He held a scholarship at the Studienstiftung from 1983 to 1984. From 1984 to 1993, Heizmann was a research assistant at the Scandinavian Seminar at the University of Göttingen. He obtained a PhD at LMU Munich in 1987, and completed his habilitation at the University of Göttingen in 1994.

Since 1994, Heizmann taught at the University