Kilian Jornet won the Western States 100 in 2011. He was 23. Trail running barely had a mainstream pulse. He spent his preparation doing what he always did — just running for hours in the mountains, no particular structure, no heat protocol, no data strategy. He won anyway.
June 28, he lines up again.
A lot has changed. Jornet lives in Norway now with his wife, elite runner Emelie Forsberg, and their two kids. He co-founded a shoe brand, Nnormal. He’s climbed Everest without supplemental oxygen, set course records at UTMB, and linked all 82 of the Alps’ 4,000-metre peaks in 19 days. He’s 37.
He’s also training in a country that rarely hits 70°F, to race in California where 100°F on course is routine.
Heating His Gym to 110°F, Three Times a Week
His fix for the heat gap is not subtle. For the past 10 weeks, Jornet has been cranking his home gym to 110°F (45°C) and running inside for two to three hours at a stretch. Sometimes he wears waterproof clothing to prevent his body from cooling itself. He tracks core temperature, sweat rate, and sodium concentration throughout.
“It’s hard to train for hotter environments training normally,” he told Advnture.
Three sessions a week, indoors, in the Norwegian equivalent of Death Valley. That’s the job.
Why Most of His Training Is Deliberately Easy
The heat work is specific preparation. The foundation underneath it is something Jornet has stuck to for years regardless of what race he’s targeting: slow, long, aerobic running. Lots of it.
About 80% of his base training sits in Zone 1 — the recovery zone. Easy effort, low heart rate, long duration. He builds this aerobic base over three to four months before sharpening toward any race.
“I always do a long aerobic base period for 3-4 months with moderate to long distance journeys. That’s a must for me.”
The rest of his training sits mostly in Zones 2 and 3 — aerobic endurance and aerobic power — which is where he operates when racing. He also throws in technical mountain days, though those are more about enjoyment than structure.
“I like being alone and in my thoughts, just hearing the nature.”
Three weeks before race day, he ran 80 kilometres (50 miles) as a key simulation effort. His heart rate averaged 142 bpm across the whole run — steady, controlled, the product of months of base work. This kind of 80/20 training approach — where the vast majority of miles are deliberately easy — is something many elite endurance athletes swear by.
How He Actually Uses His Watch
Jornet uses a GPS watch and heart rate monitor during training, paying attention to effort pace — a metric that adjusts for gradient and individual physiology. But he’s honest about the order of operations.
“I train mainly based on feel.”
Data comes in when something feels off. A heart rate creeping up while pace holds flat means fatigue is building. Effort pace dropping with a steady heart rate sends the same signal. He responds in the moment.
“If I see that effort pace or heart rate is dropping from what I planned, then I accelerate.”
For specific training blocks — altitude work, neuromuscular sessions — he looks at more targeted numbers like blood oxygen, cadence, stride length, and ground contact time. But that’s the exception. The default is always feel.
Fitting Elite Training Around Two Kids and a Shoe Brand
In 2011, Jornet’s preparation was blunt-force volume. “I wasn’t training specific back then, I would just spend hours out in the mountains training.”
Now he trains around kindergarten hours. Sessions happen while the kids are in school. Weekends are short efforts while they sleep. The margins are tighter.
“With kids, there’s less time to train and a much more marked routine, and I want to spend time with the kids.”
He doesn’t frame this as a handicap. His view is that it’s forced him to be better at the thing most endurance athletes are worst at — precision. Every session has a purpose. Every long run tests something specific, whether that’s terrain, nutrition, pacing strategy, or gear.
“I am a much better athlete and I am performing much better, but I need to train smarter.”
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