From 1982 Schulz boxed for the army sports club Vorwärts in Frankfurt (Oder), later becoming the East German youth champion. From 1986 onward, he was a Stasi informer under the codename "Markus". At the junior European championships in Denmark in 1986, Schulz won the light-heavyweight title, and in 1988, under the tutelage of Manfred Wolke, he became East German heavyweight champion. In 1989 he won the Chemiepokal in Halle (Saale), the silver medal at European Championships in Athens, and a bronze medal in the world championships in Moscow, where he lost to Félix Savón.