100-Mile FKT Across Antarctica in Under 24 Hours: ‘I Have No Plans to Do This Again’

Until November 7, 2024, no human being had ever run 100 miles across Antarctica in less than 24 hours. But this month, when Paul Johnson and Rob Sembiante came jogging across the finish line, they made history. The two endurance athletes covered 100 miles in one of the planet’s driest, coldest, harshest environments in just 23 hours, 22 minutes, and 57 seconds.

Johnson is a GOREWEAR-sponsored endurance runner and naval officer. Earlier this year, he completed the 3,000+ mile transcontinental run in just over 51 days and 2 hours. However, according to the website fastestknowntime.com, he has no previously verified FKTs, and the site has yet to confirm his Antarctica accomplishment.

During the transcontinental effort, Sembiante was Johnson’s crew chief. According to Johnson, this Antarctica objective was his idea.

“He has wanted to run 100 miles in Antarctica for a long time now, and when the opportunity arose, we took advantage of it,” Johnson told GearJunkie.

Sembiante currently holds the FKT for “The BRAWL,” a 293-mile linkup trail that follows the Wasatch mountains from southeastern Idaho to Herbert City, Utah. Despite his extensive experience as an endurance runner, this particular endeavor took its toll on him.

“These were the hardest conditions I have ever operated in any capacity,” Sembiante wrote in an Instagram post about the accomplishment. “By far the coldest night I have ever had in my life.”

The effort was facilitated by Antarctic Ice Ultra by Runbuk at Ultima Ice Camp. GearJunkie caught up with Johnson following the world record.

100 Miles on the World’s Harshest Continent

Johnson only trained for this world record attempt for a couple of months. He said his training for the transcontinental effort had been so extensive that he was still well-prepared on a fitness level. In the 3 months leading up to November, he ran between 50 and 80 miles a week and did 1-hour lifting sessions three times a week.

By the time he and Sembiante were heading to Antarctica, Johnson felt prepared — especially when their weather window opened up, he said.

“I have consistently run 100 miles in only 19 hours in longer races before. I also run extremely well in the cold, so the unknown and limiting factor was going to be the wind,” Johnson said. “Entering with high confidence that we could get it done put us in a good mental space.”

Johnson never worried that he and Sembiante wouldn’t make 100 miles in under 24 hours. But he did question how fast they would be able to do it. At one point, Johnson was so fatigued he was falling asleep on his feet.

“My initial goal was under 22 hours, but after being well on track for pace at mile 50, I was really struggling with staying awake and doing a lot of sleep running and walking for about an hour,” he said. “Took on a lot more caffeine and was able to fight through the low, but [that] definitely affected my mental space on [my] ability to go sub-22 hours.”

He tried maintaining his heart rate under 160 beats per minute and constantly slammed snacks as they moved. Their bodies were burning calories at an exorbitant rate in the freezing conditions just to stay warm, he explained. The windchill was -13 degrees for most of their run, and they climbed over 6,300 vertical feet.

Finally, 23 hours, 22 minutes, and 57 seconds after Johnson and Sembiante started, they arrived at the finish with a new world record. They’d broken the previous Antarctic 100-mile record by over an hour.

A World Record Johnson Won’t Soon Defend

Johnson is extremely proud of his accomplishment with Sembiante despite not breaking the sub-22-hour goal he’d had his sights on. And he invites other runners to come try and take it from him. He’s not going to be defending this one.

“Records are meant to be broken. Don’t worry about me trying to take the record back,” he said. “I have no plans to do this race again any time in the near future. If you fail, you still get to have an incredible experience in such an amazing place.”

Johnson is now “onto the next adventure.” He plans to upload a mini-documentary covering this 100-mile world record on his YouTube page in the “coming weeks.”

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