Introduction: It has been hypothesised that the ability to avoid a decline in cerebral oxygenation (Cox) during maximal endurance exercise is a critical determinant of performance, and may distinguish between elite and near-elite performers (1). To date, no study has ever tested this hypothesis in elite Kenyan runners, whose success in endurance running remains unelucidated. Therefore, the aim of this study was to investigate Cox responses during maximal self-selected and imposed pace running trials in elite Kenyan runners. Methods: Nine elite Kalenjin Kenyan runners (24.6 ± 3.2 years and 28.9 ± 0.4 min 10-km race time) performed a maximal incremental peak treadmill speed test (PTS) and a 5km time-trial (TT) on a treadmill. Changes in Cox were monitored via near-infrared spectroscopy every minute during the PTS test and every 0.5 km during the 5kmTT through concentration changes in oxy- and deoxyhaemoglobin (d[O2Hb] and d[HHb]). Tissue oxygenation index (TOI = d[O2Hb]/ d[O2Hb] + d[HHb]) was calculated and the normalised tissue haemoglobin index was used as an index of change in regional blood volume. Results: During the 5kmTT, d[O2Hb] rose over the first 2.5 km, and then remained constant until completion. TOI declined during the first 1.5 km, before remaining stable for the remainder of the 5kmTT. In contrast, during the PTS test there was a significant progressive decline in both d[O2Hb] and TOI during the last half of the test (p=0.001). Despite the significant decline during the PTS test, TOI was maintained at lower levels during the 5kmTT than at exhaustion in the PTS test (61.6 ± 7.3% vs. 69.2 ± 4.1%, p<0.05; ES=1.28). Discussion: Elite Kenyan runners are able to maintain Cox during self-paced 5kmTT, which is in contrast with previous studies investigating well-trained runners (2). Interestingly, elite Kenyan runners also appear to tolerate lower TOI values during a self-paced 5kmTT than during imposed maximal incremental exercise, suggesting a limitation to exercise other than cerebral oxygenation per se. The ability to maintain cerebral oxygenation within a stable range during self-paced strenuous exercise may partially explain the Kenyan running phenomenon.
© Copyright 2014 19th Annual Congress of the European College of Sport Science (ECSS), Amsterdam, 2. - 5. July 2014. Published by VU University Amsterdam. All rights reserved.