Source: The Conversation – Canada
The most watched sporting event in the world kicks off on June 11 co-hosted by Canada, Mexico and the United States. With 2026 already expected to be one of the hottest years on record, experts and players have warned that organizer FIFA is not doing enough to protect the players from extreme heat.
Our new research shows the heat stress players may face could negatively affect their performance and pose a threat to their health. Many of the players representing their country at this year’s FIFA World Cup were on show at the 2025 FIFA Club World Cup, where the 32 best club teams from six continents faced each other.
Matches were played at the same spring-summer transition as this year’s tournament (June-July) and at several of the same venues that will be used. Therefore, this tournament served as a great case study to identify likely challenges and possible solutions.
We used FIFA’s own technical reports to identify player performance — low- to high-speed running and total distance covered per player — and publicly available data for environmental conditions (e.g. air temperature and humidity, solar radiation and wind speed).
Of the 63 matches played, we analyzed data from 57, ignoring the six matches played inside Atlanta Stadium due to the closed roof and air conditioning keeping it a comfortable 22 C. How hot is too hot to play soccer?
The FIFA heat guidelines are used as default policy to protect player health. Like many sports organizations, FIFA uses the Wet Bulb Globe Temperature (WBGT) to calculate heat stress. This measure accounts for air temperature, radiant heat from sunshine, and the cooling effect of evaporation and air movement.
FIFA’s guidelines use a WBGT “near, at or above 32 C” to define an extreme risk of heat illness, where cooling breaks become mandatory or the match may be postponed or cancelled. Of the 57 matches during the 2025 FIFA Club World Cup, 31 (54 per cent) were played at a WBGT of 28 C or higher.
Thirteen of these matches were played at 30 C or higher and two were played at 32 C or higher. According to experts from the American College of Sports Medicine, these 31 matches should have been cancelled. In other words, players were more often than not exposed to extreme risk of heat illness.
Spare a thought for the spectators, too, as they arrive early, watch the match and then leave later without air conditioning. A heat wave for central and eastern U.S. meant that more than 100 million people across 726 counties experienced record daily maximum temperatures from June 22 to 25, 2025.
Heat and player performance We used statistical modelling to assess how environmental conditions affect high-speed (20–25 m/h), moderate-speed (15–20 km/h) and low-speed (0–15 km/h) running, as well as total distance covered during the matches. We found that the higher the WBGT or ambient temperature, the lower the distances covered by players at all speeds, whereas higher ambient humidity reduced high-speed running only.
Players running slower and less distance can be explained by the heat increasing their deep body and muscle temperatures. They choose to slow down (pacing) in order to avoid a heat injury or illness. It also explains why in the heat, players and teams choose a possession-oriented over a transition-based style of play.
Time of day, player position and age Thirty-three matches (58 per cent) were played in the afternoon (5 p.m. or earlier). The remaining 24 matches (42 per cent) were played in the evening (6 p.m. or later). Players ran longer distances in the evening than in the afternoon, with the simple explanation that matches were played under lower levels of heat stress.
Ambient temperature and humidity, solar radiation and WBGT were all lower in the evening than in the afternoon. Player position and age were important factors determining performance irrespective of heat stress. Defenders ran lowest distances, midfielders ran greatest distances and attackers ran the greatest distances at high speeds.
The older the player was, the less distance he covered at all speeds. What should FIFA do with this data? Matches should not be scheduled for the afternoon when WBGT and ambient temperatures are highest.
This should not be a problem for FIFA, which moved the last World Cup to winter (November-December) to avoid Qatar’s extreme summer heat. However, FIFA’s scheduling reflects their attempt at balancing playing conditions for player health against lucrative broadcasting windows.
Alternatively, FIFA could use stadiums with a closed roof and air conditioning. Seven of the eight stadiums at the 2022 World Cup used air conditioning. Although FIFA has introduced a mandatory three-minute hydration break midway through each game’s half, ensuring drinks are cold and adding cold towels would improve effectiveness at half-time.
Coaches should also be aware of environmental conditions and adapt their game plan to the expected conditions.
For example, when it is hot, players should select a possession-oriented style of play more, employ a high-pressure strategy (to recover the ball) less and make more early substitutions during the match.
Toby Mündel receives funding from the Natural Sciences and Engineering Research Council (NSERC) of Canada (2023-04492), and Canada Research Chairs Program (100752).
Samuel Penna Wanner receives funding from the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG, grant APQ-01828-23) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, grant 407925/2023-6)
Original source: https://analysis1.mil-osi.com/2026/06/01/should-fifa-be-doing-more-to-protect-soccer-players-from-the-world-cup-heat/