The Cold Hard Facts | Part 2
The second installment of an exploration of the science behind cold water immersion therapy
Context
In last week’s article, part 1 of this short series, we explored some of the physiological processes underlying the effects of cold exposure, specifically in relation to Mental State and Metabolism.
Today, in part 2 of the series, we will focus on the effects of cold exposure on the immune system and the role of the breathe within this context.
Note: The use of “cold exposure” in this article is specifically referring to short-duration, intense cold water immersion. This differs from longer duration exposure to mild/cold temperatures, which is believed to increase risks of illness, particularly upper respiratory infections (aka why one of the most common infectious diseases, viral rhinitis, is known as the “common cold”).
Cold Immersion, T-Cells, and NK Cells
Cold water immersion has been reported to increase the level of T-cells (specifically, peripheral T lymphocytes). This has been observed both (1) in the short term after a single treatment/swim, as well as (2) in a longer, sustained manner after a period of multiple treatments per week.
T-cells, also known as T lymphocytes, are a type of white blood cell that are derived from bone marrow stem cells and mature in the thymus gland. They play an essential role in fighting off infection. With an ability to “recognize” and “remember” germs that they have seen before, they can quickly respond if they see that germ again.
In other studies, similar increases have been observed for NK (Natural killer) cells. NK cell activity has been observed to increase both briefly after a treatment and in a sustained manner following consistent and repeated immersions.
Natural killer (NK) cells are a type of white blood cell that can quickly recognize and destroy infected or cancerous cells without prior exposure or activation. NK cells do not require prior exposure to antigens, which are proteins or other molecules that can trigger an immune response. Instead, they use a variety of receptors to detect abnormal cells and then release toxic substances to kill them.
Cold Immersion & Cancer
Although the science is still developing, there is reason to believe cold water immersion may help prevent the risk of tumors and cancers.
In a study done on lab mice, a “somewhat reduced spontaneous incidence of tumors, especially sarcomas” was observed among the group of mice that endured repeated cold stress (cold swims). It has also been reported that Cold-inducible RNA binding protein (CIRP) may function as a tumor suppressor via suppressing proliferation. Finally, there’s been a clinical review performed by the National Institute of Health (NIH) exploring the cold’s ability to stimulate “anti-tumor immunity”, which concluded this area deserves “more research as a major target for cancer therapies.”
We look forward to the progression of this research.
The Role of the Breath
Western biomedical research is gradually discovering the significance of the way in which we breathe, in relation to the body and its many physiological processes. Among these discoveries are how deliberate breathing techniques can 1) increase our tolerance to extremely cold environments and 2) alter immune function in real time.
Let me highlight the significance of these discoveries: For centuries, modern (Western) medicine considered these processes (circulatory system, immune system, sympathetic nervous system) autonomic or involuntary, meaning they are unable to be controlled consciously. Recent research has slipped this understanding upside down - essentially, deliberate breathing practice is a superpower.
There is *incredible* research on breathing methods/techniques beyond the scope of this article, spanning brain function, enlightened & hallucinogenic states, mood/emotion control, and more. We encourage you to explore it if you’re interested, and we hope to come back to the topic in a future article/series.
The first groundbreaking study was done on Wim “The Ice Man” Hof, himself. In 2011, researchers at Radboud University injected Wim Hof with endotoxin, a treated form of bacteria that triggers a general immune response, as Wim practiced his breathing technique. The results were astounding:
“…levels of inflammatory mediators in Hof's blood were much lower. On average, Hof's immune response was decreased by 50 percent compared to other healthy volunteers. In addition, hardly any flu-like symptoms were observed.”
At first, this study was a target of skepticism. With a sample size of 1, it was unclear whether the results were reproducible or simply Wim Hof producing an outlier result as an individual. However, it was enough to encourage further exploration.
In 2014, a study published in the National Library of Medicine sought out to reproduce the 2011 results in average “healthy participants”. The intervention group was trained for just 10 minutes in Hof’s breathing technique, and then both groups were administered with the endotoxin.
“In the intervention group, practicing the learned techniques resulted in intermittent respiratory alkalosis and hypoxia resulting in profoundly increased plasma epinephrine levels. In the intervention group, plasma levels of the anti-inflammatory cytokine IL-10 increased more rapidly after endotoxin administration, correlated strongly with preceding epinephrine levels, and were higher. Levels of proinflammatory mediators TNF-α, IL-6, and IL-8 were lower in the intervention group and correlated negatively with IL-10 levels. Finally, flu-like symptoms were lower in the intervention group.”
In summary, the results were successfully reproduced, and the researchers concluded that it is possible to voluntarily activate the sympathetic nervous system and affect immune response through deliberate breathing technique.
Hof’s breathing technique shook the biomedical science industry again in 2018, this time after he showed humans can consciously enhance their ability to survive in extremely cold conditions (beyond what was previously thought possible). The study concluded that deliberate breathing technique resulted in “increased sympathetic innervation and glucose consumption in intercostal muscle, generating heat that dissipates to lung tissue and warms circulating blood in the pulmonary capillaries.”
Conclusion
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Stayed tuned for part 3 next week.