Previewing UTMB: 3 Days of Running around Mont Blanc

After speaking with a local in Girona who won his division at CCC in 2013 (one of the shorter distance races held during UTMB week), I decided that my last long training run would be a 3-day preview of the UTMB course. His advice was to run the course over 2-3 days in early August a bit faster than race pace and then to taper from there. He told me this was what Kilian did his first year at UTMB, and what he and others had done as well. Sounded great to me. Andrea and I had planned to stay in Chamonix for the month of August anyway, so this would give a bit more structure to the time there.


I opted for 3 days of running and used the official UTMB course profile to plan out my run.

After looking at the course profile and where I could get sleeping accommodations at Refuges, I broke down the 3 days as follows:

My target of ~27 hours running time was based off of Marathon du Mont Blanc’s 90km race winner Xavier Thevenard (who also won UTMB last year); at the 90km race in June he was approximately 35% faster than me on uphill segments and 45% faster on downhill segments. Based on past run times for the winners at UTMB, I applied a 25% delta to the uphill segments and a 35% delta to the downhill segments, hoping (in a best case scenario) my training in Andorra in July would have a more incremental boost to my performance than his July training would add to his, given he is at the top of his game almost all racing season long and I’m still progressing. Applying those offsets, I came to the 27 hour target time. Andrew Skurka has a great post here about creating his pace chart for UTMB, which I used as a template for mine.

I booked two Refuges using the central booking website for all the Refuges along the Tour of Mont Blanc, a popular hiking path that the UTMB race course follows in many areas. My first refuge would be in Les Chappieux at the Refuge de la Nova and my second one in Champex at the Gite Bon Abri. For the actual running route, I found a Suunto route for UTMB that seemed trustworthy, which I then added to my watch and also downloaded to my phone.


Nutrition is a big part of any long-distance run, especially a race like UTMB, so a big goal for this run was to dial in my nutrition plan for the race – what to eat, how often, etc. Following advice from a cycling friend in Girona, I would target 250 calories per hour for the 27 hours, for a total of 6.750 calories. Since Overstim.s is the official nutrition sponsor for UTMB and would be at all the aid stations, I would use their products for my run, that way I would feel comfortable and confident using their products at the aid stations (or learn in the training run that their products don’t jive with my stomach in which case I would know I couldn’t use their food at the aid stations come race time and would need another plan). My nutrition calculations looked like this:

Rather than carrying all my calories on me, I decided I would save on weight by picking up 1.000 calories per day along the run. Since I wouldn’t need to carry this extra weight during the race given the aid stations with food every 10-20km, this would allow me to better simulate a race pace during my running time.


For gear, I planned to bring all the required gear for UTMB to simulate my race pack for the day of the race along with €50 cash. With the exception of 3 days worth of calories stuffed into my pack, this would be the same race pack and gear I would have at the start line of UTMB:

  • Salomon S/Lab boxer, shorts & jersey
  • Salomon S/Lab Ultra 2 shoes
  • Salomon S/Lab Sense Ultra Vest 8
  • Salomon windbreaker
  • Salomon Pulse Belt
  • Suunto Ambit 3 Peak
  • Black Diamond collapsable sticks
  • Petzl Bindi headlamp
  • Visor
  • 500ml soft flasks x2
  • 250ml soft flask
  • Overstim.s Hydrixir 54g sachet x 12, Energix gels x4, Coup de Fouet gels x3, UTMB Bars x6, Authentic bar x1
  • Cold weather kit (mandatory): Buff, Salomon Jacket, Pants & Gloves
  • Emergency Blanket (mandatory)
  • Phone (mandatory)
  • Back-up lamp (mandatory)
  • Cup (mandatory)
  • Waterproof jacket (mandatory)
  • Passport, ID, credit card & €50 cash

Pace Chart

I put all the most important information, along with target splits, segment speed and elevation information onto a pace chart that I put in a zip-lock bag that went into my pack. I referenced this often over the course of the run.


I didn’t want to run in rain, so I checked the forecast for the 3 days I would plan to run and if all looked good it would be a go. The forecast looked promising with moderate chance of thunderstorms, which is pretty common for this type of year, but thankfully no forecast for sustained rain (or snow, which is possible at the higher elevations).

The Run

Day 1: Chamonix to Les Chappieux

I started around 11:30 on Saturday morning. I wanted to time my runs to arrive at the Refuges between 19:00 and 20:00 (when they typically serve dinner) so I could get food as soon as I finished running for the day, followed by sleep. I broke Day 1’s running down into the following 5 segments:

Segment 1: Chamonix <> Les Houches
I tried to take this segment easy – to relax, see how my body was feeling and to get into a rhythm knowing it was going to be a long few days. Starting from Chamonix town center, the segment is mostly flat with a few short uphill and downhill sections. You can definitely run this segment fast, though I’ve been warned by former racers to take it easy here – a lot of “newbies” will blast through this section powered by enthusiasm and excitement at race time, only to pay the price later on. I stuck pretty close to my target pace here.

Segment 2: Les Houches <> Saint Gervais
From Les Houches, you have your first climb to Le Delevret, followed by an 8km descent to Saint Gervais. The climb was about 800m in elevation gain in a little over 6km for a grade of around 13,6%. I did this in a little under an hour while staying fairly relaxed. It was getting hot out, so I definitely took that into consideration in deciding how much effort to put out. The descent to Saint Gervais was fast – a bit too steep in a lot of sections to run all out but a nice wide cat-track to run on most of the time which made the running fairly easy (vs some of the rutted trails later in the day). I was a bit ahead of pace in this section and feeling relaxed. I needed to find 1.000 calories in Saint Gervais per my plan (had I known there were so many shops in Les Contamines I would have waited until then) and found a “sports restaurant” that made me a potato omelette with cheese and gave be a baguette and block of cheese to take on the go, which I had to carry in my hands for the next few hours as I slowly made my way through the food (thankfully I wasn’t using my sticks at this point and had a free hand to spare!).

Segment 3: Saint Gervais <> Les Contamines Montjoie
This 10,2km section has 626m of climbing and 284m of descent but I really don’t remember where they came from. The section felt easy and rolling with no major climbs, and think I ran most of it.

Segment 4: Les Contamines Montjoie <> La Balme
This 8,1km segment was a fairly easy climb of 530m, and quite enjoyable. The first part of the climb started out a bit steep but it was mostly moderate after that. The initial part of the climb started on a fire road popular with local families and hikers, although the crowds thinned out as you made your way higher. The trail opened up as you climbed, revealing beautiful views of the mountains above an around. I filled up with water and continued on.

Segment 5: La Balme <> Les Chapieux
This 10,8km segment continues the climb that began in the last segment, gaining another 800m before descending 936m to Les Chapieux. The climb gets a little steep in a few parts but is enjoyable given the beautiful views. I imagine it would get hot in the middle of the day since there is no tree cover, but since I was doing the climb fairly late in the day the temperature was quite nice. There was one snow crossing before a fairly steep ascent to the Col du Bonhomme. From there you still had a bit more ascending to do but mixed in with some flat sections as well before arriving to the Croix du Bonhomme at nearly 2.500m. It was a bit windy at top so I put on my windbreaker that I had attached through the belt on my waist for easy access, before starting the descent to Les Chapieux. The descent was very rutted and proved difficult to get into a rhythm on. I was happy I didn’t have any falls on the way down here and curious how things will play out for UTMB when we descend this section at night. I arrived to the Refuge in Les Chapieux around 19:00h feeling relaxed and good, albeit hungry and a bit cold. The husband and wife owners were incredibly friendly and helpful (and funny, asking “what took me so long?” to get there). I checked in and began eating right away.

Here are a few photos from this climb between the Col du Bonhomme and Croix du Bonhomme:

Looking back on the trail from Col du Bonhomme to the Croix du Bonhomme. An alpine ibex off to the right observing a hiker making their way down the trail.
Another view from on the trail from the Col du Bonhomme to the Croix du Bonhomme.
On my way up to the Croix du Bonhomme. I took a lot of photos here!
Looking off to the right of the trail as I make my way up to the Croix du Bonhomme.
Looking up to the Croix du Bonhomme.

Targets vs Actuals

According to my watch data, I made up about 26 minutes compared to my target time, but unfortunately I paused and forgot to restart my watch when a group of hikers going the opposite direction asked me how long I thought it would take them to get down to Les Contamines. I’m missing 85m of elevation gain from my data (compared to what I should have gotten for the day) so probably need to add about 10-15 minutes to my actual duration. Therefore, day 1 actuals are pretty close to my target times. I maybe gained 10 minutes over the course of the day, which is pretty negligible.

TrainingPeaks Data

Day 2: Les Chappieux to Champex, Switzerland

This was a long day. I knew it would be long, so I woke up at 5:40h and was running by 6:00h. Since the refuge didn’t serve breakfast until 07:00h, I had to forego breakfast, which made me sluggish to start and for the first part of the day. Starting a 12-hour run with little in the tank was less than ideal, but it was either that or miss dinner at the next refuge.

Segment 1: Les Chapieux <> Lac Combal
There was a lot of climbing in this segment – a little over 1.200m. From Les Chapieux you follow a fire road for a couple of kilometres before hopping on a trail that follows the fire road before starting a steeper climb up to the Col de la Seigne. Once you are there you’ve crossed over into Italy and completed a little over 10km of the 17,2km segment, before beginning a nice downhill for about 1,5km until you turn off the main trail (which continues downhill – be careful, I missed this turn!) to begin the final part of the climb up to the Col des Pyramides Calcaires. There was a small snow crossing to get to the top before beginning a descent that I found challenging, especially in the beginning as you make your way down a large rock garden. Thankfully, there is a small path cut through the rocks, but it is still a path of large, loose rocks that for me was difficult to find a rhythm on. I feel like I was pretty slow down this descent.

Segment 2: Lac Combal <> Col Checrouit Maison Vieille
From Lac Combal there is a fire road for 2 kilometres before turning off to the right to begin the next climb of about 450m before starting an enjoyable descent. While parts of the climb were steep, it didn’t seem too tough. There was a stream along the way that I used to refill my water and to splash on me to cool down a bit. The one nice thing about the climb were the views from the top looking over to Mont Blanc and the peaks nearby. I took a few photos before beginning the descent, which was runnable and fun and after about 5km brought me into the refuge at Col Checrouit. From here Courmayeur is within sight.

Segment 3: Col Checrouit Maison Vieille <> Courmayeur
This was the most difficult descent for me of the entire run. First, it was steep, as you descend 772m in a little under 3km or so (the entire segment is 4,3km but the final part is relatively flat as you make your way into Courmayeur and to the Sports Center. Second, the steepest sections were very short and steep switchbacks that I found a bit awkward and difficult to move through with any speed. As I was descending there were also a lot of hikers coming the opposite direction who had the right-of-way which broke up my flow a bit more. I was happy to get to the bottom and into the beginning of town where there was a nice fountain and trough to refill my bottles before continuing on to the Sports Center. Here I was able to grab my 1.000 calories I needed to pick up for the day. I had 2 chocolate croissants and an espresso, and grabbed a sandwich and banana for the road.

Segment 4: Courmayeur <> Refuge Bertone
Courmayeur was humming with tourists as I made my way through around 11:00h. It was refreshing to see all the people out as I made my way up the paved road for a few kilometres before it dead-ended into a trail that would take me to Refuge Bertone. This was a steep climb, and it got hot on the way up but I felt pretty good overall, having just refuelled with food in Courmayeur. I drank 2 cokes at the Refuge, refilled my water bottles and continued on to Refuge Bonatti.

Segment 5: Refuge Bertone <> Refuge Bonatti
This was one of the more enjoyable segments – nice rolling trails with only 280m of ascent and 240m of descent over the 7,3km segment. I had a lot of fun here. I was able to run pretty fast and very much enjoyed all the views.

A view looking across the valley along the rolling paths from Refuge Bertone to Refuge Bonatti.
Another view looking across the valley along the rolling paths from Refuge Bertone to Bonatti.

Segment 6: Refuge Bonatti <> Arnouvaz
This was another really fun segment with amazing views as you cut across the mountain. Again, not much climbing or descending over this 5,2km segment. You climb 105m and descent 334m to Arnouvaz, where a restaurant buzzing with people greets you, at least when I passed through. The descent was very runnable and fun – not technical. I passed a group on the downhill who told me I was “running like Kilian.” I smiled knowing he goes at least twice as fast, which still I don’t understand how that is possible.

Wildflowers along the path to Arnouvaz.
Making my way toward Arnouvaz.

Segment 7: Arnouvaz <> La Fouly
This is a big segment – ~14km with a massive climb of nearly 1.000m over the first 4km, bringing you to the tallest point of the UTMB course at the Gran Col Ferret at 2.490m, where you also cross from Italy into Switzerland. By the time I got to the start of the climb, around 16:00h, it was hot, and it felt like it took me forever to get up this climb. The views, however, are invigorating and helped get me to the top, where I devoured the sandwich I had bought in Courmayeur before beginning the long and fast descent of 1.138m into La Fouly. I know this climb will be an important part of the UTMB race – especially the mental win of being able to get to this point feeling relatively good – and one that split up the leaders in 2017. As I had been able to get in a good amount of calories, I enjoyed this descent and felt good.

Looking back toward Arnouvaz. Mont Blanc is off to the right hiding in the clouds.
Heading up along the path to Gran Col Ferret.

Segment 8: La Fouly <> Champex-Lac
This 14,3km segment is mostly rolling downhill before beginning a 4km climb of ~500m up to Champex-Lac. The rolling downhill is fast, and by this point in the day I was getting tired and my feet were starting to feel sore. I know come race time I’ll have to figure out how to push through here as there are a lot of “easy” kilometres to be had at a fast pace. I passed through a couple small towns, admired a chicken coup just outside the town limits of one of them, before getting to the turn off to begin the climb up to Champex-Lac. The climb felt steep, but this was probably because I over 70km and 12:00:00 total hours (including stops) into my day. It was cool and shaded, and other than feeling tired was a nice climb. I was excited to make it to the top where I stopped my watch for the day, but from there had to navigate to my Refuge which was still a few kilometres away. I was able to call them and let them know I was coming to make sure they saved me food. The staff was super friendly (like the first Refuge) and assured me food would be waiting. When I got there I used a hose outside to wash off my feet (typically no shoes are allowed inside the Refuges, mine by that point in time being a great example of why not…) before heading in to eat. After having been greeted with a meal with meat (I had requested vegetarian), I was quickly given the replacement vegetarian meal, along with a beer on the house. I used the nearby power outlets to charge my watch and phone while I ate, and following the meal had hot water to warm up a bit (it gets cold quickly when the sun goes down). I had reserved a bunk bed, which at this Refuge were divided among a handful of rooms, with 6 bunks per room. The managers of the Refuge showed me to my room, and I think the other 5 people in that room (who were all in one group) were surprised to see that I would be joining them for the night. I said hello and quickly went to sleep.

Targets vs Actuals

As you can see above, I was pretty close to my target times again, with 2 exceptions: the first segment where I was nearly 20 minutes off, as well as the third segment which was a steep, short descent to Courmayeur. I think the delta on the first segment reflects not having had breakfast and being short of energy going into a big climb. As far as the descent goes, I will have to adjust my time here for the race to make it more realistic. This section is super steep, and I’m not sure I would want to push it any harder than I did come race time on this section. After food in Courmayeur my times seemed to pick up. Had I been on my target time on the first section, I would have been 35 minutes ahead of my target time for the day.

TrainingPeaks Data

Day 3: Champex, Switzerland to Chamonix

I started off Day 3 with a massive breakfast at the Refuge: yogurt with granola and honey; 2 slices of bread with Nutella; 5 slices of cheese; 2 cups of coffee and 2 cups of orange juice. While this meant I would start the run slow to let my food digest, it paid dividends over the course of the day. Day 3 would take me a bit over 45km with a little over 2.700m of climbing and 3.100m of descending. My goal was to complete this section in ~8 hours of running time.

I left the Refuge at a quarter till 8:00h, crossed the bridge out the back and made my way up a set of stairs to a fire road that should have been the course route. As I made a right onto the fire road and started slowly making my way down the trail, it seemed my path was diverging more and more from the GPS on my phone (which I would use in the beginning of runs to make sure I was on the right path, or in towns with lots of streets like Courmayeur, or when the path would diverge into more than 2 trails as it provides much higher fidelity than my watch). Not confident I was going the right direction, I began making my way back uphill to where I had started and where I was confident my current location matched the location of the trail on my phone. If at that point there were no other trails nearby that I could take, then the trail that I was on had to be the right one. As I started making my way back up, in the distance I saw a group of 3 runners running toward me. When they approached, I asked if this was the “UTMB trail” hoping they spoke English or understood “UTMB.” The one runner in the group who spoke English replied “yes,” and asked where I was going to which I replied “Chamonix.” He waved his arm and said “follow us.” Turns out, they too had spent the prior night in Champex-Lac and were running the same route that I was back to Chamonix. The 3 runners were also doing a UTMB training run and had started the prior day in Courmayeur. This was a chance encounter that turned out to be quite amazing, as I was able to share the trails with this group all day long. After spending the last 6+ months running by myself (since moving to Europe), it was quite special to be able to run with other people.

Segment 1: Champex-Lac <> Trient
Day 3 breaks down, roughly, into 3 back-to-back climb/descend segments, with the final segment being the final descent into Chamonix. Segment 1 from Champex-Lac to Trient is the first of these 3 climbs. This climb took us up 914m in a little under 6km. I found the climb fairly enjoyable, probably because I was topped off with calories, the weather was cool and I was sharing the trails with fellow runners. Our group of 4 split into me and one of the French runners pushing the pace a bit off the front, with the other 2 runners following up behind us. This runner and I would spend much of the day running together. He was strong, and I’m thankful he was there as he encouraged me to push myself throughout the day in a way I probably wouldn’t have had he not been there, instead allowing myself instead to “enjoy” the day after 2 long back-to-back days. We made it to the top 5 minutes or so in front of the other group. We waited for everyone to regroup before we began the descent, where he and I again went off the front. About a quarter of the way down, a thunderstorm started overhead so we paused for a few seconds to pull out our rain jackets and put them on. Despite the rain there was still pretty good traction, and we made our way down the ~1.000m at a pretty fast pace. This would be how much of the day went: he and I pushing ourselves up the climb, waiting for everyone to regroup, then the two of us pushing each other on the downhills and again waiting for everyone to regroup.

Beginning the descent to Trient (or Vallorcine!)

Segment 2: Trient <> Vallorcine
Honestly, this section felt like a repeat of the last section. A big climb followed by a fast descent. When we made it to the bottom, the group had a sandwich (I had already eaten one at the top of the climb as I waited for the group to reassemble) and we continued on to Le Flegere.

The group stopping for a picture on the descent to Vallorcine. Lac d’Emosson in Switzerland in the background – a stop on the Mont Blanc 90km.

Segment 3: Vallorcine <> Le Flegere
After a runnable uphill, you get to one of the steepest climbs of the entire course – about 600m in just 2,4km. This section is exposed to the sun and felt hot, and I was sweating a lot as I made my way up this climb. I left the group on this climb and made it up in a little under an hour (I’m hoping to come back here before UTMB to do a workout on this climb) and waited for the rest of the group at the top of the climb.

The top of the climb where it opens up and flattens out, about 1,4km from Tete aux Vents. This picture is looking back into the valley from which we came.

There is still a bit more ascending to do before reaching the highest point of the segment, Tete aux Vents, from where you make your way down to Le Flegere. When you do start to make your way down, Le Flegere seems a bit closer than it actually is. You can see Le Flegere in the distance but it felt like it took a long time to get there. The descent in runnable but with large rocks everywhere, making it a technical descent, at least to go fast.

Segment 4: Le Flegere <> Chamonix
There was a bit of confusion about where to go here. We had descended 200m or so before arriving to a trailhead that was closed because of construction at Le Flegere. Their GPS had them going down that trail while my GPS had us on another trail up 50m or so. We debated whether to go down the trail that was closed, hike up to the trail on my GPS or take another trail that seemed to parallel the trail my GPS said to take, only 50m below. In theory, they all would lead down to the valley bottom. After some discussion, they decided to take the closed trail whereas I decided to hike up the 50m to the trail on my GPS. This trail was quite fun, with a bit of exposure with safety chains at a couple points. I realized I was on the same trail as one of trails from the Mont Blanc 90km, just going in the opposite direction. After about 20 minutes of descending, I pulled out my phone at a trail intersection to consult the map to make sure I was taking the right path down when my French running friends again re-appeared, running down a different trail that led to the same intersection that I was at. We were definitely meant to be together that day! After rejoining together we continued down to Chamonix where we excitedly concluded our day of running with high-fives and later, beers. Andrea, Benson and Bear greeted me at the finish, and I was so excited to see them and give them all a big hug. We sat in the square for the next 30 minutes while I stretched, had a recovery drink that Andrea had brought for me and later met up with the French runners who Andrea was actually able to speak with since she speaks French.

Targets vs Actuals

I made up a lot of time on Day 3, mostly because I pushed myself in a lot of sections. Since I started a bit outside of Champex-Lac, I need to add probably 15 minutes or so to my Segment 1 time to account for the kilometres I had done the night before with my watch off as I made my way to the Refuge. Overall I was probably 1:30:00 ahead of pace for the day, which I’m happy with.

TrainingPeaks Data


My running time according to my watch data shows 24:11:41 but as I mentioned I’m missing probably 20-30 minutes, 10-15 minutes from Day 1 when I stopped to help some hikers and forgot to restart my watch, and the 10-15 minutes it would have taken me to run from Champex-Lac to where I started my run on Day 3. Most of the time I made up came on Day 3, although if I had maintained pace on the first segment on Day 2, I could have made up another 35 minutes, which I think would had been doable if I had eaten a proper breakfast in the morning. If my target time for UTMB is 27 hours, I think I was successful in running it a bit faster in this training run. Looking at my speed over the course of the 3 days, I averaged 6,9kph compared to the 6,4kph it would take to hit the 27 hour mark, putting my average speed 7,4% faster than my target race speed.

While I went into the run without complete certainty (the route, finding the refuges, where I would find the extra 1.000k) I’m thankful for the way things unfolded, especially meeting my running friends on Day 3. The only thing I think I would change were I to do it again would be to figure out how to have had breakfast on Day 2 (without missing dinner) and bringing a toothbrush and toothpaste (which I forgot) and earplugs for the Refuge to make falling asleep a bit easier (lots of snoring! Although I’m sure once I fell asleep, as tired as I was each night, that I added to the chorus).

All in all, a good 3 days. Thankful for the opportunity and hoping the universe treats me this well come UTMB in a few weeks!

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