Introduction: The purpose of this study was to test the hypothesis that there was no significant difference between the aerobic and anaerobic component of performance with the critical speed model and that training is responsible for two different physiological phenotypes in two groups of Kenyan runners belonging to the same ethnic group and village (Kissi). Methods: In order to compare the aerobic and anaerobic component of the Kenyan vs. non Kenyan best performers (from 800 to 10,000m) we compared their critical velocity and anaerobic distance capacity using the critical power model with 2 components (1). VO2 was measured breath by breath using a portable gas analyser (K4b2, Cosmed) during an incremental exhaustive running test performed on a running track. The subjects were 20 elite Kenyan runners: 13 men (10-km performance time: 10-km performance time of 28 min, 36 s ±18 s) and 7 women (32 min, 32 s ±65 s). The male runners were separated into high-speed training runners (HST: N = 6) and low-speed training runners (LST: N =7) depending on whether they train at speeds equal or higher than those associated with the maximal oxygen uptake (vVO2max). All but one woman were high-speed training runners (female HST: N =6). Subjects performed an incremental test on a 400-m track to determine VO2max, vVO2max, and the velocity at the lactate threshold (vLT). Results: There was no significant difference of critical speed or anaerobic distance capacity between Kenyan or non Kenyan runners (21.3±0.6 vs. 22.1±0.6 km.h-1, p = 0.07) for CV and (213±68 vs. 185±69 m, p = 0.45) for ADC. Within each gender among the HST group, 10-km performance time was inversely correlated with vVO2max (rho =0.86, P =0.05, and rho =0.95, P =0.03, for men and women, respectively). HST male runners had a higher VO2max, a lower (but not significantly) fraction of vVO2max (FvVO2max) at the lactate threshold, and a higher energy cost of running (ECR). Among men, the weekly training distance at vVO2max explained 59% of the variance of vVO2max, and vVO2max explained 52% of the variance of 10-km performance time. Kenyan women had a high VO2max and FVO2max at vLT that was lower than their male HST counterparts. ECR was not significantly different between genders. Conclusion The critical speed, vVO2max and ADC of the Kenyan or non Kenyan top 20 best performer middle and long distance runners were not significantly different. However, ADC is only an indirect marker of anaerobic capacity which must be explored with oxygen deficit. Caucasian non Kenyan runners have a non significant higher vVO2max extrapolated from 3000m performance considering the time limit at VO2max reported in literature (7 min). Kenyan have polarized training even inside one training session and practice skills that could contribute positively to this ability for speed variation that allows for energetic optimisation (1).
© Copyright 2009 14th annual Congress of the European College of Sport Science, Oslo/Norway, June 24-27, 2009, Book of Abstracts. Veröffentlicht von The Norwegian School of Sport Sciences. Alle Rechte vorbehalten.