A football player standing over a penalty in a hot, high-altitude stadium is dealing with more than pressure. His body is trying to keep cool. His heart and breathing may be working harder. Less oxygen is reaching his muscles. One poor decision can end his team’s World Cup.
The 2026 men’s World Cup has made fatigue harder to ignore. Some matches are being played in heat and humidity, while Mexico City’s Azteca Stadium sits more than 2,200 metres above sea level. Heat and altitude make sport uncomfortable, and they also change how the body and mind work under pressure.
Heat makes the body work harder to keep its core temperature stable. Humidity adds strain because sweat does not evaporate as easily, making it harder to cool down. At altitude, lower air pressure means less oxygen reaches the blood and muscles. Together, these conditions can affect endurance, recovery between sprints, concentration and decision-making.
Fatigue is not one state. Sport science is good at separating different kinds of fatigue because performance depends on knowing what is going wrong. Our research emphasises this point. Is the athlete slowing because muscles are tired, heart rate is high, body temperature is rising, sleep has been poor or concentration is slipping?
The answer changes the response. Heavy legs may call for pacing, which means slowing down or spreading effort so the body can cope. Fluid loss may call for cooling and replacing what has been lost through sweat. Slipping concentration may call for a mental reset, such as slowing breathing or refocusing on the next action. Dizziness or confusion means stop.
This is where sport offers a useful public lesson. The same run, tackle, pass or decision can feel much harder when the body is also fighting heat, humidity or thinner air. Research on footballers shows that heat exposure can reduce physical and cognitive performance.
The same principle applies beyond sport. Delivery drivers, nurses, teachers, care workers, chefs, builders and cleaners may also have to think, move and make decisions while working in difficult conditions. Fatigue is sometimes treated as weakness or lack of motivation. Preparation, fitness and recovery may be part of the story, but fatigue is usually more complex.
It is best understood by bringing together psychology, physiology (how the body works), medicine and neuroscience (the study of the brain and nervous system). Fatigue emerges when the body signals that effort is becoming costly, while the person still wants or needs to keep going.
In sport, this is well understood. Coaches do not usually tell players to “try harder” in extreme conditions. They plan through training, recovery, hydration, cooling, clothing, timing and warning signs.
They also train psychological skills. Players learn how to pace effort, control attention, manage emotions and use self-talk. These skills help them decide whether a sensation is expected discomfort, a cue to adjust, or a warning sign.
That distinction can decide performance. Heavy legs, a racing heart and discomfort may be expected in the heat or at altitude. Treating every unpleasant sensation as failure can damage performance. Some discomfort may need to be managed.
But discomfort is different from danger. Dizziness, confusion, nausea, clumsiness or feeling faint are warning signs. These are not signs to push through. The skill is knowing when to keep going and when to stop, cool down and get help.
Athletes playing in difficult conditions will usually have prepared, or at least they should have. Staff may monitor body weight, sweat loss, sleep, mood, soreness and running data. Players may use cooling towels, cold drinks, shaded recovery areas, pacing plans and mental routines.
Even then, fatigue can still bite. A match that goes to extra time adds another layer. A team that survives extra time and wins may carry that physical and mental cost into the next game.
Lessons beyond football
This is where the football example becomes useful beyond sport. The lesson is not to demand toughness every time. It is to judge when effort is useful, when it is costly and when it becomes unsafe.
In sport, that might mean staying composed when the body is screaming to stop. In other settings, it might mean a nurse finishing urgent care, a firefighter rescuing someone or a worker completing a task that cannot safely be abandoned.
Andrew Lane, Author provided (no reuse)
But effort in heat has a cost. Athletes know this. Extra effort is followed by recovery: cooling, fluids, food, sleep, lighter training and monitoring. The hard effort is not ignored once the competition is over.
Workplaces should treat heat in the same way. If people have to push through because the goal is urgent, the organisation should carry the recovery cost. That may mean cover from colleagues, longer breaks, shorter exposure, lighter duties later and permission to report symptoms without being seen as weak.
This is also a productivity issue. Research on occupational heat exposure links workplace heat with health risks, reduced productivity and greater strain on workers. The basic protections are familiar: water, rest, shade, cooler work areas, adjusted schedules and sensible task planning.
The lesson is not that workers should act like elite footballers. It is that if people are expected to work in athlete-like conditions, organisations need athlete-like planning.
Practical coping still helps. A person working in heat could drink before thirst becomes intense, use shade early, slow the pace where possible, share heavy tasks, check on colleagues and use a phrase such as “slow down, cool down, reset”.
These strategies do not replace safe working conditions. They are ways of coping when heat has already arrived and perfect protection is not available.
In the World Cup, teams that measure fatigue well, adapt their tactics and recover properly may gain an advantage. Teams that misjudge heat or altitude may find tired legs and slower decisions appearing when pressure is highest.
For everyone else, the lesson is closer to home. Fatigue is information. But information only helps when people can interpret it, and when they have the power to act before the heat has already taken over.
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