From freezing showers to cryotherapy tanks, cold exposure is in vogue amongst health-conscious people. And rightly so, given its potential to boost fat burning, shield the nerves, strengthen the immune system, and more. In this article, we will explore the science behind cold exposure, ways to practice it, and important precautions.
What is Cold Therapy?
Cold therapy is not a new invention; it is among man’s earliest medical treatments. The Edwin Smith Papyrus (3500 BC), the most ancient medical text, repeatedly mentioned cold therapy [1].
However, until the late 1980s, cold exposure remained relatively unappreciated by modern, allopathic medicine [1].
More recently, cold therapy has been increasingly used to prevent or mitigate various types of neurologic injury [2].
Even so, the numerous benefits of cold therapy remain relatively hidden and untapped. Hopefully, this article will give you an insight into how you can leverage cold exposure to optimize your health and performance.
Benefits of Cold Exposure
This post doesn’t suggest rapid immersion into cold water. That may cause dangerous, and even fatal, changes in the breath and heart rates, known as the cold shock response [3].
Be cautious with any form of sudden temperature change in your environment, especially if you have heart disease or other chronic conditions. Make sure to consult your doctor before making any major changes to your daily routine.
1) Aids Fat Burning
Humans have stores of active brown fat tissue (BAT). Unlike white fat, which stores energy and comprises most body fat, brown fat is active in burning calories and using energy [4].
BAT can essentially turn calories from food into heat [5, 6].
Indeed, studies show that cold exposure increases BAT activity which leads to increased calorie expenditure. Researchers concluded that frequent cold exposures might be an acceptable and economical complementary approach to address the current obesity epidemic [7].
According to preliminary research, a lack of BAT has been linked with obesity [8].
Cold exposure increases shivering and nonshivering thermogenesis. These processes increase calorie expenditure [9].
Exposure to cold temperatures leads to increased levels of adiponectin, a protein that increases fat burning. Low levels of adiponectin are associated with obesity [10, 11, 12].
In one study, subjects who were exposed to cold stress had an 80% increase in their metabolism over “warm” levels [13].
In one study, cold-exposed rats burned so many extra calories that they ate 50% more than control rats but still weighed less than controls [14].
2) Fights Inflammation
Exposure to cold temperatures raises adiponectin, a protein that combats inflammation [15].
Another study found that exercising in the cold reduced the inflammatory response seen in regular temperature environments [16].
This same study found that exercising past a certain time in the cold can actually increase the inflammatory response, so moderation is important [16].
3) May Support Longevity
A study found that flies lived twice as long when kept at 21°C than 27°C [17].
Similarly, research on worms found that a 5 °C drop in temperature increased lifespan by 75% [18].
A number of studies on insects have also found a negative relationship between temperature and lifespan [19, 20, 21].
Fish also seem to live longer at lower temperatures. For example, one study showed that a 6 °C drop in temperature increased the average fish lifespan by 75 % [22, 23].
In 1986, one researcher immersed his lab rats in shallow, cool water for four hours per day. The rats burned so many extra calories that they ate 50% more than control rats. The cold-exposed rats still weighed less than the control rats and lived 10% longer [14].
Another study lowered the core temperature of mice by 0.3 °C (males) and 0.34 °C (females), resulting in an increase in the average lifespan of 12 and 20% respectively [24].
Increased longevity via cold-exposure could be due to hormesis. Hormesis refers to the paradoxical adaptation that makes animals stronger and more efficient if they are exposed to environmental stresses [25].
Other researchers prefer the ‘rate of living hypothesis’. This theory suggests that lower temperature promotes longevity by slowing down the rate of reaction of various metabolic processes. This means fewer by-products of metabolism, such as reactive oxygen species (ROS) [6].
Alternatively, increased longevity from cold exposure may be due to a modulation of genes, such as TRPA-1 and DAF-16 [26].
Promising animal research in this field should spark further investigation and clinical trials that would examine the anti-aging effects of cold exposure in humans.
4) Strengthens the Nervous System
The increase in fat burning during cold exposure is modulated by the sympathetic nervous system. Cold temperatures act as a mild “workout” for the nervous system, which adapts and strengthens [27, 28].
5) May Support and Speed up Recovery
The physiological effects of cold therapy include reductions in blood flow, swelling, inflammation, muscle spasm, and metabolic demand [29].
There is some preliminary evidence that ice plus exercise is effective at increasing healing speed after an ankle sprain or surgery [30].
Cold exposure has a positive effect on muscular enzymes linked to muscle damage (e.g. creatine kinase and lactate dehydrogenase) [31].
One study looked at 360 people who either rested or submerged themselves in cold water after resistance training, cycling or running. 24-minute cold water baths (50 – 59 °F) prevented sore muscles after exercises [32].
This approach is becoming increasingly popular among professional athletes.
6) Regulates Blood Sugar Levels
One study found adiponectin levels increase by 70% after cold exposure. Adiponectin is a protein involved in blood glucose regulation, with low levels often found in insulin resistance [11, 12].
In rat studies, cold exposure increased glucose uptake in the peripheral tissues. Thus, cold exposure may be beneficial during a fast, as fasting can cause peripheral insulin resistance [33].
Cold exposure can enhance the body’s response to insulin, allowing glucose to be cleared from the blood more efficiently [34].
7) Improves Sleep Quality
Natural daily temperature fluctuations are an important regulator of sleep cycles [35].
The nonprofit National Sleep Foundation recommends keeping bedroom sleeping temperatures between 60 and 67 degrees F [36].
8) Strengthens the Immune System
One clinical study looked at the effects of 6 weeks of cold water immersion (14C for 1hr) on the immune system. Participants had increased levels of IL-6, CD3, CD4, CD8 and activated T and B lymphocytes, suggesting a more active immune system [37].
Engaging in exercise before cold exposure enhances the immune-stimulating effects of cold therapy, but the available research is limited.
9) Combats Oxidative Stress
One study found that people who regularly swim in ice-cold water had relatively high levels of reduced glutathione, an antioxidant that’s vital for detoxing [38].
Cryotherapy can enhance antioxidant status, allowing the body to deal with free radicals more effectively [31].
10) Reduces Pain
According to anecdotal evidence, blasts of cold significantly improve the quality of life for patients suffering from phantom limb pain.
Cold compression therapy provides more pain relief than popular, alternative interventions [39].
Cold application alone may be effective in reducing pain associated with migraine attacks [40].
Cold Exposure and Will Power
This benefit is anecdotal and not backed by scientific research.
Many people have noticed a huge increase in will-power from taking regular cold showers.
Nobody wants to get in a cold shower. Getting under freezing cold water every morning trains the brain to do things it doesn’t spontaneously want to. This attitude could then translate to other areas of your life.
Cold Exposure Suggestions and Precautions
This post doesn’t suggest rapid immersion into cold water. That may cause dangerous, and even fatal, changes in the breath and heart rates, known as the cold shock response [3].
Be cautious with any form of sudden temperature change in your environment, especially if you have heart disease or other chronic conditions. Make sure to consult your doctor before making any major changes to your daily routine.
It is essential to build up cold exposure gradually.
You could start by occasionally turning the central heating down, and going for minimally (but legally) clothed short walks. Then move on to cold showers. When comfortable with these you might be ready for cold baths and, finally, ice baths.
Cryotherapy (brief exposures to air temperatures below -100°C) is becoming more mainstream and, as a result, more affordable. However, at the moment there is insufficient evidence to suggest it offers advantages over traditional methods of cold exposure [31].
