Cold plunging and the human body - health benefits and risks

Nowadays, hardening is a very popular trend. We hear that it is a physically and mentally healthy hobby. If you are one of the hardening enthusiasts, are thinking about trying it or want to read something about hardening, then this article is the right one for you. You will read why people harden and what is good about it, how to start hardening and how much time to devote to it.

What do you understand by the term hardening?

The Czech word "otuzování" does not have a literal translation in English, as it covers a whole range of activities. The common criterion for these activities is exposing our bodies to cold . After a while, the body reacts to the cold with small changes that bring benefits in the long term.

The most popular methods of hardening include swimming in water in the winter , immersion in a bathtub or barrel of ice water , alternating ice water with warm water or a sauna, walking in the winter without warm clothing , or visiting a cryochamber .

How does the body react to exposure to cold?

Our body has various mechanisms to deal with adverse situations. Even in the case of cold, we can adapt to a certain extent.

To prevent unnecessary heat loss , small blood vessels constrict, especially in the subcutaneous tissue (peripheral vasoconstriction), and the contact between flowing blood and cold is limited.

When body temperature begins to drop below 36.5-36.2 °C , shivering is added to vasoconstriction, in which small muscle contractions generate heat .

Brown adipose tissue , which has many mitochondria and is very metabolically active, can generate additional excess heat . In the non-hardy population, brown fat plays a role only in children , adults have only a few grams of it, but the situation changes a little with hardening. ¹

Why toughen up?

Cardiovascular health

In people who practice hardening for months, we can observe changes down to the molecular level . Compared to the general population, we find differences in apolipoproteins, homocysteine, enzymes and even some hormones. These changes suggest that hardened people have a lower risk of developing and progressing heart and vascular disease and, according to some studies, type 2 diabetes mellitus.

Weight loss

Long-term hardening creates additional brown fat cells , which, through their activity, can influence the correction of obesity and metabolic syndrome .

Training in cold conditions (winter sports, swimming in ice water) in men causes increased fat mobilization and is therefore a possible method of effective weight loss ; this benefit has not been proven in women training in the cold.

Endurance

The bodies of hardy individuals gradually become more physically resistant to cold , which is manifested by the onset of shivering up to 40 minutes later and delayed cooling compared to the general population (reduced sensitivity to cold and the feeling that ice water is not so cold is only a temporary issue that ends a few weeks after the end of the hardy period).

Brain protection

Experimentally, it has been found in mice that hardening leads to genetic changes that protect synapses and therefore delay neurodegenerative diseases such as Alzheimer's disease. However, it is impossible to say whether hardening has the same effect in humans.

Immunity

Hardening increases the number of white blood cells and their effects in the blood, which ensure an immune response and also have an anti-inflammatory effect. Swimmers in icy waters have a lower incidence of respiratory diseases, with a milder course.

Mental health

The release of noradrenaline and endorphins during hardening stimulates the brain in a way that has the potential to help people with psychological problems, especially depression .

Hardening and regeneration

By acting anti-inflammatory and reducing oxidative stress, hardening is beneficial for athletes . Swimming in 10-15 degree water for 10-15 minutes after a hard workout subjectively relieves pain and at the same time allows you to repeat a similar performance in a shorter time. ^{1, 2, 5}

Is hardening always positive?

Hardening can be very healthy and beneficial for the body and mind. In order for it to be positive for us, we must avoid unnecessary risks . Hypothermia and the development of health problems should not occur, so it is necessary to start gradually and not immediately at full speed. It is advisable to get used to the cold and gradually lower the temperature and increase the time exposed to the cold . This will avoid hypothermia , pulmonary edema , shock and the development of cardiac arrhythmia or even pneumonia . Personally, we would not recommend hardening to people with a weak heart and people with an ongoing infection.

In comparison of weightlifters and weightlifters, there was no demonstrated benefit in muscle growth , explosiveness , muscular endurance , and even reduced protein synthesis. ^{2, 3, 4}

How to start and how often and for how long to harden?

The beginnings are always the hardest, which is why it is necessary to start hardening gradually to avoid complications .

The most popular way is to harden yourself in water . You can use a bathtub , tub or barrel of cold water or go swimming in a pond , stream or river in winter . Start hardening yourself early , optimally from the beginning of autumn at least once , better twice a week .

How much time to spend hardening is purely individual . It can be a few minutes or up to half an hour , depending on your endurance and the temperature of the water. A tip from experienced hardeners is to spend about as many minutes in the water as the temperature of the water.

Alternative methods include walking outside in the winter with minimal clothing, which is also a good idea to start doing from the first cold days. Taking a cold shower for 1-3 minutes or alternating between cold and warm showers can be done all year round or used as a preparation before hardening in ice water.

Summary at the end

Hardening can be a good helper for improving overall health, improving immunity, losing weight, regenerating or alleviating depression. However, it is not a miracle method that solves all problems, but rather an aid. You need to start doing it gradually, at least twice a week for several months. By combining hardening with a quality diet, an active lifestyle and enough sleep, you will do your best for yourself.

Resources

1. Esperland, Didrik et al. "Health effects of voluntary exposure to cold water - a continuing subject of
2. debate.” International journal of circumpolar health vol. 81.1 (2022): 2111789. doi:10.1080/22423982.2022.2111789
3. Knechtle, Beat et al. "Cold Water Swimming—Benefits and Risks: A Narrative Review." International journal of environmental research and public health vol. 17,23 8984. 2 Dec. 2020, doi:10.3390/ijerph17238984
4. Petersen, Aaron C, and Jackson J Fyfe. "Post-exercise Cold Water Immersion Effects on Physiological Adaptations to Resistance Training and the Underlying Mechanisms in Skeletal Muscle: A Narrative Review." Frontiers in sports and active living vol. 3 660291. 8 Apr. 2021, doi:10.3389/fspor.2021.660291
5. Kwiecien, Susan Y, and Malachy P McHugh. "The cold truth: the role of cryotherapy in the treatment of injury and recovery from exercise." European journal of applied physiology vol. 121.8 (2021): 2125-2142. doi:10.1007/s00421-021-04683-8