After missing the 2011 season with a back injury, Theisen bounced back in 2012 with a personal best score of 6440 to win her third NCAA heptathlon title. She also became the second-highest scoring Canadian heptathlete in history and the second-highest scorer in NCAA meet history.
A graduate of the University of Oregon, Theisen has represented Canada at three World Championship events (Youth, 2005; Juniors, 2006 and Seniors 2009). She won Canadian heptathlon titles in 2009 and 2013. Also in 2013, Theisen won the prestigious Hypo-Meeting in Götzis, Austria. In July 2013 she married American decathlete Ashton Eaton, the 2012 Olympic champion.