Mental Fatigue: The Influence of Nutrition on Decision-Making in Football.

Have you ever wondered why great players miss decisive penalties, execute poor shots, or make bad decisions in extra time?

The answer may lie in their plate… or the lack thereof.

The brain also takes the field. Football demands much more than strength and speed. In every play, athletes need to perceive, process, and decide in fractions of a second.

This constant cognitive load, scientifically termed mental fatigue, is a psychobiological state characterized by a feeling of tiredness, lack of energy, and decreased executive function, resulting from long periods of high cognitive activity.

A review published in Sports Medicine (Smith et al., 2018) already documented that mental fatigue in footballers causes significant drops in physical, technical, tactical, and especially decision-making performance.

However, what recent science reveals is that nutrition plays a direct role in this process. What happens to the brain during a match? The brain consumes glucose as its main fuel source.

The prefrontal cortex, the region responsible for planning, inhibitory control, and decision-making, is particularly dependent on a stable energy supply. Research in cognitive neuroscience indicates that highly complex tasks, such as executive tasks involving working memory and mental flexibility, are more vulnerable to drops in glucose levels than automated tasks.

This means that the more demanding the game is at a tactical reasoning level, the more the athlete depends on an adequate nutritional state to make good decisions.

In 90 minutes of play, and especially in the 30 extra minutes of overtime, muscle and brain glycogen consumption combines with accumulated mental fatigue, creating a high-risk scenario for making decisive errors.

Penalties: it's not just pressure, it's biochemistry.

A study published in PMC (2025) investigated the impact of mental fatigue on penalty kick accuracy in collegiate footballers.

The results were clear: mental fatigue significantly reduced shot accuracy (with both the right and left foot), in addition to decreasing motivation and increasing perceived effort.

Most revealing: fatigue affects decision-making, but not the execution time of the movement itself; that is, the athlete knows how to shoot, but decides where less effectively. Overtime as a fatigue laboratory. Overtime is when everything intensifies.

A 2023 study published in Medicine & Science in Sports & Exercise showed that extra time exponentially exacerbates fatigue and compromises athletes' physiological responses. It is no coincidence that more than 85% of World Cup and Euro Cup finalists in the last two decades played 120-minute matches.

It is precisely in this scenario that nutrition enters the competition… gels, sports drinks, and carbohydrate recovery products cease to be a detail and become a strategy.

What nutrition can do (and what science says).

Carbohydrates: the fuel for decision-making.

UEFA Guidelines recommend a carbohydrate intake of 30 to 60 g per hour during a football match.

A randomized clinical trial published in 2025 in Performance Nutrition evaluated different rates of carbohydrate intake during simulated 120-minute matches and their effects on physical, technical, and cognitive performance, reinforcing that carbohydrate availability maintains passing accuracy and the ability to sprint throughout an extended-duration match.

The logic is direct: maintaining stable glucose levels protects the prefrontal cortex and preserves the quality of decisions in critical moments.

Halftime as a strategic window. Halftime is one of the most underutilized opportunities in sports nutrition.

With only 15 minutes available, the athlete faces two simultaneous challenges: replenishing glycogen partially depleted in the first half and cognitively preparing for the next 45 minutes, which tend to be the most decisive.

A systematic review published in Nutrients (2024) analyzed studies with footballers and found that an intake of 30 to 60 g of carbohydrates per hour of play, including a strategic dose at halftime, raised blood glucose levels at the end of the first half, at halftime itself, and in the last 30 minutes of the match, compared to the placebo.

This effect translates directly into less fatigue and higher technical and cognitive quality in the second half.

Experts from Barça Innovation Hub, a global reference in applied football science, recommend an intake of 30 to 60 g of carbohydrates before warm-up and another equivalent dose at halftime, preferably through sports drinks or gels, which reduce gastrointestinal discomfort and allow for faster absorption.

Hydration: water is not enough.

During a football match, an athlete can lose between 1 and 3 liters of sweat per hour, depending on temperature and intensity.

This loss does not only involve water; electrolytes such as sodium, potassium, magnesium, and calcium, essential for muscle contraction and neurological function, are also lost. Replenishing only with water, in addition to being inefficient, can even be harmful: without electrolytes, the body does not retain fluid properly, and the risk of cramps and performance drops increases.

This is where isotonic and carbohydrate-containing drinks come in. For matches lasting more than 80 minutes, such as any football match, the use of sports drinks with a concentration of between 6 and 9% carbohydrates and between 0.5 and 0.7 g of sodium per liter is well established in scientific literature as an effective strategy for maintaining blood glucose, delaying fatigue, and preserving cognitive function.

A comparative study with carbohydrate and electrolyte drinks in intermittent exercises simulating a football match showed that regular intake of these drinks, even in restricted windows such as halftime and game breaks, was sufficient to maintain blood glucose and technical performance (including shooting accuracy and dribbling), compared to the placebo group.

The practical recommendation is to consume approximately 150 ml of the drink every 15 or 20 minutes, whenever there is an opportunity: during game breaks, at halftime, and in extra time.

A temperature of between 15 and 20 °C favors absorption and palatability.

Other compounds with evidence in football.

A recent review published in PMC (2025) analyzed the supplements with the most scientific support for elite footballers.

Among the highlights:

Creatine: improves high-intensity, short-duration efforts. Beta-alanine and sodium bicarbonate: reduce muscle acidity in repeated efforts. Nitrates: improve blood flow and oxygen delivery to muscles.

Protein: accelerates recovery and reduces muscle damage.

From science to practice: Mental fatigue and physical fatigue are not rivals; they are cumulative. A player facing extra time with low glycogen, without a nutritional strategy during the competition, and without cognitive support, is making decisions with a brain operating below its potential.

The good news is that this is a modifiable factor. Carbohydrate replenishment at halftime, hydration with isotonic or carbohydrate drinks during game breaks, and nutritional planning before the competition are interventions with a solid scientific basis for maintaining performance in the most decisive moments of the match.

When it comes to a penalty, preparation begins long before the penalty spot.