An Idaho Runner Wore 125 Shirts Through a Marathon. It Nearly Put Him in the Hospital.

During the Idaho Potato Marathon in May, one of David Rush’s support runners peeled off the course to a pro shop at a golf course to grab ice, because the man he was pacing, buried under 125 T-shirts, was overheating badly enough to risk a hospital stay. “That ice was the only reason I didn’t end up in the hospital,” Rush said afterward. He finished anyway, and the shirts he wore that day are now a Guinness World Record.

Rush, a 41-year-old from Boise, Idaho, ran 5:54:50 on May 16, beating the race’s six-hour cutoff by roughly five minutes. Guinness World Records certified the mark, its record for “most T-shirts worn during a marathon,” in July. It broke the previous record of 100 shirts, set by Britain’s Brendan Matthews at the 2024 London Marathon.

Getting dressed took about 30 minutes. Once the shirts were on, Rush could not lower his arms to his sides. His crew sprayed him down, helped him drink water, and packed him with ice to keep his core temperature from spiking. The bundle soaked up sweat as the race wore on, weighing about 43 pounds by the end and leaving what he called “bloody, five-inch-long chafing marks where the bottom of the shirts had ground against my skin.” That kind of friction is a routine marathon hazard; Rush’s version was extreme. He still made room for the obvious line: “I just so happened to look like a potato.”

The record is stranger than the recaps let on, and the likely reason is heat. Rush set the half-marathon shirt record in 2025 at 137 shirts, twelve more than he managed over the full 26.2 miles. Over the longer distance, the limit probably had less to do with how many shirts a person can button than with how much heat a body can shed. Cotton holds sweat instead of letting it evaporate, so 43 pounds of soaked shirts stops cooling a runner and starts insulating him, trapping the heat his own effort produces. A half-marathon’s worth of that is survivable. A full marathon generates far more heat over far longer, which helps explain why the emergency ice mattered so much, and why the heat, more than the weight, is likely what pushed Rush to the edge.

Rush is not a marathoner by trade. He is a Boise record-breaker and STEM-education advocate who holds more Guinness World Records at once than anyone, and he uses each attempt to tell students that big goals are reachable with preparation and stubbornness. The marathon fits the pattern: in May he also set a record by pulling on 32 T-shirts in a single minute. His run joins a long line of costume and endurance oddities at marathons, from a Sydney runner who wore 53 pairs of underwear to a Bostonian who raced dressed as a banana. Guinness World Records, which documented the run and Rush’s account of it, billed it as the hardest of his record attempts, and UPI first reported the ice run and the chafing.

For now the record stands at 125. Beating it means running 26.2 miles under even more soaked cotton, and shedding even more heat than Rush could.