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.

Enhanced muscular oxygen extraction in athletes exaggerates hypoxemia during exercise in hypoxia

“…In HYP, frontal cortex TOIs consistently were ϳ25% lower than in NOR in both of the groups. TOI slightly dropped from rest to EX 100W and further during EX MAX , but with no differences between the groups, which corroborates earlier reports from other groups (27,48,53). Still, compared with CON, the tHb increment produced by EX 100W and EX MAX was blunted in ATL.…”

Intermittent Palm Cooling’s Impact on Resistive Exercise Performance

“…levels within blood traveling to the brain. Perturbations to blood metabolite levels, such as lower O 2 or excess heat, produce higher RPE values and centrally mediated sensations of fatigue [25]. A subjective measure, RPE values were not obtained in our study, but offer insights into the brain's perceptions to various exercise bouts [25].…”

“…Perturbations to blood metabolite levels, such as lower O 2 or excess heat, produce higher RPE values and centrally mediated sensations of fatigue [25]. A subjective measure, RPE values were not obtained in our study, but offer insights into the brain's perceptions to various exercise bouts [25]. An activity that causes less heat to be sensed by the carotid bodies should be interpreted by the brain as being easier and elicit lower RPE values [21,25].…”

“…A subjective measure, RPE values were not obtained in our study, but offer insights into the brain's perceptions to various exercise bouts [25]. An activity that causes less heat to be sensed by the carotid bodies should be interpreted by the brain as being easier and elicit lower RPE values [21,25]. Exercise bouts with palm cooling elicited lower core temperature and RPE values, which caused the brain to perceive that workout required less effort vs. those with no palm cooling, or afforded the former exercise bout heightened neural drive [21].…”

Cerebral Regulation in Different Maximal Aerobic Exercise Modes

“…This system monitors the tissue absorption via optical fibers optodes with light sources and detectors. The COX was monitored with optodes placed over the prefrontal lobe at the Fp1 position, according to the international 10–20 system (Subudhi et al, 2008 ; Billaut et al, 2010 ; Santos-Concejero et al, 2015 ). The MOX was monitored over the right vastus lateralis (VL) muscle, the optodes were positioned at ~15 cm proximal and 5 cm lateral from the superior border of the patella (Subudhi et al, 2009 ); the adipose thickness was ≤5 mm at this point.…”