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Istria 100 by UTMB
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Istria 100 by UTMB® 110K

UTMB World Series
110.0km·3900m+
April 12, 07:00 AM
Umag,
Croatia
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Race Pace Calculator · GPX Analyzer · Trail Finder

Other races: Croatia

Read

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  • Hill Training for Trail Runners: Train the Descents
  • Downhill Running Muscle Damage: Why Descents Wreck Quads

Full calendar: Croatia100K trail race calendar

Istria 100 by UTMB® 110K · Race profile

Distance
110km
Gain
3900m+
FlatKM
135.8
Max
1006m
Min
1m

About Istria 100 by UTMB® 110K

Istria 100 by UTMB® 110K is the 110km ultra trail at Istria 100 by UTMB 2025 (Umag, Croatia). The race starts on April 12, 2025 at 07:00 AM.

Race strategy

Hold a steady pace and save energy for every section.

  • 1038m descent. Go easy, save your quads.
  • The finish is runnable. Save your legs to run it all the way.
  • Long race. Control your HR and effort. Early mistakes cost the most.
  • Control your HR on the first climb, save your quads on the descents until 65.4km, then run your race pace.
  • Start · 0.0km–1.7km · Race-day nerves push your heart rate up: don't follow the crowd, find your own rhythm.
  • Settle in · 1.7km–14.3km · Climb of 576m. Ease in: hold back more than feels necessary. The race is still ahead. Climb by heart rate or breathing, not pace. Running pays off here: run wherever you can.
  • Work · 14.3km–55.7km · Descent of 324m averaging 12%, descent of 1038m averaging 9%, descent of 327m averaging 11%. Plus 3 more climbs. This is where the race is built: steady, solid effort. Climb by heart rate or breathing, not pace. This descent is hard on the legs: short steps, stay in control, poles if you have them. Running pays off here: run wherever you can.
  • Fade · 55.7km–85.1km · Descent of 378m averaging 13%, climb of 567m. Plus 2 more climbs and 1 descent. Your energy fades, and that's normal: hold a steady effort and stop counting the miles. Climb by heart rate or breathing, not pace. This descent is hard on the legs: short steps, stay in control, poles if you have them. Your heart rate drifts down on its own: don't chase your early-race numbers, go by feel.
  • Home · 85.1km–110km · 25.3km of runnable trail. No heroics: settle back into your own effort and hold it to the line. Running pays off here: run wherever you can.

Course

The course climbs 3900m+. With 35m/km of climbing, this is a rolling, mostly runnable course. By gradient, 32% of the distance is uphill, 34% downhill and 34% flat. The longest climb runs 10.4km at an average 5.5% grade (567m of vertical). The longest descent runs 11.6km at an average 9.0% grade (1038m of vertical). The steepest climb averages 23.9% over 0.7km. The steepest descent drops at 30.8% over 0.2km. Surface: 46% trail, 31% smooth, and 19% road. Flat-equivalent effort: 135.8 FlatKM.

Summits

The highest summit on the course is Gomila (1027m), 23.5km from the start. Other named summits along the route: Žbevnica (1014m). The course also passes close to Lobardina (888m).

Poles

Poles bring little benefit here: only about 14.9km of pole-friendly terrain.

Quad damage

Quad damage risk is moderate (index 46 of 100), with 63% of the load in the first half: 4 descents deserve a plan and a couple of downhill sessions before race day.

  • Control your HR on the first climb, save your quads on the descents until 65.4km, then run your race pace.
  • #2 · 23.5–26.2 km · 324 m D−, -12.0% · 84.1 km ahead → control
  • #1 · 31.3–42.9 km · 1038 m D−, -9.0% · 67.4 km ahead → control
  • #3 · 52.7–55.7 km · 327 m D−, -11.0% · 54.6 km ahead → control
  • #4 · 62.6–65.4 km · 378 m D−, -13.4% · 44.9 km ahead → control
  • 75.8–80.4 km · 282 m D−, -6.0% · 29.9 km ahead → your pace

Results

387 finishers completed the 2025 edition. Men's winner: Zan Zepic (Slovenia) in 9:56:14. Women's winner: Nicol Guidolin (Italy) in 12:17:58.

This page has the full results and splits, a pacing and nutrition planner, a gradient matrix, an interactive elevation profile and historical weather for Istria 100 by UTMB® 110K.

Other distances of Istria 100 by UTMB 2025Istria 100 by UTMB® 168K (168km)·Istria 100 by UTMB® 69K (69.0km)·Istria 100 by UTMB® 42K (42.0km)·Istria 100 by UTMB® 21K (21.0km)

Other editions of Istria 100 by UTMB® 110K2027·2026

Official websiteistria.utmb.world