In 1925 Sipilä broke the world record at the unusual distance of 20,000 metres, running 1:06:29.0 in Stockholm and breaking Ville Kyrönen's record of 1:07:07.2 from the previous year. At the 1928 Summer Olympics Sipilä represented Finland in the marathon, but only placed 15th; a month after the Olympics he broke the world record for 30,000 metres at Tampere, running 1:43:07.8. In the same race, Martti Marttelin broke the 25,000 m world record as a split.