Isaksen competed at the 2008 Summer Olympics at age 16. She finished in 21st place in the women’s modern pentathlon event. She finished first overall in the women’s modern pentathlon event at the 2011 Pan American Games. This qualified her for the modern pentathlon event at the 2012 Summer Olympics where she placed fourth, despite having suffered from mononucleosis only a few weeks before. Isaksen went on to win the 2013 Rio World Cup, shortly thereafter.