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Results 451 - 500 of 813
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Chapman R F - - 1998
Moderate-altitude living (2,500 m), combined with low-altitude training (1,250 m) (i.e., live high-train low), results in a significantly greater improvement in maximal O2 uptake (V(02)max) and performance over equivalent sea-level training. Although the mean improvement in group response with this "high-low" training model is clear, the individual response displays a ...
Ciuffreda K J - - 1998
PURPOSE: Some aspects of accommodation may be slightly abnormal (or different) in myopes, compared with accommodation in emmetropes and hyperopes. For example, the initial magnitude of accommodative adaptation in the dark after nearwork is greatest in myopes. However, the critical test is to assess this initial accommodative aftereffect and its ...
Bailey D M - - 1998
Elite distance runners participated in one of two studies designed to investigate the effects of moderate altitude training (inspiratory partial pressure of oxygen approximately 115-125 mmHg) on submaximal, maximal and supramaximal exercise performance following return to sea-level. Study 1 (New Mexico, USA) involved 14 subjects who were assigned to a ...
Gore C J - - 1998
Haemoglobin mass (Hb mass), maximum oxygen consumption (VO2max), simulated 4000 m individual pursuit cycling performance (IP4000), and haematological markers of red blood cell (RBC) turnover were measured in 8 male cyclists before and after (A) 31 d of altitude training at 2690 m. The dependent variables were measured serially after ...
Liu Y - - 1998
Living high-training low (LHTL), living at high altitude and training at sea level, is reported to be beneficial in enhancing physical performance. Effect of LHTL on cardiac function which is one of major determinants in performance, however, was not examined. To address this issue, 21 well-trained triathletes divided into control ...
Fulco C S - - 1998
BACKGROUND: Exercise performance data of numerous altitude research studies and competitive sporting events of the last four decades are reviewed. METHODS: The primary focus is on the wide interindividual variation associated with maximal and submaximal exercise performance that occurs at different altitudes and for different periods of time at altitude. ...
Boutillon M - - 1998
The parameter m2 governing the volume recombination in ionization chambers has been measured under conditions which allow strict application of the basic theory. The method consists of measuring the ratio of ionization currents I(V1) and I(V2) obtained at two given voltages V1 and V2 as a function of I(V1). The ...
Rodas G - - 1998
The differences in ventilatory response to exercise of some highland ethnic communities is a controversial issue. We have evaluated the differences in ventilatory response to exercise at sea level between two groups of elite climbers, four Himalayan Sherpas (S) and four Caucasian lowlanders (C), after descent from extreme altitude. All ...
Fernando R - - 1998
A Thai Airbus, carrying 99 passengers and 14 crew members, traveling from Bangkok to Kathmandu, hit a mountain and crashed several minutes before landing. There were no survivors. Recovered human remains, none of which was easily identifiable, varied in size from a small piece of muscle to mutilated bodies. Of ...
Sim┼ček S - - 1998
The authors analyzed refractive results of patients who underwent radial keratotomy (RK) at sea level and high altitude and evaluated the effects of the altitude. A total of 102 eyes undergoing RK procedures performed in two clinical centers having different altitude were analyzed. The results compared between subjects who had ...
Muñoz Olivas R - - 1998
Speciation of inorganic selenium using hydride generation method is a widespread analytical method nowadays. However, a reduction step of Se(VI) to Se(IV) is necessary as the hydride-forming species is HSeO(3)(-) (oxydation state+IV). This paper describes the development of a batch assisted microwave system allowing a rapid (<5 min) conversion of ...
Kramer M R - - 1998
BACKGROUND: In patients with COPD, oxygen therapy has been shown to improve exercise capacity and survival. Increase in barometric pressure at low altitude can serve as a simple way to improve arterial oxygenation in hypoxemic patients. We have tried to evaluate the effect of staying at low altitude on arterial ...
Ferraro F R - - 1998
Individuals scoring either High, Medium, or Low on the Homosexism Short-Form scale (Hansen, 1982) made speeded decisions to neutral (N), mildly provocative (MP), or very provocative (VP) statements regarding issues relating to homophobia. These three groups did not differ on age, education, reading rate, or vocabulary ability. It was predicted ...
Moore L G - - 1998
Studies of the ways in which persons respond to the adaptive challenges of life at high altitude have occupied an important place in anthropology. There are three major regions of the world where high-altitude studies have recently been performed: the Himalayas of Asia, the Andes of South America, and the ...
Curran L S - - 1998
Few environments challenge human populations more than high altitude, since the accompanying low oxygen pressures (hypoxia) are pervasive and impervious to cultural modification. Work capacity is an important factor in a population's ability to thrive in such an environment. The performance of work or exercise is a measure of the ...
Beidleman B A - - 1997
Following 2 to 3 wk of altitude acclimatization, ventilation is increased and heart rate (HR), plasma volume (PV), and lactate accumulation ([La]) are decreased during submaximal exercise. The objective of this study was to determine whether some degree of these exercise responses associated with acclimatization would be retained upon reintroduction ...
Böning D - - 1997
The importance of oxygen transport and consumption in the body for endurance performance is the reason why altitude training as preparation for competitions at sea level has become popular. In hypoxia maximal O2 uptake decreases. Thus for equal work load training at altitude is harder and stimulates adaptation processes more ...
Hashimoto F - - 1997
The objective of this study was to examine how pulmonary ventilatory function, including response to bronchodilation, is related to altitude during high-altitude trekking. This cohort experiment consisted of multiple spirometric tests before and after bronchodilation in participants at baseline (1624 m) and at different altitudes (3404-4896 m) during a 2-week ...
Savourey G - - 1997
In order to study relationships between acute mountain sickness (AMS) observations done both during a short-term hypoxic exposure in a hypobaric chamber, and in field conditions during a high altitude expedition, nine subjects were submitted to a 9-h hypoxic exposure in a hypobaric chamber. Then, they experienced a high altitude ...
Svedenhag J - - 1997
The effects of long-term altitude training on altitude and sea-level physiological characteristics in elite endurance athletes were investigated. Seven Swedish elite cross-country skiers (five men, two women; mean age 27 years) spent 1 month training at 1900 m above sea level in Italy. Rollerski treadmill tests were performed before and ...
Bailey D M - - 1997
Acclimatisation to environmental hypoxia initiates a series of metabolic and musculocardio-respiratory adaptations that influence oxygen transport and utilisation, or better still, being born and raised at altitude, is necessary to achieve optimal physical performance at altitude, scientific evidence to support the potentiating effects after return to sea level is at ...
Levine B D - - 1997
BACKGROUND: More than 5 million people/year over age 60 visit high altitude, which may exacerbate underlying cardiac or pulmonary disease. We hypothesized that the elderly would exhibit an impaired functional capacity at altitude, with increased myocardial ischemia compared with sea level (SL). METHODS AND RESULTS: Twenty veterans (68+/-3 years) were ...
Butcher J D - - 1997
A 35-year-old, active duty Army officer presented for a screening physical exam before entering special training for HALO (High Altitude Low Opening) parachute qualification. This training involves jumping from aircraft at extreme altitudes with deployment of the parachute at relatively low altitudes (free fall). At the time of this evaluation ...
Chen Q H - - 1997
The difference was studied between O2 transport in lifelong Tibetan adolescents and in newcomer Han adolescents acclimatized to high altitude. We measured minute ventilation, maximal O2 uptake, maximal cardiac output, and arterial O2 saturation during maximal exercise, using the incremental exercise technique, at altitudes of 3,417 and 4,300 m. The ...
Ali K Z - - 1997
Paraffin-embedded histological material was examined from 10 placentae from uncomplicated pregnancies at high altitude (3000 m). This was compared with material from 10 placentae delivered at low altitude (500 m). The sample groups were matched for maternal age, gestational age and parity. Within terminal and intermediate villi the volume-weighted mean ...
Garrido E - - 1997
Himalayan Sherpas are well known for their extraordinary adaptation to high altitude and some of them for their outstanding physical performance during ascents to the highest summits. To cast light on this subject, we evaluated the cardiorespiratory response during exercise at sea level of six of the most acknowledged Sherpa ...
Bailey D M - - 1997
OBJECTIVES: This investigation was designed to monitor altitude acclimatisation in an elite cohort of distance runners and follow the subsequent recovery from infectious mononucleosis which developed in one of these athletes. METHODS: Twenty six national standard distance runners performed treadmill tests 24 days before they travelled to an altitude camp ...
Forte V A VA - - 1997
Because air is less dense at high altitude (HA), airway resistance is reduced and maximum inspiratory and expiratory flows are greater than at sea level (SL). Despite the reduction in airway resistance, ventilatory muscle endurance may be decreased by hypobaric hypoxia and, thus, may be a factor in limiting exercise ...
Pollard A J - - 1997
1. Both hypoxia and hypocapnia can cause broncho-constriction in humans, and this could have a bearing on performance at high altitude or contribute to altitude sickness. We studied the relationship between spirometry, arterial oxygen saturation and end-tidal carbon dioxide (ETCO2) concentration in a group of healthy lowland adults during a ...
Wood R J - - 1997
This study compared the measurement of oxygen saturation of haemoglobin (SaO2) by two pulse oximeters (Ohmeda Biox 3700e and Criticare 504 USP) with the measurement of SaO2 in arterial blood samples by CO-oximetry. Unlike many previous validation studies, arterial blood was sampled in ground glass rather than plastic syringes. Twenty ...
Robach P - - 1997
We tested the hypothesis that prolonged exposure to high altitude would impair the restoration of muscle power during repeated sprints. Seven subjects performed two 20-s Wingate tests (WT1 and WT2) separated by 5 min of recovery, at sea level (N) and after 5-6 days at 4,350 m (H). Mean power ...
Fairclough S H - - 1997
A field study was conducted to assess the impact of continuous time headway feedback on following behaviour. An equipped vehicle was fitted with a microwave radar connected to a head-down display. The display was supplemented by an auditory tone which sounded if headway decreased below 1 second. Sixteen subjects participated ...
Böning D - - 1997
The aim of the study was to investigate blood alterations caused by altitude acclimatization which last more than few days after return and might play a role for exercise performance at sea level. Measurements were performed in 12 mountaineers before, during and either 7/8 or 11/12 days after a Himalaya ...
Zaccaria M - - 1997
During chronic high-altitude (HA) exposure, basal and exercise-induced noradrenaline (NA) increases do not parallel blood pressure (BP) changes observed; unlike beta-adrenergic receptors, to our knowledge no data are available on alpha-receptors. We studied platelet alpha 2- and leucocyte beta-receptors and basal catecholamine levels in 11 trained climbers before and after ...
Schmeisser E T - - 1997
Field exercise studies were performed at two altitudes (2,200 and 4,200 m) in 2 successive years using different sets of young male volunteers. Visual function indices were measured both at sea level and during a strenuous exercise regime at altitude. Volunteers were grouped in the first study by initial rest ...
Loftin K C - - 1997
BACKGROUND: Several previous studies indicated that exercise during prebreathe with 100% O2 decreased the incidence of hypobaric decompression sickness (DCS). We report a meta-analysis of these investigations combined with a new study in our laboratory to develop a statistical model as a predictive tool for DCS. HYPOTHESIS: Exercise during prebreathe ...
Wagner P D - - 1997
O2 uptake in the lungs, and therefore arterial oxygenation, is favored by a low Hb-P50 but this inhibits tissue O2 extraction, raising the question of optimal P50 during maximal exercise when VO2 is limited by O2 supply. Using a model of the lungs and muscles connected by the circulation so ...
Ueno N - - 1997
In response to high-altitude long-term hypoxemia, the cerebral arteries of fetal and adult sheep show decreased contractile responses to norepinephrine (NE) and other agonists. To test the hypothesis that hypoxia-induced developmental and vessel specific cerebral artery contractility changes are mediated, in part, by changes in alpha1-adrenergic receptor (alpha1-AR) density and/or ...
McCrory P - - 1997
Active patients may suffer not only from the common headache syndromes that plague the general population, but also from headache brought on by exercise. Valsalva-type maneuvers can bring on exertional headache; maximal or submaximal aerobic activity can precipitate effort headache. Trauma to the head and neck can lead to posttraumatic ...
Vasankari T J - - 1997
We investigated the effect of training and racing at moderate altitude (MA) on oxidative stress by assessment of serum diene conjugation (DC) and serum antioxidant potential (TRAP). Nine male top level skiers were studied during a national race (20-30 km) at sea level (SL). Thereafter, the athletes trained for 2 ...
Barreto A B - - 1997
Two adaptive signal processing algorithms are applied to the estimation of the relative delay between Blood Volume Pulse (BVP) signals collected by independent sensors on the subject's index finger. Both the LMS Adaptive Predictor and the Adaptive Delay System are evaluated for the delay estimation in synthetic test signals and ...
Schoene R B - - 1997
Ventilatory acclimatization to high altitude has been discussed in a chronologic fashion, i.e. the acute, prolonged, and chronic or lifelong phases, and the integration of exercise ventilation as it relates to each of these phases has been outlined. Unanswered questions in each of these areas have been posed as fertile ...
Saito T - - 1996
To obtain the basic data of gas exchange of rice (Oryza sativa L. cv. Nipponbare), rates of ethylene release, photosynthesis and transpiration of the rice plant were measured by using a closed-type chamber. Each rate increased until the heading stage and thereafter decreased. Ethylene release rate (E) gradually increased with ...
Buttarello M - - 1996
In this study the ability of the Coulter MAXM analyzer to quantify reticulocytes was evaluated. The results were compared with those obtained by a microscopic method according to NCCLS H44-P recommendations and with the results from the automated analyzer Sysmex R-1000. Duplicate samples from 330 patients were analyzed. The reference ...
Kayser B - - 1996
We tested the hypothesis that the reported low blood lactate accumulation ([La]) during exercise in altitude-native humans is refractory to hypoxianormoxia transitions by investigating whether acute changes in inspired O2 fraction (FIo2) affect the [La] vs. power output (W) relationship or, alternatively, as reported for lowlanders, whether changes in [La] ...
Banfi G - - 1996
Although there are various descriptive reports concerning exercise-induced gastrointestinal distress, the role of gastrointestinal hormones and/or enzymes is not definitively established. In this study we investigated the behaviour of pepsinogens (PGI and PGII) after an endurance race performed at an altitude of 4,300 m by 13 well-trained marathon runners, with ...
Desplanches D - - 1996
Twenty healthy high-altitude natives, residents of La Paz, Bolivia (3,600 m), participated in 6 wk of endurance exercise training on bicycle ergometers, 5 times/wk, 30 min/session, as previously described in normoxia-trained sea-level natives (H. Hoppeler, H. Howald, K. E. Conley, S. L. Lindstedt, H. Claassen, P. Vock, and E. R. ...
Roberts A C - - 1996
We tested the hypothesis that exposure to altitude decreases reliance on free fatty acids (FFA) as substrates and increases dependency on blood glucose. Therefore, the effects of exercise, hypobaric hypoxia, and altitude acclimatization on FFA, glycerol and net glucose uptake and release [= 2(leg blood flow)(arteriovenous concentration)] and on fatty ...
Bigard A X - - 1996
This study was conducted to test the hypothesis that a branched-chain amino acid (BCAA) supplementation would minimize changes in body composition and alterations in plasma amino acid profile induced by prolonged exercises at altitude. Twenty-four highly trained subjects participated in six successive sessions of ski mountaineering (6-8 hr duration, altitude ...
Yamamoto Y - - 1996
It has been shown that fluctuation of human heartbeat intervals [heart rate variability (HRV)] reflects variations in cardiac autonomic nervous system activity. The present study was designed to investigate whether the acute exposure to moderate levels of simulated altitude and the resultant hypoxia could modify HRV during exercise. Seven healthy ...
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