Want to race or run super long races, like the Race Across America, Cape Epic, Dirty Kanza or the Transcontinental? We’ve got you covered!

As Certified Sports Nutritionist Coach Sofi Marin (INSCYD user since 2017) says: “During a 4-hour ride, you can underfuel and get away with it. However, during a 48-hour event, it’s essential to pace and fuel yourself appropriately and spare glycogen for as long as possible.”

The goal therefore is, to go as fast as possible, without running out of energy.

Simplified speaking, we can use fatty acids and carbohydrates as an energy source. Carbohydrates can be turned into energy quite fast, but we only have a limited amount of carbohydrates stored in the body.

With fat it’s kind of the opposite: without training, it takes time to turn fat into energy, but we have a lot of it stored in the body.

Refueling carbohydrates and increasing the fat combustion are 2 strategies to make sure you don’t run out of carbohydrates.


From a fuel perspective, not running out of carbohydrates is your biggest challenge in long endurance events. If you do run out of it, you will “bonk” and start considering calling a taxi.

We all have carbohydrates stored in the muscle. This carb store is called glycogen. Glycogen plays a crucial role in all endurance events. Read more about glycogen via this article.

To prevent a depleted glycogen store, you need to make sure you absorb more carbohydrates than you burn. However, there is a maximal amount of carbohydrates you’re able to absorb per hour (~60-90 grams per hour). And it’s easy to exercise at an intensity at which your burn more carbs than that. This is where the metric CarbMax helps.

CarbMax is the intensity (speed or power) at which you burn 90 grams of carbohydrates per hour. If you exercise above CarbMax, then you are not able to refuel the amount of carbohydrates that you are burning.

Disclaimer 1: of you want to be able to actually absorb 90 grams of carbs per hour, you need to “train the gut” by consuming these high amounts of carbohydrates during training. If you don’t, you might not even be able to absorb 60 grams of carbs per hour. Therefore your CarbMax intensity would even be lower. That’s why we provide you a max. carb intake bandwidth in the INSCYD report:

Fat and carbohydrate combustion in running
Your carb combustion rate (red) increases with intensity. When it's above the horizontal max carb intake bandwidth, you'll not be able to fully refuel.

Disclaimer 2: we’re deliberately talking about absorbing carbohydrates. Just because you can eat a lot of carbohydrates, doesn’t mean your gut is able to absorb it. Find your INSCYD coach to measure your CarbMax and start training your carb intake.

As an ultra endurance athlete, you want a high CarMax intensity. This ensures that you can go fast, while still being able to refuel.


Another way to make sure you do not run out of glycogen and carbohydrates is by using a different fuel: fat. Since we all have enough fat on board to finish an ultra event, it makes sense to train your body to burn as much fat as possible.

If you’re able to use fat as an energy source while exercising at a high intensity, you can go fast and save carbohydrates. That’s why all endurance athletes are interested in (training) fat combustion.

Learn all you need to know about fat combustion via this article and whitepaper.

Example: Race Across Italy (750 km)

Eugenio Rezia Loppio’s story is just one example of how INSCYD can help you succeeding in long distance tasks.

Rezia Loppio is an Italian entrepreneur with a big passion for cycling. He doesn’t only enjoy the classic weekend ride or the hard high-intensity training session — he loves going long, crazy long.

Last year, the 43-year-old from Rome took part in several sportives and in his first ultra cycling race: the Race Across Italy. You may be familiar with the format by now: from A to B in the quickest time, although the road to get from one point to the other is not short. In 2018, to be precise, the RAI (also the acronym for Italy’s state-owned television) was conceived as a big loop from and to Silvi Marina, a small sea resort in the region of Abruzzo.

The race snaked from the Adriatic coasts all the way to the Tyrrhenian sea for a coast to coast Made in Italy of 750 km (480 miles) and 10,000 metres (32,000ft) of elevation gain. Not exactly a walk in the park.

In his first ultra cycling event, Rezia Loppo finished in the top 20 and took one of the slots available for the Race Across American — making the RAI one of the world’s qualifiers for the big American crossing. Lucky result? Nope. Random? Not that either. Good performances never are.

“With INSCYD we worked the whole season by keeping our focus on the optimisation of fat burning,” says Loppo. “It was this aspect that fascinated me the most when I followed an INSCYD presentation from performance coach Marco Orsini.”

Coach Orsini: “The Ultra cycling races are races where the fat max power and the functional strength for cycling long events are fundamental,” says Orsini. “INSCYD helped him to improve his maximum fat power and also helped him to plan the correct nutritional strategy by reducing the impact of his glycolytic power (VLaMax).”

Rezia Loppo’s training schedule — despite having a good amount of volumes for an amateur (17 hours average per week) — was not only focused on long sessions though. His weekly routine included gym sessions to develop his strength, workouts on the road for his muscular endurance and specific sessions to target his VO2max with the Billat protocol, as well as other sessions to target his lactate shuttling and FatMax.

Wrap up

If you have big long-term goals too, don’t waste your precious training time. Understand your exact physiological needs and optimise your training schedule with INSCYD.