Career
Youth
Tiernan took up distance running in his home town, Toowoomba where he ran road races up to the 10K distance. Collegiate
Tiernan was recruited by Villanova in January 2013 and missed out on the first indoor and outdoor track seasons. At the 2014 National Collegiate Athletic Association DI Indoor T&F Championships, Tiernan finished in seventh place in the 5000 meters final round.
At the 2014 National Collegiate Athletic Association DI Outdoor T&F Championships, Tiernan placed sixth in the 5000 meters, earning his first All-American honors in track and field in his National Collegiate Athletic Association collegiate career.
He placed second overall at the 2015 National Collegiate Athletic Association DI Cross Country Championships behind Edward Cheserek. 2012: 1st, Gold Coast 10km run, Gold Coast, Queensland, Australia.