We did our research and found numerous studies proving that cold water is one of the best health hacks that can be incorporated into your daily life with a minimum effort and no cost!
Mindset and energy levels
Taking a cold shower or jumping in a cold ocean, lake or river every morning is probably the simplest health hack. A regular cold plunge will stimulate the vagus nerve, the largest nerve in our body that connects the brain and the gut. Vagus nerve stimulation can improve mood, digestion and sleep, and decrease stress and inflammation levels.
When you first get into the cold water, your sympathetic system gets activated, which triggers the release of epinephrine/adrenaline, thus making you more alert and efficient in fighting infections. Once you acclimatise, your parasympathetic system kicks in (aka vagus nerve).
In a nutshell, cold water in the morning makes you alert but calm if you practice calming your mind down while in the shower and staying long and often enough to acclimatise. It also increases your mental and physical resilience.1
Cold exposure might be one of the best anti-ageing and longevity methods alongside exercise and fasting as it increases mitochondria and improves mitochondrial function. We need mitochondria to produce energy in cells, and this function declines with ageing or with poor lifestyle habits. The degradation of mitochondria also inactivates the brown fat and turns beige fat into white fat.2
Cold exposure affects thyroid hormones and increases brown and beige fat, which are metabolically active tissues that can help you get lean. Active brown/beige fat upturns energy expenditure, and it's also associated with reducing blood sugar and blood cholesterol levels. Its degeneration and inactivation have been linked to obesity and ageing. Some studies concluded that even daily facial cooling increased fat loss!
Numerous studies indicated that regular exercise in the cold increases fat metabolism. The reasons include a cold-induced release of ketones and increased metabolic rate, decreased circulating insulin levels, and increased release of dopamine, epinephrine (adrenaline), and norepinephrine.3
Inflammation and post-training recovery
Cold exposure improves circulation and reduces inflammation (that's why it's great after a long run). If you love ice baths and cold water exposure for post-training recovery, be aware that it can diminish your strength gains. Cold-water exposure is beneficial after endurance training (i.e. long run) as it reduces inflammation. But you need the inflammation to grow. The best recovery method conducive to muscle hypertrophy is sauna straight after your strength training session.4
Research indicates that cold-water immersion before endurance events in hot and humid environments can enhance performance. This so-called pre-cooling prolongs the time to exhaustion as it delays the onset of overheating. This only works for shorter endurance events that don't require many neuromotor skills. Don't try this before lifting weights or before engaging in complicated movements performed at high speed.5
Cold exposure can potentially relieve depressive symptoms because it stimulates peripheral nerve endings to the brain and causes the release of endorphins, adrenaline and dopamine. A study hypothesised that open water swimming is therapeutic not only due to the cold exposure but also because of the sense of achievement (i.e. overcoming the cold) and the blue and green therapy associated with open water swimming.6
Cold exposure boosts our immune system as it causes epinephrine release, which, in the short term (1-4 days), makes our body more efficient in fighting infection. Any short-term stress that causes epinephrine release will have this effect, i.e. high-intensity exercise.7
Cold-water exposure is a stress to the body. Your legs get stronger if you stress them by doing heavy squats, and your heart gets stronger if you expose yourself to extreme cold or heat. This applies to healthy individuals, and if you suffer any cardiovascular illness or disorder, you should always consult with your doctor first. Doing heavy squats with a broken leg wouldn't be a great idea either.
Cold exposure makes your heart stronger, increases heart rate variability and lowers heart rate, which is what happens when you engage in regular endurance training such as running.8
- Mäkinen, T. M., Mäntysaari, M., Pääkkönen, T., Jokelainen, J., Palinkas, L. A., Hassi, J., Leppäluoto, J., Tahvanainen, K., & Rintamäki, H. (2008). Autonomic nervous function during whole-body cold exposure before and after cold acclimation. Aviation, space, and environmental medicine, 79(9), 875–882. https://doi.org/10.3357/asem.2235.2008
Cairó, M., & Villarroya, J. (2020). The role of autophagy in brown and beige adipose tissue plasticity. Journal of physiology and biochemistry, 76(2), 213–226. https://doi.org/10.1007/s13105-019-00708-1
Chung, N., Park, J., & Lim, K. (2017). The effects of exercise and cold exposure on mitochondrial biogenesis in skeletal muscle and white adipose tissue. Journal of exercise nutrition & Biochemistry, 21(2), 39–47. https://doi.org/10.20463/jenb.2017.0020
Lettieri-Barbato, D., & Aquilano, K. (2020). Aging and Immunometabolic Adaptations to Thermogenesis. Ageing research reviews, 63, 101143. https://doi.org/10.1016/j.arr.2020.101143
Kovaničová, Z., Kurdiová, T., Baláž, M., Štefanička, P., Varga, L., Kulterer, O. C., Betz, M. J., Haug, A. R., Burger, I. A., Kiefer, F. W., Wolfrum, C., Ukropcová, B., & Ukropec, J. (2020). Cold Exposure Distinctively Modulates Parathyroid and Thyroid Hormones in Cold-Acclimatized and Non-Acclimatized Humans. Endocrinology, 161(7), bqaa051. https://doi.org/10.1210/endocr/bqaa051
Shephard R. J. (1993). Metabolic adaptations to exercise in the cold. An update. Sports medicine (Auckland, N.Z.), 16(4), 266–289. https://doi.org/10.2165/00007256-199316040-00005
Stanley, L. (2020). Recovery Methods for Endurance Athletes. NSCA, 7(2), 30. https://www.nsca.com/globalassets/education/nsca-coach/nsca-coach-7.2.pdf#page=30
Poppendieck, W., Wegmann, M., Hecksteden, A., Darup, A., Schimpchen, J., Skorski, S., Ferrauti, A., Kellmann, M., Pfeiffer, M., & Meyer, T. (2020). Does Cold-Water Immersion After Strength Training Attenuate Training Adaptation?. International journal of sports physiology and performance, 16(2), 304–310. https://doi.org/10.1123/ijspp.2019-0965
Tipton, M.J., Collier, N., Massey, H., Corbett, J. and Harper, M. (2017), Coldwater immersion: kill or cure?. Exp Physiol, 102: 1335-1355. https://doi.org/10.1113/EP086283
Shevchuk N. A. (2008). Adapted cold shower as a potential treatment for depression. Medical hypotheses, 70(5), 995–1001. https://doi.org/10.1016/j.mehy.2007.04.052
Van Tulleken, C., Tipton, M., Massey, H., & Harper, C. M. (2018). Open water swimming as a treatment for major depressive disorder. BMJ case reports, 2018, bcr2018225007. https://doi.org/10.1136/bcr-2018-225007
Kox, M., van Eijk, L. T., Zwaag, J., van den Wildenberg, J., Sweep, F. C., van der Hoeven, J. G., & Pickkers, P. (2014). Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans. Proceedings of the National Academy of Sciences of the United States of America, 111(20), 7379–7384. https://doi.org/10.1073/pnas.1322174111
- Jungmann, M., Vencatachellum, S., Van Ryckeghem, D., & Vögele, C. (2018). Effects of Cold Stimulation on Cardiac-Vagal Activation in Healthy Participants: Randomized Controlled Trial. JMIR formative research, 2(2), e10257. https://doi.org/10.2196/10257