 He was also a member of the German relay team which was disqualified in the final of the 4 × 100 m relay after a fault with its second baton passing.Rau started competing in flat sprint and hurdles in 1908, winning several national championships and setting 20 national records over his career, often under pseudonym Richard Einsporn.After retirement he ran a sports shop, and in 1933 joined the Nazi Party, reaching the rank of SS Hauptsturmbannführer in 1938.