance, the 10-second supramaximal test and endocrine hormones were evaluated before and after an expedition to Peak Lenin. Four subjects (3 male and 1 female, age (30.5 +/- 16.5) years) were recruited into the study. Three sets of tests were performed, including a basic test at sea level and 20 days before first arrival at the base camp (3600 m), a middle test done at day after returning from the summit to the base camp and the post test at the 10th day after return to the sea level. Both the supramaximal test, performed by a cycle ergometer, and body composition, performed by bioelectrical impedance analysis, were completed before the basic test and post test. The endocrine hormones including cortisol, growth hormone, testosterone, noradrenaline, adrenaline, dopamine, glucagon and beta-endorphin were measured at all tests. Comparing the conditions before and after the expedition, the body measurement parameters were decreased after the expedition, i.e., body weight (-4.22%, P < 0.05), fat-free mass (-2.09%, P < 0.01) and body fat (-8.95%, P = 0.172). The peak power relative/body weight ratio (PP/BW) was similar ((9.70 +/- 1.97) vs (9.11 +/- 1.80) W/kg, P = 0.093), while mean power/body weight ratio (MP/BW) was reduced significantly after the expedition ((9.14 +/- 1.77) vs (8.33 +/- 1.74) W/kg, P < 0.05). Peak power/fat-free mass (PP/FFM), mean power/fat-free mass (MP/FFM) and fatigue index (FI) were significantly lower after the expedition (PP/FFM: (11.95 +/- 1.71) vs (10.99 +/- 1.59) W/kg, P < 0.05; MP/FFM: (11.26 +/- 1.50) vs (10.04 +/- 1.55) W/kg, P < 0.005; FI (85.55 +/- 4.17)% vs (77.25 +/- 4.40)%, P < 0.05). Hormone assays showed a significant increase of noradrenaline (basic vs middle, P < 0.05) as well as decrease of adrenaline (P < 0.05). Meanwhile, a trend towards an increase in dopamine (basic vs middle) and a decrease of beta-endorphin (basic vs post) were also noted. These results suggested that an expedition to an extreme altitude may have negative effects on anaerobic performance. It showed that a significant increase of noradrenaline (basic vs middle) as well as decrease of adrenaline after the expedition to Peak Lenin had occurred. The real physiological significance needs to be further investigated.

Reduced oxygen due to high‐altitude exposure relates to atrophy in motor‐function brain areas

At high altitudes barometric pressure is reduced and, thus, less oxygen is inhaled. Reduced oxygen concentration in brain tissue can lead to cerebral damage and neurological and cognitive deficits. The present study was designed to explore the effects of high-altitude exposure using a quantitative MRI technique, voxel-based morphometry. We studied nine world-class mountain climbers before (baseline) and after (follow-up) an extremely high-altitude ascent of Everest and K2. We investigated the effects of repeated extremely high-altitude exposures by comparing mountain climbers' scans at baseline with scans of 19 controls. In addition, we measured the effects of a single extremely high-altitude expedition by comparing mountain climbers' scans at baseline and follow-up. A region of reduced white matter density/volume was found in the left pyramidal tract near the primary (BA 4) and supplementary (BA 6) motor cortex when mountain climbers at baseline were compared with controls. Further, when mountain climbers' scans before and after the expedition were compared, a region of reduced grey matter density/volume was found in the left angular gyrus (BA 39). These findings suggest that extremely high-altitude exposures may cause subtle white and grey matter changes that mainly affect brain regions involved in motor activity.