On September 3, 1970, at the 1970 Summer Universiade in Turin, she set a world record in the long jump at 6.84 m [3] that stood for almost six years.

She won the long jump gold medal in the 1972 Munich Olympics with a leap of 6.78 m, one centimetre ahead of Diana Yorgova of Bulgaria.

To further prove her versatility, Rosendahl helped the West German 4 × 100 m team with Christiane Krause, Ingrid Mickler-Becker and Annegret Richter to the gold medal and a world record.

She had a degree in physical education and worked as athletics coach at TSV Bayer 04 Leverkusen (1976–1990) and Deutsche Leichtathletik-Verband (1993–2001).

She is married to John Ecker, an American basketball player who won the 1969, 1970 and 1971 NCAA Championships as a member of the UCLA Bruins.