Damn, that's interesting!

My point is, you are putting too much emphasis on genetic gifts. Take a sport like basketball, where being tall is clearly an advantage. It's a much bigger advantage than "small calves" are in running. You basically can't play in the NBA at all unless you're 6ft or taller.

Even among people 6ft 9 and up, you really have to practice with a good teacher. Someone who's a foot shorter will easily beat you if they are good.

Running isn't just "moving your legs". There's strategy that these guys learn from their running group at a young age. They practice running as a sport. That's why they're good.

It's the same reason why people from the US, who are all genetically different, play basketball and baseball better than most other countries. They practice it competitively when they're young.