I knew a fellow boy scout who was black sans fat. He absolutely sunk like a rock. It was very difficult for him to tread water.
Some professor was studying racial differences and his funding got axed.
I knew a bodybuilder who said they had to cut calf muscle development from judging for that sport because blacks have higher placed / smaller calf muscles than whites. This gives blacks a decisive advantage in sprinting - the calf placement and fast twitch muscles.
If there are 19 of the top 20 of a specific sport of a specific race... might be a correlation to physiology.