 He won two medals at the 1964 Winter Olympics, a silver in the 4 × 10 km relay and a bronze in the 50 km.Additionally, Tianen won two medals at the FIS Nordic World Ski Championships, a silver in 50 km (1966) and a bronze in the 4 × 10 km relay (1958).Tianen's biggest cross-country skiing success came at the Holmenkollen ski festival, where he won the 50 km event in both 1964 and 1965.