Effects on Human Health Due to Exposure to Cold

During the recent years, research regarding exposure to cold and its effects on human health has been a topic of interest. From cold showers to specific cryotherapy chambers, it is becoming quite a trend among health conscious people and rightly so since it is linked to a number of health benefits. Some notable people including famous celebrities, athletes and body builders regularly take cryotherapy sessions and swear by its benefits. However, cryotherapy is quite expensive and not readily available to common folks, alternatively, you can reap the benefits of cold exposure by simply taking a cold shower, ice bath or just exposing yourself to bearable cold by not wearing excessively warm clothing.

Even though it seems to be a new concept, it actually is not. In fact, it is among the earliest known medical treatments available to man as it is mentioned in some of the most ancient medical manuscripts. 1 It was, however, underappreciated by the modern medical practices until recently when its numerous benefits for the optimization of physical and mental function were supported by research. 

It is said that ‘use it or lose it’, which means if you do not use a skill or ability, you might end up losing it. It is true for physical strength, endurance and stamina too. Human body needs stress to adapt and come out stronger, not the kind that causes irreversible damage but something just strong enough to stimulate your nervous system into activating a cascade of physiological changes that are normally skipped by your conscious brain. Various environmental extremes tend to have different effects on the body. However, no extreme exerts as many effects on the human physiology as cold does. Hemodynamically, it initially decreases blood circulation and then increases it. It also causes increased metabolic heat production, heightens awareness, reduces the sensation of pain and fine tunes the glucose metabolism. However, the specific type of changes depends upon a number of factors such as core temperature and duration of cold exposure. 

Cold exposure
(The author does not recommend rapid immersion in cold water as it can be dangerous, even lethal, causing Cold Shock Response.) 2

Known Benefits:

Resolution of Inflammation and Pain: 

Cold exposure is known to reduce inflammation and symptoms associated with it such as pain, redness and swelling. This explains why cold compresses help after a tooth extraction. However, these effects are not only limited to locally inflamed areas but extend systemically. A study carried out in this regard revealed reduced exercise related immune response when done in a cold environment rather than a neutral one. 3 As exercise can cause acute system-wide inflammatory response, this observation can be greatly helpful in avoiding that. Another study carried out on mice revealed the beneficial role of cold exposure in reducing tendon inflammation. 4

Stimulation of Fat Burning: 

Human body contains white and brown fat tissue. White fat tissue is a major energy storage form while brown tissue is an active form involved in generation of energy for consumption. Numerous studies have suggested that cold exposure stimulates brown fat activity resulting in increased calorie expenditure. The researchers concluded that this discovery can be beneficial as a complementary and economical approach in dealing with obesity rampant in modern societies. 5 in addition, cold exposure leads to shivering and non-shivering thermogenesis which further contributes to calorie expenditure. 6

Strengthened Immune System: 

Many studies support an association between cold exposure and increased immune system components such as leukocytes (White Blood Cells). One study in particular studied the effects of cold exposure over a period of 6 weeks by cold water (14°C) immersion for one hour a day. The participants were found to have increased levels of certain immune components (such as CD3, CD4, CD8 and activated T and B lymphocytes) suggesting an increase in immune activity. 7 

Fighting Oxidative Stress: 

Oxidative stress is a state of imbalance between oxygen free radicals and anti-oxidants. Free radicals are highly reactive compounds naturally produced in our body as a part of the immune system. However, they need to be regularly neutralised by anti-oxidants to avoid cell damage. Oxidative stress is associated with numerous diseases such as diabetes, asthma, cardiovascular disorders, Parkinson’s disease and even cancer! Studies have revealed a relation between cold exposure and increased levels of anti-oxidants such as reduced glutathione, a compound vital for cell health. Since cold exposure increases anti-oxidant levels, it allows the body to deal with oxidative stress more efficiently; curtailing a number of diseases. 8

Improved Sleep Quality: 

Natural daily fluctuations in bodily temperature play an important role in the regulation of sleep wake cycle. 9 When we fall asleep, our body temperature begins to drop. Insomniacs, however, are unable to regulate their temperature resulting into difficulty falling asleep.10 Existing research suggests keeping the room temperature between 60 and 67 degrees Fahrenheit (15.5-19 degrees Celsius) to help you snooze longer and better. 

Regulation of Blood Sugar Levels: 

Cold exposure increases adiponectin levels. Adiponectin is a protein involved in metabolism of glucose and its low levels are associated with insulin resistance. 11,12 Cold exposure also increases sensitivity to insulin, allowing a more efficient glucose metabolism. 13

Supports the Nervous System: 

Increased fat metabolism in response to cold exposure is regulated by the sympathetic nervous system. Studies suggest that it can serve as a mild ‘exercise’ for the nervous system, strengthening it. 14

Potentially Supports Longevity: 

Cold exposure can possibly extend life as demonstrated by several animal studies. However, this needs to be supported by further evidence as several other studies suggest otherwise. Increased life span due to cold exposure is explained by two theories ‘hormesis’ and ‘rate of living hypothesis’. 15 This can serve as a basis for further studies regarding anti-aging effects of cold.

Stimulates Cold Diuresis:

Cold diuresis is cold-induced urination. It is a protective phenomenon induced by constriction of superficial blood vessels to reduce blood flow to the skin and save warmth for more vital internal organs. This causes increased blood pressure as there is less space available for blood to circulate. As a result, the kidneys start to filter out excess water to reduce the volume of blood and regulate blood pressure. Currently, no scientific research is available that can possibly inform us about the specific temperature, length of exposure and other factors that bring about diuresis. 

Supports Recovery: 

Cold exposure exerts a number of physiological effects provided that it is carried out properly, following the guidelines and protocols. These effects include reduced swelling, inflammation, blood flow, muscle spasm and metabolic demand. 16 Evidence suggests that cold exposure aids in healing following a muscular injury. 17 Owing to these beneficial effects, cryotherapy is becoming quite popular among the athletes. 

Increased Appetite: 

A study published in European Journal of Clinical Nutrition supports the idea that colder temperatures enhance appetite. Additionally, another study reported that working out in colder environments stimulates our sense of hunger. 18 This finding can be helpful for those struggling to maintain a healthy appetite. 

Even though cold exposure has a number of benefits as proven by science, it is important to be careful. Make sure to consult your doctor before making any drastic changes in your routine especially if you suffer from chronic conditions such as cardiac diseases. 

Always when trying something new, first learn how to perform it correctly from someone who is more experienced and never try it for the first time by yourself.  You can join Mr Activated for one of his programs or events where  he teaches you the correct way to perform cold exposure to obtain optimum results.

Sudden exposure to cold temperature in any case is harmful. Excessively low temperature can cause dehydration, numbness, immersion foot, hypothermia, frostbite and even death. Make sure to build up cold exposure gradually, starting from cold showers and moving on to ice baths. Although cryotherapy is becoming popular during recent years, there is no evidence that it is more beneficial compared to traditional ways of cold exposure 19

References:

1 Wang, H., Olivero, W., Wang, D., & Lanzino, G. (2006). Cold as a therapeutic agent. Acta neurochirurgica148(5), 565-570.

2 Eglin, C. M., Butt, G., Howden, S., Nash, T., & Costello, J. (2015, December). Rapid habituation of the cold shock response. In Extreme physiology & medicine (Vol. 4, No. 1, p. A38). BioMed Central.

3 Gagnon, D. D., Gagnon, S. S., Rintamäki, H., Törmäkangas, T., Puukka, K., Herzig, K. H., & Kyröläinen, H. (2014). The effects of cold exposure on leukocytes, hormones and cytokines during acute exercise in humans. PLoS One9(10).

4 Zhang, J., Pan, T., & Wang, J. H. C. (2014). Cryotherapy suppresses tendon inflammation in an animal model. Journal of orthopaedic translation2(2), 75-81.

5 van Marken Lichtenbelt, W., Kingma, B., Van Der Lans, A., & Schellen, L. (2014). Cold exposure–an approach to increasing energy expenditure in humans. Trends in Endocrinology & Metabolism25(4), 165-167.

6 van der Lans, A. A., Hoeks, J., Brans, B., Vijgen, G. H., Visser, M. G., Vosselman, M. J., … & Schrauwen, P. (2013). Cold acclimation recruits human brown fat and increases nonshivering thermogenesis. The Journal of clinical investigation123(8), 3395-3403.\

7 Janský, L., Pospíšilová, D., Honzova, S., Uličný, B., Šrámek, P., Zeman, V., & Kaminkova, J. (1996). Immune system of cold-exposed and cold-adapted humans. European journal of applied physiology and occupational physiology72(5-6), 445-450.

8 Bleakley, C. M., Bieuzen, F., Davison, G. W., & Costello, J. T. (2014). Whole-body cryotherapy: empirical evidence and theoretical perspectives. Open access journal of sports medicine5, 25.

9 Yetish, G., Kaplan, H., Gurven, M., Wood, B., Pontzer, H., Manger, P. R., … & Siegel, J. M. (2015). Natural sleep and its seasonal variations in three pre-industrial societies. Current Biology25(21), 2862-2868.

10 van den Heuvel, C., Ferguson, S., & Dawson, D. (2006). Attenuated thermoregulatory response to mild thermal challenge in subjects with sleep-onset insomnia. Sleep29(9), 1174-1180.

11 Imbeault, P., Dépault, I., & Haman, F. (2009). Cold exposure increases adiponectin levels in men. Metabolism58(4), 552-559.

12 Ukkola, O., & Santaniemi, M. (2002). Adiponectin: a link between excess adiposity and associated comorbidities?. Journal of molecular medicine80(11), 696-702.

13 Gasparetti, A. L., de Souza, C. T., Pereira‐da‐Silva, M., Oliveira, R. L., Saad, M. J., Carneiro, E. M., & Velloso, L. A. (2003). Cold exposure induces tissue‐specific modulation of the insulin‐signalling pathway in Rattus norvegicus. The Journal of physiology552(1), 149-162.

14 Cypess, A. M., Chen, Y. C., Sze, C., Wang, K., English, J., Chan, O., … & Kahn, C. R. (2012). Cold but not sympathomimetics activates human brown adipose tissue in vivo. Proceedings of the National Academy of Sciences109(25), 10001-10005.

15 Keil, G., Cummings, E., & de Magalhaes, J. P. (2015). Being cool: how body temperature influences ageing and longevity. Biogerontology16(4), 383-397.

16 Malanga, G. A., Yan, N., & Stark, J. (2015). Mechanisms and efficacy of heat and cold therapies for musculoskeletal injury. Postgraduate medicine127(1), 57-65.

17 Bleakley, C. M., Bieuzen, F., Davison, G. W., & Costello, J. T. (2014). Whole-body cryotherapy: empirical evidence and theoretical perspectives. Open access journal of sports medicine5, 25.

18 Wasse, L. K., King, J. A., Stensel, D. J., & Sunderland, C. (2013). Effect of ambient temperature during acute aerobic exercise on short-term appetite, energy intake, and plasma acylated ghrelin in recreationally active males. Applied Physiology, Nutrition, and Metabolism38(8), 905–909. doi: 10.1139/apnm-2013-0008

19 Bleakley, C. M., Bieuzen, F., Davison, G. W., & Costello, J. T. (2014). Whole-body cryotherapy: empirical evidence and theoretical perspectives. Open access journal of sports medicine5, 25.


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