Халуун цаг уурын нөхцөлд Английн шигшээ багийн сорилт

In The Athletic’s World Cup performance series, Alan McCall draws on more than 20 years of experience in elite football to explain the science behind the challenges teams are facing this summer and the strategies they will use to cope.

For England’s quarter-final clash with Norway in Miami, he turns his attention to how heat influences players and shapes the game — and why preparation matters.

Having faced the challenge of playing at altitude against Mexico in the last round, England now face the challenge of playing Norway in hot and humid conditions in Miami. Temperatures are expected to reach 92F (33C) but the humidity will make it feel much hotter on the pitch.

In this instance, the conditions do not confer an advantage on either team as both Norway and England will find them challenging. How they manage the heat will be crucial.

Reflecting on Germany’s 2014 World Cup win in Brazil, Per Mertesacker recalls something that still surprises him: “I stopped celebrating goals.” Essentially, he changed how he celebrated them — staying back with the goalkeeper to recover and rehydrate instead.

“Sometimes it was so hot that any stoppage in the game was a relief,” the former centre-back says. “Pressure and heat give you a double whammy. Fatigue sets in quicker. I was in energy-save mode.”

As a central defender, celebrating with team-mates often meant sprinting 70 or 80 metres up the pitch before quickly reorganising defensively. “And it was even worse if you got caught in the middle of the celebrations, with players jumping on you,” says Mertesacker. “It’s a weird feeling — you can’t breathe.”

For Mertesacker, every unnecessary sprint could come at a cost later in the match. “The match isn’t over after you score: in tournament football, it comes down to tiny margins,” he says.

Former England midfielder Alex Oxlade-Chamberlain remembers a similar feeling from the same 2014 World Cup in Brazil. “The heat and humidity gets you physically, but it’s more from a mental point of view,” he says. “As humans, you find reasons something might be harder. In the heat and humidity, with the sweating, you anticipate: ‘This is going to be hard’.”

That anticipation may matter as much as the physical strain itself. Heat raises core temperature, increases sweating and makes exercise feel harder — the body is genuinely working more. But players are not simply reacting to fatigue as it arrives; they are also managing it in advance, becoming more selective about when to accelerate, press, pass or take risks.

The game slows not only because bodies tire more quickly, but because players begin pacing themselves earlier — conserving energy for the moments that matter most.

Data from the hottest matches at the 2014 World Cup — classified using wet-bulb globe temperature (WBGT), a measure combining temperature, humidity, wind and solar radiation to estimate heat stress on the body — pointed in the same direction.

In those matches, players performed around 10 per cent fewer sprints than in matches with lower heat stress — roughly 40 fewer sprint efforts across a team over a full match. High-intensity running also dropped, while jogging and walking increased.

Overall distance covered remained broadly similar, and pass completion rates even increased slightly, from around 74 per cent to 77 per cent — potentially reflecting players favouring shorter, simpler passes or more controlled ball circulation.

The pattern extends beyond a single tournament. Across professional football, as heat stress rises, players tend to make fewer passes, touches and dribbles, appearing to simplify their decisions and preserve energy for decisive moments.

“Decision-making goes down with fatigue,” says Oxlade-Chamberlain. “In the heat, you’re struggling more, and then you’re probably more prone to making an error.”

Managing those demands — simplifying decisions, controlling tempo and conserving energy — may be as much a feature of playing in the heat as the physical strain itself. Players are not only working harder to maintain the same output; they are thinking and playing differently, too.

Survive or thrive in the heat

As the tournament moves deeper into the knockout rounds, heat becomes one more challenge to manage rather than simply endure.

The foundations for whether a team survives those conditions or thrives in them were laid long before the first knockout match — through pre-World Cup preparation and the adaptations built over the opening weeks of the tournament. As the physical and mental demands continue to accumulate, those preparations begin to reveal their value.

Norway’s Martin Odegaard tries to stay cool during their game with Brazil (Elsa/Getty Images)

Perhaps the most important tool teams had available was heat acclimatisation — repeated exposure to hot conditions before competition so the body adapts to performing in them.

Scientific guidelines generally recommend around 10 to 15 days of heat training, although the speed and extent of adaptation varies between players depending on fitness, recent environment and previous exposure to heat.

For many teams, however, time was limited by players arriving late from club competitions, creating a delicate balance between adapting sufficiently while still reaching the tournament physically and mentally fresh.

Stay cool, stay hydrated

Several weeks into the tournament, most teams should already have experienced some degree of heat adaptation. Yet, as Oxlade-Chamberlain points out, acclimatisation is not the same as feeling comfortable in the heat.

“The science might show you acclimatise in a few weeks, physiologically,” says Oxlade-Chamberlain, recalling England’s time in Manaus — one of the hottest and most humid venues at the 2014 World Cup — “but when we got off the bus in Manaus, we thought: ‘Wow, this is unbearable heat’. When I moved to play in Turkey it took me three or four months to feel normal (while playing).”

Physiological adaptation and actually feeling comfortable in the heat are not always the same thing — and in a World Cup tournament, that gap could matter.

Staying hydrated is essential to maintaining performance levels (Charly Triballeau/AFP via Getty Images)

That is where cooling and hydration come in. Cooling reduces the thermal and physiological burden of playing in the heat; hydration replaces the fluid losses that heat and effort continuously produce.

Acclimatisation builds resilience; cooling and hydration buy time. The aim is not to eliminate the heat, but to reduce its physiological and perceptual cost.

Hydration probably needs little introduction. Cooling strategies may be less familiar: applying cold externally through ice vests, ice neck and shoulder wraps, cold towels or ice packs, or internally through cold fluids, ice slushies or ice pops.

Foot-cooling overshoes also attracted attention ahead of the 2026 World Cup, although similar concepts have existed in other sports for several years. Evidence supporting their use remains limited compared with more established cooling strategies.

As is often the case in elite sport, the foundations still carry the strongest evidence. Internal and external cooling strategies work best when combined with good hydration, and all three run throughout the matchday.

Pre-cooling typically begins anywhere from 10 to 30 minutes before teams warm up. The aim is simple: lower skin and core temperatures before exercise starts, but limit the effects on leg muscle temperatures. Ice vests, cold towels to the head and neck, and ice slushies consumed at around 0-2C cool the body from the outside and inside, while hydration begins with players arriving well hydrated before a ball is kicked. Teams are generally more cautious about cooling the legs, however, because cold applied directly to working muscles immediately before a match can temporarily blunt explosive actions such as sprinting. Cooling is therefore usually focused on the head, neck and torso.

In-game cooling is about limiting heat build-up during the match itself. Every stoppage becomes an opportunity — cold towels to the head and neck, cold fluids, or menthol mouth rinses that may make sustained effort feel more manageable.

At this World Cup, mandatory three-minute cooling breaks have provided a guaranteed window to do this, and teams that have rehearsed using them effectively may benefit most.

Hydration during matches is not just about replacing fluid losses but also maintaining fuel intake, with carbohydrates supporting energy demands and electrolytes improving the palatability of drinks, helping players drink more. If extra time arrives, cooling and hydration become even more important.

For all the high tech, cold towels applied to the neck and head can be the most effective way to cool down (Robert Cianflone/Getty Images)

Recovery cooling is when the heavy burden of competing in the heat often becomes most obvious. Speaking after one particularly intense match in Brazil, Mertesacker joked that he was about to spend the “next three days in an ice bath” — though beneath the humour was the reality of how physically draining the conditions had become.

“The hardest bit is the aftermath,” says Oxlade-Chamberlain, recalling England’s warm-up games in the Florida heat. “The recovery is hard — you’ve lost maybe 3kg (in sweat). Hydration is the biggest thing.”

By full time, core temperature remains elevated, and the body is still under considerable thermal and cardiovascular strain. Cold water immersion can help accelerate cooling and support the recovery of thermoregulation — the body’s ability to regulate its own temperature — and cardiovascular function — how efficiently the heart and circulation are working — toward baseline. The sooner both recover, the better prepared a player will be for the next match.

Done well, cooling and hydration can help restore some of what heat takes away. Pre-match cooling lowers the starting point, in-game cooling limits the build-up, and recovery cooling completes the cycle. Importantly, the goal is not simply to feel more comfortable — it is to allow players to maintain the same physical output for a lower physiological cost.

A player who has cooled effectively may complete the same or more running in a hot match while experiencing less strain than one who has not — they may even feel cooler despite working just as hard. Used consistently across the matchday, these strategies may help players feel cooler and potentially preserve high-intensity actions later in matches — though individual responses vary and effects in elite match conditions are not always predictable.

Professor Rob Duffield of the University of Technology Sydney, whose research team tested cooling strategies in football match conditions in Monterrey — one of the hottest expected venues at the 2026 World Cup — puts it directly: “A mixed-method approach — combining hydration with practical pitch-side cooling tools — creates a larger cumulative effect and works better for players and support staff because of the logistics and individual player preferences involved.

“The larger the cooling dose, used more regularly before and during matches, the more likely you are to preserve thermal comfort and maintain physical performance. But it also needs to be done in a way players find palatable and will actually engage with.”

Simple often wins

It can sound like the job is to do everything — pre-cooling, in-game cooling, recovery-cooling, rehydrate, immerse, repeat. Throw everything at the problem and hope something sticks. But the most effective approach is rarely the most elaborate one. The goal is simpler: find what works for each player, practice it until it becomes second nature, and execute it consistently under pressure.

Mertesacker remembers trying ice vests during Germany’s 2014 World Cup preparation. “We tried things, we tried the ice vests, I didn’t like them, everything felt kind of wet.” What works for one player does not always work for another.

Kylian Mbappe uses the sprinklers to help cool down (Dan Mullan/Getty Images)

Germany’s then head of performance, Shad Forsythe, had anticipated exactly this. Long before the squad arrived in Brazil, he had already built the strategies into training — replicating match times, rehearsing cooling breaks and testing the technologies they were considering. “We were testing if they worked or not and for who,” he says. “It sounds simple, but you take for granted they’ll just do it, they’ll understand it — but you need to practise, well in advance of the competition.” The best plan, he says, is the one “players believe in and will actually use”.

And the research points consistently to where that effort matters most: the head and neck. These areas are far more sensitive to cooling than much of the rest of the body, meaning simple strategies can have a meaningful effect. Cold towels at the stadium. Drinks in the freezer overnight. Teams do not always need specialist cooling equipment to make a difference. For players who dislike ice vests or teams with fewer resources, that is not a compromise — it is often the highest-return intervention available.

Energy-save mode

But thriving in the heat is not only about what coaches, medical staff and performance staff do for the players. As Mertesacker describes it, thriving in the heat also comes down to what he calls “individual tactics”: “You have the team tactics,” he says, “but you also need your own individual tactics.”

His were simple: change celebrations, conserve energy, use every stoppage to drink and recover. “It felt good,” he says. “I needed those moments — the fluids, the rest — that was a relief to me.”

As a leader, one of those tactics even shaped how he communicated during matches. “Talking — you even need to be careful talking. You have to be precise, on point. Playing in hot conditions, your lips are dry, you need to understand each other with fewer words.” Mertesacker had even rehearsed that in training, treating communication like any other aspect of Germany’s heat preparation: identifying what mattered most, then making it instinctive.

As the knockout rounds continue, look beyond the temperature. Watch the team tactics — the cooling, hydration and recovery strategies — but also the individual tactics Mertesacker describes: when players sprint, when they recover and how they manage their energy.

Individually, none of those decisions may seem decisive. Collectively, over 90 minutes, extra time and the cumulative demands of an entire tournament, they may be the difference between simply enduring the heat and continuing to perform within it.