Annexed by Germans in 1870, the region Alsace became French again, in 1918. After a triumphal welcom for the French troops, the Alsatians, influenced by 47 years of German presence, showcase very timidly their new nationality. In a France that cultivates anti-Germanism, the political and professional scenes do not, however, allow to claim the German heritage. It is different in the field of sport, which cultivates contradictions by playing its neutral and apolitical image. The local associations of sport maintains a special relationship with the borders and with those who live over the border. At the same time, the relationships are made of porosities and exchanges with Germany and of looking at the French territory or even at the Alsatian aera. This ambiguous positioning leads them to hesitate in two ways : on the one hand, They adopt a public posture advocating their attachment to the Republic; on the other hand, they undertake an "infrapolytic" posture of fiddling with the new borders. We will illustrate this phenomenon through the monograph of a rowing club, the “Cercle Nautique de Strasbourg”.