Prior to joining LIU, Runkel most recently served as an assistant coach at Manhattan College for the past two seasons. At Manhattan, Runkel helped coach the defense and special teams units. During the 2019 season, he helped mentor first team All-MAAC goalkeeper Brendan Krebs and also assisted with the top-ranked man-down unit in Division I during the 2018 and 2019 seasons. Prior to Manhattan, Runkel was a volunteer assistant coach at Yale University where he helped the Eli's to two-consecutive Ivy League Championships in 2016 and 2017. He began his coaching career at Georgetown University as a volunteer assistant coach in 2015.

A 2014 graduate of Loyola University (Md.), Runkel received USILA All-America honors as a goalkeeper and helped the program win its first NCAA Division I National Championship in 2012. He was named to the 2012 NCAA All-Tournament Team and also earned Patriot League Goalie of the Year accolades in 2014. Runkel and the 2012 Loyola defense hold the record for the fewest amount of goals given up in a National Championship game (3).