Sara Alonso is a 24-year-old professional trail runner who recently came back from a serious injury to win the Experience Trail Courmayeur (ETC), the brutal 15km race in Courmayeur, from the infamous Ultra-Trail du Mont Blanc (UTMB) World Series on August 29th, 2023. With the ETC 2023 final now in the record books, we take a deep dive into 1st place female finisher Sara Alonso. Sit back and relax as we take you through the inspiring story behind her win in Courmayeur, Italy.

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Analysis tool: COROS Training Hub

The Rise Back From Injury

In December 2022, Sara was diagnosed with a hip stress fracture from training after an amazing competitive year, winning the Marathon du Mont Blanc earlier in the season. A stress fracture often occurs with overtraining among athletes and could lead to several months and up to a year to recover and prevent any more permanent damage to the bones. For professional athletes, this type of injury can easily destroy a career if not taken seriously.

Sara's cross-training from March to August 2023. Base Fitness tracks your daily training load over a 42-day average.

With advice from doctors, Sara has been off all activities that could lead to an impact on her hips, including running. From that moment, she could only rely on her bike to maintain and eventually build fitness while her body recovers before hopefully making a comeback to running competitions this season. It was a daunting objective but a high motivation for Sara. Below you will find a quick breakdown of her training phase from the injury all the way to race day.

Dec 2022 to June 2023Cross-training on the bike
June 2023First 10-min walk/run and build up to consistent slow runs
July 2023Introducing uphill intervals to limit impact
August 2023ETC from UTMB Race

Cross-Training Leading Up To UTMB World Series

After a few weeks of full recovery, Sara has been able to resume training on the bike to prepare for the race. As seen in the photos below, she has spent over 180 hours on her bike from March 1st to June 1st, 2023, while she only completed four runs for a total of nearly 90 minutes in this timeframe. Sara then fully relied on cross-training to build fitness and prepare for ETC 2023.

Bike activities from 03/01 to 06/01.

Run activities from 03/01 to 06/01.

However, Sara has taken pleasure in training on her bike over the past few months. With a strong desire to race but the inability to run, she has decided to take part in the Cycling National Championship Qualification in Spain in early June, where she successfully qualified for it. Only three weeks later, Sarah competed in one of the most prestigious cycling events in Spain, her home country, with only a few months of cycling-focused training.

A Dive Into Her Win At ETC from UTMB World Series

At the start of ETC, Sara was not feeling good, but she pushed through the uphill to find herself leading the female's field only 30 minutes into the race. She then did a fantastic job in managing her effort and leading the race all the way to the finish line to finish 1st female at 1:37:18!

While her pace was 6'42"/km (below her aerobic endurance), her average effort pace was captured at 4'06"/km, which falls within her aerobic power zone. Sara was then able to maintain a hard but sustainable intensity throughout the race, which allowed her to take the lead early on and maintain it until the end.

Full race information from Sara's race from Training Hub.


Despite facing her scariest injury to date, Sara has stayed patient, overcoming the fear of potentially not competing again and building up fitness entirely through cross-training activities such as cycling. Sara's training leading up to her ETC win this year proves that consistency is much more important than specific workouts, as she has remained a competitive trail running athlete while spending nearly seven months without a running workout.

COROS wants to congratulate Sara Alonso for her win at the ETC 2023 from UTMB World Series! Despite facing one of the scariest injuries an athlete can encounter, Sara has been able to remain patient through the process and find alternative strategies to ensure she would be in competitive shape, leading up against one of the best fields this sport has to offer. If you found this analysis informative or interesting, we would urge all COROS customers to look deeper into their data. This analysis was performed using our free Training Hub software featuring data that is 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!