D
uring the 2022 summer U.S. Open, world-ranked No. 3 singles tennis player Daniil Medvedev looked into a courtside camera and said, “One player is going to die, and they’re going to see.”

He was speaking of the extreme heat he and his opponent suffered during the nearly three-hour match in which he cooled himself with towels full of ice.

Medvedev wasn’t the first athlete to complain. Two years earlier at the Tokyo Summer Olympics, tennis player Paula Badosa of Spain was helped off the court in a wheelchair due to heat stroke.

Medvedev also suffered there: The umpire at his Olympic match asked if he was OK to continue. Medvedev replied, “I can finish the match but I can die. If I die, is the ITF (International Tennis Federation) going to take responsibility?” (He won that match.)

And Jamie Farndale, a U.K. rugby player, shared his experience training for the Dubai Rugby Sevens in Rings of Fire — Heat Risks at the 2024 Paris Olympics, a report prepared by Australian advocacy group FrontRunners and released as extreme heat broke records around the world.

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“I remember we prepared for Dubai Sevens one year by doing heat chamber sessions at our training base in Scotland. … You just couldn’t cool down all day, you were tense and angry — fights would break out in our sessions, which never ever happened normally. It was pretty scary to see the effects! On the pitch I remember just wanting to get through the match — which is crazy! Something you dedicate your life to because you love it so much and here you are on the world stage willing it to end!

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“What we do is push ourselves to our limits, and if we have to do so in conditions that are unsafe, I don’t think the athlete would hold back. It is not in an athlete’s DNA to stop and if the conditions are too dangerous, I do think there is a risk of fatalities.” This fear is not unfounded.

“Oppressive environmental conditions — temperature, humidity, radiation and wind speed — are one of, if not the greatest, risk factors for exertional heat illnesses,” says Samantha Scarneo-Miller, who studies heat injuries at West Virginia University.

“As these environmental conditions worsen, it makes it difficult for our body to dissipate heat. When we produce more heat than we are able to dissipate, we can eventually reach ‘uncompensable heat stress,’ which can lead to exertional heat illnesses.”

Heat-related illnesses, some life-threatening, are increasing and can impact major organs.

Skin deep

The skin is the largest of the human organs, and it plays a vital role in cooling the body. It protects internal organs, communicating with the brain to regulate body temperatures. When skin temperatures spike or fall, the skin’s thermoreceptors signal the hypothalamus in the center of the brain, which produces hormones to regulate heart rate, hunger and temperature.

Blood vessels relax, increasing blood flow that carries excess heat to the skin’s surface. Sweat allows that heat to leave the body and cool us down.
The body’s optimum internal temperature is 37.1 degrees Celsius. And the internal thermostat will always work to return the body to this temperature.

But what if it can’t?

CAPTION: Hot Wheels

By: Jade Sterling

Didier Pironi gave the most to win the 1978 24 Hours of Le Mans race for his team. He took the last two stints of the race, driving for four hours in a non-air-conditioned cockpit under a Plexiglas roof in June. He took the checkered flag, parked up and promptly collapsed. The race doctor unzipped his fire suit and covered him in ice. In 2005, Stephane Sarrazin said his cockpit reached 80 degrees Celsius. Air conditioning became a requirement in 2007. Read more›››

Racing drivers are no strangers to feeling the heat in competition but racing is definitely heating up. The Formula One Singapore Grand Prix is renowned as the most difficult race of the year as ambient temperatures stick around 40C — at night, when the race is run — and the 2023 Qatar Grand Prix saw many drivers seek medical attention for either dehydration or heat exhaustion after a race run in 30°C and high humidity.

A warming planet and higher ambient temperatures only exacerbate the conditions racing drivers experience. Many formulae see the drivers sat directly in front of the engines, surrounded by electronics heating the cockpit. Brakes can reach 1,000C and even catch fire. Drivers must wear fire-retardant, long-sleeved safety clothing, topped with a race suit, gloves, balaclava and helmet, all of which store heat and prevent any heat exchange. Thermoregulation becomes very difficult even on cooler days.

Studies have found the peak post-race core temperature of V8 supercar drivers was 39.7C and 38.6C for NASCAR drivers. A reminder that normal body core temperature generally ranges from 36.5 to 37.5C. Hyperthermia is considered anything over 38.5C. Another study found drivers in closed-cockpit races were halfway to their peak temperature after just 10 minutes of racing.

Any rise in temperature can see fatigue and impaired mental performance start to creep in, the last thing you want at 220mph.‹‹‹ Read less

“From a thermoregulation standpoint, the pre-optic area of the hypothalamus (POAH) is the area that controls temperature for the body. At some point during extreme exercise in the heat, the POAH is affected and is unable to effectively regulate the body, though the specific mechanism and timing for this is not well known. As these physiological changes continue to worsen, it affects our body’s ability to thermoregulate, eventually leading to exertional heat illnesses,” Scarneo-Miller tells KUST Review.

A body unable to cool itself due to extreme heat can experience heat exhaustion. Symptoms include nausea, vomiting, headaches and muscle cramps. Most of these can be alleviated by releasing the heat, resting, replenishing fluids and cooling down.

Most athletes, however, as rugby player Farndale noted, are often hard-wired to never give up.

The problem is that heat exhaustion can develop into heatstroke. Results can include traumatic brain injury or death.

One way to minimize these illnesses, experts say, is by adapting to higher temperatures.

This is better known as heat acclimation or reducing the impact on heart rate and body temperature via training.
Though “there are no validated technologies to monitor and prevent completely exertional heat-related illnesses,” Scarneo-Miller says, preventative measures like heat acclimatization are necessary.

“Heat acclimatization is the process of gradually increasing the intensity of physical activity in the heat. Intensity is inclusive of duration of activity (e.g., time), when the activity is performed (e.g., time of the day when it is hottest), equipment worn (e.g., football helmets), amongst other elements,” she adds.

Diving in

Some athletes travel to the competition site weeks in advance to train.

According to the Gatorade Sports Science Institute, for highly fit athletes this might take one to two weeks of 90-minute daily heat exposure.

If moving to training locations isn’t on the cards, some athletes simulate the heat where they are. The Belgium field hockey team, for example, set its heat chamber to 50C to prepare.

Marathoners will also train for hotter climates. Some spend time in a sauna post-training or wear outfits over their clothes to bring their body temperature higher during training.

Canadian marathoner Rory Linkletter says he wears extra clothing during some of his training runs. “You are an engine, and if the engine is hot, it burns faster, so it’ll slow you down. The number one thing you can do is train your body to be a little less bothered by the heat,” he tells the New York Times.

Putting it to the test

Athletes are capable of pushing their bodies to extremes. But how much further can they push themselves in the heat? What is the human limit?

Every human is different, so results vary. Testing can also pose ethical questions. Therefore, until recently, this type of human testing had never been done.

But as global temperatures soar, it’s something athletes and everyone else on the planet needs to know for their own safety.

That’s why a team of researchers at the Heat and Health Research Centre at the University of Sydney, Australia, tested humans in a heat chamber set to a wet-bulb temperature (heat combined with humidity) of 54C and 26 percent humidity – a threshold a research team 15 years ago proposed no human could survive for six hours.

One study participant runs 100 kilometers per week, is 31 years old and spent a week acclimatizing prior to his time in the climate chamber.

The experiment, intended to last three hours, ended at the 2.5-hour mark after the participant’s core temperature reached 39C – the max allowed.

The experiment was done several times under different temperatures and conditions. This was the first time the subject was unable to withstand the three-hour mark.

The first-of-its-kind experiment is ongoing and aims to answer the question how much heat is too much?

Turning to tech

In the meantime, to help athletes keep a cool head, some are turning to technology.

Current wearables on the market track heart rate, blood pressure and respiration rate. But for those training to withstand extreme temperatures, body-temperature readings need to be part of the mix.

Core wearable by Zurich-based company Greenteg tracks every element of athletes’ performance. The device monitors heat entering and exiting the skin, allowing it to track the core body temperature.

Cool threads

Scientists are working hard to keep us cool with just the clothes on our backs. Read more›››

A group of researchers at the University of Massachusetts have created a natural film that can be added to clothing, and the results show that this coating of calcium carbonate — the main ingredient in limestone, marble and chalk — helps reflect the sun’s energy back into the atmosphere and still allows body heat to escape.

“We see a true cooling effect,” says Evan Patamia, a chemistry graduate student on the project. “What is underneath the sample feels cooler than standing in the shade.”

The resulting temperature reduction under clothing is approximately 4.5 degrees Celsius. There is no electrical component, less need for carbon-intensive cooling measures and zero environmental impact.

“What makes our technique unique is that we can do this on nearly any commercially available fabric and turn it into something that can keep people cool,” Patamia says. The team is working with a start-up company that may provide scalable production.‹‹‹ Read less

This helps athletes to not only ensure thermoregulation for safety, but enhance performance: Thermoregulation in athletes enables maximum performance without the risk of overheating. “Thermoregulation is also used in targeted heat training to continuously extend time to fatigue without risking injury,” according to the company website.

The data also includes skin temperature; heat strain, which tells us how hard the body works to cool itself; and temperature zones, which train the body and can improve performance. Finally the device tracks thermal load, or how long the athlete remained within the heat training zone.

For team sports with breaks, cooling technology is helping with thermoregulation.
heat

A 2022 study about the need for face-, head- and neck-cooling technology that can be worn during and after training mentions that after the human face, the hands are the next on the cold thermosensitivity scale, particularly the palm and sole.

A 2023 study from the University of North Dakota concluded that cooling the palms led to increased endurance.

Hands out

But why the palms? The palms contain a high number of arterio-venous anastomoses (AVA), which are located below the skin and provide a shortcut for the blood to quickly move from arteries to veins.

It’s this shortcut that lets the body release heat efficiently. So, when you’re overheating, more blood is flowing through the AVA, bringing heat to the skin’s surface.

This means the palms are an effective heat-offloading site.

Sports tech company Apex Cool Labs says the technology used in its palm-cooling device, Narwhals, reduces heat stress and accelerates recovery time, allowing for enhanced performance not only for endurance sports but also for strength training.

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Stanford University’s Craig Heller studied human temperature regulation and found that the primary heat exchange surfaces of human bodies are the hairless skin of the palms, soles and face.

This led to the development of CoolMitt, which some U.S athletes used to cool core body temperatures at the 2024 Summer Olympic games.

“If you can eliminate fatigue, you can increase the work volume, you get a huge conditioning effect,” Heller tells CBS News.

While there is tech that helps us cool and prevent heat injury, West Virginia University’s Scarneo-Miller says updated policy should be part of the solution.

“Sport organizations need to be very cognizant that as the environment continues to warm, we need to make policy changes to protect our athletes. Developing strong and proactive policies now will allow us to be better prepared for these worsening environmental conditions.

“Policies such as requiring heat acclimatization, an athletic trainer at every sports organization, cold-water immersion tubs available within five minutes of all venues, and emergency action plans all can help recognize and manage a patient suffering from exertional heat illnesses, especially exertional heat stroke, which can be fatal,” Scarneo-Miller tells KUST Review.

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