Taskinen was Finnish national under-19 champion at 800 m in 1970 and national under-21 champion at both 400 m and 800 m in 1971. He won his first national senior titles in 1973, winning both 400 m (47.9) and 800 m (1:50.0) at the Finnish championships. He repeated as 800 m champion in 1974, but was not expected to even make the final at that year's European Championships in Rome.