thought Rojo's comments here were very interesting regarding lack of Japanese success in running on the track compared to Americans, esp all american NCAA x-country runners who are, like me, almost all of european descent
The Japanese have 4 (3.5 if you count Hakim Sani Brown as half japanese) sub-10 second 100 meter runners!
One country in Asia alone has produced more sub-10 second 100 meters athletes than every white nation in the world together has produced. America has never produced a white sub-10 second 100 meter runner, Japan has produced 4(3.5) and has several more now on the edge of going sub 10
the 100 meters is probably the one track event that emphasizes genetic endowment the most. i have no doubt the Japanese could produce 3:4x milers and 12:xx 5k runners, but they are a people who obsess over running in only the extreme ends and have little regard for the event in between.
It seems Japanese are also genetically designed for sprinting as well as marathoning and Judo and wrestling and increasingly boxing