When the stadium becomes too hot
Is Global Sport ready for the age of extreme heat?
FIFA WORLD CUP 2026
6/4/20266 min read
As rising temperatures reshape the conditions of competition, the debate is shifting from hydration breaks to a harder question: when should sport simply stop?
For generations, heat was treated as part of sport’s theatre. The exhausted marathoner, the footballer drenched in sweat, the tennis player battling through a five-set afternoon: endurance in difficult conditions was celebrated as evidence of toughness.
Sports medicine now demands a more precise conversation.
Exercise produces heat. The harder an athlete works, the more heat the body must dissipate. When environmental conditions make that increasingly difficult, core temperature can rise and performance can deteriorate. At the severe end of the spectrum lies exertional heat stroke, a medical emergency involving extreme hyperthermia and central nervous system dysfunction.
The problem for global sport is not whether heat can be dangerous. That is established.
The difficult question is where danger begins—and who has the authority to decide when competition should be modified, delayed or stopped.
The 2026 FIFA World Cup has placed that debate under an unprecedented spotlight. The tournament spans Canada, Mexico and the United States, with matches played across dramatically different climates. FIFA introduced mandatory three-minute hydration breaks midway through both halves of every match, regardless of weather conditions.
It is a visible intervention. But the wider medical debate is more complicated than the availability of water.
THE NUMBER THAT TRIES TO MEASURE HEAT
The temperature displayed on a weather app does not tell an athlete everything.
Sports organisations frequently use the Wet Bulb Globe Temperature, or WBGT, to assess environmental heat stress. Unlike air temperature alone, WBGT incorporates factors related to temperature, humidity, radiant heat and air movement.
That makes it useful—but not infallible.
The International Olympic Committee’s consensus guidance on sport in the heat recognises WBGT as a widely used environmental index while also emphasising that risk is influenced by the athlete, the sport, the environment and the specific demands of competition.
A 30°C afternoon does not create the same physiological challenge everywhere. High humidity can impair the evaporation of sweat, one of the body’s primary cooling mechanisms. Direct solar radiation can increase thermal load. Wind can alter heat exchange. Clothing and protective equipment matter. So do exercise intensity, acclimatisation, fitness, body characteristics and medical history.
This is why a universal “danger temperature” is scientifically difficult.
It is also why thresholds are contested.
Different sports and organisations use different heat policies. Some rely on WBGT bands that trigger modifications; others use sport-specific systems or additional meteorological information. The result is a global landscape in which conditions considered sufficient to alter one competition may not produce the same response in another.
The debate is therefore not merely about measurement. It is about precaution.
WHY THE THRESHOLD MATTERS
In football, player representatives have argued for stronger protections during extreme heat.
FIFPRO has advocated a more precautionary approach and has said that a WBGT above 28°C should trigger measures including cooling breaks, while conditions above 32°C should lead to the delay or postponement of matches. During the 2025 FIFA Club World Cup in the United States, extreme heat became a major player-welfare issue and intensified discussion ahead of the 2026 World Cup.
FIFA’s decision to introduce scheduled hydration breaks in every 2026 World Cup match removes one uncertainty: players know that two breaks will occur.
But hydration and cooling are not identical.
A player can drink fluid and still accumulate dangerous heat. A short interruption can provide an opportunity to consume fluids, receive tactical instructions and use cooling methods, but it does not automatically neutralise the thermal load created by intense exercise in severe conditions.
That distinction matters because heat illness is not simply dehydration.
An athlete can develop dangerous hyperthermia without being profoundly dehydrated. Conversely, dehydration can impair performance and increase physiological strain without necessarily progressing to heat stroke.
The old instruction to “drink more water” is therefore inadequate as a complete heat-safety policy.
HYDRATION WITHOUT THE MYTHS
Modern hydration science has moved away from simplistic universal prescriptions.
Sweat rates vary substantially between individuals and can change with environmental conditions, exercise intensity and acclimatisation. Sweat also contains electrolytes, particularly sodium, in concentrations that differ between athletes.
The objective during prolonged exercise is generally to limit excessive dehydration while avoiding excessive fluid intake.
That second danger is important. Drinking far beyond physiological need can contribute to exercise-associated hyponatraemia, a potentially serious condition involving abnormally low blood sodium concentration.
Elite teams can individualise hydration strategies using information such as body-mass changes, sweat-rate estimates and previous responses to heat. But even sophisticated hydration planning cannot make every environment safe.
Water supports thermoregulation. It does not repeal physics.
THE SCIENCE OF GETTING COOL
Cooling interventions have become increasingly sophisticated.
Before competition, athletes may use cold fluids, ice slurries, cooling garments or other strategies designed to reduce thermal strain. During breaks, teams can use cold towels, ice, fans, shade and chilled drinks. After exercise, rapid cooling becomes particularly important when exertional heat illness is suspected.
Yet cooling is not one intervention but a spectrum.
A cold towel around the neck may improve thermal sensation. Internal cooling through cold drinks can influence heat storage. Whole-body cold-water immersion is a powerful method for rapidly reducing core temperature in exertional heat stroke when applied appropriately by trained medical personnel.
The purpose also matters. A strategy designed to make an athlete feel cooler is not necessarily sufficient to treat dangerous hyperthermia.
For governing bodies, this creates a practical challenge. A heat protocol cannot simply state that “cooling should be available.” It must consider what equipment is present, whether medical teams are trained, how rapidly an athlete can be assessed and cooled, and whether emergency transport arrangements are appropriate.
Preparedness is logistical as well as scientific.
ACCLIMATISATION: THE BODY CAN ADAPT
One of the most effective protections against heat stress is preparation.
Repeated exposure to exercise in hot conditions can produce heat acclimatisation. Adaptations can include an earlier and more effective sweating response, improved cardiovascular stability and reduced physiological strain at a given workload.
International consensus recommendations commonly describe programmes involving repeated heat exposure over several days, with longer periods generally producing more complete adaptation.
But major tournaments complicate the process.
Footballers may arrive after demanding club seasons. Travel schedules can be compressed. Players come from different climates and possess different levels of recent heat exposure. Adding strenuous heat sessions immediately before competition can itself create fatigue.
Acclimatisation must therefore be planned, not improvised.
And it does not create invulnerability.
A heat-acclimatised athlete can still develop heat illness. Adaptation reduces risk; it does not eliminate it.
THE PROBLEM WITH A SINGLE GLOBAL RULE
Sport wants clear thresholds because thresholds make decisions easier.
Medicine is less cooperative.
The same WBGT can affect athletes differently depending on the metabolic demands of the event. A marathon runner continuously generating large amounts of metabolic heat faces a different challenge from an athlete in a sport with frequent stoppages. A football goalkeeper has a different workload from a midfielder. A tennis match can last far longer than expected.
This is why the IOC has argued for sport-specific and context-specific approaches rather than assuming that one environmental number can perfectly predict individual risk.
WBGT itself has limitations. It estimates environmental heat stress; it does not directly measure an athlete’s core temperature or determine whether a particular individual will develop heat illness.
Yet uncertainty cuts both ways.
The absence of a perfect threshold does not justify the absence of precaution.
WHO GETS TO SAY STOP?
This is ultimately the central question.
Athletes are trained to continue. Coaches are employed to compete. Organisers face broadcasting schedules, ticketing commitments and enormous commercial pressures. In that environment, relying on an athlete to voluntarily withdraw because conditions feel dangerous is an imperfect safety system.
Effective heat policy must therefore reduce the burden on the individual.
Medical teams need authority. Competition regulations need predetermined responses. Organisers need reliable environmental monitoring. Scheduling decisions should consider predictable heat risk before a tournament begins, not only after players are already on the field.
The strongest intervention may be the least technologically impressive: changing the time of competition.
Evening scheduling, additional recovery time, access to shade, appropriate medical infrastructure and the ability to delay or postpone events can all reduce risk.
THE NEW DEFINITION OF TOUGHNESS
Global sport is medically better prepared for heat than it was decades ago. Knowledge of acclimatisation, hydration, cooling and emergency treatment has advanced significantly. Major competitions increasingly employ environmental monitoring and formal heat protocols.
But preparedness should not be confused with completion.
A protocol can exist and still be too permissive. A cooling break can help without making conditions safe. A hydrated athlete can still overheat. A governing body can follow its own rules while scientists and player representatives legitimately question whether those rules are sufficiently precautionary.
As extreme heat becomes a more persistent challenge for international sport, the argument will increasingly concern acceptable risk.
The future of heat safety will not be decided by finding one magical temperature at which sport becomes dangerous. It will depend on combining environmental data, medical science, sport-specific demands and a willingness to change schedules—or stop competition—before an emergency provides the evidence that action came too late.
For generations, sport glorified the athlete who refused to stop.
In the age of extreme heat, wisdom may lie in knowing when the game should.
