Careth Arnold

About

Careth Arnold is an American ultrarunner born in Bangkok, Thailand and based in Paonia, Colorado, whose trajectory from first-ever trail race in 2021 to winning one of ultrarunning's most prestigious events in 2025 is one of the most extraordinary four-year arcs the sport has ever produced. Introduced to trail running by her sister-in-law, professional trail runner Lotti Brinks, during visits to Austin in 2020, Arnold ran her very first trail race — the Swamp 30K in Florida — in 2021 while still breastfeeding and won overall. She never competed in high school or college athletics. By 2025 she had secured at least six outright victories that included the men's field, and in August she became the first American (male or female) to win the TDS — the 148-kilometre race from Courmayeur across the Italian and French Alps to Chamonix with 28,000 metres of cumulative elevation gain — finishing in 22:58:52 with an 85-minute winning margin over second place. Just ten days later she won the Hurricane 100K in West Virginia, and she closed a stellar season with second place at the High Lonesome 100 in Colorado. Named the 9th UltraRunner of the Year for 2025, Arnold is an Altra Running sponsored athlete and mother of two daughters who has described herself as a stubborn woman who enjoys testing the limits of mind and body.

Notable Wins

• — TDS 2025 (first American to win
• — 22:58:52)
• — Hurricane 100K 2025
• — High Lonesome 100 2025 (2nd)
• — #9 US UltraRunner of the Year 2025
• — Swamp 30K 2021 (overall winner on debut)
• — Canyons 100K Golden Ticket finisher

Upcoming Races

Race History