title: Long-term intermittent hypoxia increases O2-transport capacity but not VO2max.
abstract: Long-term intermittent hypoxia, characterized by several days or weeks at altitude with periodic stays at sea level, is a frequently occurring pattern of life in mountainous countries demanding a good state of physical performance. The aim of the study was to determine the effects of a typical South American type of long-term intermittent hypoxia on VO2max at altitude and at sea level. We therefore compared an intermittently exposed group of soldiers (IH) who regularly (6 months) performed hypoxic-normoxic cycles of 11 days at 3550 m and 3 days at sea level with a group of soldiers from sea level (SL, control group) at 0 m and in acute hypoxia at 3550 m. VO2max was determined in both groups 1 day after arrival at altitude and at sea level. At altitude, the decrease in VO2max was less pronounced in IH (10.6 +/- 4.2%) than in SL (14.1 +/- 4.7%). However, no significant differences in VO2max were found between the groups either at sea level or at altitude, although arterial oxygen content (Ca(O(2) )) at maximum exercise was elevated (p < 0.001) in IH compared to SL by 11.7% at sea level and by 8.9% at altitude. This higher Ca(O(2) ) mainly resulted from augmented hemoglobin mass (IH: 836 +/- 103 g, SL: 751 +/- 72 g, p < 0.05) and at altitude also from increased arterial O(2)-saturation. In conclusion, acclimatization to long-term intermittent hypoxia substantially increases Ca(O(2) ), but has no beneficial effects on physical performance either at altitude or at sea level.
authors.affiliation: Department of Sports Medicine and Sports Physiology, University of Bayreuth, Germany. nicole.prommer@uni-bayreuth.de
authors.forename: Nicole
authors.initials: N
authors.lastname: Prommer
authors.forename: Katja
authors.initials: K
authors.lastname: Heinicke
authors.forename: Teresa
authors.initials: T
authors.lastname: Viola
authors.forename: Jorge
authors.initials: J
authors.lastname: Cajigal
authors.forename: Claus
authors.initials: C
authors.lastname: Behn
authors.forename: Walter F J
authors.initials: WF
authors.lastname: Schmidt
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000097:blood*; D000704:Analysis of Variance; D001810:Blood Volume; D002677:Chile; D004906:Erythrocyte Count; D004911:Erythrocyte Volume; D004921:Erythropoietin / Q000097:blood; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D000860:Hypoxia / Q000097:blood*; D008297:Male; D008889:Military Personnel; D010101:Oxygen Consumption