25 March 2026
This April, our Tracomex colleague from Oosterhout, The Netherlands, Onno Claessen will take on the Marathon des Sables Legendary in Morocco! An iconic ultra-endurance race through the Sahara Desert, and in 2026 even more special as it marks the 40th edition, from April 5th until April 11th.
- Location: Sahara Desert, Morocco
- Distance: ~ 250 km spread over multiple stages
- Conditions: Extreme heat, sand dunes, elevation changes
- Runners carry their own equipment and supplies
- Marathon des Sables (MDS) Legendary is the original race and the most demanding edition
- Often described as one of the toughest foot races on earth
The MDS Legendary is the original 250 km self-sufficient race in the Sahara and remains the most extreme version. Today, the Marathon des Sables has expanded into a global series of shorter, more accessible stage races under the same concept.
Seven years ago, at the age of 29, I was looking for a challenge that would really test me. Something that makes you question whether you can actually finish it. I signed up for the Marathon des Sables and started preparing for a full year. My training built up from 5 km runs to 60–100 km per week.
Then COVID hit. The race was cancelled just weeks before the start. I remember finishing my last long run in The Hague and realising how much it meant to me. That moment stayed with me. I knew I would come back to it one day.
Six years later, both my personal life and career are stable, and it felt like the right time to return to this unfinished goal. Since January 2025, I have been fully focused on preparing for this race. It has been on my mind every single day.
A mix of excitement, tension and nerves, but above all a lot of motivation. I am really looking forward to this experience.
The biggest challenge is not only the race itself, but everything leading up to it. Training almost every day for a year requires discipline and also means making choices in terms of diet, social life and recovery. With peak weeks of 100 to 120 km and long runs up to 50 km, the combination of physical strain and mental focus is demanding.
What I look forward to most are the moments when things get really tough, and especially crossing the finish line after six stages. The emotions, the sense of achievement and everything coming together at that point.
I am also curious to see how my body and mindset respond to the extreme conditions: the heat, the distance, sleeping in the desert and operating with limited food.
I train six days a week following a structured schedule. To prepare for the heat, I often train in extra layers and take hot baths afterwards. In addition to running, I focus on strength training twice a week and include stretching and yoga to stay flexible and avoid injuries.
Nutrition and recovery are essential, as well as listening carefully to my body. To better prepare for the heat and reduce stress, I have spend a month training in warmer conditions in the Philippines.
The race itself is fully self-supported. This means carrying everything: food, sleeping gear and equipment. You need to bring at least 2,000 kcal per day, while burning roughly double that. Altogether, you run with a backpack of 8 to 10 kg, plus water.
Working towards one clear goal over a long period gives me focus and energy. I enjoy that structure and build-up.
During the race, I hope to experience what it means to perform under extreme conditions, both physically and mentally. I want to learn how to stay close to myself, manage my thoughts and emotions and trust my body.
Most of all, I hope to experience a strong sense of fulfilment and pride in what I am capable of.
Support Onno
Onno is also raising funds for cancer research. Every contribution supports the work of KWF (The Dutch Cancer Society), as one in every two people in the Netherlands will face a cancer diagnosis in their lifetime.