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While you’re reading this, more than 3,000 people are currently running through the Croatian wilderness. The Istria 100 by UTMB, one of the toughest trail races in Europe, takes place this week. 168 kilometres, 7,600 metres of elevation gain, coastal paths, forests and medieval villages. And that’s just one of 64 UTMB World Series events this year. Trail running is no longer a niche. It’s a movement.

What the numbers say

Trail running has evolved over the past 30 years from the hobby of a handful of mountain‑mad enthusiasts into a global sport ecosystem. The figures from the International Trail Running Association (ITRA) leave no doubt: roughly 2 million registered trail runners worldwide, 611.000 annual entries just in the ultra segment. That represents growth of 1.676 percent since 1996.

And in the last ten years alone: plus 345 percent. This isn’t just statistical fluff. It’s thousands of people lining up at a start line somewhere in the world each week, where there is no road any more—only trails, roots, rocks and a finish line hidden behind a mountain. What the numbers don’t show is how many people simply run. No race registration, no GPS watch, no Strava upload. They head into the woods in the morning and return with muddy shoes in the evening. They’re not in any statistic, but they’re the reason Hoka and Salomon can’t produce trail shoes fast enough. Over 80 percent of trail‑running consumption now happens digitally, according to Nielsen Sports—livestreams, social media, podcasts, real‑time results platforms. You don’t have to be in Chamonix to experience the UTMB. You can sit in your living room and watch Courtney Dauwalter race. Then head out yourself the next morning. That’s exactly what’s happening millions of times right now.

Istria 100: Trail Running this week

  The Istria 100 by UTMB takes place from 10 to 12 April 2026 on the Croatian peninsula of Istria. 3.000 runners from around the world. Five distances: 168 Kilometer (the full 100 miles), 110 Kilometer, 69 Kilometer, 42 Kilometer and 21 Kilometer. The race has existed since 2013 and has become one of the most important UTMB World Series events in Europe. What makes the Istria 100 special: the course combines coastal paths along the Adriatic with dense forests and medieval towns inland. You run through Grožnjan, an artist village on a hill that looks like a movie set at night. You cross the Mirna Gorge. And if you run the 100‑mile distance, you do it all at night. With a headlamp, in a field of crazy people who know exactly why they are there. The top 3 of the 50‑Kilometer, 100‑Kilometer and 100‑Mile distances qualify directly for the three UTMB World Series finals. Anyone who finishes the 100 Kilometer under 18 hours is eligible for the lottery for the Western States Endurance Run 2027. Western States is the oldest 100‑mile race in the world and for many trail runners what the Marathon is for road runners. Almost 30 percent of all starters in the last edition were women. 92 percent of them finished. That is no coincidence. According to ITRA, the female share in trail running has risen from 15 percent in 2005 to 38 percent in 2024. Trail running is one of the few endurance sports where the gender gap is visibly shrinking. That also has to do with the course: on technical trails, technique matters more than pure strength. The longer the distance, the smaller the performance gap between men and women. In races over 200 miles, there are women who win the overall classification.

Why Trail Running is different from Running

  Anyone who has ever veered off the road onto a forest path knows: it’s a different sport. On the road, pace matters. On the trail, not falling matters. And that you find the way. And that you have enough water with you. And that you know when to turn back. Trail running is running plus adventure plus risk management. Trail running challenges your whole body. Every step is different. Roots, rocks, descents, climbs. Your ankle joints work constantly, your core stabilises every stride, your eyes scan the ground three metres ahead. Your brain runs just as hard as your legs. If you can zone out on the road, you have to stay highly focused on the trail. And that’s exactly what many people love about it.