Altitude: how does it affect players and how big is England’s disadvantage?

England play in Mexico City on Sunday, 2,240m above sea level, and research shows high-speed running is harder and recovery is slower

England have made it into the last 16 of the World Cup, and will face Mexico on Sunday (1am Monday BST). But they will also be up against another opponent: altitude.

We take a look at how playing in the Estadio Azteca in Mexico City, 2,240m above sea level, might affect their performance.

How does altitude affect footballers?

As altitude increases, the air becomes thinner.

“By 2,240m we’re definitely going to be seeing a physiological effect,” said Dr Neil Maxwell, an expert in applied environmental physiology at the University of Brighton.

Maxwell noted that while the percentage of oxygen in the air is the same at altitude as it is at sea level, the barometric pressure is lower.

“Therefore, the kind of forcing function of that pressure, pushing the oxygen into your red blood cells, is reduced. And that’s the physiological challenge – they’re not getting the oxygen into the red blood cells,” he said. “And because of that, their heart is having to beat quicker, they’re having to ventilate quicker to try and compensate. But obviously, there’s a limit to how much they can do that.”

Over 90 minutes, Maxwell said, that will put considerable stress on players. “So the feeling that they may feel at the end, or towards the last quarter, of a match, they’re going to be feeling that in the first half,” he said.

Maxwell also said players will experience a greater energy depletion in their muscles, and probably sweat more.

While the Mexico team also will tire during the match, Maxwell said their altitude training means they would not be expected to experience the same extent of fatigue as the England team, adding the latter will not be able to recover between sprints as rapidly as at lower altitudes, so won’t be able to get to the ball as quickly.

Dr Rebecca Neal, of Bournemouth University, said data from unacclimated athletes suggests there could be a 3-9% reduction in total running distance during the match and 21% decrease in high-velocity running, noting that might impact midfielders the most.

“On top of this, they will alter their pacing and experience greater neuromuscular fatigue meaning, even if their technical skills are not impaired, they might need to use unfamiliar tactics,” she said.

Maxwell said if athletes ascend rapidly and have not acclimatised, there is a risk of altitude illness, noting this can range from headaches, dizziness and disturbed sleep through to much rarer but more serious forms of altitude sickness – although such risks tend to become more relevant above about 2,500 m.

When should players head to a high altitude location?

The England team are due to arrive in Mexico two days before the match.

“A useful altitude training protocol would involve repeated sprints in hypoxia for up to four weeks in the run-up to and maintained throughout the World Cup and could have been advantageous for this match,” said Neal.

According to Maxwell, arriving the day before the match wouldn’t help the team much. “There is a bit of a myth that you’ve got 24 hours of grace when you get out to altitude, before it has an effect,” he said. “Your body starts reacting to the hypoxia, to the altitude environment, straight away. Within six hours, they’re going to be feeling the effects of this.”

Does altitude affect the game in other ways?

It could affect the way the ball flies. Prof Barton Smith, an expert in mechanical and aerospace engineering at Utah State University, notes air density in Mexico City is about 25% less than at sea level – meaning there is less drag to slow the ball down.

“But, I would be surprised if that has a large effect on the game, especially for short shots,” he said.

However, Smith noted air density is also important for the Magnus effect: a phenomenon in which a spinning ball bends as the ball hurtles through the air. Lower air density means a smaller Magnus effect and so the ball will curve or “move” less.

“When the ball moves less, there cannot be as much finesse to shots,” said Smith. 

Will England be at a disadvantage?

Without altitude training England team may find the conditions challenging. Neal noted research has demonstrated high-altitude-based teams score more and concede fewer goals than low-altitude teams, with every 1,000m altitude difference giving the home team approximately a half-goal advantage, adding this could have a greater impact in the second half.

However, Maxwell noted previous matches have taken place in hot conditions. “There is a cross tolerance or a cross-adaptive benefit from heat to altitude. So actually [England] getting better in the heat will give them a little bit of a benefit in the altitude environment,” he said.

“For a team such as England, with medical support and careful preparation, the greatest concern is likely to be the physiological strain caused by hypoxia [low oxygen availability] and the effect this has on workrate, recovery and decision-making rather than any major health risk,” he said.

Neal also noted there could be some crossover of benefits from adaption to the heat, but said the research is limited and mixed, especially for football.

“Instead, England has opted to focus on mitigating the impact of heat and any final ‘least bad’ approaches for this specific game,” she said.

Are there any short-term fixes? 

Maxwell stressed the importance of England players relaxing before they head to Mexico, and once there staying hydrated, getting used to the ball flight, and not exerting more energy than they need to.

“For England, they’ve got to be trying to rely upon what is in their control rather than what is not in their control,” he said, stressing the importance of adapting their tactics.

He said the use of substitutes will be critical, and suggested England should press less. “I’m not saying they won’t have some intense bouts to try and score, but they will probably have to keep hold of the ball more and be moving it around the back and then just looking for those few opportunities to press forward,” he said.

Neal also stressed the importance of strategy. “Without time to adapt, staying healthy and focusing on tactics during the second half of the match will be key at this late stage,” she said.