The Power of Cold Shower

?? In this Nexus:

?? ?altmir? - always dying from cold

?? What happens to our body after a cold shower?

?? The mechanism behind the exposure to cold water and it's benefits

?? Can exposure to cold water be harmful?

?? Practical tips for incorporating cold showers into your routine

I am a big believer that small changes can provide a significant impact. There is a perception, that you need to have a lot of money, to follow the longevity trend and to live healthily ever after. Well, until gene editing or other age reversal therapies are tested in human and are widely available (which I think will still take at least 10 years from now), you can spend this time doing small but powerful changes to your daily routine to live healthier, and when the time comes for the revolutionary procedures - to be in your best shape possible.

In this Nexus edition I zoom in to an almost free of charge method (because you take shower anyway), which can help you improve your overall health - cold shower or cold water immersion. I discuss how I managed to incorporate cold shower into my routine, what are the health benefits of exposure to cold, what are the scientific proofs behind and some actionable tips for you, in case you decide to give it a try.

?altmir? - Always Dying From Cold

In Lithuanian language we have a word ?altmirys (for men) / ?altmir? (for women). The dictionary explains it as sensitive to cold. A more direct translation would be dying from cold (as ?altas means cold and mirti means to die). So this is me, I am ?altmir?. I am cold in the office when the temperature is below 21'C. I am always cold-feet during winter (those memes about women putting their frozen feet on their partner's body to get warm are so true!). Even when it is still quite warm on the summer evening, I would put a sweatshirt or a jacket on, while others would still sit with short-sleeve T-shirt. I think you get the point, it's always colder for me.

To start practicing cold showers was a real challenge, as I love my shower super hot. However, my colleague was doing it for a long time and it came up in some discussions about health and wellness. As this person was fit and healthy, and also looked way younger than what was written in the passport, I gave it a chance.

What helped me start was really minimal temperature reductions at the beginning and short intervals of cold. But what convinced me to continue was my smart watch. One time after doing some cardio, I didn't stop the activity and went to the shower with the timer still ticking and parameters showing. And then I saw kind of a miracle. I noticed how my heart rate is going up after putting myself to cold. It was similar as if I was doing some high intensity training! When I decided to investigate it more and check the benefits that it may provide. And I continue to practice cold shower or contrast shower to date. I will share what I found about it as you continue to read this Nexus.

What Does Science Say?

What Happens to Our Body After a Cold Shower?

Cold showers, defined as water exposure at temperatures below 15°C (59°F), have been utilized for their energizing and therapeutic effects. Cold-water exposure, similarly as exercise and hypoxia, presents a significant physiological challenge to the body's organ systems. To preserve the temperature of the brain and core organs, the body must adapt to the cold environment through the precise regulation of heat production and heat loss mechanisms. The primary physiological effects of acute cold exposure on the human body are shown in the figure below (1).

Acute exposure to cold water triggers a series of physiological responses in the body, including peripheral vasoconstriction to conserve heat, an increase in metabolic rate to generate additional heat, and shivering to produce heat through muscle activity. The initial vasoconstriction (the narrowing, constriction of blood vessels) reduces blood flow to extremities, preserving core temperature. After a few minutes, a process called cold-induced vasodilation (the widening of blood vessels) occurs, cyclically increasing blood flow to the extremities to prevent tissue damage from excessive cooling. Additionally, cold exposure stimulates the release of stress hormones such as adrenaline and cortisol, enhancing alertness and potentially improving immune function.

The Mechanism Behind the Exposure to Cold Water and It's Benefits

Recent scientific inquiries have shed light on the potential benefits of cold exposure on health and longevity. There are several physiological mechanisms that can explain what happens to our body after the exposure to cold. This includes improved blood circulation, enhanced immune response, metabolic boost, hormetic stress (biological phenomenon where a beneficial effect results from exposure to low doses of an agent that is otherwise toxic or harmful at higher doses) and cellular resilience. During repeated exposure to cold stress, mechanisms of resistance are replaced by mechanisms of adaptation. The effects of cold water exposure to our body are nicely summarized in the figure below.

Cardiovascular and Metabolic Benefits

Cold exposure triggers vasoconstriction, reducing blood flow to the skin and extremities, which conserves core body heat. Upon rewarming, vasodilation occurs, enhancing blood flow and oxygen delivery to tissues. This cycle promotes cardiovascular health by improving vascular tone and reducing the risk of hypertension and cardiovascular diseases.

Cold exposure also triggers the metabolic boost and responses to hormetic stress. In a study by published in the Journal of Thermal Biology, the effects of cold adaptation on cardiovascular risk factors, thyroid hormones, and the ability to counteract oxidative stress were examined by comparing winter swimmers with a control group. The cold-adapted swimmers showed significant reductions in the ApoB/ApoA1 ratio, plasma homocysteine levels, GPX1 activity, and oxidative stress markers. They also exhibited increased levels of triiodothyronine (T3), PON-1 activity, and zinc concentration compared to the control group. These results suggest that regular cold water immersion can improve cardiovascular risk factors and enhance the body's capacity to mitigate oxidative stress, indicating a cardio-protective effect (2).

Activation of Immune Cells

Cold exposure has been shown to stimulate the production and activation of leukocytes, including natural killer cells, which play a crucial role in immune defence. Studies indicate that regular cold showers can increase lymphocyte count, bolstering the body's ability to ward off infections and potentially reducing the incidence of chronic inflammatory diseases.

A study published in PLoS One aimed to investigate the effect of cold showering on health and work. It included 3018 participants between 18 and 65 years without severe comorbidity and no routine experience of cold showering. They were randomized (1:1:1:1) to a (hot-to-) cold shower for 30, 60, 90 seconds or a control group during 30 consecutive days followed by 60 days of showering cold at their own discretion. A routine (hot-to-) cold shower resulted in a 29% reduction in sickness absence for (hot-to-) cold shower regimen compared to the control group (3).

Brown Adipose Tissue Activation and Obesity

Cold exposure activates brown adipose tissue (BAT), which generates heat through non-shivering thermogenesis (the process by which the body generates heat through metabolic reactions, primarily in response to a trigger, to maintain core body temperature). This process not only helps maintain body temperature but also enhances metabolic rate and insulin sensitivity, thereby potentially reducing the risk of obesity and type 2 diabetes.

Until quite recently, the presence of brown adipose tissue was thought to be relevant only in small mammals and infants, with negligible physiologic relevance in adult humans. A small study published in the New England Journal of Medicine has demonstrated that the brown adipose tissue activity was observed in 23 of the 24 subjects (96%) during cold exposure but not under thermoneutral conditions. The activity was significantly lower in the overweight or obese subjects than in the lean subjects. The study concluded that brown adipose tissue may be metabolically important, and the fact that it is reduced yet present in most overweight or obese subjects may make it a target for the treatment of obesity (4).

Can Exposure to Cold Water be Harmful?

A short answer is YES, definitely, but as always - it depends. While I focused on the potential health benefits of cold water immersion, it is important to also address the possible negative health effects. These risks are complex and influenced by factors such as age, general health, body composition, experience, water temperature, and immersion duration. Thus, if you have any medical condition or health issues, please consult with your physician and be wise before doing anything extreme.

Accidental immersion, such as falling overboard into very cold water, poses additional risks beyond recreational swimming. The most common risks include cardiorespiratory problems due to cold shock and the prevalent danger of hypothermia. The consequences of hypothermia can lead to both freezing and non-freezing cold injuries, though these are more typical in activities not involving water immersion (1). In the next paragraph I give you some tips on how not to harm yourself by diving into a cold shower.

Practical Tips for Incorporating Cold Shower Into Your Routine

Here are some practical tips from me on how to start with cold showers, not to do harm to your body and how to make it part of your routine:

Gradual Adaptation. As with anything related to your health and fitness - start small, don't be a hero, you need to get used to it and it's better for your body as well. Start with warm showers and gradually reduce the temperature over several weeks to acclimate your body to the cold.

Duration and Frequency. Aim for 2-3 minutes of cold exposure per shower. Begin with shorter durations (like 15-30 sec.) and progressively increase as your tolerance builds. Incorporate cold showers 3-4 times per week initially, and adjust based on personal comfort and health status.

Timing. Cold showers in the morning can provide a great start to the day by increasing alertness and energy levels. Alternatively, post-exercise cold showers can aid in muscle recovery and reduce inflammation. For me it was way easier to start incorporating cold showers after exercise, as the body is much warmer and it is easier to put it under clod conditions. It's also highly refreshing after sports. Mornings are hard for me, but when you get used to it, it is okay.

Breathing Techniques. Employ controlled breathing techniques to manage the initial shock and discomfort of cold exposure. Deep, slow breaths can help stabilise heart rate and reduce the sensation of cold. It's not a rocket science, just breathe deeply at the time of exposure to the cold.

Only when healthy. I never practice cold shower if I am not well, especially when I get flu or similar condition. As this is a short term stress to your body, don't give additional stress if it is already under one.

Listen to Your Body. Pay attention to your body's signals. If you experience excessive discomfort, dizziness, or prolonged shivering, end the cold exposure. As mentioned in the beginning of this section, don't try to be a hero or a champion in taking cold showers.

So are you ready to try the power of cold next time you go for a shower? Hope I managed to convinced you. At least from the energy boost perspective - it is worth a try! If you enjoyed this edition and already looking forward to reading my next Nexus article, make sure to subscribe, in order not to miss it! Will ping you again with the portion of healthspan and longevity advice in two weeks!