i'm talking of genetic heritage not actualy physical strength.
such that, most often, if a child has a white parent and a black parent, the child will be more likely to be black than white.
or if one parent is bruenette and the other red head, the child will more likely be brunette.
of course it also relies on the actual person, some people have "stronger" genes than other people.
also generally the areas that produce the "strongest men" are relatively cold, generally areas where things are cold people are bigger, stronger, call it what you will, because you need a certain amount of mass to survive in that kind of enviroment, where as generally areas where black people heritage from are a lot hotter, more equatorial, therefore they are broadly leaner.
there are of course other influences which are a lot greater, like the old soviet states generally aimed very strongly towards the olympic games, and as such set up a very intensive training program - using large sums of money - where as predominatley black places (be they in Africa or even the USA) are poor.