In 1938, philosopher and music theorist Theodor Adorno compared modern popular music (and mass "serious" music too) to sport, considering both detrimental symptoms of a dehumanised modernity, marked by "a strict differentiation from games" and an "animalistic seriousness". This essay shows that the interwar avant-garde Czech music, despite its clearly playful character, did not avoid this animalistic seriousness, nor did it avoid sport or jazz. Quite the opposite: it accepted them as important inspirations, or even allied cultural productions: new music, sport and jazz were the building blocks of the new culture.