BOSTON, MA — The Boston Marathon Expo is typically a place for picking up bibs, testing out carbon-plated shoes, and soaking in the pre-race jitters. But on Saturday, April 18, 2026, the thousands of runners flowing through the Hynes Convention Center became witnesses to a historic feat of endurance that redefined the limits of stationary running.
Elite ultrarunner Ashley Paulson didn’t just break the women’s 100-mile treadmill world record; she systematically dismantled it, finishing in a staggering unofficial time of 12 hours, 47 minutes, and 10 seconds.
Pending official ratification by Guinness World Records, Paulson’s performance lops approximately 88 minutes off the previous mark of 14:15:08. For those of us on the ground watching the belt spin mile after mile, it was a display of metronomic consistency and raw mental grit.
The Anatomy of a Record: 3:46 AM to Glory
The journey began in the hollow, quiet hours of the early morning. At 3:46 a.m., long before the first cup of coffee was poured on Boylston Street, Paulson stepped onto the stage. The strategy was ambitious: maintain a pace hovering around 7:40 per mile—a speed that many marathoners struggle to hold for 26 miles, let alone 100 miles on a stationary machine.
Treadmill running is notoriously more taxing mentally than road running. Without the changing scenery of a trail or city street, the “pain cave” becomes a psychological vacuum. Supported by her husband, Matt, Paulson remained locked in. She took only five brief bathroom breaks over the course of the day, never letting the momentum dip.
The Science of the Slay: Fueling and Focus
A key component of Paulson’s strategy involved a highly calculated fueling protocol. As a brand ambassador for Aspire BioPharma, she utilized their Buzz Bomb™ liquid caffeine supplement to maintain cognitive focus and manage the massive physical fatigue of 100 miles.
The fast-acting delivery system appeared to pay dividends. As the hours ticked into the double digits—the point where many ultra-athletes begin to “fade” or experience gastrointestinal distress—Paulson looked remarkably fluid. The combination of high-octane fueling and her legendary cardiovascular engine kept the belt moving at a clip that shocked the spectators gathered at the Expo.
From Solitude to a “Wall of Sound”
As the Expo doors opened to the general public, the atmosphere shifted from a quiet endurance test to a high-energy arena. By the time Paulson hit the 75-mile mark, a massive crowd of Boston-bound runners had formed a semi-circle around the stage.
The energy was infectious. Every time the treadmill’s display ticked over another mile, the crowd erupted. This “wall of sound” provided the external motivation needed to combat the physiological toll of the final 20 miles. Paulson, a 44-year-old mother of four from St. George, Utah, thrived in the spotlight, acknowledging the crowd even as she maintained her punishing pace.
The “Year of Ashley” Continues
This performance serves as a massive exclamation point on what has already been a career-defining year for Paulson. Only two months ago, she set the road world record for 100 miles at the Jackpot 100 in Nevada, clocking a 12:19:34.
Transitioning that speed to a treadmill is a feat of technical brilliance. On a treadmill, there is no “coasting” or natural variation in stride that comes with terrain changes; it is a relentless, repetitive motion that can lead to significant muscular imbalances and fatigue. Paulson’s ability to remain injury-free and efficient over 100 miles of stationary movement is a testament to her training and biomechanical efficiency.
Monday’s Big Question
With the 126th Boston Marathon scheduled for Monday, the question on everyone’s mind at the Hynes was simple: Is she still running? While most humans would require weeks of recovery after a 100-mile world record attempt, Paulson is known for her freakish recovery times. Whether she lines up in Hopkinton or chooses to celebrate her new world record from the sidelines, she has already provided the most memorable performance of the weekend.
For the community at Marathon Journal, witnessing this level of athletic excellence first-hand serves as a reminder of why we cover this sport. Ashley Paulson didn’t just move a treadmill belt today; she moved the bar for what is possible in the world of ultra-endurance.
