 Complete the following phrase:  Larsen became the Danish national 5,000 and 10,000m champion in 1937, earning Helsingør IFs first running title. He went on to capture ten more national championships, nine in the marathon 1941, 19431950 and one in the 20 km 1950, as well as coming in third place in the 10,000m in 1938. In 1946 he set the Danish national record for the marathon at 2:38:36 and competed in that years 