Issues of purity are central to modern sport, as well as to modernity in general. This paper ponders the role of purity in modern sport by also including its counterpart, hybridity, in the discussion. In sport studies, the concept of the 'human' is identified as something taken for granted, and therefore remains under-theorized. Bruno Latour's conception of modernity and scientific practice is here combined with Sigmund Loland's analogy between scientific experiments and sport competitions. Purity is assumed to be related to the idea of modern sport as a practice, which revolves around distilling samples of 'humanness' that should not be polluted by non-human interference. This paper argues that while modern sport strives to minimize non-human impact, it acknowledges the hybrid material that sport results are moulded from. The concept 'Human' is therefore not an a priori in modern sport but an a posteriori.