John Muir Trail FKT: Ultrarunner Fights Hallucinations to Beat Record by 8 Minutes

In her effort to set a new FKT on the John Muir Trail, Caroline Himbert suffered painful blisters, an injured knee, and hallucinations so intense her team almost called for rescue. For all that effort, she earned an FKT just 8 minutes faster than the previous unsupported record for women.

Does she think it was worth it? You betcha. And it wasn’t for sleep deprivation, she might have reached her goal of crushing all 223 miles in under 4 days. She’s already considering her next effort — built on the brutal lessons she learned on the trail this month.

Who Is Caroline Himbert?

Like many long-distance runners, Himbert, 32, started off as a thru-hiker. She first got a taste of scaling mountains and trekking long distances when she completed the Pacific Crest Trail (PCT), which included hiking the John Muir Trail.

Next, she took on the 3,100-mile Continental Divide Trail. Soon after, she started signing up for ultra races, starting with 50K and progressing to 100-milers.

Himbert, who works full-time as a cancer researcher, found that the mental resiliency she had built with thru-hiking transferred well to ultras. “I really enjoyed the kind of mental part of thru-hiking. Not every day is a good day out there. Learning how to navigate that is just really interesting and so is learning your body really well,” she said.

After running in the famed Ultra Trail du Mont Blanc last year, Himbert felt ready to pull the trigger and commit to training for an FKT on the John Muir Trail. Himbert wanted to break the northbound unsupported record for women, which stood at 4 days, 5 hours, and 6 minutes, set by Amber Monforte in 2016.

What Is the John Muir Trail?

The John Muir Trail, which is part of the PCT, is one of California’s most scenic backpacking trails, crossing both Mt. Whitney and Yosemite Valley. Most hikers typically complete the trail in 2 to 3 weeks.

The route scales 10 passes in the High Sierras, making for a series of challenging ascents and descents. The total elevation gain on the route is 46,000 feet and the total loss is 38,000 feet, demanding serious fitness.

Many elite ultra-runners have come to the John Muir Trail to test their mettle and try to nab a FKT. Fastest known times can be completed supported (with aid and resupplies from crew members) or unsupported (completely solo). Runners can take the route northbound or southbound; most people go northbound so that the route’s highest point, Mt. Whitney, comes at the beginning and not the end.

Trail Gear

Since Himbert was running unsupported, she had to bring everything she needed for several days on her back. She estimated that her base weight was around 9 pounds, with an additional 10 to 15 pounds of food. It’s required that anyone staying overnight in the area bring a bear can, so that definitely upped her weight.

For sleeping, Himbert kept it simple with just a thermal bivy bag and a Gossamer Gear sleeping pad. A lightweight puffer from Backcountry was essential. As soon as she stopped moving, Himbert would begin shivering, her body shutting down.

Her gear MVP (or is that Most Valuable Gear?) was her Arc’teryx Aerios 35 pack: “It cinches down so much so it keeps things tight even when your backpack gets lighter and lighter,” she said. “It’s built like a running vest in the front … and there’s a legit hip belt. I think that was really important just to take some of the pressure off my shoulders.”

Himbert’s FKT Run

Going into the FKT attempt, Himbert’s strategy was to move around 22 hours per day and sleeping around 2 hours per day. Given the up-down, up-down nature of the trail, she power-hiked the ascents and then jogged the descents. On Day 1, Himbert was in the zone.

“I was just stoked to be out there being back on trail. It felt like just going back to my roots,” she said.

On Day 2, she prioritized fueling herself and making sure she was consuming adequate calories — even if it meant stopping for a few minutes. Near the end of Day 2, every ultra-runner’s sworn enemy — blisters — began to make themselves known. At one point, a large blister formed on the entirety of Himbert’s heel and eventually ripped off.

Pinchot Pass (12,100 feet) and Mather Pass (12,080 feet) felt harder than Himbert expected, and getting up Muir Pass (11,955 feet) was a long, slow slog. Reaching the top of Muir, however, revitalized Himbert.

“It was beautiful up there. It kind of got my spirits back up,” she said. “Usually, there’s always people there and I was all alone at sunset. I just ‘yippee-hurray-ed’.”

Things Go South

The end of Day 3 is when the trouble really started for Himbert. Not only had her blisters gotten even worse, but she had also tweaked something in her knee, causing the joint to severely swell up. She took a 30-minute power nap instead of her usual 2-hour one, and the sleep deprivation was rapidly diminishing her mental acuity.

Her decision-making abilities were almost nonexistent. At some points, she would walk backward on the trail instead of moving forward.

“My coach was saying to keep my brain at 80%. How quickly your mind can change from 80% to absolutely 0% is wild to me,” Himbert said.

She hallucinated a group of people and cars that promised they would take her back down the mountain. “At some point, the tree bark was moving really weird, and I must have just laid down and slept,” explained Himbert, who fell asleep off-trail for 5 hours. “My people who were going to pick me up at the end were pretty worried because they didn’t hear from me for 5 hours … They almost called SAR.”

A Sprint to the Finish

When Himbert woke up, she was disoriented, but managed to find her way back to the trail. She did the math and realized that even with this long pause, she might still be able to break the record. She ran 12 miles in 3 hours, going without water for the last 10 miles.

“I was like, ‘How am I running on these feet right now?’ Because my feet before that nap were hurting so bad, and then I just ran down, which was totally absurd. I must’ve looked like a maniac,” she said.

Her tracker that sent updates to her team only updated every 30 minutes, so they didn’t know that she was close to the finish line until right before. Himbert ultimately beat the FKT by approximately 8 minutes, finishing in 4 days, 4 hours, and 58 minutes on August 13.

Completing a FKT on part of the PCT — the same trail that introduced her into the wonderful wide world of long-distance hiking — was a full-circle moment for Himbert. “Back when I was doing the PCT, there were all these FTKers that I was looking up to, and it was like, ‘Wow, I could never do this,’” she said. “It was really about going back to where this journey for me started.”

What’s Next

Moving forward, Himbert would love to do more ultramarathons and races. She’s also toying with the idea of attempting a FKT on a longer route on something like the 567-mile Colorado Trail.

Himbert would be lying if she said she didn’t think about that 5-hour nap. Without that long pause, Himbert would’ve broken the record by a healthy margin.

“Even though it’s so fresh, I still think I would do it again, because I know I can get it under 4 days,” she said. “I just have to figure out how to manage sleep a bit better.”

Don’t be surprised to see her name pop up again next summer in conjunction with the John Muir Trail.