Rainer won the bronze medal in the women's singles event at the 1979 FIL World Luge Championships in Königssee, West Germany.

[2] In addition, she won two medals at the FIL European Luge Championships with a silver (women's singles, 1980) and a bronze (mixed team, 1988).

Rainer also won the overall Luge World Cup title in women's singles in the 1985–86 season.

Competing in four Winter Olympics (1976–1988), Rainer had her best finish of sixth in the women's singles event at Sarajevo in 1984.

[1] Later in her career, Rainer served as race director of the women's singles event at the 2006 Winter Olympics in Torino.