Shortly after Shelton began running ultramarathons she won several races and soon became one of the top female ultrarunners in the United States.
[5] In 2006, she traveled with Scott Jurek, Christopher McDougall, and several other ultrarunners as the sole female runner to Copper Canyon in the remote southwestern part of the state of Chihuahua in Mexico to run with the Tarahumara, for McDougall's book Born to Run.
[6] She has criticized the book's accounts of the Tarahumara people for "romanticizing" their lifestyle and for not adequately describing their poverty.
[7] In May 2007 she gained publicity by being the first woman finisher at the Frederick Marathon, in a women's course record of 2 hours 53 minutes 44 seconds, racing in a bikini rather than conventional running kit.
[11] She is sponsored by Patagonia[12] and competed in the 2012 U.S. Olympic Marathon Trials, but suffered a hamstring injury and did not finish.