 Zadro started boxing under Jimmy Sharman in 1972 at Mareeba, North Queensland, and he trained in Judo under the Kodokan Judo Association from 1973 to 1975.After moving to Sydney with his family, he studied Tae Kwon Do from 1975 to 1979 at the Marconi Club in Bossley Park, and attained the rank of Junior Black Belt.In 1979 he went on to study Ken Sei Kan Karate Do and continued on until 1981 at Greystanes, Sydney where he attained the rank of Shodan (first degree black belt).