Ireland’s Caitriona Jennings has set a new women’s 100-mile world record at the 2025 Tunnel Hill 100 Mile in Vienna, Illinois, finishing in 12 hours, 37 minutes, and 4 seconds, more than five minutes faster than Camille Herron’s previous record of 12:42:40, set on the same course in 2017.
Running in her first-ever 100-mile race, Jennings averaged a pace of 7:34 per mile (4:42/km) over the 160.9 km distance. Her splits were remarkably consistent, within a few seconds per mile through the first 80 miles, before only slightly slowing in the final hours.
She placed fourth overall in the race and first among women.
“Words can’t describe this feeling,” Jennings wrote on social media after the race. “Big shout to Camille Herron for showing us it was possible. I’m truly honoured to take this record from a true champion.”
The Tunnel Hill 100 is known for its fast, flat course along the Tunnel Hill State Trail, a crushed-gravel rail trail in southern Illinois that passes through its namesake tunnel.
The race, which also hosts a 50-mile event, has been the site of multiple world records, including Herron’s 2017 mark and several age-group bests. Jennings’s new record will be subject to ratification by the International Association of Ultrarunners (IAU).
Jennings, who represents Letterkenny AC, has steadily built a reputation as one of Ireland’s top ultrarunners.
Earlier this year, she set the national 50k record at the Donadea 50k in 3:16:33, and she already held the Irish 100k record of 7:43:01, set in 2021. She also won the 2022 IAU 50k European Championships and has finished in the top 10 at the Comrades Marathon multiple times.
Before turning to ultras, Jennings competed in the marathon at the 2012 London Olympics, and her background on the roads has clearly transferred well to the demands of the ultradistance, particularly her ability to hold pace hour after hour.
Her record at Tunnel Hill caps off a strong year for Irish distance running and adds to a growing list of standout women’s performances at long-distance ultras. It also underscores how much the 100-mile distance continues to evolve as more elite road athletes take it on with professional-level preparation and pacing precision.
Jennings’s performance will now await official verification, but for now, her mark stands as the fastest women’s 100-mile time ever recorded.
