title: Graded hypoxia and blood oxidative stress during exercise recovery.
abstract: Altitude exposure and exercise elicit oxidative stress in blood; however, exercise recovery at 5000 m attenuates oxidative stress. The purpose was to determine the altitude threshold at which blood oxidative stress is blunted during exercise recovery. Twelve males 18-28 years performed four-cycle ergometry bouts (60 min, 70% VO2max, at 975 m). In a randomised counterbalanced crossover design, participants recovered 6 h at 0, 1667, 3333 and 5000 m in a normobaric hypoxia chamber (recovery altitudes were simulated by using a computerised system in an environmental chamber by lowering the partial pressure of oxygen to match that of the respective altitude). Oxygen saturation was monitored throughout exercise recovery. Blood samples obtained pre-, post-, 1 h post- and 5 h post-exercise were assayed for ferric-reducing antioxidant plasma, Trolox equivalent antioxidant capacity, uric acid, lipid hydroperoxides and protein carbonyls. Muscle biopsies obtained pre and 6 h were analysed by real-time polymerase chain reaction to quantify expression of hemeoxgenase 1, superoxide dismutase 2 and nuclear factor (euthyroid-derived 2)-like factor. Pulse oximetry data were similar during exercise, but decreased for the three highest recovery elevations (0 m = 0%, 1667 m = -3%; 3333 m = -7%; 5000 m = -17%). A time-dependent oxidative stress occurred following exercise for all variables, but the two highest recovery altitudes partially attenuated the lipid hydroperoxide response (0 m = +135%, 1667 m = +251%, 3333 m = +99%; 5000 m = +108%). Data may indicate an altitude threshold between 1667 and 3333 m, above which the oxidative stress response is blunted during exercise recovery.
authors: a Cardioprotection Laboratory, School of Kinesiology , Auburn University , Auburn , AL , USA.
authors: Bridget
authors: B
authors: Peters
authors: a Cardioprotection Laboratory, School of Kinesiology , Auburn University , Auburn , AL , USA.
authors: Christopher
authors: C
authors: Ballmann
authors: a Cardioprotection Laboratory, School of Kinesiology , Auburn University , Auburn , AL , USA.
authors: Graham
authors: G
authors: Mcginnis
authors: a Cardioprotection Laboratory, School of Kinesiology , Auburn University , Auburn , AL , USA.
authors: Erin
authors: E
authors: Epstein
authors: a Cardioprotection Laboratory, School of Kinesiology , Auburn University , Auburn , AL , USA.
authors: Hayden
authors: H
authors: Hyatt
authors: b University of Nebraska at Omaha , Omaha , NE , USA.
authors: Dustin
authors: D
authors: Slivka
authors: c Department of Health and Human Performance , University of Montana , Missoula , MT , USA.
authors: John
authors: J
authors: Cuddy
authors: c Department of Health and Human Performance , University of Montana , Missoula , MT , USA.
authors: William
authors: W
authors: Hailes
authors: c Department of Health and Human Performance , University of Montana , Missoula , MT , USA.
authors: Charles
authors: C
authors: Dumke
authors: c Department of Health and Human Performance , University of Montana , Missoula , MT , USA.
authors: Brent
authors: B
authors: Ruby
authors: a Cardioprotection Laboratory, School of Kinesiology , Auburn University , Auburn , AL , USA.
authors: John
authors: J
authors: Quindry
mesh_terms: D000293:Adolescent; D000328:Adult; D000531:Altitude; D000975:Antioxidants / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood; D002839:Chromans / Q000097:blood; D018592:Cross-Over Studies; D015444:Exercise / Q000502:physiology*; D015870:Gene Expression; D006801:Humans; D000860:Hypoxia; D008054:Lipid Peroxides / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D050050:Protein Carbonylation; D014527:Uric Acid / Q000097:blood; D055815:Young Adult
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D002839:Chromans; D008054:Lipid Peroxides; D014527:Uric Acid; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; D010100:Oxygen
keywords: altitude; exercise; oxidative stress; reactive oxygen species