Tucker, R.Onywera, V.O.Santos-Concejero, J.2014-11-142014-11-142014International Journal of Sports Physiology and Performance [2014]1555-02651555-0273http://ir-library.ku.ac.ke/handle/123456789/11658PURPOSE: This study aimed to investigate the ethnicity of Kenya's most successful international runners, tracking their evolution over the period of their international emergence and current dominance. METHODS: We analysed male track distance events from 800m upwards from all the major global athletics championships from 1964 to 2013, and the annual Top-25 world marathon performances since 1990. RESULTS: We found that the percentage of Top-25 marathon performances and medals won by Kenyan and Kalenjin runners have increased over time with Nandi sub-tribe outperforming the rest of the world outside Africa (r>0.70; large effect). However, Europe, North America, Oceania, Asia and South America decreased over time in Top marathon performances and track medals won by (r>0.70; large effect). The tribe and sub-tribe distribution was different in the marathon than in the track: Maasais were more likely to feature in medals won in shorter track events than in the Top-25 of the world marathon rankings (RR=9.67; very large effect). This was also the case for Marakwets (RR=6.44; very large effect) and Pokots (RR=4.83; large effect). On the other hand, Keiyos, Kikuyus, Kipsigis, Sabaots and Tugens were more likely to succeed in the marathon than in shorter track events (RR>2.0, moderate effect). CONCLUSION: These data emphasise that the previously documented emergence of African distance runners is primarily a Kenyan phenomenon, driven by the Kalenjin tribe and in particular the Nandi sub-tribe. This supports the complex interaction between genotype, phenotype and socio-economic factors driving the remarkable dominance of Kenyan distance runners.enArticle