American ultramarathoner Ashley Paulson has stepped onto a treadmill at the Boston Marathon Expo with a world record in her sights and an audience measured in the tens of thousands. The 44-year-old Utah-based athlete, who in February 2026 ran 12:19:34 to take the women's road 100-mile world record at the Jackpot Ultra Running Festival in Nevada, is attempting the female world record for the fastest 100 miles on a treadmill live on the main stage at the Hynes Convention Center on Saturday. The existing mark, 14:15:08, would require Paulson to average just under 8:34 per mile for the duration of the attempt.
The effort has been built around the iFIT-hosted stage at the expo, where a treadmill has been set up in full view of runners collecting their Monday marathon bibs. Paulson, who serves as a global brand ambassador for a caffeine product marketed to endurance athletes, is being supported through the attempt by a rotating team of pacers, a medical adviser and a nutrition crew working from a pit area next to the belt. The attempt requires her to run continuously apart from short breaks for fuel and brief bathroom stops, with every mile tracked by officials and the treadmill display mirrored on a screen behind the stage.
Paulson is arguably the logical candidate for a treadmill crack at the record. Her road 100-mile run in February broke the previous mark of 12:37:04 set by Ireland's Caitriona Jennings at Tunnel Hill in 2025 by more than 17 minutes, a performance that required her to hold an average pace of 7:34 per mile. By comparison the treadmill record demands a slower clip over the same distance but introduces an entirely different challenge: a belt that does not vary, a view that does not change and, crucially, the psychological weight of running in place for the length of a working day. Paulson has spoken in interviews this spring of using the relentlessness of the belt as a training tool, repeatedly returning to the treadmill during the build to Jackpot to rehearse pacing discipline.
The timing of the attempt, on the Saturday of Patriots' Day weekend, is no accident. Boston Marathon weekend draws roughly 30,000 competitors to Boston and many multiples of that number of fans through the expo's doors across three days. An attempt of this kind, in that kind of venue, effectively blends the storytelling model of a single-distance world record with the scale of a marathon sponsor activation. It also leans into ultrarunning's growing crossover into mainstream endurance culture, in which treadmill records — historically the preserve of Guinness World Records ceremonies in car parks and gyms — have begun to be contested with the infrastructure once reserved for stadium records.
Whether or not the 14:15:08 mark falls on Saturday, Paulson's attempt is likely to serve as a waymark in a busy 2026 ultrarunning calendar. Major American ultras from the Western States 100 in June to the UTMB US Series events continue to expand, the women's 100-mile world record has now changed hands twice inside twelve months, and athletes at the sport's front end are increasingly comfortable staging record attempts as standalone events. A successful bid would give Paulson concurrent world records at 100 miles on the road and on the belt, an unprecedented combination for a single athlete. A narrowly missed attempt would still leave one of the most watched record bids in the event's history unfolding a few blocks from Monday's Boston Marathon start line.