Career
He competed internationally on the track, road, and also in cross country competitions. He ran in the Marathon at the 1991 World Championships in Tokyo, finishing in 16th place with a time of 2:22:17. That year he also competed in the IAAF World Cross Country Championships, but he only managed to finish in 29th position.
The following year he competed at the 1992 Summer Olympics, but he did not finish in the Olympic Marathon race.
At the Amsterdam Marathon in 1993, he took second behind Kenichi Suzuki with a time of 2:12:27. At the Paderborner Osterlauf Half Marathon in Germany, Dirks took first place 1989 and again 1991.
Dirks retired from competitive athletics in 1995 and began training athletes, including Luc Krotwaar, Miranda Boonstra.