Whole-body cryotherapy - threats and benefits

The historical endorsements of the health advantages linked to cool water immersion, whether it be in a spa or the sea, trace back over centuries. Documentation as far back as 1750 advocated for sea swimming, and astonishingly, even the consumption of sea water, as treatments for various ailments. Recently, there's been a notable surge in individuals embracing open, cold water swims. Considering that certain risky bodily responses to cold water seem to reach their peak when submerged within the temperature of 15 to 10°C, it's logical to define cold water as anything below that range. Nerve blockages, for example, might arise following exposure to a temperature 5-15°C for a duration of 1 to 15 minutes, resulting in a dysfunction akin to peripheral paralysis.
An article featured in the Experimental Physiology journal concludes that cold water immersion (CWI) stands as a significant contributor to international fatalities. However, the positive impacts of CWI are noteworthy, spanning from improved performance under heat stress, post-exercise CWI aiding in recovery, to CWI serving as a potential treatment for inflammation-related ailments, while also fortifying the immune system. Each of these domains carries plausible explanations and theories, yet the overarching question remains intricate. The effects of CWI can oscillate between advantageous and harmful, contingent upon the delicate interplay of factors like the duration and intensity of exposure to cold water and the extent of hyperthermia.