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  • AutorenbildMichael Mutter

Ice bathing, holotropic breathing and the Wim Hof method - beneficial for diving?

Aktualisiert: 15. Feb.

Ice bathing is very trendy and courses in breathing techniques are popping up like mould. The hype doesn't stop at the dekoblog either. Readers wanted to know whether ice bathing, the Wim Hof method and holotropic breathing have benefits for diving. In the first part, I would like to shed some light on ice bathing.


Worth seeing. The Ice Dive on Netflix.


A long tradition

In northern countries, ice bathing has a long tradition and is practised under various terms such as ice swimming, winter swimming or cold swimming. In general, there is a distinction between swimming in ice water with temperatures from -2 to +2°C, ice-cold water from +2.1 to 5°C and cold water from +5.1 to +9°C. This article provides an overview of the effects of ice bathing without making clear distinctions between the terms and makes no claim to be complete.


Personally, I have little doubt that regular, moderate exposure to cold has a favourable effect on health and well-being. But what does science say?


Short-term risk...

Immersion in cold water initially harbours risks, as it triggers two different autonomic reactions: the cold shock reaction and the diving reflex. The latter, triggered by the moistening and cooling of the face and nostrils, leads to a slow pulse (sinus bradycardia), peripheral vasoconstriction (narrowing of the peripheral vessels) to divert blood to vital organs and cessation of breathing. Conversely, the cold shock reaction, triggered by cold receptors in the skin, leads to a rapid pulse (tachycardia), gasping for air, hyperventilation and high blood pressure. It is now recognised that this so-called autonomic conflict contributes to cardiac arrhythmia and is one of the causes of silent drowning syndrome when swimming in or jumping into cold water. An ice bath is therefore an immediate cardiovascular risk and cardiac patients should exercise caution in this regard.


... with long-term benefits

Similar to the sports paradox, which states that the mortality during exercise is increased in the short term, but (endurance) sport leads to a lower mortality in the long term, regular ice bathing appears to have favourable effects, provided it is practised within reasonable limits.


It has a favourable effect on cardiovascular risk markers in the blood related to atherosclerosis ( calcification of the arteries) and thrombus formation (clots), which indicates a cardioprotective effect. Exposure to cold increases blood pressure acutely, but regular ice bathing does not appear to increase it sustainably and does not lead to high blood pressure. In addition, regular ice bathing significantly reduces the cold shock response.


If the peripheral vasoconstriction is not sufficient to keep the body temperature constant, continuous, asynchronous muscle contractions, which we know as shivering, set in from a core body temperature of just over 36°C. This is known as chills. It increases the metabolic basal rate up to fivefold and therefore generates less energy than active exercise, but is more effective in cold water, as less heat is lost through convection when keeping still.


Adaptation of heat generation

In addition to this form of heat generation (thermogenesis), there is another: that of brown adipose tissue, which plays an important role as a heat supplier in newborns. Its function in adults is controversial due to its small residual quantity. However, there is increasing evidence that white adipose tissue can partially take on the function of brown adipose tissue under regular exposure to cold. Winter swimmers have a higher level of thermogenesis, which causes shivering to set in with a delay of up to 40 minutes compared to non-winter-swimmers. Adaptation therefore appears to be considerable, and regular ice bathers feel more comfortable in cold water.


However, the effect on comfort only seems to last if one is regularly exposed to cold water. After a few cold baths, the body quickly becomes acclimatised to the cold, which lasts for a few weeks, but without permanent adaptation. A study of Korean female pearl divers, the ama, showed that even veteran divers slowly lost their comfort in the cold as soon as they switched from traditional cotton diving clothing to better insulating neoprene suits.


Exposure to cold also affects the hormone system, for example by upregulating adiponectin, a key adipose tissue protein that protects against diabetes and atherosclerosis.


Good vibes hormones

Although winter swimming is an enormous stress factor, many people practise it as an enjoyable leisure activity. Acute exposure to cold causes the adrenal medulla to release catecholamines, stress hormones, every time, even during regular ice baths. Their effect in the blood and the secretion of noradrenaline in the synapses of the brain in interaction with other neurotransmitters such as beta-endorphin and dopamine, also known as happiness hormones, which are triggered by the very strong cold stimulus from the periphery, directly affect the limbic system, where emotions are processed and generated. This is the basis for the hypothesis that cold water triggers an "adrenalin kick" and has an antidepressant effect. In fact, regular winter swimmers feel in a better mood and more energised. Ice baths appear to have a positive effect on tiredness, listlessness, pain and the well-being of people with chronic rheumatic diseases.


Inhibition of inflammation

In addition to catecholamines, other stress hormones such as cortisol and ACTH as well as various tissue hormones are released in cold water, which act as powerful anti-inflammatory agents. The direct, favourable effect on the immune system is also well documented, although it is an open question whether moderate winter swimmers actually suffer less frequently from respiratory tract infections than the average person.


Ice baths have become an integral part of regeneration measures in competitive sport. Their effect on recovery is well supported by sports medicine, whereby the mechanism is also largely based on the favourable modulation of repair and inflammation processes.


Possible hazards

The main danger here is acute cardiovascular stress due to the cold shock reaction and diving reflex. Acute exposure also leads to constriction of the coronary arteries with the risk of reduced blood flow to the heart muscle. This may result in heart attacks (angina pectoris), pumping dysfunction and arrhythmia. In addition, SIPE (swimming induced pulmonary edema) appears to occur more frequently in cold water. Coughing, shortness of breath and spitting up blood after swimming should always be considered as SIPE. It is not surprising that excessive cold swimming leads to increased respiratory infections, especially with prolonged chills during and after swimming. In this context, it should be borne in mind that inhaling cold air and the cooling of the body surface lead to a narrowing of the bronchi and increased vasoconstriction with reduced blood flow to the nasal mucosa, impairing the local immune defence and favouring infections.


Benefits for diving?

Part of the favourable effect disappears if one is not regularly exposed to cold water. It is difficult to derive a direct benefit for diving. A friend reports that although he feels healthier and fitter since he regularly swims in cold water, he still feels just as chilly when scuba diving without heating. It is not possible to scientifically determine specific effects for diving beyond the general improvement in health.


Conclusion

Regular bathing in cold water may have a positive effect on various areas such as the cardiovascular system, hormones, the immune system, the inflammatory cascade and mental health. At the same time, however, it can also pose a health risk. This is particularly true for people with cardiovascular problems. To make the most of the benefits of cold water swimming, a gradual acclimatisation programme is recommended. A few minutes of cold water swimming is likely to be all it takes to have a positive effect. Whether bathing in "ice-cold" or only "cold" water probably does not play a significant role either. Ultimately, as always, it seems to be a question of judgement as to whether the benefits outweigh the harms.

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