Karlsen competed in one of the 1996 World's Strongest Man qualifying heats and narrowly missed qualifying for the finals.
Some of Karlsen's other notable strongman titles include Europe's Strongest Man 2001, 3 time runner-up at the Arnold Strongman Classic 2002-04, World Muscle Power Championships 2001 winner, and 3 time Norway's Strongest Man in 2003, 2005 and 2006.