Krüsmann also competed in the individual distance, and finished fifth. In domestic competitions, Wellmann represented the sports club VfL 1848 Bochum. After retiring he became a coach.
He was German 400 metres trainer from 1990 to 1996.
During this period the 4 x 400 metres relay team finished third at the 1993 World Championships.
At the 1966 European Championships he won a silver medal in 4 x 400 metres relay, together with teammates Friedrich Roderfeld, Jens Ulbricht and Manfred Kinder. At the 1972 European Indoor Championships he won a silver medal in the 4 x 360 metres relay, together with Peter Bernreuther, Georg Nückles and Ulrich Reich. He won the bronze medal at the 1966 West German championships and the silver medal at the 1967 West German indoor championships.
