At the peak of Japan’s last heatwave in August 2019 – the same month when this year’s Olympics take place – 57 people died and 18,000 were hospitalised over just one weekend of peak heat.
In competition, some athletes’ core body temperature will hit above 40 degrees as they push themselves to the limit in their quest for Games glory.
The effects of heat stress are very real. Triathlon gold medal hopeful Jonny Brownlee is living proof as evidenced by his body memorably giving way in the home straight of the World Triathlon in Cozumel, Mexico, in the same year as the last Olympics.
Looking drunk, his legs increasingly gave way as he staggered around looking lost and no longer in control of his limbs, brother Alistair scooping him up and carrying him over the line, aware of the acuteness of the situation.
“Unfortunately, the worst-case scenario is death if we’re talking heat illness that goes wrong and you can’t cool the body,” explains Laura Needham, the co-head of physiology at the English Institute of Sport as well as responsible for avoiding a repeat for Brownlee as the senior physiologist for British Triathlon in Tokyo.
Standard temperatures for British athletes in Japan this summer will be about 32 degrees with 80 per cent humidity - as Needham puts it “a bit of a cooker”.
For an elite athlete, 42 degrees appears to be the absolute peak for core body temperature and then “death occurs at 44”. In many ways, elite athletes are a danger to themselves in pushing themselves beyond a normal human being’s capabilities.
“Elite athletes have this ability to override,” she said. “You and I would probably stop whereas they are programmed a little bit differently. They have an extraordinary ability to push beyond their limits.
“And we have a dual role. We’re about performance and health. Athletes need to be safe but they have to be able to perform in those conditions as well.”
Some of the preparation work both before leaving home and at the holding camp across three sights in Yokohama and Kawasaki is incredibly simplistic, being warned to apply suncream, walk in the shade or else make use of the hundreds of Team GB umbrellas shipped over to Japan to keep athletes out of direct sunlight.
Ice vests and other “innovative garments” have been introduced to supporting cooling, while hot baths are not uncommon for acclimatising athletes, the messaging of ‘Embrace the Sweat’ from Team GB.
The team have hundreds of ice pops to help with the cooling process as well as the seemingly British addition of a pop-up greenhouse.
Paul Ford, the deputy chef de mission for performance services for Team GB in Tokyo, explained: “It’s a portable greenhouse – I won’t glorify it much more than that. It’s as it sounds. The pop-up element means we can move it around.”
Its importance is key at the holding camp. Japan’s rainy season ended abruptly last week and turned into hot summer in an instant. On cooler days at the holding camp, the greenhouse enables support staff to exaggerate the heat.
Heat chambers have been central to the UK-based preparation - the EIS have three in Manchester, Loughborough and Bisham Abbey.
They take an hour to get to the right heat and humidity, and inside them, athletes are put through different physical – such as cycling or running – and even cognitive tests.
“I don’t think anyone likes it but it’s part of the process and it’s always worse at the beginning,” said Needham. “It’s like if you go on a hot holiday and go for a run. The first run is awful isn’t it? But then it doesn’t feel so bad.
“It’s amazing how quickly the body will respond and adapt to the heat. It’s unlike altitude. Typically, an altitude camp is four weeks, with the heat you’ll do it much quicker. We’ll see changes within five to 14 days to be fully acclimatised.”
But in terms of the holding camp, there are more than the simplistic approaches. The camps have been intentionally selected in Greater Tokyo to give British athletes the best possible chance of acclimatising to the heat and humidity.
“Different sports have different strategies,” said Ford, who first travelled to Tokyo in March 2015 to prepare the required camp. “A hockey match is 70 minutes, the 100metres is 10seconds and gymnastics compete in an air condition area. And where the holding camp is athletes and living and breathing the conditions they will compete in.”
But there is no one-size-fits-all solution for elite athletes, with each responding very differently to the heat and understanding how elite athletes respond to heat stress is still a work in progress. For Needham herself, it is the subject of her PhD.
Some sports are more “at risk” to the heat and humidity, among them triathlon, marathon running, open-water swimming and team sports.
Much of the EIS and sport-by-sport approach is preventative but there will be instances where things go wrong in Japan for an athlete.
“There’s a tipping point with the human body where it goes ‘no we can’t cope with this’,” said Neednham. “There’s a fine line and our job is finding out.”
If it does go wrong, the answer is “aggressive cooling” followed by handing over to the emergency services. The hope is all the work in advance negates such a risk.