title: Training in normobaric hypoxia and its effects on acute mountain sickness after rapid ascent to 4559 m.
abstract: In a randomized, placebo-controlled, double-blind study, we tested a 4-week program in normobaric hypoxia that is commercially offered for the prevention of acute mountain sickness (AMS). Twenty-two male and 18 female healthy subjects [mean age 33 +/- 7 (SD) years] exercised 70 min, 3 x /week for 3 weeks on a bicycle ergometer at workloads of 60% VO2max either in normoxia (normoxia group, NG) or in normobaric hypoxia (hypoxia group, HG), corresponding to altitudes of 2500, 3000, and 3500 m during weeks 1, 2, and 3, respectively. Four passive exposures of 90 min in normoxia (NG) or hypoxia corresponding to 4500 m (HG) followed in week 4. Five days after the last session, subjects ascended within 24 h from sea level to 4559 m (one overnight stay at 3611 m) and stayed there for 24 h. AMS was defined as LL (Lake Louise score) > or =5 and AMS-C > or =0.70. The AMS incidence (70% in NG vs. 60% in HG, p = 0.74), LL scores (7.1 +/- 4.3 vs. 5.9 +/- 3.4, p = 0.34), and AMS-C scores (1.50 +/- 1.22 vs. 0.93 +/- 0.81, p = 0.25) at the study endpoint were not significantly different between the groups. However, the incidence of AMS at 3611 m (6% vs. 47%, p = 0.01) and the functional LL score at 4559 m were lower in HG. SpO2 at 3611 m, heart rate during ascents, and arterial blood gases at 4559 m were not different between groups. We conclude that the tested program does not reduce the incidence of AMS within a rapid ascent to 4559 m, but our data show that it prevents AMS at lower altitudes. Whether such a program would prevent AMS at higher altitudes, but with slower ascent, remains to be tested.
authors.affiliation: Department of Sports Medicine, Medical Clinic, University Hospital Heidelberg, Heidelberg, Germany. kai.schommer@med.uni-heidelberg.de
authors.forename: Kai
authors.initials: K
authors.lastname: Schommer
authors.forename: Neele
authors.initials: N
authors.lastname: Wiesegart
authors.forename: Elmar
authors.initials: E
authors.lastname: Menold
authors.forename: Ute
authors.initials: U
authors.lastname: Haas
authors.forename: Katrin
authors.initials: K
authors.lastname: Lahr
authors.forename: Hermann
authors.initials: H
authors.lastname: Buhl
authors.forename: Peter
authors.initials: P
authors.lastname: Bärtsch
authors.forename: Christoph
authors.initials: C
authors.lastname: Dehnert
mesh_terms: D000064:Acclimatization; D000328:Adult; D000532:Altitude Sickness / Q000453:epidemiology / Q000517:prevention & control*; D001784:Blood Gas Analysis; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D000860:Hypoxia; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010092:Oximetry; D010806:Physical Education and Training / Q000379:methods*
chemical_list: D006454:Hemoglobins; D019344:Lactic Acid