title: Maintained cerebral oxygenation during maximal self-paced exercise in elite Kenyan runners.
abstract: The purpose of this study was to analyze the cerebral oxygenation response to maximal self-paced and incremental exercise in elite Kenyan runners from the Kalenjin tribe. On two separate occasions, 15 elite Kenyan distance runners completed a 5-km time trial (TT) and a peak treadmill speed test (PTS). Changes in cerebral oxygenation were monitored via near-infrared spectroscopy through concentration changes in oxy- and deoxyhemoglobin (Δ[O2Hb] and Δ[HHb]), tissue oxygenation index (TOI), and total hemoglobin index (nTHI). During the 5-km TT (15.2 ± 0.2 min), cerebral oxygenation increased over the first half (increased Δ[O2Hb] and Δ[HHb]) and, thereafter, Δ[O2Hb] remained constant (effect size, ES = 0.33, small effect), whereas Δ[HHb] increased until the end of the trial (P < 0.05, ES = 3.13, large effect). In contrast, during the PTS, from the speed corresponding to the second ventilatory threshold, Δ[O2Hb] decreased (P < 0.05, ES = 1.51, large effect), whereas Δ[HHb] continued to increase progressively until exhaustion (P < 0.05, ES = 1.22, large effect). Last, the TOI was higher during the PTS than during the 5-km TT (P < 0.001, ES = 3.08; very large effect), whereas nTHI values were lower (P < 0.001, ES = 2.36, large effect). This study shows that Kenyan runners from the Kalenjin tribe are able to maintain their cerebral oxygenation within a stable range during a self-paced maximal 5-km time trial, but not during an incremental maximal test. This may contribute to their long-distance running success.
authors.affiliation: Department of Physical Education and Sport, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain; UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa; jordan.santos@ehu.es.
authors.forename: J
authors.initials: J
authors.lastname: Santos-Concejero
authors.affiliation: Department of Kinesiology, University Laval, Quebec, Canada;
authors.forename: F
authors.initials: F
authors.lastname: Billaut
authors.affiliation: Department of Sport Science, University of Stellenbosch, South Africa; and.
authors.forename: L
authors.initials: L
authors.lastname: Grobler
authors.affiliation: Department of Physiology, European University of Madrid, Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Oliván
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa;
authors.forename: T D
authors.initials: TD
authors.lastname: Noakes
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa;
authors.forename: R
authors.initials: R
authors.lastname: Tucker
mesh_terms: D000328:Adult; D056352:Athletes / Q000706:statistics & numerical data*; D002560:Cerebrovascular Circulation; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007630:Kenya / Q000208:ethnology; D010100:Oxygen / Q000097:blood*; D012420:Running / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: African runners; blood flow; near-infrared spectroscopy; oxyhemoglobin; performance