Simpson was contending before the mishap about halfway through the race.
The 2015 Carlsbad 5000 was the 30th edition of the "World's Fastest 5K"
Bernard Lagat sets the masters world record at the 5K road distance.
These fast women are ready to tear up the road this weekend at Carlsbad.
She's rewritten the record books in track. Now she's hitting the roads.
She has never been beaten on the storied Hayward Field.
The Ethiopians aren't competing against each other.
Both the men's and women's fields are well represented by the East African nation.
19-year-old holds off rival Agnes Chebet Tirop at the finish.