Cold water immersion (deliberate cold exposure)

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Views & opinions are personal, and do not necessarily reflect Swiss Re's.

Cold water immersion: This is my new thing. I started having cold showers in 2021 after reading Dopamine Nation by Anna Lembke. The idea that by stressing the body and causing "pain" or discomfort, the body responds by releasing chemicals and hormones to help deal with that - endogenous dopamine. And the author, a psychiatrist, describes cases of how cold water immersion really helped some people, in particular a man who had a significant cocaine addiction but couldn't give it up. I had also read of the beneficial autonomic nervous system effects cold water immersion can have.

But then, after speaking to Beat Strebel in South Africa last September, and hearing the benefits he and his wife experienced by spending 20 minutes every morning in the very cold Atlantic Ocean at Camps Bay in Cape Town for an entire year, it motivated me from progress from simply having regular cold showers to "next level" stuff (for me anyway). I swam in the Camps Bay tidal pool that trip which was about 13 degrees Celsius, and then when I got home to Zurich made sure to keep the little pool we have outside going (we normally take it down in winter).

Most days my wife and I immerse ourselves up to our necks in water which varies between 0.7 degrees (coldest, with a couple of inches of ice on top we have to break through - not easy!) to about 5 degrees. We try to spend 5 to 10 minutes in the water with some practiced breathing techniques (cf. Wim Hof aka "The Iceman" Welcome to the Official Wim Hof Method Website).

Initially I had warm showers after immersion but then read that there is real benefit in your body reheating itself rather than being externally heated, so changed tack. Now its out of the pool, drying off (feeling nothing as one's body numb for a few minutes), and then putting on many layers of clothing and suddenly feeling VERY cold a few minutes later. And this can last a hour or more depending on duration, water temperature and I guess practice/acclimatization. (Its why I might look cold and have many layers on during morning video calls!)

Theory is the blood starts circulating back to the surface layers, cools down, and then the body realizes that one's core temperature might drop a little. That necessary creation of heat drives behaviour change of fat cells. White fat (usually just stores and releases fat) starts behaving like brown fat (which while also storing and releasing fat, actually metabolizes fat creating heat, even when not really needed). Its good to have brown fat! In essence wasting energy. Not a bad thing if one is in a food abundant rather than a food scarcity world.

Benefits I have read about include positive mental health effects, increased immunity, weight loss, lower heart rate, lower blood pressure (last 2 related to the autonomic nervous system modulation). It really gives me a mental boost, and my BP is lower than ever. But is this all placebo effect? It seems not.

A study from Czech republic randomly dividing army recruits into those that do and those that do not cold immerse. Impact of cold exposure on life satisfaction and physical composition of soldiers | BMJ Military Health

49 (male and female) Czech soldiers (19–30 yrs) were randomly assigned to one of the two groups (intervention and control). The intervention group regularly underwent cold exposure for 8 weeks, in outdoor and indoor environments.?

• considerable increase (6.3% compared with the pre-exposure period) was observed in self-perceived health satisfaction
• in men, there was a reduction in waist circumference (1.3%, p=0.029) and abdominal fat (5.5%, p=0.042)
• significantly lowered perceived anxiety in the entire test group
• (and weirdly... ?significant increase of 6.2% in self-perceived sexual satisfaction compared with the pre-exposure measurements)

This paper shows increased thermogenesis in cold water swimmers: Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men: Cell Reports Medicine

It concludes with :

"...?propose winter swimming as a potential strategy for increasing energy expenditure."

And if you are really interested, have a look at this Using Deliberate Cold Exposure for Health and Performance - Huberman Lab