Kåshagen competed at the European Athletics Team Championships six times between 2009 and 2017, three times in the lesser "First League" and three times in the Super League, the highest tier of competition.[1] In the First League, his best overall finish was 4th in the 4 × 400 m relay at the 2014 edition, and his best individual finish was 5th in the 400 m at the 2017 edition. In the Super League, Kåshagen only competed in the 4 × 400 m, finishing 11th in all three appearances in 2010, 2013, and 2015.[1]
Kåshagen's 2011 season was cut short due to a hip flexor injury, which Kåshagen's said was particularly frustrating because the winning time at the Norwegian Athletics Championships that year was only 48.99 seconds.[4]
At the 2015 Summer Universiade, Kåshagen competed in both the individual 400 m and the relay. In the individual event, he advanced past the first round on time but did not make the finals, registering the slowest overall time in the semis.[1] In the relay, Team Norway finished 4th in the heats and did not qualify for the final.[1]
In 2016, Kåshagen set personal bests in the indoor 200 metres and 400 metres of 21.36 seconds and 46.88 seconds respectively, times which are also better than his outdoor personal bests in those events. His 400 metres time stood as the Norwegian indoor national record until Olympic gold medalist Karsten Warholm broke it later in the season.[1] In June, Kåshagen was told that he was selected to compete in the individual 400 m at the 2016 European Athletics Championships, but that offer was controversially rescinded the next day as the Norwegian Athletics Association claimed they had made a mistake.[5] Kåshagen was nonetheless invited to competed on the 4 × 400 m relay, where his team finished last place in the heats despite being led off by Karsten Warholm.[6]
