Neversecond: Asker Jeukendrup on Fueling for The Tour

Serving as the performance nutrition manager for Jumbo-Visma, Asker is a predominant figure affecting endurance athletes' carbohydrate consumption guidelines.

This webinar is the day before Bastille Day - a massive stage at the Tour. Asker will review how to effectively fuel to be successful in an incredibly demanding stage. We will also cover the fueling trends we see from the Tour and how to optimize your fueling strategy.

Myth: We should not eat within the hour before exercise.

This is because of Rebound or Reactive Hypoglycemia - where the initiation of exercise and high levels of insulin both pull glucose into the body and draw blood sugar down. Yet, no evidence has shown that this experience at the beginning of exercise affects overall performance.

Myth: Bigger athletes require more carbohydrates than smaller athletes.

Since the rate-limiting factor of carbohydrate oxidation (or ingestion to utilization) is how much an athlete can process per hour, there is no reason a smaller athlete should have fewer carbohydrates.

Myth: There is a perfect ratio of carbohydrates.

There is no optimal ratio because it depends on the amount of fuel you are targeting. The NeverSecond ratio targets a 90g per hour goal using 2:1 (glucose:fructose).

Myth: Endurance athletes need electrolytes during exercise.

Sodium is the main component here. However, its power has been a bit overestimated for in-duration exercise.

How much sodium you need is dependent upon how much you drink; while how much you drink is dependent upon the exercise duration and how much you sweat.

There has not been proof in the literature that electrolytes (or a lack of) during exercise has limited performance.

Q: How would you vary the intake of breakfast before an event?

It is important to eat earlier before the event if possible. If you can eat 3hr before, you can take in a much larger breakfast and wait for it to absorb into your stores.

If you cannot afford 3hrs prior, then you just need to reduce your breakfast a bit to accommodate the shorter time for absorption. In this case, the day prior takes a bit more importance.

Q: Is it true that there's a difference between the needs of men and women?

No, this is not necessarily accurate. When it comes to carbohydrates, it is the same situation as comparing various body masses: there is no difference in fueling recommendations.

When it comes to fluid, this is the same as differences in men and it’s individualized to your hydration needs.

Q: How do I avoid cramps?

There is no perfect answer for this. While it is a combination of things, the general explanation is that the muscle is not 100% conditioned to what you are asking it to do.

Q: After sweat rate calculations are made, what is the percentage of fluid loss to use/watch for racing?

At the end of the race, I want to be 2% lighter than the start. The amount of fluid to drink is dependent upon your sweat rate in addition to the duration of that event, as to calculate how to get around 2% by the end.

Q: What goes into determining the fueling protocol for a stage like today [the Bastille Day stage]?

Their protocol and preparation begin months in advance; there is a plan for every stage and for every rider. Depending on the role of the rider, you will have various expenditures and power outputs – this can change the carbohydrate/energy needs for the day.

On big mountain days like this one, each rider will have their own targets and preferences. With Neversecond, we tried to make the process easy; they can decide for themselves how to get to that target of, say, 90g an hour.

Each rider also has their own fluid target depending on their sweat rates.

Q: Do any of the riders [Jumbo-Visma] prefer solid fuel, and what if so?

Yes, and during the first part of the race is where most of the riders will eat solid food. Then, they transition towards liquid towards the end of the race.

Q: Is there merit to the ability to train yourself to accommodate more carbohydrates?

Yes, there is a training effect. That is seen in improved gastric emptying (more carbs absorbing through the stomach), less bloating, and an overall ability to handle that intake.

Q: Thoughts or beliefs on fasted rides?

Well, we do fasted rides [at Jumbo], so that should tell you. Just like training, you want to provide various stimuli to the body. So some days we push the system to take on lots of carbs but on other easy days we will do low carb/fasted rides to develop the machinery.