Daniel Ricciardo has detailed the effect the Mexico City Grand Prix has on Formula 1 drivers owing to the high altitude experienced.
At 2240 metres above sea level, Mexico City is the highest race of the season, presenting cars and drivers with challenges not present elsewhere on the calendar owing to thinner air.
Air is less dense at that level meaning teams can run Monaco-spec wings but only get Monza-levels of downforce while the lack of air can also affect the drivers.
Ricciardo has been a veteran of every Grand Prix at the Autodromo Hermanos Rodriguez since it returned to the calendar in 2015, with the AlphaTauri driver believing the actual driving is not too different from any other event.
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Ricciardo's altitude adjustments
"In the car, it doesn't feel that different, maybe it is because we are sitting and maybe the muscles we use don't really spike the heart rate too much," Ricciardo told media including RacingNews365.
"I don't know what it is, but I remember the races here not being that much more physical, but I definitely feel it when I sleep.
"Whenever I wake up in the morning, I just feel a little bit short of breath, as if someone has put a pillow over your face, so I'll make sure I've locked my room properly.
"It's just a little bit less sleep than in the gym, like if we get on the treadmill or anything like that, you feel it.
"We don't have the luxury of coming out here three weeks in advance and preparing for the altitude, so you've just got to suck it up.
"As I said, in the car, it is not too bad.
"Like if we were coming here to run a marathon, we would definitely need to prepare differently, but it's not too bad for us."