England’s players will not collapse to the ground when they land in Mexico City on Friday around 48 hours before their World Cup Round of 16 tie against Mexico at the Azteca kicks off. They will not require medical assistance or oxygen, or at least they shouldn’t. Mexico City isn’t high enough, not quite, for acute altitude sickness to be a concern for the vast majority of people.
That doesn’t mean it won’t cause them problems, though, despite that when most people do give any thought to altitude
sickness and the negative effects of rapid elevation gain that’s how they tend to view it. As a binary. Yes or no. On or off. You either have it or you don’t. That simply isn’t the case.
The higher you go, the thinner the air gets and the lower the pressure drops. This drop in atmospheric pressure leads to hypoxia, your heart, brain, and tissues no longer receiving sufficient oxygen and your body triggering a rapid breathing response and increased heart rate in an attempt to compensate. If the body’s supply of oxygen remains insufficient, over time the cumulative effects can lead to mental confusion, an inability to focus, insomnia, difficulty eating, and numb and discoloured extremities.
Your body’s efforts to compensate aren’t without downsides, either. That rapid breathing, along with the thinner and drier air at elevation, leads to accelerated dehydration that can exacerbate effects over time, though from the moment you arrive at altitude there is a significant impact on physical performance, stamina, and endurance. In the first day, before the cumulative effects start to take their toll, this is the main concern. In the second and third days, those cumulative effects of existing in a state of mild hypoxia for an extended time—headaches, cognition issues, creeping nausea—become increasingly prominent.
For almost everyone, the question isn’t if you’re impacted, it’s how much—or if you’re a tourist, whether perhaps you can blame your headache and sluggishness on staying out late without realizing the primary reason you feel terrible is actually the altitude. Fitness capacity at sea level also bears no correlation to how susceptible you are. Someone who’s never run more than for the bus may be only slightly impacted; a professional athlete could be nearly incapacitated.
Somewhere around day four your body’s efforts to adjust, to produce more red blood cells, to transport more of the oxygen that is available to your ailing, deprived muscles and foggy brain begins to pay off. It takes longer to fully acclimatize—a week, ten days, for some even longer—but for the majority of negative altitude effects, day two and three are the worst and by the end of day four is when it usually starts to get markedly better.
This has led to a situation in American sports where teams that travel to Denver at 5,200’ (1,600m) to play baseball’s Rockies or basketball’s Nuggets or American football’s Broncos, seek to fly in mere hours before the game, seeking to at least avoid the cumulative effects of altitude. When it comes to elevation, though, Denver is like the first rung on the ladder. Mexico City is considerably higher and a solid step up from that.
England have also decided to fly in on Friday night, meaning they will arrive in Mexico City 48 hours before kickoff. This is because FIFA regulations demand teams arrive no latter than the night before for the knockout rounds. It is also because while England were originally set to fly in Wednesday night immediately following their Round of 32 tie against DR Congo, they belatedly chose instead to return to their Kansas City base with fears of spying on their training were they to relocate to Mexico City the stated reason.
As a result, England’s Round of 16 tie will kick off just about when their second day at altitude ticks over into day three. Anyone with experience with altitude, particularly in an athletic context, will tell you is when you are likely to be at your worst. This does not seem ideal.
At around 7,300’ (2,200m), Mexico City is higher than the vast majority of the human race lives. Most people will never even visit that kind of altitude. Globally, only around 200 million people live above 6,600’ (2000m). Once you get above 8,200’ (2,500m), which includes Andean cities like Bogota in Colombia and Quito in Ecuador, it’s around 80 million people. Go above 11,500’ (3,500m) and it’s around 15 million, including Andean cities like La Paz in Bolivia and Cusco in Peru.
Outside South America’s Andes and the Sierra Madre that runs up through Mexico, the only places in the world where major population centres are at all common at those kinds of altitudes are the Ethiopian Plateau and the Tibetan Plateau. There are more than eight billion people in the world. More than 97.5% live at elevations lower than Mexico City.
The aforementioned highest major population centre in the United States, Denver, sits at 5,200’ (1,600m). In Europe, the highest major population centres are in Spain, with Madrid sat at just around 2,200’ (670m) and a few smaller nearby cities in that neighbourhood or a few hundred feet higher. Even in a place built tucked into a massive mountain range like Nepal in the Himalayas, capital city Kathmandu sits at around 4,600’ (1,400m). To get to real altitude, even in Nepal, you have to leave the people behind and head into the mountains.
To live, to work, and to play sport at Mexico City’s elevation is simply not normal to the human experience, and it isn’t what the human body is built to cope with, at least not easily and without acclimatization. Though when it comes to England and Mexico City and preparing to face them at the imposing Estadio Azteca, well, at least it isn’t Bolivia.
In Bolivia, they’ve embraced the elevation, putting their national team stadium not in La Paz proper at 12,000’ (3,650m) but in the neighbouring sprawl of El Alto (or, in English, The High), which sits on a plateau above La Paz at a quite ridiculous 13,600’ (4,150m). Since moving the national team there for home games in 2024, Bolivia have six wins and two draws in competitive fixtures at home, including wins over Brazil, Chile, and Colombia.
On the road over that time Bolivia have 3 wins, a draw, and 12 defeats. Their road victories came over Suriname, Trinidad and Tobago, and Jordan. The effects of altitude are very, very real, and if you can be acclimatized while your opponent isn’t it is a major advantage.
Bolivia are able to take that approach because as a lower-ranked nation with no significant international stars, their players mostly play their domestic football in Bolivia. Colombia and Ecuador, by comparison, countries that have their own extreme altitude major cities in Bogota and Quito, respectively, but who see their stars playing in Europe and the Brazilian league have mostly moved their home games to lower altitudes.
Colombia now play all of their home games in Barranquilla, at sea level. Ecuador still play some games in Quito at elevation, but marquee friendlies and key qualifiers are now played in Guayaquil, also at sea level. Ecuador, when they faced Mexico in Mexico City in the Round of 32, were not acclimatized—and they clearly suffered, physically.
That’s because acclimatization only lasts a week or two once a person leaves altitude—the time it takes to gain acclimatization, more or less, is the time it takes to lose it, even if you were born and grew up there. At that point, you have to adjust all over again. It’s worth noting, though, that having a window where your body maintains its ability to more efficiently utilize available oxygen when moving to sea level from elevation does mean if Mexico progress past England they will bring a slight if temporary stamina boost with them.
The ideal approach to altitude is time, and there simply isn’t any getting around that—and that if you don’t have time there are no perfect options. Full acclimatization takes weeks. For sports involving elevation and endurance like cycling, riders typically spend an entire month at a high altitude training camp to prepare for something like the Tour de France, where in 2025 climbs in the Pyrenees and Alps contributed to riders ascending over 54,000’ (16,500m) in three weeks, regularly finishing racing stages at altitudes where elevation becomes an issue.
Here at the World Cup, that kind of preparation simply isn’t possible, at least not for England. Meanwhile, the Mexico team have been playing and training at altitude for more than a month. The conventional wisdom then says to either arrive a few hours before kickoff or at least four days out, with every additional day beyond that a benefit. England instead will split the difference and arrive 48 hours before.
Of all the bad options, and without knowing what may be happening behind the scenes to at least try to mitigate the issues, it at least appears England have chosen the worst. Having done so, they can at least consciously over-hydrate to avoid some of the cumulative ill-effects. Medication, be it simple ibuprofen to reduce tissue swelling or something prescribed that masks symptoms and makes the adjustment period less unpleasant, can help, though it won’t be a magic bullet that will allow them to perform as though still at sea level.
It’s also not uncommon for athletes to sleep in altitude tents to simulate the lowered pressure and oxygen of high altitude environments, forcing the body to ramp up red blood cell production. It isn’t a perfect replacement for actually spending time at altitude, but it’s better than nothing. If England are smart they will have been using them from the moment they saw where the bracket was likely to send them.
While it’s now too late for it, England also could have sought to hold their World Cup base camp in a higher elevation location like Denver once it became clear any pathway to World Cup glory likely led through Mexico City. Denver, being lower, would not have fully acclimatized them for the Azteca, but elevation is like steps on stairs or rungs on a ladder.
If you’re in Denver on step one and fully acclimatized to that it’s a heck of a lot easier on your body to go up to Mexico City and step two and then to Bogota or Quito and step three and then Cusco or La Paz and step four. Skip a step or two, go directly from sea level to Mexico City or from Denver to Cusco, and it’s harder.
Going from Kansas direct to Mexico City simply isn’t a good idea, not in a sporting context and not if you want to perform physically, and England appear to have ended up in a position where they only have bad options. If there ever was a time when there might have been a better approach open to them, it’s too late now. But then at least they’re not going to Bolivia and El Alto, where players grasp for oxygen masks at halftime to give their starved and aching muscles a reprieve.
It seems inevitable, though, that England will suffer. They will suffer from the rabid atmosphere of a Mexican home game at one of world football’s most imposing stadiums. And they will suffer due to altitude. In Kansas City or in Miami, where the next round will be played for either England or Mexico, the Three Lions would be counted by almost everyone as favourites against this Mexico side. Here it seems a coin flip at best. England might be underdogs. None of this, from an England point of view, is ideal. It’s not going to be a pleasant experience.
