title: Effects of short-term normobaric hypoxia on haematology, muscle phenotypes and physical performance in highly trained athletes.
abstract: This study aimed to determine the impact of short-term normobaric hypoxia on physiology and performance in highly trained athletes. Twelve (7 male and 5 female) athletes were randomly assigned into two groups and spent 8 h per night for two consecutive nights a week over 3 weeks under either short-term normobaric hypoxia (simulating 3636 m altitude, inspired O2=13%) or in normobaric normoxia in a single-blind study. Following a 3 week washout period, athletes were then exposed to the other condition. Athletes were tested for maximal oxygen consumption and time to exhaustion on an electromagnetically braked cycle ergometer before and after each treatment in addition to being tested for anaerobic performance (Wingate test) on a modified Monark cycle ergometer. Blood samples were taken throughout the experiment and vastus lateralis muscle biopsies were taken before and after each treatment. Increases in red blood cell count, haematocrit, haemoglobin, platelet number and erythropoietin concentration were observed following short-term normobaric hypoxia. Except for a modest decrease in phosphofructokinase activity following short-term normobaric hypoxia, no changes were observed in muscle enzyme activities, buffer capacity, capillary density or morphology. No performance measures were changed following short-term normobaric hypoxia or normobaric normoxia. Although short-term normobaric hypoxia exposure increased levels of a number of haematological parameters, this was not associated with improved aerobic or anaerobic performance in highly trained athletes.
authors.affiliation: School of Human Kinetics and Recreation, Memorial University of Newfoundland, St John's, NL, Canada A1C 5S7. fbasset@mun.ca
authors.forename: Fabien A
authors.initials: FA
authors.lastname: Basset
authors.forename: Denis R
authors.initials: DR
authors.lastname: Joanisse
authors.forename: Frédéric
authors.initials: F
authors.lastname: Boivin
authors.forename: Josée
authors.initials: J
authors.lastname: St-Onge
authors.forename: François
authors.initials: F
authors.lastname: Billaut
authors.forename: Jean
authors.initials: J
authors.lastname: Doré
authors.forename: Richard
authors.initials: R
authors.lastname: Chouinard
authors.forename: Guy
authors.initials: G
authors.lastname: Falgairette
authors.forename: Denis
authors.initials: D
authors.lastname: Richard
authors.forename: Marcel R
authors.initials: MR
authors.lastname: Boulay
mesh_terms: D000531:Altitude; D001274:Atmospheric Pressure; D018592:Cross-Over Studies; D004906:Erythrocyte Count; D004921:Erythropoietin / Q000097:blood; D005080:Exercise Test; D005260:Female; D006400:Hematocrit; D006801:Humans; D000860:Hypoxia / Q000097:blood / Q000201:enzymology / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D010101:Oxygen Consumption; D025203:Phosphofructokinase-1, Muscle Type / Q000378:metabolism; D005082:Physical Exertion / Q000502:physiology*; D010976:Platelet Count; D016037:Single-Blind Method; D013177:Sports / Q000502:physiology*
chemical_list: D004921:Erythropoietin; D025203:Phosphofructokinase-1, Muscle Type