Introduction
Cold exposure as a therapeutic and health-promoting practice has been used for centuries. In modern times, it is primarily used for reducing muscle soreness and promoting muscle recovery after physical activity. However, the benefits of cold exposure may extend beyond muscle recovery. It may improve glucose and lipid metabolism, decrease inflammation, enhance immune function, and improve cognitive performance. These effects may be attributed to hormesis, a favorable biological response to a mild stressor that triggers protective mechanisms that provide protection from future, more harmful stressors. Despite the potential benefits associated with cold exposure, it also poses risks, particularly in unsupervised or uncontrolled conditions. This article aims to provide an overview of the different modalities of cold exposure, physiological responses, health effects, and safety concerns associated with the practice.
Modalities of Cold Exposure
Common modalities of cold exposure include cold water immersion, local cryotherapy, and whole-body cryotherapy. Cold-water immersion entails submerging one’s body in water typically at or below 59°F (15°C). Local cryotherapy generally involves placing ice packs on specific areas of the body, such as joints or muscles. Whole-body cryotherapy involves exposure to cold air for a few minutes at temperatures as low as -289°F (-178°C), typically in a cryotherapy chamber, wearing protective garments on the extremities. Cryotherapy chambers must be colder than water because thermal conductivity, the rate at which heat is transferred, differs between water and air.
Physiological Responses to Cold Exposure
Exposure to cold temperatures elicits a range of acute physiological responses collectively referred to as the cold shock response. The goal of the cold shock response is to reduce heat loss and increase heat production. Norepinephrine increases heart rate, activates thermogenesis (the production of heat), constricts blood vessels, and modulates immune function. Norepinephrine release can also activate peroxisome proliferator-activated receptor gamma coactivator 1-alpha, or PGC-1 alpha, a key regulator of genes involved in energy metabolism. However, long cold exposure durations of one hour may not necessarily be required to induce norepinephrine release.
Cold shock proteins, a large family of highly conserved proteins induced by various cellular stressors such as cold exposure, DNA damage, and hypoxia, ameliorate the harmful effects of cold. Notable cold shock proteins include cold‐inducible RNA binding protein, which promotes cell survival and activates antioxidant enzymes under conditions of mild hypothermia, and RNA binding motif 3, or RBM3, which may be neuroprotective. Mitochondrial biogenesis is the process by which new mitochondria are produced. Increased mitochondrial biogenesis within skeletal muscle is associated with greater aerobic capacity and performance and reduced risk factors for various diseases. Cold exposure increases metabolic heat production through a process called thermogenesis. Shivering thermogenesis, as its name implies, involves shivering to produce heat. The primary role of brown fat is thermogenesis.
Health Effects of Cold Exposure
A study showed that immersion in a colder temperature (14°C) increased noradrenaline by 530 percent, dopamine by 250 percent, and energy consumption by 350 percent compared to pre-immersion levels. Cold shock proteins are produced, which promote cell survival.
Increasing Energy and Focus
Cold exposure causes a significant release of epinephrine (adrenaline) and norepinephrine (noradrenaline) in the brain and body. These chemicals make us feel alert and can make us feel agitated and as if we need to move or vocalize during the exposure. Their ongoing effect is to increase our level of energy and focus, which can be applied to other mental and physical activities.
Building Resilience and Grit
By forcing yourself to embrace the stress of cold exposure as a meaningful self-directed challenge, you exert what is called ‘top-down control’ over deeper brain centers that regulate reflexive states. This top-down control process involves your prefrontal cortex — an area of your brain involved in planning and suppressing impulsivity. That ‘top-down’ control is the basis of what people refer to when they talk about “resilience and grit.” Importantly, it is a skill that carries over to situations outside of the deliberate cold environment, allowing you to cope better and maintain a calm, clear mind when confronted with real-world stressors.
Enhancing Your Mood
Cold exposure causes the prolonged release of dopamine, a powerful molecule capable of elevating mood, enhancing focus, attention, and goal-directed behavior. Even short bouts of cold exposure can cause a lasting increase in dopamine and sustained elevation of mood, energy, and focus.
Metabolism
In the short-term, cold exposure increases metabolism as the body has to burn calories to increase core body temperature. The conversion of white fat (energy storage) to beige or brown fat (which are highly metabolically active) can be beneficial for cold adaptation and triggering further and more sustained increases in metabolism
Different types of Adrenaline
The crucial difference about the type of adrenaline rush from cold exposure is that, compared to the rush from sugar, drugs or pornography, the rush declines gradually over a long period of time. When taking drugs for example the adrenaline rush spikes within seconds, but also declines rapidly within a short period of time even below baseline leaving you unhappy and apathetic, whereas cold exposure is likely to raise the level of your baseline adrenaline long-term.
The reason is that in order to get this spike of adrenaline and dopamine, you have to overcome something hard. That is what dopamine is designed for, to help us overcome something, that feels painful or dreadful. On the other hand taking drugs or eating lots of sugar does not require a certain type of commitment or overcome, so it is easily accessible (more or less) and does not require any hard work or work at all. This leads to a rapid downfall of adrenaline levels.
Safety Concerns of Cold Exposure
Despite the potential benefits associated with cold exposure, it also poses risks, particularly in unsupervised or uncontrolled conditions. Prolonged cold exposure may lead to hypothermia, a potentially life-threatening condition that occurs when the body loses heat faster than it can produce heat. Exposure to cold can cause tissue damage, hypothermia, and even death in extreme cases.
Cold exposure should be avoided or minimized in people with certain medical conditions, including but not limited to Raynaud’s disease, diabetes, hypertension, and cardiovascular disease. Individuals who are pregnant or have respiratory conditions, such as asthma, should also use caution when exposing themselves to cold.
Cold exposure should always be supervised by a qualified professional, especially when using modalities like whole-body cryotherapy.
Conclusion
In conclusion, cold exposure has become more popular in modern times due to its ability to reduce muscle soreness and promote muscle recovery after physical activity. Regular exposure to cold temperatures may also improve glucose and lipid metabolism, decrease inflammation, enhance immune function, and improve cognitive performance. However, cold exposure poses some risks, especially in unsupervised or uncontrolled conditions. Therefore, it is essential to understand the different cold exposure modalities and their physiological responses, health effects, and safety concerns before engaging in the practice.
Common questions:
How Cold?
“This is really cold (!), and I want to get out, BUT I can safely stay in.” This is the key temperature range for cold exposure, according to Dr. Andrew Huberman, a neuroscientist and tenured professor of neurobiology at Stanford University.
For some, that temperature might be 15°C (60°F), whereas for others, it might be as low as 5°C (40°F).
Ice bath, cold shower or cryo?
The most effective form of cold exposure is an ice bath or cold water immersion up to the neck, but cold showers can also work, especially for “beginners”. Cryotherapy is expensive and not as accessible for most people, also there is not much variation in protocols.
How long?
To achieve the benefits of cold exposure, it is recommended to engage in deliberate cold exposure for at least 11 minutes per week, spread out across 2–4 sessions lasting between 1–5 minutes each. The water temperature should be uncomfortably cold but still safe to remain in for a few minutes. While you can do more, this is the minimum amount suggested.
Can or should I shiver?
Dr. Susanna Søeberg’s research has led to the development of the Søeberg Principle, which suggests that to maximize the metabolic benefits of cold exposure, it’s important to allow the body to naturally reheat itself. This can be achieved by “Ending With Cold.”
In addition, shivering can further enhance the metabolic effects of cold exposure. When the body shivers, it releases succinate from the muscles, which activates brown fat thermogenesis.
To increase shivering during or after cold exposure, try to avoid huddling or crossing your arms and refrain from towel-drying. Instead, let your body reheat and dry naturally, which may be challenging but can be more effective in achieving the desired metabolic effects. Although it may be tempting to take a hot shower and towel dry after cold exposure, this approach may limit the metabolic benefits
How to further enhance the effects?
To increase the effectiveness of cold exposure you could start moving your limbs while in the water. Staying still in cold water allows a thermal layer to surround your body, insulating you from the cold. However, by moving your limbs while keeping your hands and feet in the water, you break up this thermal layer, making the water feel much colder.
This technique can be compared to slowing down the movement of a weight lift to reduce momentum and provide more tension on the working muscles. By moving your limbs in cold water, you increase the tension on your body and make it work harder, which can lead to increased resilience and health benefits.
More detailed Information
The information on deliberate cold exposure is seemingly endless, unlike this post, which is supposed to briefly mention the risks and benefits of this practise, as well as applicable protocols. However if you want to look at this topic in more detail Dr. Rhonda Patrick has an extended article on her website foundmyfitness.com. Also Dr. Andrew Huberman talks in his podcast about deliberate cold exposure in more detail about different effects on the brain and body and several applicable tools and protocols for cold exposure. Dr. Patrick on the other hand focuses more on the neurochemical processes in the brain and body, as well as several conducted studies about cold exposure. These were also my main sources while writing this article.
