Trason was a top runner in high school, but a knee injury kept her from competing in college.
Trason's ultra career began when she entered the 1985 American River 50 Miler at age 24 and both won and set a course record (she returned 8 years later and dropped her time an hour to establish the 6:09 course record that still stands).
Trason did not finish her first two times trying to run the Western States 100; in 1987 she dropped out due to knee problems and in 1988, near the finish line, from dehydration. She finished and won it in 1989. She has won Western States 14 times in all, most recently in 2003. She held the women's division course record for 18 years (17:37:51, set in 1994) until it was broken by Ellie Greenwood in 2012.
Trason appears in Christopher McDougall's accounts of the Leadville Trail 100 in the 1990s in his 2009 book, Born to Run: A Hidden Tribe, Superathletes, and the Greatest Race the World Has Never Seen. Her time of 18:06:24 in the Leadville which she ran in 1994, is the women's course record.
In both 1996 and 1997 Trason performed the "double" of winning the Western States 100 just 12 days after winning the 56-mile Comrades Marathon in South Africa.
Trason and her ex-husband and training partner Carl Andersen co-directed The Dick Collins Firetrails 50 from 2000 through 2010. Trason set the female course record on the Firetrails 50 the one time she ran it, in 1987.
- 6:09:08 – American River 50 mile
- 3:59:32 – Cool Canyon Crawl 50K
- 7:31:24 – Firetrails 50 mile (1987)
- 6:13:54 – Hunter Thompson 50 mile
- 18:06:24 – Leadville Trail 100 women's record (2nd place overall in 1994)
- 8:55:49 – Miwok 100K Trail Race (2001)
- 6:43:00 – Quicksilver 50 mile
- 7:29:36 – Silver State 50 mile
- 7:00:47 – World 100K (1995)