The purpose of the present study was to clarify the following: (1) whether steady state oxygen uptake (VO(2)) during exercise decreases after short-term intermittent hypoxia during a resting state in trained athletes and (2) whether the change in VO(2) during submaximal exercise is correlated to the change in endurance performance after intermittent hypoxia. Fifteen trained male endurance runners volunteered to participate in this study. Each subject was assigned to either a hypoxic group (n=8) or a control group (n=7). The hypoxic group spent 3 h per day for 14 consecutive days in normobaric hypoxia [12.3 (0.2)% inspired oxygen]. The maximal and submaximal exercise tests, a 3,000-m time trial, and resting hematology assessments at sea level were conducted before and after intermittent normobaric hypoxia. The athletes in both groups continued their normal training in normoxia throughout the experiment. VO(2) during submaximal exercise in the hypoxic group decreased significantly (P<0.05) following intermittent hypoxia. In the hypoxic group, the 3,000-m running time tended to improve (P=0.06) after intermittent hypoxia, but not in the control group. Neither peak VO(2) nor resting hematological parameters were changed in either group. There were significant (P<0.05) relationships between the change in the 3,000-m running time and the change in VO(2) during submaximal exercise after intermittent hypoxia. The results from the present study suggest that the enhanced running economy resulting from intermittent hypoxia could, in part, contribute to improved endurance performance in trained athletes.
"However, a study by Burtscher et al. (2010) showed that three 2-hour IHE sessions per week for 5 weeks can improve running performance and exercise economy, although the benefits tend to depend on an athlete's training phase. Likewise, the ability of longer IHE to improve exercise economy was also reported by Katayama et al. (2004). "
[Show abstract][Hide abstract] ABSTRACT: Different hypoxic training modalities have become a common addition to endurance athletes’ training during the last few decades. Recently, technological advancements allowing for the simple simulation of altitude exposure by employing normobaric hypoxia have led to an even greater increase in their utilisation. It has been suggested that, besides classical hypoxic protocols employing longer exposures (> 12 h∙day-1), performance can also be enhanced by intermittent protocols utilising shorter daily exposures (< 6 h∙day-1) either at rest or combined with exercise. Even though the latest study findings regarding their influence on improved performance are ambiguous, they are habitually used in elite and recreational sport, chiefly due to their convenience and simple application. This short review will focus on currently used hypoxic training modalities with special reference to the effects of protocols utilising short exposures on performance at sea level and altitude. Moreover, the main underlying physiological mechanisms that can lead to improved performance following protocols utilising short hypoxic exposures will be reviewed. We will also examine the individual variability in response to hypoxic stimuli and possible combinations of hypoxic modalities for enhancing performance following hypoxia manipulations. The cumulative body of knowledge, as reviewed in this paper, does not indicate a robust improvement in performance as a consequence of short intermittent exposures in normobaric hypoxia. However, beneficial adaptations can be anticipated in some athletes and an individualised approach is thus warranted.
"The changes in physiological functions experienced by explorers returning to sea level from high altitudes were documented as early as 1908 . High-altitude de-acclimatization has been noted in explorers , athletes , military personnel , high-altitude railway workers , and workers in high-altitude mines . Hypoxia is always considered the main threat to mammals at these altitudes, so high-altitude de-acclimatization is also considered de-acclimatization to hypoxia . "
[Show abstract][Hide abstract] ABSTRACT: The syndrome of high-altitude de-acclimatization commonly takes place after long-term exposure to high altitudes upon return to low altitudes. The syndrome severely affects the returnee's quality of life. However, little attention has been paid to careful characterization of the syndrome and their underlying mechanisms. Male subjects from Chongqing (n = 67, 180 m) and Kunming (n = 70, 1800 m) visited a high-altitude area (3650 m) about 6 months and then returned to low-altitude. After they came back, all subjects were evaluated for high-altitude de-acclimatization syndrome on the 3(rd), 50(th), and 100(th). Symptom scores, routine blood and blood gas tests, and myocardial zymograms assay were used for observation their syndrome. The results showed that the incidence and severity of symptoms had decreased markedly on the 50(th) and 100(th) days, compared with the 3(rd) day. The symptom scores and incidence of different symptoms were lower among subjects returning to Kunming than among those returning to Chongqing. On the 3(rd) day, RBC, Hb, Hct, CK, CK-MB, and LDH values were significantly lower than values recorded at high altitudes, but they were higher than baseline values. On the 50(th) day, these values were not different from baseline values, but LDH levels did not return to baseline until the 100(th) day. These data show that, subjects who suffered high-altitude de-acclimatization syndrome, the recovery fully processes takes a long time (≥100(th) days). The appearance of the syndrome is found to be related to the changes in RBC, Hb, Hct, CK, CK-MB, and LDH levels, which should be caused by reoxygenation after hypoxia.
PLoS ONE 07/2013; 8(5):e62072. DOI:10.1371/journal.pone.0062072 · 3.23 Impact Factor
"This AT model, in which athletes exercise in hypoxic conditions from seconds to hours for periods lasting from days to weeks (Millet et al., 2010). Hypoxia is produced artificially in rooms or hypobaric chambers as well as using hypoxicators, which enable the breathing of a gas mixture (Katayama et al., 2004). This solution was also used in swimmers (Truijens et al., 2003). "
[Show abstract][Hide abstract] ABSTRACT: It is possible to plan an altitude training (AT) period in such a way that the enhanced physical endurance obtained as a result of adaptation to hypoxia will appear and can be used to improve performance in competition. Yet finding rationales for usage of AT in highly trained swimmers is problematic. In practice AT, in its various forms, is still controversial, and an objective review of research concentrating on the advantages and disadvantages of AT has been presented in several scientific publications, including in no small part the observations of swimmers. The aim of this article is to review the various methods and present both the advantageous and unfavourable physiological changes that occur in athletes as a result of AT. Moreover, AT results in the sport of swimming have been collected. They include an approach towards primary models of altitude/hypoxic training: live high + train high, live high + train low, live low + train high, as well as subsequent methods: Intermittent Hypoxic Exposure (IHE) and Intermittent Hypoxic Training (IHT). Apnoea training, which is descended from freediving, is also mentioned, and which can be used with, or as a substitute for, the well-known IHE or IHT methods. In conclusion, swimmers who train using hypoxia may be among the best-trained athletes, and that even a slight improvement in physical endurance might result in the shortening of a swimming time in a given competition, and the achievement of a personal best, which is hard to obtain by normal training methods, when the personal results of the swimmer have reached a plateau.
Journal of Human Kinetics 06/2011; 28(-1):91-105. DOI:10.2478/v10078-011-0026-9 · 1.03 Impact Factor
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