I’ve been signed up for the UTMB (Ultra-Trail du Mont-Blanc) for a couple of months now and I realized I haven’t really shared any information about the training and preparation for the race. Here we go – UTMB Training: Volume and Intensity.

The event takes place this coming August 30th with a start in Chamonix, France. Organized by The North Face the UTMB is a 105 miles ultra marathon. 31,500 feet of elevation gain and a cut off time of 46 hours. For instance, this means that the elevation gain is more than climbing Mt Everest from sea level! Also, at 4,810 m (15,782 ft) the Mont Blanc is the highest mountain in Western Europe. 2300 athletes will run around the mountain, going through France, Italy, and Switzerland. It’s the first ultra during which I will have to carry my passport!


First, being born in France and having spent a fair amount of time in the Alps this is a dream come true. I have been fortunate to be able to qualify and to secure a spot in the race. Additionally, going home for what is considered the Olympic Games or the Tour de France of trail running is a very exciting and emotional prospect for me. By the time the race starts, it will have been about a year since my mom passed away not too far from Chamonix. I dedicate this challenge to her and I wish she could be at the finish line.

I would not have developed the endurance and resilience necessary to undertake a running adventure at this level without what she taught me and in particular her courage fighting cancer for four years. On my long mountain runs my mind sometimes presents me with a visual of her waiting for me at the finish line, sitting in a wheelchair with a blanket, craning her neck to catch a glimpse of me coming in the chute.

Finally, preparing for this race is complex, tedious and fun! There are a couple of dimensions I would like to cover  in order perhaps to help future runners but also to keep my sanity in check and reflect on what I’m doing! We will cover training volume/intensity, nutrition, and gear preparation. Let’s start with the training.


Compared to last year when I was training for the Rio del Lago 100 mi the training volume has increased by about 25% (700 vs 860 miles in the 13 weeks leading up to the race)

For RDL weekly milage was between 45 and 55 miles and for the UTMB weekly milage is between 60 and 65 miles.UTMB TRAINING: VOLUME & INTENSITY rio del lago comparison

Although this seems like a sizable increase the most important part of the UTMB specific training is not in the increase in the milage. I was planning on running a 100 miler in June (DRTE100) but downgraded to a 100K (SBRT100) which I downgraded to a 50K (see post here). It was important to put myself through the rigors of being on the trails for over 12 hours but this hasn’t happened until recently when I ran 60 miles in the backcountry in the Eastern Sierra Nevada (between Mammoth Lakes and Yosemite).


First, what has changed is the intensity and the nature of the terrain I train on. A year ago I didn’t train with as many steep hills and mountains. This year for the UTMB I amped up the elevation gain on every run and also trained in the Sierra Nevada, at high altitudes. 8,500 to 11,500ft which is actually higher than the altitudes reached the UTMB. I also increased the number of technical trails (fewer fire roads) and I’m carrying the same pack I will be carrying at the UTMB. It weighs between 7 and 10 lbs depending on how much food and water I’ve consumed. More on the pack when I write about the gear aspect of the UTMB.




First, last Friday I ran a 100K (60 miles) in the backcountry in 15 hours – there was about 15,000ft of elevation gain. This was a huge confidence booster and I could test my nutrition and hydration strategy and discipline. A miracle actually as I wasn’t tired at the end or sore the next day. I had run distances of 35 and 45 miles at the same altitude and was more tired after it. However, let’s bear in mind that the UTMB is probably going to last 20 hours longer!

In other words, this 100K was really important for me. It went well and even better than expected. I had a lot of fun and I was able to focus on many elements of running long in the wilderness. A little wary of mountain lions. They are there – they just don’t care about us. 


The weather was very clement which is unlikely to happen at the UTMB. Terrain is similar and as I said I was running at altitudes higher than the UTMB (my starting point and where I sleep in Mammoth is higher than the highest point on the UTMB course).

backcountry 100K

In addition, I was in heaven because for me mountain running is a spiritual experience like meditation. The mountains in the Sierra Nevada are so beautiful I don’t miss the Alps (well a little bit). And, more than once I had to stop and take in the immensity,  the beauty and the majesty of the landscape, the perception that we are made of the same stuff and that our planet is truly beautiful and there for us.


Finally, I encountered a couple of hikers and it was nice to share a moment! Also I didn’t see much wildlife with the exception of some chipmunks. The experience showed that my training periodization was working well.


First, I have planned my training more meticulously than last year (last year was also very stressful because I was traveling to France a lot and I was running Pikes Peak in August). The chart above shows better periodization (peak in 3 weeks – one week of rest). Similarly, within a given week I also only run 4 days. The other three days are for swimming (2 days) and hiking with my son or cycling. I believe this is what keeps me injury-free.UTMB TRAINING: VOLUME & INTENSITY

Finally, for both races, I do a 2-week taper and I believe this is enough. For me, too long the taper and I lose a certain edge – too short and there is no sufficient recovery. I will get to Chamonix 6 days before the race. This should give me enough time to recover from the flight. However, also re-accustom myself to French food (don’t laugh – I actually don’t eat a typical French diet. I’m more on the Californian Paleo side now).

In conclusion, the training goes on. I haven’t really touched on the mental aspect of preparing for the race. There is some fear and anxiety that everything won’t go as planned but nothing that is impairing.

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Arno Kroner