Career
In October 2010, after winning two world titles at the inline skating championships in Colombia, he ended second in the USOC Athlete of the Month competition. As of January 7, 2010, Mantia held the world records for the road race over 500 m (386 seconds), 10,000 m (13 minutes and 46801 seconds) and 20,000 m (28 minutes and 56189 seconds), and the world records for the track race over 300 m (24250 seconds) and 15,000 m (22 minutes and 32644 seconds). In 2011, Mantia switched to speed skating on ice, finishing fourth at the 2011 United States speed skating championships over 5000 m, tenth in the 1000 m and eighth in the 1500 m.
He represented team United States of America at the 2014 Sochi Winter Olympics.
Personal records
As of February 20, 2016, his ranking on the all-time Adelskalender is 45th.