title: Greater performance impairment of black runners than white runners when running in hypoxia.
abstract: This study aimed to compare the response of performance-matched black and white runners during maximal and sub-maximal running in normoxic and hypoxic conditions. 14 well-trained runners (8 black, 6 white) performed 2 incremental maximal exercise tests and 2 fatigue resistance tests at 21% O2 (normoxia) or 14% O2 (hypoxia). Respiratory parameters, heart rate (HR), lactate concentration ([La(-)]) as well as arterial saturation (SpO2) were measured. Enzyme activities and myosin heavy chain content (MHC) were also measured. White runners reached a significantly greater peak treadmill speed and a higher HRmax than black runners in hypoxia (p<0.05). Additionally, White runners achieved a greater time to fatigue than black runners (p<0.05), with black runners displaying a greater decline in performance in hypoxia compared to normoxia (20.3% vs. 13.4%, black vs. white, respectively). However, black runners presented lower [La(-)] and higher SpO2 than white runners in hypoxia (p<0.05). Black runners had a higher proportion of MHC IIa and higher lactate dehydrogenase activity (p<0.05). The greater performance impairment observed in black runners in hypoxia suggests a greater performance sensitivity to this condition, despite the maintenance of physiological variables such as SpO2 and [La (-) ] within a smaller range than white runners.
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, South Africa.
authors.forename: J
authors.initials: J
authors.lastname: Santos-Concejero
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, South Africa.
authors.forename: R
authors.initials: R
authors.lastname: Tucker
authors.affiliation: Stellenbosch University, Department of Physiological Sciences, Stellenbosch, South Africa.
authors.forename: K H
authors.initials: KH
authors.lastname: Myburgh
authors.affiliation: Swedish University of Agricultural Sciences, Department of Large Animal Clinical Sciences, Uppsala, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Essen-Gustavsson
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, South Africa.
authors.forename: T A
authors.initials: TA
authors.lastname: Kohn
mesh_terms: D000328:Adult; D000886:Anthropometry; D044383:Black People; D005080:Exercise Test; D005221:Fatigue / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology; D018995:Myosin Heavy Chains / Q000378:metabolism; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000502:physiology*; D012119:Respiration; D012420:Running / Q000502:physiology*; D044465:White People; D055815:Young Adult
chemical_list: D019344:Lactic Acid; D018995:Myosin Heavy Chains; D010100:Oxygen