How Kilian
Jornet Trains.

Who is Kilian Jornet

Jornet grew up in a mountain hut in the Pyrenees where his father was the guardian. He raced ski mountaineering before running, and still does both. He lives in Norway with his family and co-founded the outdoor brand NNormal.

How he trains

• Huge aerobic volume. He has shared yearly totals well above 1,000 hours of training, much of it in the mountains, on foot and on skis.
• Vertical, not distance. He measures training in hours and metres climbed more than kilometres. Big days often have several thousand metres of gain.
• Mostly low intensity. The great majority is easy, aerobic work. He has written openly about using heart rate and data to keep it that way.
• Winter on skis. Ski mountaineering builds the same engine with less pounding.
• Strength for the descents. Downhill running and strength work protect the legs.

What normal runners can take from it

• Think in time, not just kilometres. On trails an hour is a better unit than a kilometre. Plan your long run in hours.
• Keep it aerobic. Climbs push heart rate up fast. Walk the steep parts and keep the effort inside your Zone 2 or MAF range.
• Cross-train in winter. Skiing, cycling or hiking keeps the engine going with less impact.
• Train the descents. Downhill running causes most of the muscle damage in mountain races. See hill running.
• Build over years. Jornet's base took two decades. Start with aerobic base.

Sources: UTMB and Western States results; American Alpine Journal and NNormal on States of Elevation (September to October 2025); Kilian Jornet's own writing and shared training data.