Why are Kenyan Runners Superior?

During the last three decades, Kenyans have dominated middle- and long-distance races. In fact, 55 per cent of the Top 20 lists for men in distances from 800m to marathon are Kenyans. Furthermore, the number of Kenyans in the top 50 lists in the same distances has increased more than 150 per cent from 1990 to 2000.

In addition, 70 per cent of these achievements have been made by runners belonging to a group of eight small tribes called Kalenjin even if this group only constitutes about 11 per cent (3 million) of the Kenyan population. This is a unique phenomenon within the world of sports. The reasons for this dominance are still not known but factors that may play a role are genetic endowment, upbringing and training.

Outstanding performance in long distance running requires primarily an optimal combination of high capacity for aerobic energy output, a high fractional utilisation of VO2max during competition and good running economy. Therefore, different studies of these parameters were performed on Kalenjin elite runners as well as untrained Kalenjin (Nandi) boys and were compared with Danish counterparts. Different factors of importance for the above mentioned parameters were investigated and comparisons of the physiological response to 12 weeks of endurance training for untrained Kalenjin town and village boys as well as Danish boys were made.

The studies revealed that Kalenjin and Danish elite runners have very high but similar VO2max and that untrained Kalenjin boys had the same VO2max as Danish boys. Regarding VO2max untrained Kalenjin boys show similar response to endurance training as Danish boys.

Kalenjin elite runners have superior running economy compared to their Danish counterparts just as untrained Kalenjin town and village boys have better running economy than untrained Danish boys. The adaptation to training of the running economy was similar in the three groups of boys. A moderate correlation between lower leg volume divided by lower leg length (mean lower leg thickness) and running economy was observed for the untrained boys as well as for elite runners.

Kalenjin village boys run significantly faster in a 5000m competition following 12 weeks of endurance training compared to Danish boys having similar VO2max despite the fact that both groups of boys are running at the same percentage of VO2max as judged from the mean heart rates during the competition. The superior performance of the Kalenjin village boys is probably due to the observed better running economy of these boys.

Kalenjin and Danish elite runners have similar muscle fiber composition and oxidative capacity (CS-activity) in their leg muscles. Untrained Kalenjin and Danish boys have similar oxidative capacity and adapt to endurance training to the same extent.

Conclusions

• Untrained Kalenjins and Danes have similar initial VO2max and show the same trainability of VO2max. Kalenjin and Danish elite runners can reach very high but similar VO2max.
  
  
• Kalenjin elite runners as well as untrained Kalenjin boys have superior running economy compared to their Danish counterparts. This is probably due to the fact that the Kalenjins have more slender legs and thus use relatively less energy for swinging the legs when running. Therefore, moderately trained Kalenjin boys perform better in a competition than Danish boys who have completed similar endurance training.
  
  
• Moderately trained Kalenjin and Danish boys run at a very high but similar percentage of VO2max during a 5000m competition.