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

Abstract

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.

Diving experience and the aerobic dive capacity of muskrats: does training produce a better diver?

“…The paucity of experimental studies linking underwater experience with physiological diving capability is surprising, given the considerable attention devoted to the potential benefits of altitude hypoxia in boosting the body oxygen reserves of terrestrial mammals -especially humans (see Böning, 1997;Rodríguez et al, 2000). Exercise physiologists have repeatedly demonstrated that training at altitude increases Hct, Hb and serum erythropoietin levels (Mairbäurl, 1994;Klausen et al, 1996;Böning, 1997).…”

“…There is also evidence that altitude hypoxia in combination with exercise is more potent in stimulating erythropoiesis than is hypoxia alone (Mairbäurl, 1994). In a more recent study, Rodríguez et al (2000) reported that brief, intermittent episodes of hypobaric hypoxia presented over a 3-week period were sufficient to stimulate erythropoiesis and boost red cell mass, Hct and Hb levels of humans. The effects of hypoxia conditioning on muscle oxygen reserves are equivocal, though Terrados et al (1990) observed increased Mb levels in human leg muscle following hypobaric hypoxic training.…”

Effects of Intermittent Altitude Exposures on Acclimatization of 4,300 M

“…If RBC volume can be increased apart from a decrease in PV, then total blood volume could be increased and potentially enhance endurance performance following intermittent altitude exposures. However, given the unchanged [RBC] (24,25,70,72,80,88,104), whereas others (all from the same lab) have reported large increases in one or all of these parameters (19,86,87). The higher [Hb] and Hct reported in those studies (19,86,87) may be possible if there was also a large decrease in PV.…”

“…A recent study by Katayama et al (51) reported no change in V0 2ma x and HRmax, measured in hypobaric hypoxia, after lowlanders were exposed to 4,500 m for 1 h-d" for 7 d, but found a 5% increase in resting and maximal exercise Sa0 2 . Rodriguez et al (87) increase in exercise Sa0 2 , and a 22% increase in exercise VE, measured in hypobaric hypoxia, in lowlanders exposed to 5000 m for 2 h»d" 1 for 14 d. All of these studies on lowlanders suggest that resting intermittent exposures to high altitude induce a large degree of ventilatory acclimatization and some degree of hematological acclimatization. However, as in the studies on trained mountaineers, adequate measures of AMS and submaximal endurance performance were not made.…”

Entrenamiento en hipoxia intermitente y rendimiento ciclista en triatletas / Intermittent hypoxic training and cycling performance in triathletes

“…De este modo, la duración del programa o de la sesión puede modificar el grado de adaptación del individuo, siendo la duración mínima de la sesión para que esta sea un estímulo que supere el umbral de adaptación y produzca una reacción aguda de 90 min en los programas de IHE (Rodríguez et al, 2000) y de 60 min en los de IHT (Millet et al 2010). Hay que tener también en cuenta la frecuencia semanal, la altitud simulada o el tipo de hipoxia (hipobárica o normobárica), ya que son elementos que inciden en la variabilidad de los resultados y que deben de esclarecerse para una correcta aplicación de estos métodos (Millet el al., 2010).…”