Photo Illustration by Elena Scotti/Gizmodo/GMG, photos via Getty Images

Nearly three thousand athletes have made their way to the Winter Olympic this month, and probably at least a couple are cursing the day they ever decided to become world-class bobsledders: Reports out of Pyeongchang list the temperature at or around a murderous subzero, putting this year’s games on track to be the coldest since 1994—with matters not much helped by the fact that, in their haste to get a stadium in shape, South Korea’s builders neglected to include a roof.

The athletes have devised a couple of novel coping methods—many have been seen plastering their cheeks with athletic tape—but you can’t properly luge in a scarf and huge puffy coat. Which brings us to the subject of this week’s Giz Asks—namely, how are these people not freezing, dressed like that? According to the kinesiologists, physiologists and extreme weather experts we spoke to, they almost certainly are freezing—but the human body apparently has ways of warming itself when engaged in strenuous physical activity, Olympic-level competition very much included.

Stephen S. Cheung

Professor of Kinesiology, Brock University

In the cold, your body temperature is a function of the heat you are losing to the environment on the one hand, and the amount of heat your body is producing on the other. If the cooling becomes too much, you can risk your body temperature dropping to the point of hypothermia. Not only can this affect your athletic performance, but it can ultimately lead to death. Therefore, you can manage your body temperature by the level of insulation (amount of clothing) you have, and also how hard you are exercising. There’s a surprising amount of high-tech insulation built into many of the skin-tight clothing (e.g., Alpine skiers, sliding sports). The athletes are working extremely hard, and therefore generating a massive amount of heat (e.g., Nordic skiing, biathlon). Whenever you exercise, only about 20% of the energy is in the form of mechanical energy to move your body, and the remaining 80% is converted to heat. Therefore, you can stay very warm and even overheat during exercise in the cold if you are working hard.

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Guillaume Millet

Professor, Kinesiology, University of Calgary

Take, for example, a car engine. In Europe, we have lots of vehicles that run on diesel gas. There’s a risk, with diesel gas, that it will freeze. But this risk only exists when the car is at rest. As soon as you start driving, you’re good. The same thing applies to the human body: If you don’t contract your muscles, you’re definitely at risk, but that changes as soon as you start exercising: Only one of every four calories spent is used to actually contract your muscle, and the rest produces heat. It depends on the intensity, of course, but Olympians are competing at full-speed, so they’re producing lots of heat.

If you start to get below minus twenty, that’s a different story, because then the extremities are at risk. The extremities don’t have much muscle contraction, so there’s not much heat produced. As long as you have glycogen, as long as you’re not tired and you can maintain the base, then there is no issue. Bu, of course, the longer the exercise, the lower the intensity, so at some point the intensity wont be high enough to produce enough heat. It’s a compromise between how much heat you produce and how cold it is.

The 1994 Olympics were in Lillehammer, Norway; I remember that because one of my best friends in France [participated] as a cross-country skier. He didn’t do very well, [partly] because he was too skinny, and was shaking with cold. But I remember after the race the winner was basically naked—he didn’t have any shorts on. That was at the end of the race, right after crossing the finish line. He’d produced so much heat that he was able to stay like that for several minutes.

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Mike Tipton

Professor, Extreme Environments Laboratory, University of Portsmouth

They are wearing a lot of clothing insulation (more static sports) or they are generating a lot of heat (e.g. cross country skiers). Humans can generate up to 2 kW of heat through exercise, which is about the same a two bar fire. We are about 20% efficient (same as a car engine), that means that 80% of the energy we consume is converted and released as heat.

Frostbite, non-freezing cold injury, and hypothermia are unlikely to be problems in athletes exercising, but possible problems include discomfort (distraction), local/extremity cooling, impairing neuromuscular function (e.g. grip strength, dexterity), cold-induced diuresis and respiratory water loss leading to dehydration.

The best way to mitigate [these risks] is to maintain skin blood flow by maintaining average skin temperature and deep body temperature.

Other interventions can help in one way or another, but it depends on the problem (i.e. comfort vs. functionality). So heated pads, balms, sock and drinks may increase comfort and local skin temperature (tape on face), but will do little to increase local blood flow or body temperature.

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Carl Foster

Professor of Exercise Science and Director of the Human Performance Lab at the University of Wisconsin

Well, depending on the weather, sometimes they are quite cold.

However, uniform design, particularly over the last few years, focuses on the aerodynamic qualities of the surface of the racing suits, which sometimes sacrifices the breathability of the suit, which can make it warmer than you might expect. Speed skaters, for instance, are often quite sweaty inside their suits—it’s the combination of the suit being designed to reduce air friction (even at the expense of not breathing well) and a very high rate to heat production.

Also, in almost all the [winter] sports the heat production from exercise is quite high. Even in alpine skiing, where the speed work is done by gravity, the muscle work required to control the skis is enormous.

Lastly, remember that high level athletes can produce a lot more work with their muscles than normal people. They were selected from very talented athletes, who have trained very hard. In an elite endurance athlete, like a cross country skier, they can work at essentially double the rate of a normal person of the same age. And, because 75% of energy production results in heat production, they produce a lot of heat.

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John Emmett

Professor, Exercise Science, Eastern Illinois University

There are a few things that the body does, acclamation-wise, when people are exposed to the cold over time. One is there’s an increase in basal constriction of the blood vessels, which helps keep the heat the body makes inside, rather than letting it go to the skin where it can be lost to the environment—it kind of increases the thermal layer, the skin-level, and that keeps some of the heat locked in a little better. This would happen gradually over time—it doesn’t make a huge difference, but every little bit helps. (The opposite happens in the heat, where the blood vessels will dilate so that all that heat is transferred through the bloodstream to the skin and lost.)

There’s also a response called non-shivering thermogenesis. One way to keep warm in the cold is through shivering, which generates heat. It’s a good first response to try to keep the body temperature elevated, but you can’t do that all the time—you just wear out. But non-shivering thermogenesis is where the cells of the body, on their own through repeated cold exposure, carry a little bit more heat than usual, which helps keep body temperature elevated.

The biggest risk in the cold is obviously your core temperature—your internal temperature—getting too low, but when you exercise you produce heat to keep you warm, so it’s probably easier for the athletes to tolerate the cold, as opposed to the spectators, who just have to stand or sit there and watch (although they have the option to wear more layers).

Sometimes that cold dry air can provoke respiratory irritation, causing people to have a little bit of a cough or something like that—but then extremes like frostbite take pretty prolonged exposure to severe cold.

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