title: Peak oxygen uptake and regional oxygenation in response to a 10-day confinement to normobaric hypoxia.
abstract: We investigated the effect of hypoxic acclimatization per se, without any concomitant influence of strenuous physical activity on muscle and cerebral oxygenation. Eight healthy male subjects participated in a crossover-designed study. In random order, they conducted a 10-day normoxic (CON) and a 10-day hypoxic (EXP) confinement. Pre and post both CON and EXP confinements, subjects conducted two incremental-load cycling exercises to exhaustion; one under normoxic, and the other under hypoxic (F(I)O(2)  = 0.154) conditions. Oxygen uptake (V˙O(2)), ventilation (V˙(E)), and relative changes in regional hemoglobin oxygenation (Δ([HbO(2)]) in the cerebral cortex and in the serratus anterior (SA) and vastus lateralis (VL) muscles were measured. No changes were observed in the CON confinement. Peak work rate and V˙O(2peak) were similar pre and post in the EXP confinement, whereas V˙(E) increased in the EXP post normoxic and hypoxic trials (P < 0.05). The exercise-induced drop in VL Δ[HbO(2)] was less in the post- than pre-EXP trial by 4.0 ± 0.4 and 4.2 ± 0.6 μM during normoxic and hypoxic exercise, respectively. No major changes were observed in cerebral or SA oxygenation. These results demonstrate that a 10-day hypoxic exposure without any concomitant physical activity had no effect on normoxic or hypoxic V˙O(2peak), despite the enhanced VL oxygenation.
authors.affiliation: Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.
authors.forename: S N
authors.initials: SN
authors.lastname: Kounalakis
authors.forename: M E
authors.initials: ME
authors.lastname: Keramidas
authors.forename: O
authors.initials: O
authors.lastname: Eiken
authors.forename: P
authors.initials: P
authors.lastname: Jaki Mekjavic
authors.forename: I B
authors.initials: IB
authors.lastname: Mekjavic
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D002540:Cerebral Cortex / Q000378:metabolism* / Q000502:physiology; D018592:Cross-Over Studies; D015444:Exercise / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D010108:Oxyhemoglobins / Q000378:metabolism; D005082:Physical Exertion / Q000502:physiology*; D052097:Quadriceps Muscle / Q000378:metabolism* / Q000502:physiology; D019265:Spectroscopy, Near-Infrared; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; D010100:Oxygen
keywords: altitude acclimatization; cerebral frontal cortex; exercise; intercostal muscle; near-infrared spectroscopy