Maybe some countries are that much better at sports because they invest money into it? Facilities, medics, training, athlete development programs etc.
Providing facilities, medics, dietitians, etc. does not hurt, of course. Makes for great PR. Having your guys in charge of testing for dope helps create the actual results, though.
That said, if you truly believe superhumans exist, that's fine too. Even if it strikes me as rather naive. It helps patriotism and whatnot. A man needs his pride