They sampled 74 Kalenjin adults aged 18-61, ... Generally, it is easier for men to develop not just upper-body strength, but strength in any body part, compared to women, ...

The Kalenjin people dominate long-distance running, and it seems there's no one secret. Their body structure, training regimen and traditions all appear to contribute to their incredible success.

“There were 32 Kalenjin who did it in October of 2011.” There certainly are several factors at play in the Kalenjin dominance, but one is their particular body type.