Zimmermann won the German individual épée championship in 1955 and 1957.[2] He was a consistent presence at the top of German épée fencing over the following decade, finishing runner-up at the national championships in 1962, 1965, and 1968, and third in 1961, 1964, and 1966.[3] With the DFC Düsseldorf team, he won the Solinger Schwert tournament in 1961, and the club also won the German team épée championship in 1964.[4] Later in his career, he won multiple German senior (veterans') championships.[4]
Zimmermann represented the United Team of Germany at the 1960 Summer Olympics in Rome, competing in the men's team épée, where Germany finished equal fifth.[1][5]
Ahead of the 1964 Summer Olympics, Zimmermann ranked third on the West German épée list and would have been eligible for selection. However, sports official Güse deemed him "nicht mannschaftsdienlich" (not conducive to team spirit) and excluded him from the squad. The criticisms levelled against him included making frequent reclamations to referees, offering lengthy explanations for his own defeats, and his habit of screaming during bouts—his characteristic "Hööh" was said to make both himself and the team look ridiculous.[6] The practice of screaming—to signal a perceived touch to the referee or to psychologically unsettle an opponent—has since become commonplace in competitive fencing.[7]
Zimmermann returned to the Olympics at the 1968 Summer Olympics in Mexico City, representing West Germany. In the individual épée, he was eliminated in the third round, finishing tied for 13th place—the best result among the West German entrants, alongside Franz Rompza.[1] In the team épée, the West German squad of Zimmermann, Rompza, Dieter Jung, Max Geuter, and Paul Gnaier narrowly missed a medal, finishing fourth.[1][5]
