Fuel-90 NextGen: validation of a questionnaire to assess youth players’ knowledge of carbohydrate guidelines for soccer

Imagine a soccer player as a high-performance race car. You can have the most talented driver and the sleekest chassis in the world, but if you don't put the right fuel in the tank, the engine is going to sputter, overheat, and eventually stall. In the world of sports science, that "fuel" is often carbohydrates—the body's preferred energy source for running, jumping, and sprinting. Just like a car needs a specific amount of gas to finish a long race without running out, a soccer player needs a precise amount of carbohydrates to keep their muscles firing and their brain sharp during a match. If they don't eat enough, or if they eat it at the wrong time, they might feel tired too early or get injured.

For years, scientists and coaches have known exactly how much fuel these young athletes need. They have written down the rules: eat this much before a game, drink this during the match, and refuel this way afterwards. But here's the tricky part: knowing the rules is different from following them. It turns out that many young soccer players, even the ones training at the very top levels, aren't always eating the right things. Why? Maybe they just don't know the rules, or maybe they think they do but are actually guessing. To fix a problem, you first have to measure it. You can't teach someone to drive better if you don't know if they even know where the gas pedal is.

This is where a new study comes in, acting like a mechanic's diagnostic tool for the mind. The researchers wanted to build a special test—a questionnaire—to see if young soccer players actually understand the rules about carbohydrate fueling. They didn't just want to ask random questions; they wanted to create a reliable "knowledge check" that could spot exactly where players were getting confused. They called this new tool the "Fuel-90 NextGen" questionnaire. The goal was simple: create a quick, easy test that coaches and nutritionists could use to see if their young players were running on empty or if they just needed a little bit of education to fill the tank.

The Big Test: Building the Questionnaire

The team, led by experts who work with professional soccer clubs, started by looking at the official rulebook: the 2021 UEFA expert group statement on nutrition. They took the most important rules about carbohydrates and turned them into a 25-question quiz. Think of it like a video game with five levels. Each level tested a different part of the fueling journey:

1. The Basics: How the body burns fuel and how much energy it needs.
2. Training Days: What to eat on days when practice is hard and long.
3. The Day Before: How to top up the tank before the big game.
4. Match Day: What to eat right before and during the game.
5. Recovery: How to refuel immediately after the whistle blows.

To make sure the questions were clear and actually made sense to a teenager, they tested the quiz on two groups first. One group was a bunch of professional nutrition experts (the "teachers"), and the other was a group of young academy players (the "students"). The experts checked if the questions were accurate, while the players checked if the questions were easy to read and understand. Once everyone agreed the quiz was good, they were ready for the real experiment.

The Experiment: Experts vs. Students

The researchers handed out the Fuel-90 NextGen questionnaire to 426 people in total. This included 51 professional nutritionists (the experts) and 375 young male soccer players from top English academies. The idea was simple: if the test works, the experts should score near-perfect marks, and the players should score lower, showing that there is a gap in knowledge that needs to be filled.

The results were exactly what the team hoped to see. The nutrition experts crushed the test, scoring an average of 24.0 out of 25 (which is 96%). They knew their stuff! The young academy players, however, scored an average of 14.5 out of 25 (which is 58%). This huge difference proved that the test was working. It successfully told the difference between someone who knows the rules and someone who is still learning them. This is called "construct validity"—it means the test is actually measuring what it's supposed to measure.

Is the Test Reliable?

The researchers didn't just want to know if the test worked once; they wanted to know if it was consistent. Imagine taking a driving test today and getting a passing grade, then taking the exact same test next week and failing because you forgot the questions. That would be a bad test. To check this, a small group of 32 players took the quiz a second time, between 7 and 21 days after the first time.

The results showed that the players' scores stayed very consistent. The average score on the first try was 16, and on the second try, it was still 16. There was no "learning effect," meaning they didn't just get better because they remembered the answers from the first time. The test was reliable. It also showed good "internal consistency," meaning all the questions seemed to be working together to measure the same thing, like a team of players passing the ball smoothly to score a goal.

What This Means for the Game

The study concludes that the Fuel-90 NextGen questionnaire is a solid, trustworthy tool. It's not a magic wand that will instantly make players eat better, but it is a powerful flashlight. It allows coaches and nutritionists to shine a light on exactly what young players don't know.

For example, the test showed that players were particularly confused about how much carbohydrate they need on heavy training days and what to eat right after a match. Now that these gaps are identified, nutritionists can stop guessing and start teaching. They can create specific lessons to fill those holes in knowledge. The study suggests that by using this tool, practitioners can design better education programs to help young athletes understand that carbohydrates aren't just "sugar"—they are the essential fuel that keeps their engines running at full speed.

In short, the paper didn't discover a new type of food or a secret training method. Instead, it built a better ruler to measure knowledge. And now, with a reliable ruler in hand, the soccer world can finally start measuring the gap between what players know and what they need to know to perform at their best.