Hartmann grew up in Rockford, Michigan and graduated from Rockford High School in 1999. He made his first national team as a junior runner at the 2000 IAAF World Cross Country Championships, where he finished in 66th place. He went on to earn a BA in education and sociology at the University of Oregon and competed in distance events for the Oregon Ducks athletic team. He earned six All-America honours during his time there, with highlights being fourth place in the 10,000 meters at the NCAA Outdoor Championships in 2002 and 2003, and two runner-up finishes in the event at the Pac-10 championships.