Joseph Mestrallet: When Data Science Meets Ultra-Trail
In a sport where intuition and experience have long reigned supreme, Joseph Mestrallet represents a new generation of professionals transforming athletic performance through data. From Chamonix, in the heart of the French Alps, this trained Data Scientist has become one of the key figures in trail and endurance sports performance optimization.
From Chamonix to the Peaks of Data Science
Growing up in Chamonix means being immersed from childhood in the world of mountains and endurance sports. Joseph Mestrallet is no exception. But it was during his higher education that he discovered his second passion: mathematics.
"I've always looked for a career that combines my two passions: mountains and numbers. Data science applied to endurance sports became the obvious choice."
With a Master's degree focused on Data Science, he wrote his thesis on the trail running performance ecosystem, collaborating with international athletes and the UTMB group. This immersion allowed him to understand the daily challenges athletes face and develop concrete solutions.
Enduraw: Optimizing Race Day Performance
In 2022, Joseph founded Enduraw, a company dedicated to optimizing competition performance. His mission? Harness the power of data to maximize athletes' potential on race day.
A Four-Pillar Approach
Joseph Mestrallet's approach is built on a rigorous methodology:
| Pillar | Description |
|---|---|
| Map the Athlete | Model each runner's physiological functioning to identify their strengths and response to external conditions |
| Predict Performance | Develop minute-by-minute race plans based on the athlete's actual capabilities |
| Adapt in Real Time | Guide the athlete during the race based on conditions and their physiological responses |
| Post-Race Analysis | Draw post-race conclusions to refine future training |
Advanced Physiological Testing
Enduraw offers advanced physiological tests to identify each runner's strengths and weaknesses. This data then feeds understanding models of effort, allowing the creation of ultra-personalized race plans.
An Impressive Track Record with the World's Best
Joseph Mestrallet's work has produced results with several of the planet's top trail athletes:
UTMB 2025: The Crowning Achievement
In August 2025, Joseph supported Tom Evans and Ruth Croft to victory at the UTMB, the most prestigious race in the world. A double victory that validates the data-driven approach at the highest level.
Other Notable Collaborations
- Ruth Croft & Duncan Périllat (UTMB 2023): Pacing and nutrition management
- Petter Engdahl (CCC & Transvulcania 2022): 2 victories including a course record
- Margaux Gressé (Norseman 2023): Support at the world's toughest triathlon
- Solange Jesus (World Championships Budapest): Race briefing for Olympic qualification
Data at the Service of Amateur Athletes
While Enduraw primarily works with elites, Joseph Mestrallet is convinced that the data revolution will reach all athletes:
"Strava showed the way, but we can go much further in personalization and data precision. The sports Data Scientist will become essential for making the right trade-offs between all performance factors."
Among his projects accessible to the general public:
- A Strava integration developed with Alodie Boissonnet to normalize running speeds based on external conditions
- Regular publications on LinkedIn to share his expertise
- A newsletter followed by over 1,500 enthusiasts
A First-Class Partner Ecosystem
The quality of Enduraw's work has enabled partnerships with major industry players:
Equipment: Salomon, ON Running, Compressport
Technology: Polar, Stryd, Core, Supersapiens
Nutrition: Maurten
Analysis: VO2 Master, Train Red, Nix (hydration)
Photographer and Passionate
Beyond the numbers, Joseph Mestrallet is also a passionate photographer. His shots capture the essence of the races he supports, offering a unique behind-the-scenes look at high-level trail performance.
Key Takeaways
- Joseph Mestrallet is a Chamonix-based Data Scientist specializing in trail running performance optimization
- He founded Enduraw to support elite athletes with a data-driven approach
- His work contributed to the victories of Tom Evans and Ruth Croft at UTMB 2025
- He believes in the democratization of data for all endurance runners
Learn more:
- Official website: joseph-mestrallet.com
- LinkedIn: @joseph-mestrallet
- Instagram: @josephmestrallet