|Representing West Germany|
|World Indoor Championships|
|1989 Budapest||400 m|
Arendt was born in Cologne, North Rhine-Westphalia. In 1987 she finished fourth at the 1987 European Indoor Championships, only 0.01 second behind bronze medalist Cristina Pérez. Later that year she competed at the 1987 World Championships. In the 4 x 400 metres relay she finished fifth with teammates Ute Thimm, Gudrun Abt and Gisela Kinzel. She also competed in the individual 400 metres distance, but did not reach the final round of competition.
On 20 February the next year Arendt helped set a world indoor record of 1:32.55 minutes in the 4 x 200 metres relay, with Silke Knoll, Mechthild Kluth and Gisela Kinzel of the sports club SC Eintracht Hamm. At the 1988 European Indoor Championships she won a silver medal in the 400 metres, placing between East Germans Petra Müller and Dagmar Neubauer. At the 1988 Olympic Games she finished seventh in the 400 metres and fourth in the 4 × 400 m relay, with Ute Thimm, Andrea Thomas and Gudrun Abt.
In 1989 came the highlight of Arendt's career as she won the gold medal at the World Indoor Championships. She finished ahead of American Diane Dixon, who had finished fifth at the Olympics, with a margin of 0.25 seconds. At the 1990 European Championships, however, Arendt was again knocked out before the final round of the 400 metres competition, only reaching the semi-final. She finished fourth in the 4 x 400 metres relay with teammates Karin Janke, Andrea Thomas and Silke Knoll.
Arendt represented the sports clubs Pulheimer SC, ASV Köln, SC Eintracht Hamm and LG Olympia Dortmund during her active career. She became West German champion in 1988 and 1989, as well as West German indoor champion in 1987, 1988 and 1989. Her personal best times were 23.13 in the 200 metres, achieved in July 1988 in Frankfurt am Main, and 50.36 in the 400 metres, achieved in the 1988 Olympic semi-final in Seoul.
Arendt was 1.78 metres tall; during her active career she weighed 66 kilograms.
- "Dr. Eick & Partner: Helga Arendt". Dr-eick.de. Archived from the original on 2014-07-15. Retrieved 2013-06-17.
- Kölner 400-m-Weltmeisterin starb mit 49 Jahren, express.de
- Ex-Hallenweltmeisterin Arendt gestorben, zeit.de
- 1987 European Indoor Championships, women's 400 m final - Die Leichtatletik-Statistik-Seite
- 1988 European Indoor Championships, women's 400 m final - Die Leichtatletik-Statistik-Seite
- 1988 Olympic Games, women's results - Sporting Heroes.net
- 1989 World Indoor Championships, women's 400 m final - Die Leichtatletik-Statistik-Seite
- Detailed results of the 1990 European Championships Archived 2008-01-24 at the Wayback Machine
- West German championships, women's 400 m
- West German indoor championships, women's 400 m
- World women's all-time best 200m (last updated 2001)
- World women's all-time best 400m (last updated 2001)