How do our bodies adapt to extreme temperatures?

You have already checked here at Mega Curious an article about how cold a human being can handle, explaining that the effects of low temperatures vary from person to person, but that when we are at minus 27 degrees we need to be alert and try our best to warm up the body.

Now you will learn a little more about how our bodies adapt to extreme temperatures, whether cold or hot, and how this process works.

In the video below you can see a man who is clearly not feeling very cold. The native Norwegian came to viral renown a few weeks ago on the Internet, when he skated and swam in the frigid Goksjo Lake almost naked except for a swim trunks and an ice float around his neck.

How did he not freeze? And no, it's not just about the vodka he's sending inside.

Acclimatization

According to several studies already done on the mysteries of the human body, the key to adapting to extreme temperatures is a gradual physiological process known as acclimatization. Our bodies can get used to cold or hot environments equally, but how does this process work?

First and foremost, an important distinction must be made between immediate and long-term physiological response. Our bodies can react to extreme temperatures quickly - one example is their ability to sweat, which is an almost immediate physiological response. However, the mechanism of sweat is an inaccurate characterization of acclimatization.

Acclimatization refers to the physiological responses of a deeper origin: the hormonal and metabolic programming that governs not only your tendency to sweat, but how you will sweat, when and even how much sodium your sweat carries with you. It's like an incredibly smart thermostat.

This temperature regulation system is largely controlled by a collaboration between the hypothalamus and the pituitary gland, and generates a series of physiological responses. These include the readiness with which you divert blood to the vessels in your skin (which has a cooling effect), the rhythm and sensitivity of your heartbeat.

Physiological responses also include your body's thermal energy production and the distribution of body resources to protect your liver, brain, kidneys and other vital organs. The acclimatization causes the body to undergo some adjustments to optimize the function of these responses in relation to the environment.

That is, a sweating mechanism does not configure acclimatization, but rather your body's ability to adjust to warmer temperatures to sweat faster and more profusely, with a lower concentration of sodium.

Cold and heat

An example of acclimatization happens to sports athletes engaged in extreme temperatures. According to the iO9 website, a good example is Kilian Jornet Burgada, one of the most formidable mountain runners of this or any generation.

Jornet spent his teens playing in the mountains of the Spanish Pyrenees at an altitude of 6, 500 feet (nearly 2, 000 meters) at very low temperatures. "When you are born and raised at altitude, you tend to have a higher blood volume and a higher red cell count to store more oxygen, " one physiologist tells The New York Times.

This translates into greater endurance and better performance in the sport. The acclimatization to heat and cold occurs similarly, with deep physiological adjustments that become hormonally and metabolically impregnated over long periods of time.

However, this does not mean that you have to be necessarily born and raised in the Spanish Pyrenees to support life in the cold. Generally speaking, the more time you spend in an environment, the more adapted your body becomes to achieving some particular conditions, such as diving into freezing waters.

Constant exposure

According to several studies from the 1960s onwards, about 10 to 14 days of exposure to relatively higher or lower temperatures than usual is enough to begin to reap the benefits of acclimatization.

For example, a recent study led by researcher Wouter D. van Marken Lichtenbelt supported earlier findings that ten days of cold exposure were sufficient to increase the body's ability to generate heat without shivering. The researchers observed that, after cold acclimatization, the guinea pigs began to feel the controlled environment as milder, felt more comfortable in the cold and showed less shivering.

According to the researchers, increased heat production occurs with increased activity in brown adipose tissue, in parallel with an increase in thermogenesis. The main physiological objective of this adipose tissue is to generate heat independently of the effect of cold, aiding in acclimatization.

“After prolonged exposure to cold, shivering gradually subsides but energy expenditure remains high, indicating increased shivering thermogenesis. This metabolic adaptation over time is called adaptive thermogenesis. In rodents, this adaptation can be fully attributed to brown adipose tissue. Human studies have shown that prolonged exposure to cold in healthy men also resulted in a gradual decrease in shivering, while heat production remained high, ”explained researcher Marken Lichtenbelt.