For her first race, McArthur went up against Nam Phan, a 20-year-old college student from Missouri. Anna McArthur competes during the national finals of "American Ninja Warrior." Now, with her Season 18 run officially over, fans won't see McArthur on the "ANW" course for a while. AdvertisementAdvertisement AdvertisementMcArthur has worked there since she was 11 — around the same time she gave up being a gymnast and violinist to focus on "American Ninja Warrior" training, the Deseret News previously reported. Anna McArthur competes during the qualifying round of "American Ninja Warrior" Season 18.