Doug Turnbull started training in Kyokushin in 1971 under the then Sensei John Taylor. He attained shodan in 1975, nidan in 1980, sandan in 1985, yondan in 1990, and godan in 1996. The first 4 were obtained under the banner of the Australian Kyokushin Karate Association (AKKA) which was affiliated with the IKO in Japan. The last was obtained under the International Federation of Karate (IFK), which was formed in 1991 when Hanshi Steve Arneil left the IKO.

He has been teaching karate since 1976, and founded his own dojo in Marrickville in 1982 at which he still teaches.

He attained an International Referee's certificate, which is for full-contact kumite, is accredited for non-contact kumite, including mirror judging, Kyokushin kata judging, and, while the Federation of Australian Karatedo Organisations (FAKO) still existed, had a "C" level FAKO accreditation as a judge. (The organisation has since been restructured and renamed as the AFK (Australian Federation of Karate). He is currently also an accredited National All Styles (NAS) referee.

He has participated in almost all NSW state tournaments as a judge and/or referee since 1981, and has participated in all the national training camps between and including 1983-1993. In 1997 he was a referee at the finals of the IFK World Championships in Moscow.

His competition experience includes a first place in the NSW kumite championship (quite an achievement for a man of his stature in the days before weight categories), and two kata first place titles (one at State and the other at National level).

On the administrative side, he was on the judging panel for the State Senior Gradings during 1994 and 1995, and has been a Tournament Organising Committee member since 1983. He was Editor-in-Chief of "SHIN", the national Kyokushin magazine, from 1983 to 1987. He was also Junior Vice Chairman for the New South Wales AKKA from 1990 until it split up in 1994, and is currently Chairman of the IFKKA.

He has also had the good fortune of training at Honbu dojo in Japan.