Carbohydrate intake during 120-minutes of a soccer match simulation - dose-response
Do football games that go to extra time need different in-game fuelling strategies?
Title: The effect of different carbohydrate ingestion rates on physical, skill and cognitive performance during extended simulated soccer: a randomized controlled trial
Authors: Wouter M. Peeters, Daniel Baines, Nina K. Billotto, Paul Catterson, Dan Hodges, Mark Hearris & Andreas M. Kasper
Year: 2025
Journal: Performance Nutrition
Background:
Carbohydrates are an essential macronutrient for athletic performance. During high-intensity exercise, this is the main fuel source to produce energy from. We can store carbohydrates in our body, but in finite amounts and a ~90min high-intensity exercise session is enough to reduce these stores to the extent that fatigue occurs and performance declines. Over decades, research has shown that consuming carbohydrates during predominantly endurance exercise can delay the onset of fatigue and thus improve performance. And the longer the exercise is, the higher the recommended amount of carb intake is. Most football matches are 90 minutes and based on a UEFA consensus paper by top researchers, it is recommended to consume 30-60 grams per hour during a match. But in tournament situations, sometimes matches extend to 120 minutes. Recommendations for carbohydrate intake in this scenario are absent, but perhaps with the extended duration, the intake should be higher.
What we did
A group of local football players from academy level came to our laboratory on 3 occasions to complete a 120-min simulation of a football match (running up and down an indoor track, alternating between jogging, running and maximal sprinting to match the demands of a real game). On each occasion, they received different quantities of carbohydrates during the simulation: drinks containing either no carbs at all (placebo control), 60 grams per hour (as per current recommendations for 90-min games), or 90 grams per hour (by mixing different carb sources). Throughout the simulations we tracked the performance of several things that are important in football: 15-m maximal sprint time, jumping, cognition (e.g. decision-making) and passing skill.
Scientific intermezzo: Carb sources and high intake during exercise?
If you look at the chemical structure of a carbohydrate, we can distinguish three different types of monosaccharides (smallest unit of a carbohydrate): glucose, galactose and fructose. When we breakdown and digest carbs in our food, they arrive in the small intestines where the nutrients need to be absorbed from the inside of the intestines into the blood stream. This happens through the use of transporter channels that are embedded in the cell line that separates the inside of the intestines from the blood. Glucose and galactose use the same channel for absorption (SGLT1). Fructose uses a different channel (GLUT5). The rate of absorption (and thus the rate at which carbs can be sent to muscles for energy production) depends on the amount of channels available. If more carbs are in the intestines than there are channels, these channels become saturated (e.g. the rate of absorption has plateaued/maxed out and can’t go up further even if more and more carbs are eaten). It is somewhat assumed (will be discussed in a future blog) that the maximal rate of absorption for glucose is about 1 g/min or 60 grams per hour. Eating more glucose won’t further increase the absorption rate and, even worse, because it will remain stuck in the intestines and stomach can cause serious gastro-intestinal issues. Enter the scene fructose. Because fructose uses a different channel, you can increase carb intake to about 90 grams per hour or even more by combining the two different carb sources (optimal ratios are set at 2:1 (thus 60 gr glucose and 30 gr fructose) or 1:0.8 (60 grams glucose and ~50 gr fructose). And it does improve performance as well!
What did we find:
When we analysed the data, we did not detect a difference between the three treatments (not even between the control) for any of the outcomes! Sprint speed went down over time, but not more in one treatment. Jumping height remained similar across time and cognition and skill were fairly similar as well.
What does this mean?
The findings go against the recommendations of the consensus of a UEFA panel, who recommend that 30-60 grams per hour can improve performance compared to no carbs. What could be the reason for these contrasting findings? Subtle differences in the study design compared to previous experiments that found beneficial effects of CHO intake during the game. In our study design, we gave our participants food and instructions the day before they arrived at our laboratory to maximise the body stores of CHO. Some studies that found performance benefits during 90 minutes did not control for this, or even worse, had people deplete their energy stores the evening before the test. Not really something that happens in the real world. So, it could be possible that the body itself had enough energy stored before the match to get through the 120-min without running empty and as such the extra carbs ingested during the match simulation did not do anything extra. Does this mean players don’t need to consume carbs during the game? I would still recommend players to take some as a precaution/back-up to minimise the risk of running empty and fatigue. But, the priority should be on making sure to eat enough the day before and morning of a match to maximally charge the energy stores within the body.
Personal reflections:
Collaborations. The study saw the daylight due to a direct question of the nutritionist of Newcastle United FC. A great example of how practitioners identify gaps in their nutritional strategy and approach and collaborate with researchers to find the answers through scientific experiments.
