What will happen to England players' bodies minute-by-minute at high altitude vs Mexico
You're probably already sick of hearing about altitude ahead of England's World Cup match with Mexico, but how exactly does it impact the body?
England gave us all a fright on Wednesday but managed to get their act together just in time to overcome DR Congo in the Round of 32.
Let's just all give thanks to the witchdoctor for lifting his curse on Harry Kane.
Thomas Tuchel's side's reward for their dramatic victory is a tricky trip to Mexico where they'll take on the co-hosts in a banana skin big enough for King Kong.
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Though Mexico might not look the most challenging side on paper compared to the Three Lions' array of Champions League calibre talent, there's a lot to worry about.
El Tri are yet to concede a goal in the tournament, have home field advantage so will be cheered on by boisterous support of over 80,000 (with some fans no doubt preparing to keep England players awake at their hotel before the game) and the Azteca is a fortress.
Mexico have never lost a World Cup game at their iconic stadium and have only lost two competitive matches there ever, with the last coming in 2013.
If all that wasn't enough for the hairs on the back of your neck to prick up, then the dreaded altitude definitely should.
Mexico City stands 2,240 metres, or 7,349 feet, above sea level. So altitude is going to be a major factor, something Tuchel has already admitted.
Here's exactly what it could do to the England players out on the pitch.
How does altitude impact the body?
The higher up you go, the less oxygen available in the air you breathe. The less oxygen going into your body, the less that's available for your brain and muscles.
Given we need oxygen to live, a lack of it can obviously take its toll, impacting your ability to make decisions as well as your physical capabilities.
"Whenever you go to high altitude, everything becomes harder, if you try and run up the stairs or try and play a football game. It is going to have an impact," Nick Hart, a senior performance specialist at The Altitude Centre tells LADbible.
"When you're trying to play a high performance, those small differences have a great impact."
It typically takes 10-14 days for a person to fully acclimatise to high altitudes and shake off the effects of altitude sickness.
Mexico have played their entire World Cup campaign at great heights and are used to the conditions. England have no such luxury.
Instead, they will attempt to deploy the 'fly-in, fly-out' method, a technique which sees athletes leave their arrival to high altitudes as late as possible so they can compete in their event and depart before the effects of altitude sickness take hold, which is typically just after the two-day mark.
"As such, the fly-in, fly-out method is beneficial as you minimise the early fatigue, development of high-altitude related illnesses and sleep disturbances, while living and training at altitude and maintain normal training quality," Dr Daniel Snape, Research Fellow and Environmental Physiologist at Leeds Beckett University tells LADbible.
Yet, even that method won't be perfect for England, as they have to fly in to Mexico City on Friday afternoon, rather than Saturday or even Sunday, due to a FIFA rule that states teams must train in 'venue-specific sites' close to the stadium on the day before a game from the last 16 onwards.
“The recommendation is you either go 10 days before – which is too long for us – or last minute, which is not allowed [by Fifa],” Tuchel said. “We have spoken to teams who do it and they say they travel very, very late on match day if they cannot have time to adapt. [We must] find a mixture in between.
"It will stay as a disadvantage.”
As a result, the altitude is bound to affect the manager's approach, as well as how the players fare over 90 minutes.
Minutes 1-23
Dr Snape believes the altitude will 'almost certainly' impact how Tuchel sets his side up for the game.
He expects England to modify their pressing strategy with 'selective pressing,' rather than running pedal to the metal throughout. He also predicts a 'more possession focused' approach to the match, with England looking to keep the ball rather than make it a game of transitions.
Dr Snape says England could 'start well' but 'struggle to maintain tempo and physical dominance.'
Minutes 26-45
Dr Snape explains Mexico's "prolonged exposure should be advantageous, as teams based at altitude gain an advantage of ~0.5 goals per 1,000m of elevation gain compared to teams based near sea-level."
Mexico have set up to blitz their opponents in the first half of games during the tournament, with great success. They may look to do the same against England, who were shaky early on against DR Congo.
The hydration break could be very useful in the conditions to give England a chance to catch their breath, maybe literally if they utilise oxygen masks.
Yet, the longer the half goes on, the more England could start to feel the impact of the high altitude, with their 'high-intensity output being reduced.'
Minutes 45-60
Though the half-time break gives England another chance to recuperate, the impact of altitude on the players will likely have started taking their toll.
Dr Snape explains: "Such altitude impairs sprint and repeated-sprint performance and running performance in elite footballers.
"Tactical and skill performance may also be negatively affected because altitude can impair decision-making speed, executive function and visual search ability."
Tuchel hasn't made a substitution before the 61st minute so far in the tournament, but the expert thinks we could see 'earlier and more strategic substitutions' in the game to try and keep the XI fresh.
Minutes - 60-72
It's around the hour mark where England could really start feeling the strain after so much physical exertion without taking in the amount of oxygen their body is accustomed to.
Dr Snape predicts 'early fatigue onset' after 60 minutes, which could see England 'start losing control' in the closing stages.
England will also suffer from 'lower recovery between sprints', taking longer to be ready to go again after every hard, fast run.
Minutes 72-90
With all these factors, England's energy and concentration levels could be completely zapped after the final hydration break.
That could lead to 'increased defensive vulnerability' and provide Mexico with plenty of openings to score, with them likely to be the fresher side.
Extra-time
Let's hope not.
Daniel Murphy