Fueling your training — start as you mean to go on.

You wouldn’t arrive at the start line in new — unworn — running shoes. You need to know how they feel, how they respond to changing terrain, and whether they are right for the shape of your foot. Simply, you need to have trained in them first. It’s the same for fuel. By training with race day fuel it helps the body adapt and enables a trail runner to learn what nutrition strategy could work. And what won’t. Fueling is a personal process that starts with the first step of training, not the first step of the race.

It’s about knowing what to expect. The texture, the flavor, the sensations as the body absorbs the ingredients, and the logistics — how to open and consume fuel on-the-go. You get used to all aspects of fueling, but the most important part is learning how many carbohydrates per hour the body can tolerate. 

Maurten athlete Petter Engdahl is a pure mountain specialist — as capable on skis as he is in trail shoes. A 365-day athlete who transitions from ridges and trails to couloirs and cross-country ski racing. Course record holder at the 101km Courmayeur-Champex-Chamonix (CCC), Engdahl is versatility personified. As with all multi-sport athletes, his preparation is meticulous. In this article Petter describes how he fuels his training to develop his own unique race day strategy.

“On average I train for between twenty to thirty hours per week. That amount of training requires that you get enough fuel in”, states Petter, reinforcing the point that getting fueling right is crucial, not only in the race but also in training. This volume of training is at the top end of the sport and not reflective of all race-goers, but it’s an extreme example that’s helpful for illustrating fueling need, no matter your level. Underfueling training would ultimately result in a body that becomes depleted and incapable of sustaining a plan. Finishing a session in a depleted state extends recovery time and could limit the effectiveness of the next session. At Petter’s level, where aspirations are focused on being at the front of the race, every fueling moment counts. But fueling has a big impact whether you are aiming to be first across the line or just complete the course. “The competition in trail running is getting harder and harder. People are running faster and have realized that what you eat or drink is crucial, even to just be able to finish the race.”

It’s in the detail, as Petter explains, “I plan my fueling prior to every run. I factor in things like the elevation profile, time, intensity, temperatures, the number of aid stations, if I’m able to get on-course support, and, for very remote training, if there are any freshwater streams. Overall, my philosophy is: never risk to run empty on fuel.” Where possible, Petter tries to recreate similar circumstances to what he will face in a race. “When training for a big goal, I try to find terrain that replicates the racecourse as much as possible. So, for Western States 100, even though I live in very technical mountain terrain, I ran down in the valley where the trails are smoother and have more of a flowing nature.” These are important factors to consider. Consuming fuel on a flowing trail will be easier than technical terrain where a runner will need to be attentive of foot placement or perhaps even scramble over rocks using the hands. Additionally, it can be tempting to resist fueling on the climbs if the intensity or effort feel higher. But trail runners must also consider how their stomachs will feel when pounding down steep descents after eating or drinking. It’s something that can, and should, be tried in training first.

The longer the race or the further the training session, the more time flies. It's easy to forget — to miss — your fueling. It's a quirk of endurance sport that, sometimes, the more time we have to think, the less we focus on doing the right thing. And yet — here's the crunch — the longer we're out there, the more important fueling becomes. When the racing is hectic or the trail is technical, when opportunities to stop are less frequent, when you've got your head down, concentrating, lost in thought — pushing on — fueling gets neglected. “I'll eat at the top of the climb. I'll eat when I stop next. I'll eat when I catch the person ahead.” Good intentions — but time passes. The kilometers pass. And before you realize, the fatigue has caught up with you instead.

Not every runner has the luxury of being able to access big mountains or long trail networks, but there are also advantages to this. Running a smaller loop means you can recreate regular fueling intervals or even the distance and time between race aid stations. Remember that 20km between aid stations in a trail race could be very different in time depending on the terrain between. “Every race is different, so you need to adapt and have a flexible plan, but also have some basic race nutrition principles to follow,” Petter adds.

It’s all in the mind — and the guts. “If I get it right, I feel that I have the ability to keep a constructive mindset and focus on the trails. I can stay in race or training mode much longer if I get the fueling strategy right. And the recovery — I recover a lot quicker.” Remember that fueling is personal. What one runner can tolerate may not be the same as anyone else in the race. Petter is able to consume quite high amounts of carbohydrates per hour and it’s something that he has worked up to. Race strategies are based on previous experience. With only a few race days each year, most of Petter’s learning comes from training. “During training I use the products I am going to use in the race — usually the Gel 100 and Drink Mix 320, and sometimes also the Bicarb System before higher intensity. I try to reach 80 to 100 grams of carbohydrates per hour, depending on the race. During the CCC (the UTMB race that Petter won in 2022, setting a course record on the process) I averaged even 120 grams per hour — I’ve got quite a big engine that burns a lot. In that race I really had to average that intake to be able to run that fast for ten hours.” Reinforcing the point that it requires regular fueling to sustain performance.

And as race day approaches, Petter remains disciplined with his fueling plan. “I make sure to be on top of nutrition and fueling in the weeks before a race. The strategy before is mostly the same — I need to be properly fueled when starting a race regardless of distance.”