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Istria 100 by UTMB
168km168111km11169.6km69.642km4221.5km21.5

Istria 100 by UTMB® 168K

UTMB World Series
168.0km·6800m+
April 2, 05:00 PM
Labin,
Croatia
utmb·source

Race Pace Calculator · GPX Analyzer · Trail Finder

Other races: Croatia

Read

  • Types of Runs and What Each Workout Actually Trains
  • Hill Training for Trail Runners: Train the Descents
  • Downhill Running Muscle Damage: Why Descents Wreck Quads

Full calendar: Croatia100-mile trail race calendar

Istria 100 by UTMB® 168K · Race profile

Distance
168km
Gain
6800m+
FlatKM
226.1
Max
1376m
Min
-1m

About Istria 100 by UTMB® 168K

Istria 100 by UTMB® 168K is the 168km ultra trail at Istria 100 by UTMB 2027 (Labin, Croatia). The race starts on April 2, 2027 at 05:00 PM. It starts in Labin and finishes in Umag. The time limit is 45 h.

Race strategy

Hold a steady pace and save energy for every section.

  • 640m descent. Go easy, save your quads.
  • Big early climb with 1.4km gain. Hold your pace, save your legs for later.
  • 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.
  • Go easy on the first downhill, save your quads on the descents until 96.6km, then run your race pace.
  • Start · 0.0km–1.5km · Race-day nerves push your heart rate up: don't follow the crowd, find your own rhythm.
  • Settle in · 1.5km–15.0km · Descent of 299m averaging 6%, descent of 456m averaging 10%. Plus 1 more climb. Ease in: hold back more than feels necessary. The race is still ahead. 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.
  • Work · 15.0km–82.2km · Descent of 640m averaging 10%, descent of 818m averaging 8%, descent of 790m averaging 6%. 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. Hike the steepest pitches.
  • Fade · 82.2km–136km · Descent of 977m averaging 11%, climb of 566m. Plus 2 more climbs and 3 descents. 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. Running pays off here: run wherever you can. Your heart rate drifts down on its own: don't chase your early-race numbers, go by feel.
  • Home · 136km–166km · 29.8km 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 6800m+. With 40m/km of climbing, this is a rolling, mostly runnable course. By gradient, 32% of the distance is uphill, 37% downhill and 30% flat. The longest climb runs 13.9km at an average 10.1% grade (1401m of vertical). The longest descent runs 13.8km at an average 5.7% grade (790m of vertical). The steepest climb averages 39.9% over 0.4km. The steepest descent drops at 29.7% over 0.2km. Surface: 52% trail, 25% smooth, 17% road, and 5% technical. Flat-equivalent effort: 226.1 FlatKM.

Poles

Poles bring little benefit here: only about 25.4km of pole-friendly terrain.

Quad damage

Quad damage risk is high (index 66 of 100), with 52% of the load in the first half: 6 critical descents, the last of them run on already damaged legs. Downhill-specific preparation and a controlled early pace pay off here.

  • Go easy on the first downhill, save your quads on the descents until 96.6km, then run your race pace.
  • #6 · 0.0–5.0 km · 299 m D−, -6.0% · 161.2 km ahead → control
  • #3 · 10.3–15.0 km · 456 m D−, -9.7% · 151.2 km ahead → control
  • #1 · 27.3–33.5 km · 640 m D−, -10.3% · 132.7 km ahead → control
  • #2 · 47.4–57.5 km · 818 m D−, -8.1% · 108.7 km ahead → control
  • #5 · 68.4–82.2 km · 790 m D−, -5.7% · 84.0 km ahead → control
  • #4 · 87.4–96.6 km · 977 m D−, -10.5% · 69.6 km ahead → control
  • 131.7–136.4 km · 279 m D−, -6.0% · 29.8 km ahead → your pace
  • Plus 2 more notable descents not listed: your pace.

This page has a pacing and nutrition planner, a gradient matrix, an interactive elevation profile and historical weather for Istria 100 by UTMB® 168K.

Other distances of Istria 100 by UTMB 2027Istria 100 by UTMB® 110K (111km)·Istria 100 by UTMB® 69K (69.6km)·Istria 100 by UTMB® 42K (42.0km)·Istria 100 by UTMB® 21K (21.5km)

Other editions of Istria 100 by UTMB® 168K2026·2025

Official websiteistria.utmb.world