Early erythropoietin, blood, and physiological responses to severe hypoxia in man.

Siri, William E.; Dyke, Donald C. Van; Winchell, H. S.; Pollycove, Myron; Parker, Hannah; Cleveland, Allison

doi:10.1152/jappl.1966.21.1.73

Cited by 66 publications

(17 citation statements)

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“…It may be that the changes in blood indices as a consequence of living at high altitude during training programs rather than the training intervention per se is responsible for the performance advantage claimed by coaches, athletes and some researchers (Daniels and Oldridge 1970). In the present study, acute exposure to altitude during training sessions did not alter either [Hb] or PCV, a ®nding that agrees with those of Siri et al (1966), Levine et al (1992) and Engfred et al (1994), who, with similar protocols, concluded that acute exposure to hypobaric hypoxia for »1 h per day for 5 weeks does not result in acclimatisation. This assertion is consistent with ®ndings that several hours of continuous exposure to hypoxia is needed to detect any increase in erythropoietin levels (Eckard et al 1989;Schmidt et al 1991;Schwandt et al 1991).…”

Section: Discussionsupporting

confidence: 87%

Training-induced increases in sea level V?O2 m a x and endurance are not enhanced by acute hypobaric exposure

Emonson

Aminuddin

Wight

et al. 1997

European Journal of Applied Physiology

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The present study used untrained subjects to examine the effect of acute hypobaric exposure during endurance training on subsequent exercise performance at sea level. Two groups, each of nine subjects, completed 5 weeks of endurance training [cycle ergometer exercise for 45 min, three times per week at a heart rate corresponding to 70% of that achieved at the maximal O2 consumption (VO2max) either at sea level or at high altitude] in a hypobaric chamber, under either normobaric [sea level, SL; 750 mmHg (100 kPa) approximately 90 m] or hypobaric [altitude, ALT; 554 mmHg (73.4 kPa) approximately 2500 m] conditions and the changes in SL VO2max, SL endurance time and peak blood lactate during the endurance test compared. While each group showed increases in both SL VO2max (approximately 12%) and SL endurance time (approximately 71%), there were no significant differences between the groups [SL VO2max, mean (SE)-SL group: pre-training = 42.4 (3.5), post-training = 46.1 (3.5) ml.kg-1.min-1, P < 0.005; ALT group: pre-training = 40.8 (2.6), post-training = 47.2 (3.4) ml.kg-1.min-1, P < 0.01; SL endurance time-SL group: pre-training 7.1 (1.5), post-training 11.8 (2.9) min, P < 0.01; ALT group: pre-training = 7.5 (0.6), post-training = 13.3 (1.4) min, P < 0.001]. Peak blood lactate during the endurance test was not altered by either training regimen. It is concluded that acute exposure of untrained subjects to hypobaric hypoxia during endurance training has no synergistic effect on the degree of improvement in either SL VO2max or endurance time.

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Section: Discussionsupporting

confidence: 87%

Training-induced increases in sea level V?O2 m a x and endurance are not enhanced by acute hypobaric exposure

Emonson

Aminuddin

Wight

et al. 1997

European Journal of Applied Physiology

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“…It seems hypoxia can blunt the sensitivity of adrenocortieal response to the ACTtI stimulus. Thus, although on arrival at high altitude during the early stages the adrenal cortical activity is increased and it returns to normal when acclimatization is well advanced, a higher tftre of ACTH is necessary to mainrain this activity (Siri et al, 1966). In individuals predisposed to HAPO the drop in plasma cortisol may therefore be related to a higher degree of hypoxaemia which is found in them than in those who are immune (Penaloza and Sime, 1969;Singh et al, 1967).…”

Section: As All the S U B J E C T S W E R E Known S U S C E P T I B Lmentioning

confidence: 99%

Changes in plasma cortisol, blood antidiuretic hormone and urinary catecholamines in high?altitude pulmonary oedema

Singh

Malhotra²,

Khanna³

et al. 1974

Int J Biometeorol

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“…A number of studies have demonstrated that a sojourn at high altitude increases [EPO] in the blood and urine (Siri et al 1966;Carmena et al 1967;Faura et al 1969;Abbrecht and Littel 1972;Miller et al 1973;Milledge and Coates 1985;Klausen et al 1991;Richalet et al 1994). However, the rise in [EPO] with altitude again shows great individual variability (Richalet et al 1994;Klausen et al 1996b).…”

Section: Introductionmentioning

confidence: 99%

Erythropoietin acute reaction and haematological adaptations to short, intermittent hypobaric hypoxia

Rodríguez¹,

Ventura

Casas

et al. 2000

European Journal of Applied Physiology

125

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This study aimed to determine whether brief hypoxic stimuli in a hypobaric chamber are able to elicit erythropoietin (EPO) secretion, and to effectively stimulate erythropoiesis in the short term. In two different experiments, a set of haematological, biochemical, haemorheological, aerobic performance, and medical tests were performed in two groups of healthy subjects. In the first experiment, the mean plasma concentration of EPO ([EPO]) increased from 8.7 to 13.5 mU.ml-1 (55.2%; P < 0.01) after 90 min of acute exposure at 540 hPa, and continued to rise until a peak was attained 3 h after the termination of hypoxia. In the second experiment, in which subjects were exposed to a simulated altitude of up to 5500 m (504 hPa) for 90 min, three times a week for 3 weeks, all haematological indicators of red cell mass increased significantly, reaching the highest mean values at the end of the programme or during the subsequent 2 weeks, including packed cell volume (from 42.5 to 45.1%; P < 0.01), red blood cell count (from 4.55 x 10(6) to 4.86 x 10(6).l-1; P < 0.01), reticulocytes (from 0.5 to 1.4%; P < 0.01), and haemoglobin concentration (from 14.3 to 16.2 g.dl-1; P < 0.01), without an increase in blood viscosity. Arterial blood oxygen saturation during hypoxia was improved (from 60% to 78%; P < 0.05). Our most relevant finding is the ability to effectively stimulate erythropoiesis through brief intermittent hypoxic stimuli (90 min), in a short period of time (3 weeks), leading to a lower arterial blood desaturation in hypoxia. The proposed mechanism for these haematological and functional adaptations is the repeated triggering effect of EPO production caused by the intermittent hypoxic stimuli.

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Early erythropoietin, blood, and physiological responses to severe hypoxia in man.

Cited by 66 publications

References 0 publications

Training-induced increases in sea level V?O2 m a x and endurance are not enhanced by acute hypobaric exposure

Training-induced increases in sea level V?O2 m a x and endurance are not enhanced by acute hypobaric exposure

Changes in plasma cortisol, blood antidiuretic hormone and urinary catecholamines in high?altitude pulmonary oedema

Erythropoietin acute reaction and haematological adaptations to short, intermittent hypobaric hypoxia

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