I would agree that there are groups of people who are probably better at something because of genetic predisposition that others, sprinters included, but most of the winning Olympic sprinters can trace their heritage back to a specific area within Africa, not just generally Africa.
And you can make an argument that in a specific terrain selection pressure on sprinting was very high, hence this outcome. You can not really make this argument for playing chess, at all. And your statement really does imply that blacks are not as smart as whites. Which is racist. If you want to answer that with something like: There have been less black scientists than white scientists, you would be right with that statement, but that also has nothing to do with intelligence, but with socio-economic, agricultural, historical as well as other factors which placed people from Africa and their descendants into a much worse starting position.