At the
1982 European Championships she finished fourth in the 400 m, before winning a
gold medal in the
4 × 400 metres relay, together with teammates
Kirsten Siemon,
Dagmar Rubsam and
Marita Koch. At the
1983 World Championships she finished fifth in her 400 m semifinal and was eliminated, but won another gold medal in the relay, with teammates
Gesine Walther, Koch and Rübsam. She ran her 400 m lifetime best of 49.24 in Erfurt, in June 1984, but was prevented from competing at the 1984 Olympics, due to the Eastern Bloc Boycott.
Busch switched to the 400 m hurdles in 1985, with immediate success, winning the European Cup in
Moscow in 54.13 secs, before breaking
Margarita Ponomaryova's
world record of 53.58, with 53.55 in
Berlin in September.[1] She ended the season by winning at the World Cup in Canberra in 54.44.
In 1987, Busch won the 400 m title at the
World Indoor Championships in Indianapolis. The highlight of her career came at the
1987 World Championships in Rome, where she won a clear victory in the 400 m hurdles in 53.62 secs, to become world champion. She won a second gold medal in the relay with Emmelmann, Neubauer (Rubsam) and Muller. At the
1988 Olympic Games in
Seoul she finished fourth in the final of the
400 m hurdles, being edged out of the
bronze medal by her GDR teammate
Ellen Fiedler (53.63 – 53.69). She did win a bronze medal in the relay alongside her teammates Neubauer, Emmelmann and Muller.
In 1991, Busch represented a United Germany at the
World Championships in Tokyo, where she was eliminated in the semi-finals in 55.93 secs.
Busch's career best time at the 400 m hurdles was 53.24 seconds, achieved in August 1987 in
Potsdam. As of 2013, this is still the German record.[2] Her personal best time in the 400 metres of 49.24 seconds, places her second on the German all-time list, only behind
Marita Koch.[2] On the world all-time lists, she ranks 16th at 400 m and 24th at 400 m hurdles.