Siegmund has competed at six Paralympic Games, his first in 1984 where, representing East Germany, he competed in triple jump and won silver medals in both the long jump and pentathlon. He then missed 1988 (East Germany did not participate) before returning for the 1992 Summer Paralympics where -now representing a reunified Germany- he won the B2 javelin as well as competing in various other events. 1996 saw Siegmund finish second in the javelin but miss out on the discus and shot putt. In 2000 he won his second gold medal at javelin while 2004 saw him end up second. His sixth Paralympics saw him finish seventh in the javelin.