Among all the disciplines within the realm of trail running, Skyrunning is the most spectacular. During races, athletes have to overcome steep trails both up and downhill; run along challenging ridges; and contend with technical trails. Thus, the pace for each style of Skyrunning event can range from scrambling to almost sprinting depending on the race.

This form of trail running, which is attracting more and more enthusiasts each year, is fascinating but also extremely demanding. That’s why athletes need to be well-prepared for the challenge that Skyrunning and Skyraces present. In this series of articles written by our Official Training Partner,, we are going to talk about how to thoroughly and safely prepare for the unique challenges you’ll face in Skyrunning races. is the #1 training app for trail runners–they’ve designed a set of custom training programs for the Skyrunner World Series, all of which include weekly coaching from your personal Coach. 

This first article will focus on the base-building phase of training, and is formatted as an interview with Iris Persey, a professional trail and Skyrunner for Scott and a partner athlete (see Iris’ Base Building Plan on Vert.Run). Hello Iris, how are you? You’re a professional runner competing in Skyrunning, and you’ve also worked with to design a “base-building training plan,” which is very popular with Skyrunners. Can you tell us a bit about what exactly base-building is, and why you think it’s so important to build a strong foundation for Skyrunning?  


Hey! I am good, thanks, however I’m not doing much now because I just got shoulder surgery.

To describe base-training, we first need to understand that the preparation for a season is divided in different phases. Base-building is the first, and it’s designed to build aerobic fitness to prepare for more race-specific training to come. 

Base training is essential and has many benefits: 

    • It gives you the ability to “absorb” the specific training that will come later in the season

    • It gives you the strength to “absorb” the races themselves without risking injuries or overtraining

    • It enables you to lower your training volume without losing too much fitness during the racing season, in order to arrive fresher at the start.

So many people don’t start training early enough for their race(s), rush their training, forget the base phase and end up being injured and not even taking the start. It’s sad! Now that we’ve understood why base-building training is so important for a Skyrunning season, could you explain how to make it fit into a season?


I often explain to my athletes that training for a running season is like making an ice cream:

    • The first step is to create the cone, or the structure of your season. It’s the “boring” part of your training. You should spend hours of training at an easy pace, in order to develop a strong endurance. The good news is that as trail runners, we have the ability to cross-train, we’re not forced to run. I encourage my athletes to jump on the bike, to go for long hikes or ski touring, etc.

    • The last step is about making the topping of the ice-cream, or fine-tuning the last details in your training! For a trail runner, it includes race-simulations, working the start or the finish, etc.

It’s important to do things in this order! Think about it like this: you cannot put the topping on if the ice cream isn’t made yet–just like this, you cannot start the specific training sessions without having first worked on your foundation through base-building training.

Also, training really has to be fun and varied if you don’t want to stagnate. A lot of people keep the same training routine all year long, but it doesn’t stress their system enough to progress. Can you dig a bit more into the topic of cross training during one’s Skyrunning base-building training, please?


If you look at the top trail runners in the world, many of them come from different sports. Courtney (Dauwalter) has a strong history of cross country skiing, Remy (Bonnet) or Kilian (Jornet) do a lot of ski mountaineering, etc.

I think that cross training is really good for our fitness, because many of these activities (skiing, cycling, hiking, swimming) develop your endurance base with little or no impact! It enables you to do a lot more volume than if you were just running, and reduces your chances of getting injured due to impact. In the case of training for a Skyrunning race, for example, you can even work on specific skills like cadence for the downhills on the bike! (That’s also why I include a lot of cross-training in my Base-Building Training Plan on the training app.

Mentally, I’m convinced that doing other activities allows you to arrive fresher on your key workouts, and to complete them with total commitment. That’s why I always recommend cross training to my athletes. I really think that it is crucial if you want to last long in our sport. Skyrunning (and trail running in general) is growing, and people are engaging in its various disciplines without necessarily living in the mountains. How do you think someone can train living in a flat area?


I used to live for some years in Australia, in a flat place, and I was still training for mountain running! There are a lot of ways to simulate the muscular aspects of mountain running through proprioceptive exercises, jumps, running on stairs, etc. (Note: when you train with Iris’ Base-Building training plan on, the plan adapts to your training surface–if you don’t have access to the mountains, your plan will include elevation gain alternatives.)

When you think about it, someone who lives in the mountains will often do the same loop (or 2 or 3 of them) in every training session. They often get stuck in a routine.

On the other hand, someone who is unlikely to go to the mountains (e.g. only on weekends or vacations) is likely to make the most of his opportunities, doing great runs that really stress their system.

I’ve seen many athletes falling into the trap of thinking that they should move to a place to prepare well for a race (like moving to Chamonix to train for UTMB), and many times it’s proven to be wrong.

I think people should better stay in an environment that is familiar to them, comfortable and try to make the most out of it. Thank you for these great tips, Iris! Our last question is: why do you think it’s important for everyone to follow a training plan during their season, and also during the base-building training phase?


There are SO MANY benefits to following a training plan! I’ve spent years training on my own, not doing what I didn’t like, and I wasn’t progressing much!

With a training plan, you are more likely to do the training sessions, even if you find them boring, just because they are written down (I know for myself that when I pay for it, I listen… haha!)

It also helps to keep us from falling into the trap of doing the same thing over and over, or ending up overtrained because you always add an extra rep with drills, etc. 

Finally, following a training plan is so good for us mentally, because you avoid information overload and you trust the process!

When I think about the mistakes I made when training by myself (yes, even though I work as a coach!) I cannot imagine how someone with a full-time job, who did not study sports science, can train effectively on his own. Thank you for your time Iris! Do you have any last words for our readers?


My final advice for our readers would be to have fun in the training process (not stressing out about everything), to look at the training program far in advance to have motivation for what’s to come, to take time for themselves (social activities outside of sports), and to understand that we can’t always be perfect!

I often remind myself about the rule of thirds!

    • ⅓ of your training should feel too hard

    • ⅓ of your training should feel too easy

    • ⅓ of your training should feel just right

If you have this balance, it means that you’re progressing! Last but not least, I recommend not looking too much at what other people are doing in their training, but rather focusing on your own training process! 

Thanks to Iris for taking the time to share her Skyrunning expertise. You can find Iris’ Base-Building Training Plan in the App, the #1 training app for trail running and Skyrunners!

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