UTMB is the premier trail event in the world. Serving as the World Series Final for the overall UTMB series, it brings the best athletes worldwide to race 100 miles with over 10,000 meters of elevation gain. Based in Chamonix, France, it's home to ultra-trail running and supported by a global audience and passionate local community. Below is the analysis of the 3rd place female Blandine L'hirondel as we look into the training required to get here and the race strategy to grab a podium spot on the world's largest stage!

Watch: COROS APEX 2 PRO Chamonix Edition

Accessory: COROS Heart Rate Monitor

Analysis Tool: COROS Training Hub

2023 Training

As with any athlete, training will be the foundation of any race results going forward. Blandine puts in a massive amount of training, resulting in not only her 3rd place UTMB result this year but also a 1st place World Championship result in 2021 and 2022. Beyond these accomplishments, Blandine also won OCC in 2021 (50km World Series Final) and CCC in 2022 (100km World Series Final).

Base Fitness

Base Fitness tracks your daily training load over a 42-day average.

Blandine maintains an extremely high fitness level all year. Sitting often in the 300 Base Fitness range, this means that she averages 300 Training Load each day throughout the year. For many athletes, they will sit between 100 and 150 when they are very well trained, which goes to show just how much Blandine is training on a constant basis. In the data above, Blandine's fitness lowers prior to races as this is a planned taper. As athletes recover for a race, they give up some fitness to feel fresh/recovered on race day. This is by design.

Training Volume/Cross-Training

Athletes can look at their weekly volume within the COROS Training Hub.

Blandine puts in more volume than many other athletes. While the numbers are staggering, the way she is able to do this is through cross-training. At COROS, we are starting to see more and more elite runners mix in cross-training to build overall volume in a less impactful way (running puts strain on muscles due to its load-bearing nature). The week of 6/19 to 6/25 saw Blandine complete 566 kilometers. This was accomplished through long cycling days as she dealt with an injury and wanted to maintain/build fitness without the risk of furthering her strain.

Running Specific

Athletes can sort by activity type to see how often they train in each discipline.

Throughout the last 24 weeks leading into UTMB, Blandine was able to run 1965 kilometers, averaging 81.875/week. This does include multiple tapers, so her weekly average is actually quite a bit higher when in a training focus. The noteworthy piece of information here is that, as seen above in the cross-training section, Blandine gets a lot of volume outside of running. For athletes looking to build their fitness but can't recover from the day-to-day stress of running, this is a fantastic strategy to introduce.

2023 UTMB

Athletes can analyze workouts within the Training Hub for better insights.

Blandine is an experienced runner with several races under the belt. She followed a conservative approach by letting the lead field rush ahead and settling to an easy intensity that she knew could be maintained for a long time. Blandine also used the COROS HR Monitor, which allowed her to accurately monitor her intensity and ensure she would have enough energy to attack later in the race. Below, you can see a breakdown of her race and how she managed to use her experience to secure a podium position at the 2023 UTMB.

Chamonix (0km) to Les Contamines (31.8km)

The first few kilometers at UTMB are always particularly fast for a long-duration race. Blandine did not make the exception as she maintained a threshold HR for nearly 30km to Les Contamines. Although it can be pretty hard to maintain a slow intensity right off the start in Chamonix, it is important to maintain your intensity under threshold. Spending too much time at or above it will utilize energy sources that will become important during the latter stages of the race. Blandine set up this first stage in 74th position overall and 2nd female behind Courtney Dauwalter.

Les Contamines (31.8km) to Courmayeur (81.3km)

Blandine's heart rate has settled in her Aerobic Power zone, an intensity at which she can sustain for about 6-8 hours, depending on the exercise. With several massive hills between Les Contamines and Courmayeur, Blandine averaged a pace of about 8'30"/km (13'45"/mi), but her effort pace was steady at 5'30"/km (8'50"/mi), which means she was putting up a consistent effort in her Aerobic Endurance zone throughout this stage. She reached Courmayeur in 2nd position female.

Courmayeur (81.3km) to Champex-Lac (127.0km)

With the sun finally rising, Blandine was able to catch up to several other runners on her way to Champex-Lac. With still an effort pace of around 6'00"/km (9'40"/mi), she was well within her easy intensity and in full control of her race. She entered Champex-Lac in 2nd position female at 10:46 am local time, ready to embark on the last portions of the race.

Champex-Lac (127.0km) to Vallorcine (155.0km)

This section features two massive climbs that Blandine made sure to complete without any issues. She decreased her intensity slightly with an average HR of 110bpm and an effort pace of 6'30"/km (10'30"/mi). It is a portion of the race that can easily break a runner down, and Blandine had the experience of backing off slightly and remaining conservative. Regardless, she reached Vallorcine in 4th position female, still gaining places amongst other runners on the course.

Vallorcine (155.0km) to Chamonix (172.9km)

This final section now only has two small hills and one last technical downhill back to Chamonix. With still a very low HR, Blandine fought through the last few km to complete the course even stronger with a 33rd overall position and a 3rd female position. Her overall strategy throughout the course really paid off in the end, as she was able to maintain a very consistent intensity and slowly gain positions as the race progressed.


COROS wants to give a big congratulations to Blandine L'hirondel for her amazing performance and 3rd place female at 2023 UTMB! Through her yearlong training, tactical race strategy, and phenomenal execution, Blandine was able to step on the podium on one of the most prestigious ultra-marathon races in the world. If you found this analysis informative or interesting, we urge all COROS customers to look deeper into their data. This analysis was performed using our free Training Hub software, featuring data collected on every run performed. The next time you prepare for a race, or aim to nail a race strategy, keep this analysis in mind, as it's a great example of how you can aim to achieve your best results yet!