Competing at Altitude: Friend or Foe?

The last time England played at the Estadio Azteca, Diego Maradona beat them with his hand. On Sunday they go back for the first time since, in the last sixteen of the World Cup. This time the opponent isn't a striker. It's the air itself.

I've watched what that thin air does to the best-conditioned athletes on the planet. So before the pundits reduce this to "altitude is hard," let me tell you exactly how it bites, when in a game it collects its debt, and why the science says something more interesting than the headlines.

88 per cent

At sea level, a blood oxygen saturation reading of 88 per cent gets you rushed to a hospital. We recorded it on a world champion the moment after he broke a world record.

Not at sea level. 1,887 metres up, at the velodrome in Aguascalientes, where the air is thin enough that cyclists travel there on purpose, to go faster.

In 2023 we took Jeffrey Hoogland there for the kilometre time trial. One effort, all out, fifty-five seconds of total commitment. Our judgement going in was that altitude wouldn't hurt a single maximal sprint, because that kind of effort doesn't lean on the aerobic system. It runs on anaerobic and neuromuscular systems, which the thin air leaves largely intact. If anything, less air resistance would help him go faster.

We were right about the performance. He broke the record. We were wrong about the aftermath.

Normally Jeffrey steps off the bike fatigued, panting, but in control and able to talk in short sentences. That day he collapsed, and he needed oxygen for the next hour. At sea level his oxygen saturation sits at 98 to 99 per cent. Straight after the ride it was 88.

I felt a milder version of it in my own body. I went out for an easy run. I'd normally cover 5k in around 22 minutes. Up there I couldn't break 30, gasping like I'd never trained a day in my life. Nothing was wrong with me. Nothing was wrong with the watch either. It was just telling me the truth. That is simply what altitude does to the aerobic engine.

What the science actually says

Here is where it gets useful for Monday, because there is a study that tested almost exactly the Azteca's altitude.

In 2017, Townsend and colleagues published a paper in Frontiers in Physiology measuring how altitude changes two things: critical power, the highest intensity you can sustain aerobically, and W’, your finite reservoir of work above that line, the currency you spend on sprints and attacks. Nine trained cyclists were tested at five altitudes, from near sea level up to 4,250 metres.

One of those test altitudes was 2,250 metres. The Azteca sits at 2,240. For once, the science has a data point at the exact stage of the game.

Two findings matter.

First, aerobic capacity falls, and it falls in a curve, not a straight line. At the Azteca's altitude, critical power dropped by around 13 per cent. Put simply, the sustainable aerobic engine loses roughly an eighth of its output. And because the decline is curvilinear, it accelerates the higher you go.

Second, and this is the crucial part, sprint capacity was preserved. W prime did not change meaningfully until well above 3,500 metres. At the Azteca's altitude it was untouched.

Read those two columns together and you have the whole story of Sunday. A single explosive action, a sprint, a jump, a tackle, is essentially unaffected, because it draws on the anaerobic system the thin air leaves alone. What suffers is the aerobic engine, and the aerobic engine is what clears fatigue and refuels you between efforts.

I have to be honest about the limits of that study. It is nine cyclists, on a fixed bike, in acute exposure, not a football pitch. It doesn't prove what happens to a footballer. But the mechanism it reveals is general, and it lines up with what the match-running research in team sport already shows: total distance over a game holds up reasonably well, while high-intensity running and repeated sprints drop off, and the decline deepens as the match goes on.

Why this is worse for a footballer than it was for a cyclist

The paradox England are walking into is this. The exact thin air that made altitude a gift for Jeffrey makes it a threat for a footballer. Same air, opposite outcome.

Jeffrey had to be maximal once. A footballer has to be maximal, then recover, then do it again, ninety times over ninety minutes. The single effort survives altitude. The repeatability is the casualty. And the Azteca sits 350 metres above that record velodrome, so the tax is bigger, not smaller, than the one we felt in Aguascalientes.

Thomas Tuchel has already said it is "impossible" for England to adapt in three days. He is right. Meaningful aerobic acclimatisation takes one to two weeks, and Mexico live and train at altitude every day of their lives. England cannot close that gap this week, and pretending otherwise is a fantasy.

But "cannot adapt" is not the same as "cannot compete." The team that understands where altitude collects its debt can manage it. That means refusing the relentless press that would leave them gasping by the first hydration break, keeping the ball, slowing the game, and choosing the few moments to go up a gear rather than chasing everything. It is why those so-called hydration breaks will matter more than usual. One side refuels in them. The other just stops running down for ninety seconds.

The effect nobody talks about, and it isn't fitness

There is one more consequence of thin air, and it has nothing to do with lungs. Lower air density changes how the ball moves. Less drag means longer, flatter, faster trajectories, different swerve on a struck ball, long passes running away from you, goalkeepers misjudging the flight. England scored past DR Congo in Atlanta at 312 metres. The Azteca is more than seven times higher. The ball will not behave the way it did.

For a side arriving for a single game, that disruption to skill execution can matter as much as the legs. And unlike the physiology, it is something you can actually rehearse in the days you do have.

What to watch on Sunday

Don't judge it by the scoreline early. Watch the last twenty minutes. Watch which side is still winning the second ball and which is a yard late to everything. Watch what happens after each hydration break, when one team comes back refreshed and the other just keeps declining.

That is where altitude collects. Not in the highlight sprint, which will look normal. In the fifth sprint, and the recovery before the sixth, that never quite comes.

The single effort survives. The repeatability is the casualty. That was true on a bike at 1,887 metres. It will be even more true on a pitch at 2,240.