We seem to go through this every few months. There are no differences in testosterone levels between white and black males. This has been studied thoroughly already.
Black males are not stronger or weaker, in general. Yes, the nordic Europeans seem to produce more high level strength athletes, same with Eastern Europe but there are exceptions all over.
Africans have an advantage with speed (which carries over to many sports) and some have fuller muscle bellies, particularly in the arms and shoulders.