In 1985 Ystborg won gold in the All-Around and with clubs, silver with ribbon and bronze with rope at the Norwegian Championships.[2][3] In October she made her World Championships debut in Valladolid, competing along Ellen Gunderson and Schirin Zorriassateiny, being 45th overall.[4][5]
The following year she got gold overall, with ball, and with ribbon as well silver with rope at nationals.[6] She was then selected for the European Championships in Florence, being 41st in the All-Around.[7][8]
In 1987 she took all the gold medals at the Norwegian Championships, and was called up for the World Championships in Varna, Bulgaria, being 43rd in the All-Around.[9][10]
She repeted her national accolades in 1988. In May she competed at the European Championships in Helsinki, being 45th in the All-Around.[11][12][13]
At the 1989's nationals she won gold in the All-Around, with rope, with ball and with ribbon, also taking silver with hoop.[14] After a year of stop she competed again nationally in 1991, winning gold with rope, silver with clubs and bronze in the All-Around, with hoop and with ball.[15]
In 1992 she took bronze with hoop at the Norwegian Championships.[16] She retired from the sport shortly after.