You may have recently heard about people using cold therapies to promote wellness with the cold space expanding their reach with different types of cold exposure therapies, such as the Wim Hof Method and cryotherapy (2)(8). There is a wide range of treatments that would qualify as cold exposure therapies. The simple idea behind them all is that a small amount of stress can strengthen the body over time. In the fields of biology and medicine, the rationale for these therapies is related to the phenomenon of hormesis (4). Hormesis is defined as an adaptive response of cells and organisms to moderate normally intermittent stress, whereby small amounts of a harmful agent can be beneficial for health (4). The mechanism is still not fully understood, but the theory is that in a multicellular organism, triggering one recovery mechanism also improves the functioning of other repair and recovery systems (7).
So now that we have a little more understanding of the science lets go back in time to get a better picture of why this makes sense. We, humans, are homeotherms meaning that we can maintain a constant core temperature of approximately 36.6C thanks to the hypothalamus (6). Actual utilisation of this sophisticated regulatory system is very low in modern life compared to when we lived a mostly out-door lifestyle and exposed to varying ambient temperatures (3). For most of our time on this planet, we didn’t have the luxuries of heated or air-conditioned homes or winter clothing. This rapid disappearance of thermal stress from our lifestyles compared to its presence in primates for millions of years before could be causing negative effects on our health because the thermoregulatory system and our brains are not getting enough exercise (6)(3).
Back to modern times and to counteract all the hard work we have done to build safe and warm shelters! We have to simulate the physiological stress we were accustomed to by having a cold shower to activate the sympathetic nervous system, which is responsible for priming our body for action (1). This physiological stress may have the hormesis effect we talked about earlier by forcing the body to recover normal core temperature after the cold exposure giving the indirect beneficial effects on all systems and organs including the central nervous system (5).
So, what are the purported benefits of cold therapies? There is some evidence that cold exposure using cryotherapy may help with inflammation and muscle soreness, but the research is not conclusive (8). Studies do show that cold exposure can activate your immune system and may help keep the common cold away (10). But perhaps one of the most interesting benefits users of cold therapies talk about is the overall sense of wellbeing and feeling better mentally. How can having a cold shower make you feel good?! This is related to the activation of the sympathetic nervous system which increases the blood level of noradrenaline (norepinephrine) which along a host of physiological effects priming us for action also mentally manifests in alertness, arousal, and overall readiness (9). Cold exposure has also been shown to induce the production of the neurotransmitter beta-endorphin responsible for producing the sense of well-being and suppression of pain (2).
What do you think of cold therapies? I would love to know about your experiences and what you think?
1. Acosta, F, Martínez-Téllez, B, Sánchez-Delgado, G, Alcántara, J, Acosta-Manzano, P, Morales-Artacho, A, et al. Correction: Physiological responses to acute cold exposure in young lean men. PLOS ONE13: e0200865, 2018.
2. Allen, JJ. Characteristics of Users and Reported Effects of the Wim Hof Method : A Mixed-Methods Study. , 2018.Available from: http://essay.utwente.nl/76839/
3. Daanen, HAM and Van Marken Lichtenbelt, WD. Human whole body cold adaptation. Temperature 3: 104–118, 2016.
4. Mattson, MP. Hormesis defined. Ageing Res Rev 7: 1–7, 2008.
5. Muzik, O, Reilly, KT, and Diwadkar, VA. “Brain over body”–A study on the willful regulation of autonomic function during cold exposure. NeuroImage 172: 632–641, 2018.
6. Pääkkönen, T and Leppäluoto, J. Cold exposure and hormonal secretion: A review. Int J Circumpolar Health 61: 265–276, 2002.
7. Radak, Z, Chung, HY, Koltai, E, Taylor, AW, and Goto, S. Exercise, oxidative stress and hormesis. Ageing Res Rev 7: 34–42, 2008.
8. Rose, C, Edwards, KM, Siegler, J, Graham, K, and Caillaud, C. Whole-body Cryotherapy as a Recovery Technique after Exercise: A Review of the Literature. Int J Sports Med 38: 1049–1060, 2017.
9. Shevchuk, NA. Adapted cold shower as a potential treatment for depression. Med Hypotheses 70: 995–1001, 2008.
10. Van Middendorp, H, Kox, M, Pickkers, P, and Evers, AWM. The role of outcome expectancies for a training program consisting of meditation, breathing exercises, and cold exposure on the response to endotoxin administration: a proof-of-principle study. Clin Rheumatol 35: 1081–1085, 2016.