There is a genetic component to athletic success but I wouldn't make a blanket assertion that non-blacks are slower. It has to do with genetics and numbers participating in a given sport. The Eastern block put out some great sprinters, doping notwithstanding. Are people of African (taking in account that continents do not contain a singular homogeneous population) origin simply faster than all other populations world-wide. I doubt it.
The limiting factor is amount of explosive muscle fibres you're born with and the ability of your nervous system to recruit said fibres. In the realm of strength/power/speed sports, some populations of folks may hold a genetic advantage prior to training. Just as Sherpas, when not being killed in avalanches, excel at high altitude living.
Blacks of West African lineage tend to dominate the ranks of sprinters. I don't have the numbers but it seems the majority of Blacks in the Americas trace their roots to W-A due to historical slave trading routes. That may account for the speed/power advantages for some US athletes.
But it's ridiculous to assert that whites are slower. Olympic weightlifters are among the most explosive in the world and have shown they outpace 100m guys for the first 20M. Chinese, Turks Greeks, Armenians, Russians, Bulgarians all dominate. Even Vasili Alexeyev could dunk a basketball.
Over the short haul, I'd take Don Beebe any day over any Kenyan distance runner, Sebastian Coe or Leon Lett for that matter.