As part of a UTMB® training plan, altitude training is a highly valuable asset: it adapts your body to mountain conditions and optimises your physical condition.
Why train at altitude before the UTMB®?
With altitude, atmospheric pressure drops and the air becomes thinner, while humidity also decreases. A useful clarification, as this is a common misconception: the proportion of oxygen in the air does not change with altitude; it remains around 21%. What decreases is the partial pressure of oxygen. With each breath, you therefore take in fewer oxygen molecules for the same volume of air inhaled. It is therefore essential for your body to get used to these new parameters.
This drop in partial pressure triggers the secretion of erythropoietin (EPO) by the kidneys. This in turn stimulates the production of a greater quantity of red blood cells by the bone marrow, improving performance through more efficient oxygen transport to the muscles.
What duration and timing for an altitude training camp?
For genuine, lasting adaptations, a stay of 2 to 3 weeks on site is ideal if the UTMB® takes place within the following two to three months. The first 5 to 8 days form an acclimatisation phase during which you should not push for peak performance: focus on moderate efforts while your body adapts.
The benefits are then felt in two stages once back in the lowlands: a first peak in form generally appears 2 to 4 days after returning, followed by a second, often more pronounced peak between 15 and 21 days later. It is also possible to schedule a shorter altitude stay within the 15 days leading up to the race to aid acclimatisation without aiming for full physiological adaptation.
More demanding than low-altitude training, workouts at altitude can strain your muscles and require greater cardiovascular effort. You should therefore prioritise endurance work and avoid making high-intensity workouts the bulk of your training, especially during the acclimatisation phase.
Do you really need an altitude training camp for the UTMB®?
Let’s be clear: this is an advanced runner’s tool, not a mandatory prerequisite. The highest point of the UTMB® sits at 2,584 metres at the Grand Col Ferret, an altitude where performance decline remains moderate and acute mountain sickness is rare in a healthy runner.
For the vast majority of participants, getting used to the terrain matters more than adapting to the altitude: elevation changes, technical trails, and long descents. An altitude camp makes sense if you are targeting top performance and have the necessary time, but much less so if your goal is simply to finish.
Frequently Asked Questions
How long should you train at altitude before the UTMB®?
Ideally 2 to 3 weeks for genuine physiological adaptations, with 5 to 8 days of acclimatisation at the start of the stay before chasing peak performance.
When does peak fitness appear after an altitude training camp?
In two stages: a first peak 2 to 4 days after returning to the lowlands, then a second, often more pronounced peak between 15 and 21 days later.
Is there less oxygen in the air at altitude?
No, the proportion of oxygen remains around 21% regardless of altitude. It is the atmospheric pressure that drops, and therefore the partial pressure of oxygen: you take in less oxygen with every breath.
