Search Results
Results 401 - 450 of 813
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Hendricks D M - - 2000
BACKGROUND: Supplemental oxygen delivered by mask at high altitude is used to increase arterial oxygen saturation (SaO2) thereby mitigating physiological and cognitive dysfunction secondary to hypoxemia. Historically, mask performance has not been well documented although it may be a critical factor in determining the success of an expedition. METHODS: Three ...
Wickler S J - - 2000
This study had two goals: 1) measure hematologic changes with high-altitude acclimatization in horses; and 2) assess the effect of 9 days at high altitude on subsequent athletic performance at low altitude. Six horses performed standardized exercise tests on a dirt track (before and during time at altitude) and treadmill ...
Brutsaert T D - - 2000
Arterial oxygen saturation (SaO(2)) was measured at 3,600-3,850 m by pulse oximetry at rest and during submaximal exercise in three study groups: 1) highland Aymara natives of the Bolivian altiplano (n = 25); 2) lowland European/North American sojourners to the highlands with at least 2 months of acclimatization time to ...
Jansen G F - - 2000
BACKGROUND AND PURPOSE: Impaired cerebral autoregulation (CA) from high-altitude hypoxia may cause high-altitude cerebral edema in newcomers to a higher altitude. Furthermore, it is assumed that high-altitude natives have preserved CA. However, cerebral autoregulation has not been studied at altitude. METHODS: We studied CA in 10 subjects at sea level ...
Green H J - - 2000
Exposure to altitude results in a reduction in partial pressure of oxygen in the arterial blood and a reduction in oxygen content. In an attempt to maintain aerobic metabolism during increased effort, a series of acclimatization responses occur. Among the most conspicuous of these responses is an increase in hemoglobin ...
Mazzeo R S - - 2000
The purpose of this investigation was to determine the sympathoadrenal response to exercise in women after acclimatization to high altitude. Sixteen eumenorrheic women (age, 23.6 +/- 1.2 years; weight, 56.2 +/- 4.3 kg) were studied at sea level and after 10 days of high-altitude exposure (4,300 m) in either the ...
Moore L G - - 2000
Studies of ventilatory response to high altitudes have occupied an important position in respiratory physiology. This review summarizes recent studies in Tibetan high-altitude residents that collectively challenge the prior consensus that lifelong high-altitude residents ventilate less than acclimatized newcomers do as the result of acquired 'blunting' of hypoxic ventilatory responsiveness. ...
Purkayastha S S - - 2000
BACKGROUND: Little is known about work performance of women in hypobaric hypoxia. Moreover, whether native women of moderate altitude (2,000-2,100 m) differ from their lowland counterparts in their ability to adjust to hypobaric hypoxia is also not known. Hence, physiological alterations on work performance due to mountaineering training with altitude ...
Palmowski A M - - 2000
High and low contrast multifocal ERG (MF-ERG) recordings were obtained from the right eyes of 24 patients with OAG (high-tension OAG: n=16, low-tension OAG: n=8) and compaired to those recorded from 18 healthy volunteers. High contrast MF-ERG recordings were obtained at a mean luminance of 100 cd/m2 with a contrast ...
Nummela A - - 2000
To investigate the benefits of 'living high and training low' on anaerobic performance at sea level, eight 400-m runners lived for 10 days in normobaric hypoxia in an altitude house (oxygen content = 15.8%) and trained outdoors in ambient normoxia at sea level. A maximal anaerobic running test and 400-m ...
Miyazaki S - - 2000
In this research, we hypothesized that, in rats, adaptation to high altitude (2500 m) plus training at low altitude (610 m), "living high-training low", improves physical performance at low altitude more than living and training at low altitude (610 m). Rats were divided into four groups: (1) living at low ...
Frost F J - - 2000
BACKGROUND: A cryptosporidiosis epidemic occurred among residents and visitors to Collingwood, Ontario, during March 1996. Fifty-five per cent of 36 confirmed cases were Collingwood visitors and 57% of Collingwood resident cases were under 10 years of age. The low level of reported diarrhoeal illness among adult Collingwood residents caused government ...
Schobersberger W - - 2000
The present study was performed to investigate the effects of exhaustive long lasting exercise at moderate altitude on the time course of serum immunomodulatory peptides, vascular endothelial growth factor (VEGF) and serum erythropoietin (EPO). Thirteen well trained runners participated at the Swiss Alpine Marathon of Davos (distance 67 km, altitude ...
Christensen C C - - 2000
The arterial oxygen tensions (Pa,02) in chronic obstructive pulmonary disease (COPD) patients travelling by air, should, according to two different guidelines, not be lower than 7.3 kPa (55 mmHg) and 6.7 kPa (50 mmHg), respectively, at a cabin pressure altitude of 2,438 m (8,000 ft). These minimum in-flight Pa,O2 values ...
Wolffsohn J S - - 2000
OBJECTIVE: To improve on present reading chart designs, providing a quick and accurate method to measure the near acuity threshold, of particular importance with low vision patients. DESIGN: The Practical Near Acuity Chart (PNAC) uses a single paragraph with 3 simple related words on each line (12 lower case letters). ...
Ashenden M J - - 2000
The purpose of this study was to investigate whether the modest increases in serum erythropoietin (sEpo) experienced after brief sojourns at simulated altitude are sufficient to stimulate reticulocyte production. Six well-trained middle-distance runners (HIGH, mean maximum oxygen uptake, VO2max = 70.2 ml x kg(-1) x min(-1) spent 8-11 h per ...
Inouye D W - - 2000
Calendar date of the beginning of the growing season at high altitude in the Colorado Rocky Mountains is variable but has not changed significantly over the past 25 years. This result differs from growing evidence from low altitudes that climate change is resulting in a longer growing season, earlier migrations, ...
Fulco C S - - 2000
Exercise training studies conducted at different altitudes (1250-5700 m) of varying durations (30 min to 19 wk) are critically reviewed to determine the efficacy of using altitude as a training stimulus to enhance sea level and altitude exercise performance. Four strategies are discussed: a) exercise training while residing at the ...
Patrick M L - - 2000
In this study, we demonstrate that two of the osmolytes utilized in the osmoconforming strategy of larval Culex tarsalis are regulated by two fundamentally different signals. When the external osmolality was increased using salinity (sea salts), hemolymph NaCl, proline and trehalose concentrations increased significantly. When sorbitol was used to increase ...
Sawka M N - - 2000
This paper reviews the influence of several perturbations (physical exercise, heat stress, terrestrial altitude, microgravity, and trauma/sickness) on adaptations of blood volume (BV), erythrocyte volume (EV), and plasma volume (PV). Exercise training can induce BV expansion: PV expansion usually occurs immediately, but EV expansion takes weeks. EV and PV expansion ...
Roach R C - - 2000
We hypothesized that exercise would cause greater severity and incidence of acute mountain sickness (AMS) in the early hours of exposure to altitude. After passive ascent to simulated high altitude in a decompression chamber [barometric pressure = 429 Torr, approximately 4,800 m (J. B. West, J. Appl. Physiol. 81: 1850-1854, ...
Beall C M - - 2000
High-altitude environments provide natural experimental settings to investigate adaptation to environmental stress. An important evolutionary and functional question is whether sea-level human biology constrains the adaptive response. This paper presents evidence that indigenous populations of the Tibetan and Andean plateaus exhibit quantitatively different responses to hypobaric hypoxic stress. At the ...
McElroy M K - - 2000
In a randomized, double-blind study, 24 sea-level residents drove to 3,800-m altitude in 1 day, and then slept the first night in either ambient air or 24% oxygen, and the second night in the treatment that they did not receive on the first night. Oxygen enrichment, compared with ambient air, ...
Wilber R L - - 2000
In this investigation we evaluated the effect of a 5-week training program at 1860 m on serum creatine kinase (CK) activity and serum cortisol concentration in national-caliber triathletes for the purpose of monitoring the response to training in a hypobaric hypoxic environment. Subjects included 16 junior-level female (n = 8) ...
Ricart A - - 2000
OBJECTIVE: With the ultimate goal of finding a straightforward protocol for acclimatization at simulated altitude, we evaluated the early effects of repeated short-term exposure to hypobaric hypoxia on the respiratory response to exercise in hypoxia. METHODS: Nine subjects were exposed to a simulated altitude of 5000 m for 2 hours ...
Ahlberg K - - 1999
Limiting hemodilution in neonates is difficult when extracorporeal circuits require priming volumes that are 2 to 3 times the blood volume of the newborn patient. This extreme hemodilution contributes to the development of significant postbypass coagulation disturbances. The purpose of this project was to design a low-prime neonatal bypass circuit ...
Ashenden M J - - 1999
The purpose of this study was to document the effect of 23 days of "live high, train low" on the haemoglobin mass of endurance athletes. Thirteen male subjects from either cycling, triathlon or cross-country skiing backgrounds participated in the study. Six subjects (HIGH) spent 8-10 h per night in a ...
Casan P - - 1999
This study investigates the effects of moderate-high altitude on lung function and exercise performance in 46 volunteers (19 females, 27 males), with a mean age of 42.4 +/- 1.4 years (+/- SEM) and varying smoking and exercise habits, who were not previously acclimatized. Measures obtained in the base camp (1140 ...
Ashenden M J - - 1999
The aim of this study was to document the effect of "living high, training low" on the red blood cell production of elite female cyclists. Six members of the Australian National Women's road cycling squad slept for 12 nights at a simulated altitude of 2650 m in normobaric hypoxia (HIGH), ...
Zhang L - - 1999
BACKGROUND: Female fighter pilots are flying the F-16 and F-15 with COMBAT EDGE, the positive pressure breathing under G (PBG) protection system. The standard CSU 13 B/P anti-G suit may soon be replaced with the Advanced Technology Anti-G suit. The purpose of this research was to compare human performance and ...
Saito S - - 1999
The pathophysiology of altitude-related disorders in untrained trekkers has not been clarified. In the present study, the effects of workload on cardiovascular parameters and regional cerebral oxygenation were studied in untrained trekkers at altitudes of 2700 m and 3700 m above sea level. We studied 6 males and 4 females ...
Greene H M - - 1999
Arterial and venous blood were analysed at rest and post exercise for pH, PCO2, and PO2, and bicarbonate ([HCO3-]), base excess (BE), and strong ion difference (SID) were calculated in response to a 10 day sojourn to 3800 m. Pulmonary artery pressures (PAP) were measured at rest. Post exercise samples ...
Webb J T - - 1999
Preoxygenation, breathing 100% oxygen prior to decompression, has been used for well over half of this century to reduce decompression sickness (DCS) incidence. Duration of preoxygenation has been reported to be inversely related to subsequent DCS incidence. A direct comparison of DCS incidence at 30,000 ft versus preoxygenation time is ...
Katayama K - - 1999
The present study was performed to clarify the effects of intermittent exposure to an altitude of 4,500 m with endurance training and detraining on ventilatory chemosensitivity. Seven subjects (sea-level group) trained at sea level at 70% maximal oxygen uptake (VO2 max) for 30 min/day, 5 days/wk for 2 wk, whereas ...
Cibella F - - 1999
The purpose of this study was to assess the effect of high altitude (HA) on work of breathing and external work capacity. On the basis of simultaneous records of esophageal pressure and lung volume, the mechanical power of breathing (Wrs) was measured in four normal subjects during exercise at sea ...
Roi G S - - 1999
PURPOSE: We examined the effect of altitude up to 5200 m on marathon (42,195 m) performances. METHODS: Eight elite and four good runners participated in a marathon at 4300-m altitude (A1), and five elite runners participated both in A1 and in a marathon at 5200-m altitude (A2). The maximal aerobic ...
Beidleman B A - - 1999
We hypothesized that progesterone-mediated ventilatory stimulation during the midluteal phase of the menstrual cycle would increase exercise minute ventilation (VE; l/min) at sea level (SL) and with acute altitude (AA) exposure but would only increase arterial O2 saturation (SaO2, %) with AA exposure. We further hypothesized that an increased exercise ...
Kastelein R A - - 1999
Two echolocation experiments are described. They were conducted on the same harbor porpoise housed in a sea pen, one year apart at Neeltje Jans, The Netherlands. The aims were to determine the target detection ability of an echolocating harbor porpoise, with the ultimate goal to predict the distance at which ...
Luciá A - - 1999
The aim of the present investigation was to evaluate the heart rate response of 8 professional cyclists (26+/-3 yr; 68.9+/-5.2 kg; V02max: 74.0+/-5.8 ml x kg(-1) x min(-1)) during the 3-week Tour de France as an indicator of exercise intensity. Subjects wore a heart rate telemeter during 22 competition stages ...
Burki N K - - 1999
The direct effects of hypoxia on exercise-induced breathlessness are unclear. Increased breathlessness on exercise is known to occur at high altitude, but it is not known whether this is related to the hypoxia per se, or to other ventilatory parameters. To examine the role of high-altitude hypoxia in exercise-induced breathlessness, ...
Turner M - - 1999
The aim of this research was to identify personal and environmental factors influencing individual susceptibility to motion sickness during road transport. A questionnaire survey of 3256 coach travellers was conducted. Information on passenger characteristics, travel regularity, activity during travel, use of anti-motion sickness drugs and self-reported motion sickness susceptibility were ...
Friedmann B - - 1999
The aim of the study was to test the hypothesis that iron supplementation in well-trained non-iron-depleted athletes leads to an enhanced increase of total body hemoglobin (TBH) during training at moderate altitude. Therefore, the members of the national German boxing team were randomly assigned to treatment with ferrous-glycine-sulfate (1335 mg ...
Garcia J A - - 1999
OBJECTIVES: The principal objective of this study was to examine the importance of the right ventricle for maximal systemic oxygen transport during exercise at high altitude by studying patients after the Fontan operation. BACKGROUND: High-altitude-induced hypoxia causes a reduction in maximal oxygen uptake. Normal right ventricular pump function may be ...
Abinader E G - - 1999
To evaluate the effects of low altitude on exercise performance and myocardial ischemia, 12 patients with coronary artery disease and 6 normal controls underwent ergometric and exercise echocardiography in Haifa, 130 m above sea level, and at the Dead Sea, 402 m below sea level. At the Dead Sea, exercise ...
Schoene R B - - 1999
The sport of high-altitude climbing encompasses a number of factors of stress that supersede the usual endurance activities at lower altitudes. The effect of hypoxia on both physical and mental performance can be profound and, therefore, compound the risk. Much is yet to be known, particularly about the brain. Hopefully, ...
Pilmanis A A - - 1999
BACKGROUND: It has been known since World War II that exercise at altitude increases incidence of decompression sickness (DCS). However, data on the effects of specific exercise types at altitude are lacking. This research focused on the relative hazards of exercise without motion (isometric, straining) vs. dynamic exercise involving motion. ...
Pandolf K B - - 1998
The effects of autologous erythrocyte infusion on improving exercise performance at high altitude have not previously been studied. The effects of erythrocyte infusion on 3.2-km (2-mile) run performance were evaluated during 3 days (HA3) and 14 days (HA14) exposure to high altitude (4300 m) in erythrocyte-infused (ER) and control (CON) ...
Kleinman M T - - 1998
Seventeen men with stable angina pectoris who resided at or near sea level performed cardiopulmonary exercise stress tests after they were exposed to either carbon monoxide (3.9%), carboxyhemoglobin, or clean air. Investigators conducted the tests at sea level, and they simulated 2.1-km altitudes (i.e., reduced arterial oxygen saturation by approximately ...
Nishihara F - - 1998
OBJECTIVES: Using modern transportation technology, many travelers easily access moderate altitudes of approximately 3000 m above sea level. In the present study the effects of this altitude on cardiovascular parameters were studied among office workers dwelling at sea level. METHODS: Heart rate, blood pressure, arterial oxygen saturation (SpO2), and electrocardiography ...
Tölli H - - 1998
This paper presents experimentally determined correction factors for Farmer-type chambers for absorbed dose determination in 60Co and 192Ir brachytherapy dosimetry. The correction factors were determined from measurements made in a PMMA phantom and calculation of ratios of measured charges. The ratios were corrected for the different volumes of the ionization ...
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