100 km Ultra Trail Training Plan: Complete 12-Week Program

Ultra trail training plan

Preparing for a 100 km ultra trail isn’t just about running longer. It’s about learning to manage effort, fatigue, terrain… and everything that happens after several hours outside.

This 12-week training plan helps you structure your preparation to arrive at the start with a solid base, without burning out before the race. The goal is not just to finish, but to stay consistent and effective over time.

This program was designed with the support of Matthieu Andreux, a coach specialized in endurance sports. The idea here is not to follow a “perfect” plan, but to have a coherent structure you can adapt to your level, terrain, and daily life.

👉 An ultra plan is never set in stone. If you accumulate fatigue or a session doesn’t go well, adjust. What matters is consistency over 12 weeks, not a single session.

What you will work on with this plan

Over 100 km, performance relies less on speed and more on your ability to sustain effort over time. This plan is built around three essential pillars.

Base endurance

A large part of the volume is done at a comfortable pace. This allows you to last for several hours without burning out, while recovering better between sessions.

Climbs and descents

Specific hill work is essential. Climbs build endurance, descents prepare your muscles to absorb impact without breaking down.

Mental endurance

Long runs and back-to-back fatigue sessions get you used to managing tough moments. This is often where the difference is made in an ultra.

Who is this plan for?

This plan is for runners who already have a solid base in trail or running. Ideally, you should be able to run for several hours and do multiple sessions in a week without major difficulty.

If you are new to trail running or have never gone beyond marathon distances, it might be more relevant to aim for an intermediate distance before tackling 100 km.

💡 An ultra is prepared over time. If this plan seems too intense, adjust it or extend the preparation rather than pushing too hard.

How to use this plan effectively

A plan is only useful if you can integrate it into your daily life. To get real benefits, keep these simple guidelines:

Be consistent rather than perfect. Missing one session is not a big deal, but a whole disorganized week is more serious. Listen to your body's signals, especially accumulated fatigue or persistent pain. And above all, test your nutrition, gear, and hydration during long runs — never on race day.

Download the training plan

You can find the complete plan detailed week by week in PDF format. It will serve as a base to structure your preparation over the next 12 weeks.

Download the 100 km training plan

👉 The goal of this plan is not to tire you out before the race, but to get you there ready. If you arrive at the start fresh, steady, and confident, you are already on the right track.

100% trail running since 1999

As a French brand, pioneer in Trail Running, based in Chartreuse, Raidlight is committed to designing and manufacturing eco-responsible technical, lightweight, and high-performance equipment to outfit all trail runners from head to toe. Since 1999, by sharing our expertise and commitment with a community of enthusiasts, we believe in the development of French-style Trailrunning—that is, a French brand that is committed, bold, dynamic, and proud of its products!

12-week training plan for an ultra trail