Running News Daily

In a stunning display of endurance and precision pacing, emergency-room physician and ultramarathon standout Anne Flower blazed to a new women’s world record of 5:18:57 for the 50-mile distance at the 2025 Tunnel Hill 50 Mile in Vienna, Illinois. The mark shatters the previous record of 5:31:56 held by Courtney Olsen, set on the same course last year.

Record-Setting Performance

Held on the flat, crushed-gravel rails-to-trails route of the Tunnel Hill State Trail, the race has become a proving ground for world-class performances. Flower averaged an extraordinary 6:23 per mile (3:57 per kilometer) across the full 80.47 km course, running even splits and showing no signs of strain even as temperatures climbed later in the race.l

From the opening miles, Flower stayed well ahead of record pace, never faltering and closing strongly to seal a performance that redefines the women’s 50-mile standard. Olsen, competing in the 100k event this year, passed the 50-mile mark in 5:33:59—still an elite split, but more than 15 minutes behind Flower’s record pace.

From Marathons to Ultramarathons

Based in Colorado Springs, Colorado, Flower balances her demanding career as an emergency-room doctor with elite-level training. Before moving to the trails in 2019, she competed in marathons and took part in the 2020 U.S. Olympic Marathon Trials. Her road background shows in her efficient stride and disciplined pacing.

Over the past two seasons, she has built an impressive résumé:

Winner of the 2024 Javelina 100k

Champion of the 2025 Silver Rush 50 Mile

Record-breaker at the 2025 Leadville 100 Mile, where she eclipsed Ann Trason’s 31-year-old mark in her debut at the distance

These results paved the way for her dominant performance at Tunnel Hill, demonstrating both her endurance and her remarkable consistency.

 Raising the Bar for Women’s Ultrarunning

Flower’s 5:18:57 isn’t just fast—it’s a historic leap forward. Taking more than 12 minutes off a world record at this level is rare, and doing so with such control underscores her potential for even greater achievements ahead.

Tunnel Hill has become synonymous with world-record performances, and Flower’s run further cements the race’s reputation as one of the premier venues for ultradistance excellence.

 What’s Next

With records now at both 50 and 100 miles, Flower’s next challenge may be defending or lowering her new mark—or shifting her focus toward international championship events. Whatever path she chooses, her rise through the sport has been nothing short of extraordinary.

Anne Flower has proven that it’s possible to balance a demanding professional life with world-class athletic performance. Her blend of discipline, determination, and pure endurance has elevated her into the top tier of ultrarunning’s global elite.