She finished ninth at the 2004 Olympic Games. She competed at the World Championships in 2003 and 2005 without reaching the finals.
At the 2005 European Indoor Championships her last jump was measured to 6.96 metres, which would have secured her the gold medal by a comfortable margin. However, the jump was really around 6.65 m and Kappler admitted that 6.96 was a mismeasurement. The silver medal was won in 6.64 m, while Kappler remained with 6.53 m. She was later awarded a bronze medal for fair play.
At the 2007 European Indoor Championships she finished fourth, equalling her indoor personal best of 6.63 metres.