The 2026 FIFA Men’s World Cup has seen the introduction of mandatory hydration breaks in both the first and second halves of all matches. The three minute pause in play at the mid-point of each half is nothing new, as previous tournaments and major competitions have seen them used at the officials’ discretion or if certain temperature thresholds were breached.

However, in this competition hosted jointly by the USA, Mexico, and Canada, there is no weather or temperature threshold in place, meaning the breaks take place in all games irrespective of weather conditions (i.e., in colder temperatures also), and/or if matches are played in stadia with closed roofs and/or air conditioning.

Introduced with player welfare in mind, some argue that the breaks are disrupting the flow and momentum of the game. Critics have included England manager Thomas Tuchel, who voiced his concerns after England’s win over Croatia, and former England captain Alan Shearer, who used his position as a BBC pundit to share his opinion after the Three Lions’ draw with Ghana. The FIFA president, Gianni Infantino, has also stepped into the debate by re-iterating the purpose of the hydration breaks and the rationale behind ditching the case-by-case approach to their use.

Due to the way in which the body attempts to regulate its temperature during exercise, players can routinely experience significant fluid losses over the course of a match. These losses can have important performance and, in some cases, health consequences if they’re not minimised. Given the limited opportunities outside of the warm-up, half-time, and/or any prolonged breaks in play due to injury, players may not be able to rehydrate optimally once a match kicks off – especially in warmer and more humid conditions.

Given the rules were only made public in December, little direct research or evidence exists about the actual effects of the hydration breaks. But, using extra-time, where the five-minute period preceding the extra 30 minutes is often used for hydration and energy provision as a model, does allow some insight to be gained.

Indeed, extra-time research is an area where I have published research, alongside match-day strategies to enhance the performance of team sports athletes and physiological and performance responses to intermittent exercise especially focusing on pre-match practices, half-time, substitutes, and goalkeepers.

The short five-minute break before extra-time is some of the closest comparable research we have to date regarding the possible responses to these mandatory hydration breaks.

My research highlights that when football-specific exercise stops for the period between the end of the 90 minutes and the onset of extra-time, then the body responds in specific ways, some of which persist after subsequent matchplay has restarted.

For example, while it may be beneficial to take fluids on board from hydration, energy provision, and cooling perspectives, there is the chance that any performance-enhancing effects of the prior exercise, such as those explained by muscular performance, may drop outside of an optimal window for peak performance thereafter by temporarily stopping matchplay.

In theory, any stoppage – whether due to injury, video assistant referee (VAR) review, or something less common such as a pitch invasion – could induce detrimental changes to a footballer’s body. I have researched this extensively in the contexts of pre-match warm-ups, half-time, and extra-time, and helped put mitigations in place to help protect against negative physical effects. Therefore, it stands to reason that the hydration break could also compromise performance after the game restarts.

This may be more of a consideration in some of the games played in cooler conditions given that the hydration breaks are mandatory in all matches. If it takes some time to recover these characteristics, and physical performance markers are impaired temporarily, then this could go some way to explaining a drop or a lull in intensity once matches restart – but this is yet to be confirmed by research.

Mark Russell is a Professor of Performance Nutrition and Applied Exercise Physiology at Leeds Trinity University.