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 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of previous physical conditioning on young well-conditioned mountaineers in relationship to acquiring acute mountain sickness is controversial. Data show both increased and decreased effects on the incidence of altitude illness. How general tourists at moderate altitudes are affected is unknown. To determine the influence of sea-level habitual physical activity on the incidence of mountain sickness, we surveyed 205 participants in a scientific conference at 3,000 m (9,840 ft). A 36-item questionnaire was distributed to the subjects 48 hours after arrival at altitude. Their sea-level physical activity (SLPA) was measured by a published and validated instrument that included questions about patterns of work, sporting, and leisure-time activities. Acute mountain sickness was defined as the presence of 3 or more of the following symptoms: headache, dyspnea, anorexia, fatigue, insomnia, dizziness, or vomiting. Most of the respondents were male (62%) from sea level (89%) with a mean age of 36 +/- 8.7 (standard deviation) years (range, 22 to 65). Nearly all (94%) were nonsmokers, and 28% had acute mountain sickness. The mean SLPA score was 8.0 +/- 1.3 (range, 5.1 to 12.0). No statistically significant difference in mean SLPA scores was found between those with and without acute mountain sickness (8.1 versus 7.8), nor in the individual indices (work, 2.5 versus 2.4; sport, 2.9 versus 2.7; leisure, 2.8 versus 2.7). We conclude that habitual physical activity performed at sea level does not play a role in the development of altitude illness at moderate altitude in a general tourist group.
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PMID:Sea-level physical activity and acute mountain sickness at moderate altitude. 757 57

A massive expansion of mountain tourism and the practice of sports at altitude (mountaineering, skiing, cycling, hang-gliding, parapente, etc) has been observed in the last decades. This emphasis on new forms of sports and recreation represented as a social phenomenon is accompanied by an increase in the mountain associated-disorders and related-accidents. These include headache, lassitude, pain, difficulty in breathing, rapid heartbeat, and in the worst of the cases loss of consciousness, always possible, manifest by poor judgement, fatigue, etc, and death. However, medical studies are rare, mainly because the molecular mechanisms of tissue damage induced by oxygen free radicals are still poorly understood. Therefore, the goals of the present report are: 1) to summarize the main adaptations of the body at high altitude, introducing the concepts of altitude sickness and oxygen free radicals and their relation; 2) to propose a mechanism of action of oxygen free radicals in the development of this pathology, with special attention in hypoxia and related mechanisms; 3) to suggest a role for antioxidants in the therapy of altitude-related disorders.
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PMID:Role of oxygen free radicals in altitude-related disorders. 802 27

To determine if spirometric changes reflect early high-altitude pulmonary edema (HAPE) formation, we measured the FVC, FEV1, and FEF25-75 serially during the short-term period following simulated altitude exposure (4,400 m) in eight male subjects, four with a history of HAPE and four control subjects who had never experienced HAPE. Three of the four HAPE-susceptible subjects developed acute mountain sickness (AMS), based on their positive Environmental Symptom Questionnaire (AMS-C) scores. Clinical signs and symptoms of mild pulmonary edema developed in two of the three subjects with AMS after 4 h of exposure, which prompted their removal from the chamber. Their spirometry showed small decreases in FVC and greater decreases in FEV1 and FEF25-75 after arrival at high altitude in the presence of rales or wheezing on clinical examination and normal chest radiographs. One of the two subjects had desaturation (59 percent) and tachycardia during mild exercise, and excessive fatigue and inability to complete the exercise protocol developed in the other at 4 h. The six other subjects had minimal changes in spirometry and did not develop signs of lung edema. Further, we measured each subject's ventilatory response to hypoxia (HVR) prior to decompression to determine whether the HVR would predict the development of altitude illness in susceptible subjects. In contrast to anticipated results, high ventilatory responses to acute hypoxia, supported by increased ventilation during exposure to high altitude, occurred in the two subjects in whom symptoms of HAPE developed. The results confirm that HAPE can occur in susceptible individuals despite the presence of a normal or high ventilatory response to hypoxia.
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PMID:Pulmonary function and hypoxic ventilatory response in subjects susceptible to high-altitude pulmonary edema. 841 62

Snowboarding is now a well-established winter sport and a popular mode of mountaineering. In-area and backcountry snowboarding are defined, as well as a new term, glisse, that refers to all types of skis and snowboards. New developments in equipment focus on boot and binding systems. Backcountry travel is highlighted, including ascent with snowshoes, skis, a splitboard, and crampons. Injuries are about 4-6 per 1000 snowboarding days. Upper extremity injuries are most often wrist sprains or fractures. Lower extremity injuries are primarily ankle sprains and are generally less severe than knee injuries in skiers. Fracture to the lateral process of the talus has been called snowboarder's fracture. Backcountry injuries include avalanche suffocation and trauma, deep snow immersion asphyxiation, hypothermia, frostbite, dehydration, fatigue, acute mountain sickness, and sunburn. Specific recommendations for prevention and safety are discussed.
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PMID:In-area and backcountry snowboarding: medical and safety aspects. 1251 Jul 87

High altitude is characterized by hypoxic environmental conditions that may induce a set of pathological disorders, known as acute mountain sickness. In addition to the physiological symptoms, exposure to high altitude may also produce adverse changes in motor skills, mental efficiency, and mood states, including anxiety. In the present study, we investigated the relationships between mood states, including anxiety, and performance changes in reaction time, psychomotor ability and mental efficiency in eight climbers participating in the 'Everest-Comex 97', a 31-day gradual decompression in a hypobaric chamber from sea level to 8848 m equivalent altitude. Tests of visual reaction time, manual dexterity, and number ordination were used; anxiety responses and mood states were assessed using the Spielberger State-Trait Anxiety Inventory (STAI) and the 'Profile of Mood States' (POMS), respectively. A significant positive correlation was found between the climbers' performance in reaction time and changes in state-type anxiety levels, suggesting that anxiety could lead to an improved reaction time. In addition, significant negative correlations were also found between the climbers' performance in psychomotor ability, mental efficiency, and reaction time, and several POMS factors, including Tension, Hostility, Confusion, and Fatigue. Overall, these data indicate, in agreement with previous studies, that anxiety may favour, or at least not alter, the processes of information of relatively simple tasks, such as reaction time, and further suggest that adverse changes in moods could modulate performance negatively.
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PMID:Relationships between mood states and performances in reaction time, psychomotor ability, and mental efficiency during a 31-day gradual decompression in a hypobaric chamber from sea level to 8848 m equivalent altitude. 1123 64

Rhodiola rosea is a popular plant in traditional medical systems in Eastern Europe and Asian with a reputation for stimulating the nervous system, decreasing depression, enhancing work performance, eliminating fatigue, and preventing high altitude sickness. Rhodiola rosea has been categorized as an adaptogen by Russian researchers due to its observed ability to increase resistance to a variety of chemical, biological, and physical stressors. Its claimed benefits include antidepressant, anticancer, cardioprotective, and central nervous system enhancement. Research also indicates great utility in asthenic conditions (decline in work performance, sleep difficulties, poor appetite, irritability, hypertension, headaches, and fatigue) developing subsequent to intense physical or intellectual strain. The adaptogenic, cardiopulmonary protective, and central nervous system activities of Rhodiola rosea have been attributed primarily to its ability to influence levels and activity of monoamines and opioid peptides such as beta-endorphins.
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PMID:Rhodiola rosea: a possible plant adaptogen. 1141 73

Almost every second trekker or climber develops two to three symptoms of the high altitude illness after a rapid ascent (> 300 m/day) to an altitude above 4000 m. We distinguish two forms of high altitude illness, a cerebral form called acute mountain sickness and a pulmonary form called high altitude pulmonary edema. Essentially, acute mountain sickness is self-limiting and benign. Its symptoms are mild to moderate headache, loss of appetite, nausea, dizziness and insomnia. Nausea rarely progresses to vomiting, but if it does, this may anticipate a progression of the disease into the severe form of acute mountain sickness, called high altitude cerebral edema. Symptoms and signs of high altitude cerebral edema are severe headache, which is not relieved by acetaminophen, loss of movement coordination, ataxia and mental deterioration ending in coma. The mechanisms leading to acute mountain sickness are not very well understood; the loss of cerebral autoregulation and a vasogenic type of cerebral edema are being discussed. High altitude pulmonary edema presents in roughly twenty percent of the cases with mild symptoms of acute mountain sickness or even without any symptoms at all. Symptoms associated with high altitude pulmonary edema are incapacitating fatigue, chest tightness, dyspnoe at the minimal effort that advances to dyspnoe at rest and orthopnoe, and a dry non-productive cough that progresses to cough with pink frothy sputum due to hemoptysis. The hallmark of high altitude pulmonary edema is an exaggerated hypoxic pulmonary vasoconstriction. Successful prophylaxis and treatment of high altitude pulmonary edema using nifedipine, a pulmonary vasodilator, indicates that pulmonary hypertension is crucial for the development of high altitude pulmonary edema. The primary treatment of high altitude illness consists in improving hypoxemia and acclimatization. For prophylaxis a slow ascent at a rate of 300 m/day is recommended, if symptoms persist, acetazolamide at a dose of 500 mg/day is effective. Mild acute mountain sickness may also be treated with the same dose acetazolamide. Glucocorticoids are the first line treatment of the malignant form of acute mountain sickness. Nifedipine is effective only for the prophylaxis and treatment of high altitude pulmonary edema.
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PMID:[Mountaineering and altitude sickness]. 1144 1

A 52-yr-old male scientist who participated in a geophysical survey in Antarctica from a field camp located at 3538 m (11,600 ft) experienced specific symptoms of acute mountain sickness (AMS) by Mission Day 9, and full syndrome AMS by Mission Day 12. He was treated at the field camp and evacuated to sea level on the next available flight (Mission Day 15). The concerns of this highly conscientious individual that initial signs of illness, such as fatigue with exertion, could be misinterpreted by others as poor work performance are described. The report focuses on individual personality and group processes that could lead to nondisclosure of symptoms, and the need, particularly in long-duration missions in which evacuation is difficult or impossible, to sensitize personnel to the importance of recognizing and reporting potential health problems.
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PMID:Conscientiousness and work performance while suffering from acute mountain sickness: a case report. 1195 62

A significant portion of the world's geography lies above 10,000 feet elevation, an arbitrary designation that separates moderate and high altitude. Although the number of indigenous people living at these elevations is relatively small, many people travel to high altitude for work or recreation, exposing themselves to chronic or intermittent hypoxia and the associated risk of acute mountain sickness (AMS) and less frequently, high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). The symptoms of AMS (headache, nausea, anorexia, fatigue, lassitude) occur in those who travel too high, too fast. Some investigators have linked the development of these symptoms with the condition of altered blood-brain barrier permeability, possibly related to hypoxia induced free radical formation. The burden of oxidative stress increases during the time spent at altitude and may even persist for some time upon return to sea level. The physiological and medical consequences of increased oxidative stress engendered by altitude is unclear; indeed, hypoxia is believed to be the trigger for the cascade of signaling events that ultimately leads to adaptation to altitude. These signaling events include the generation of reactive oxygen species (ROS) that may elicit important adaptive responses. If produced in excess, however, these ROS may contribute to impaired muscle function and reduced capillary perfusion at altitude or may even play a role in precipitating more serious neurological and pulmonary crisis. Oxidative stress can be observed at altitude without strenuous physical exertion; however, environmental factors other than hypoxia, such as exercise, UV light exposure and cold exposure, can also contribute to the burden. Providing antioxidant nutrients via the diet or supplements to the diet can reduce oxidative stress secondary to altitude exposure. In summary, the significant unanswered question concerning altitude exposure and antioxidant supplementation is when does oxidative stress become potentially damaging enough to merit antioxidant therapy and conversely, what degree of oxidative stress is necessary to foster the adaptive response of altitude exposure?
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PMID:Work at high altitude and oxidative stress: antioxidant nutrients. 1232 88

Acetazolamide (Acz) is used at altitude to prevent acute mountain sickness, but its effect on exercise capacity under hypoxic conditions is uncertain. Nine healthy men completed this double-blind, randomized, crossover study. All subjects underwent incremental exercise to exhaustion with an inspired O(2) fraction of 0.13, hypoxic ventilatory responses, and hypercapnic ventilatory responses after Acz (500 mg twice daily for 5 doses) and placebo. Maximum power of 203 +/- 38 (SD) W on Acz was less than the placebo value of 225 +/- 40 W (P < 0.01). At peak exercise, arterialized capillary pH was lower and Po(2) higher on Acz (P < 0.01). Ventilation was 118.6 +/- 20.0 l/min at the maximal power on Acz and 102.4 +/- 20.7 l/min at the same power on placebo (P < 0.02), and Borg score for leg fatigue was increased on Acz (P < 0.02), with no difference in Borg score for dyspnea. Hypercapnic ventilatory response on Acz was greater (P < 0.02), whereas hypoxic ventilatory response was unchanged. During hypoxic exercise, Acz reduced exercise capacity associated with increased perception of leg fatigue. Despite increased ventilation, dyspnea was not increased.
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PMID:Acetazolamide reduces exercise capacity and increases leg fatigue under hypoxic conditions. 1239 Oct 68


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