Aleuts are generally shorter than Mongolians and the Pygmies are shorter than the Watusi. The 2001 Men's Boston Marathon was won by a South Korean and an Ecuadorian finished in 2nd place. However, East Africans won 8 out of the top 20 positions. These results do not suggest that our socially constructed races explain the outcomes in this particular competition. It is notable that the winners in the men's race also came from mountainous countries.
Many distance runners train at high altitude.
Training can produce physiological adaptation, increase lung capacity, blood volume, and convert fast muscle twitch fibers to slow twitch fibers. The lack of Eastern African dominance in the women's race is particularly problematic for any racial explanation of distance performance. The Women's pattern seems robust. Women and men share 22 chromosomes in common and differ only at the Y chromosome. The Y chromosome has few genes, and it would be hard to construct a genetic theory of race on this basis.