Before her professional cycling career, Thorburn had been a cross-country runner at Grinnell College in her native state Iowa, where she earned a bachelor of science degree in chemistry. Thorburn discovered competitive cycling when she enrolled as a graduate student at Stanford University School of Medicine. An old knee injury that sidelined her running career turned her sights to cycling, and eventually, she was encouraged by some of her friends to join the university's club team. In 1998, she helped Stanford mount a second-place finish at the USA Cycling Collegiate Road National Championships. After receiving her medical degree from Stanford in 1999, Thorburn took a break from competitive cycling to undergo a professional residency in internal medicine. Upon returning to a relatively leisure schedule from her limited medicine studies, Thorburn started riding for the Webcor Builders Women's Amateur Cycling Team in 2002. She established an early breakthrough by joining the U.S. team at the UCI World Championships and by scoring her first ever triumph at the U.S. Championships in 2004, which handed her an Olympic selection. An official member of the USA Cycling team, Thorburn made her worldwide debut at the 2004 Summer Olympics in Athens, where she finished fifteenth in the women's road race, and fourth in the women's time trial, narrowly missing out the Olympic podium by twenty seconds. At the 2006 UCI World Championships in Salzburg, Austria, Thorburn joined her teammate Kristin Armstrong to stand on the podium for the first time in the event's history, as she delivered the Americans a bronze-medal time in 35:34.25. Two years later, Thorburn qualified for her second U.S. squad, as a 38-year-old, in women's road cycling events at the 2008 Summer Olympics in Beijing by receiving one of the nation's three available berths from the UCI World Cup and by being finally chosen to the USA Cycling team. In the women's road race, held on the second day of the Games, she successfully completed a grueling race with a fifty-second-place effort in 3:41:08, surpassing New Zealand'sCatherine Cheatley by a few inches. Three days later, in the women's time trial, Thorburn missed another chance to claim an Olympic medal by three seconds after finishing with a fifth-place time in 35:54.16. Shortly after her second Olympics, Thorburn announced her official retirement from competitive cycling to focus on her full-time medical career as a rheumatologist at the Palo Alto Medical Clinic. She also currently resides in Menlo Park, California with her husband Ted Huang, a prominent Mistral windsurfer and a former two-time Olympian from Chinese Taipei.
