Why is cold water exposure gaining popularity?

Jumping into a cold shower or tub full of icy water seems like a horrible way to start the day for many. But, the internet has done its thing recently and cold water exposure has blown up. Many people in influential positions, with big platforms and many eyes on them have been making many claims on this practice being good for health. But, is there science to support the claims? I’ve looked into some studies, the pros and cons, so you can better understand the reasoning and make up your own mind!

Cold water exposure is a form of immersion hydrotherapy. Hydrotherapy is not new, with examples including warm water baths, saunas, steam rooms, hot tubs, foot baths and more. People in Scandinavian countries have been practicing cold water swimming. There, it provides an opportunity to catch up with friends, socialise and get outdoors. During the pandemic and with the help of celebrities and social media influencers, cold water immersion has become a popular practice. The common claims I’ve come across are:

• It helps post-exercise recovery

• It helps improve alertness and attention

• It increases metabolism

• Improved sleep

• Lymphatic drainage increases

• Improves cardiovascular health

• Improve mental health conditions like depression and anxiety

• Boost the immune system

I’m sure I missed a few health claims, so if you have any I don’t cover, tell me in the comments section below!

What does the science say?

Brown fat

A study by Espeland et al., 2022 reviewed the body of studies into cold water immersion and looked into the health claims being made. One effect found from cold water swimming was related to increases in the amount of brown fat in the body. Our bodies have two different types of fat storage, white and brown. Infants have a higher brown to white ratio of fat stores, and as we grow, the amount of brown fat largely reduces. Brown fat has a darker colour because it’s more saturated with mitochondria (a cell’s energy source). The majority of fat in our bodies is called white fat, which stores energy. Our understanding of brown fat in humans is limited. From what we do know, brown fat has a main role, thermogenesis (creating heat) which uses energy. Increasing brown fat in the body is one of the body’s responses to cold exposure. Brown fat has also been found to have a role in reducing blood cholesterol levels, energy expenditure and blood glucose control. However, further study into the extent of the effect on health is required to make any sort of health claims. Is cold water immersion worth a little more brown fat? Well, considering that we’re talking about grams of fat with a general impact of using 20 calories per day, the effect is very small (Muzik et al).

Immune system

First thing first, lets get the wording right. You do not want to “boost” your immune system. Boosting an immune system means having an over-active immune system, which is detrimental to health.

The science behind cold water exposure on the immune system is unclear. Most of the studies look into cold water swimming and found those who experience cold water exposure have some differences in the amounts of immune system cells. Similarly, another study found cold water immersion impacts the type of immunity expressed (Brazaitis, M et al., 2014). However, clarity on what these differences mean to health and whether it is significant is not clear. Some studies have found no improved resistance in respiratory infections as a result of these differences while other studies have found that the impacts on the immune system have had cardio-protective effects and positive effects on the body’s ability tolerance to stress (Didrik Espeland et al., 2022). The lack of clarity means you will hear people cling to certain studies to make these claims. All in all, not enough good quality studies have been conducted to really substantiate these claims.

Recovery from exercise

The body of studies looking into the effect of cold water exposure to recovery is more substantial. The main findings conclude that it may not have negative effects on recovery for endurance athletes, but it may impair protein synthesis which may negatively affect strength-training athletes. Therefore, the use of cold water immersion will depend on individual goals. It is suggested by Andrew Huberman that doing cold water immersion within 4 hours of strength training should be avoided as it’s when it may impair muscle growth. However, his blog does not contain citations and I have not been able to find a study which indicates this. The main positive effect of cold water immersion is improved muscle soreness and perceived recovery (Moore, E et al., 2022).

My Conclusion:

Does the science support the claims? Eh. The science isn’t completely convincing, and the potential positive effects do not seem significant enough to begin telling the entire population to start incorporating this practice into their daily lives. The inconvenience of doing cold water immersion also needs to be taken into account. It’s another “thing” to do in an already wellness exploding society. Athletes and those with specific fitness goals need to know of the potential negative effects on their progress. Also, there are safety concerns. Done wrong, there is the potential for cold water shock. I’d say it’s not something that should be being proposed to the general population. I think the larger portion of the population would benefit from concentrating on improving their health through other ways like eating more nutrient-dense foods more often, moving their bodies more, building healthy relationships, stress management and getting enough good quality sleep. Considering there are potential positive effects for endurance athletes, they may wish to see if it works for them. At the end of the day, if you’re interested in it, then try it (do it safely!) If you see no benefit to youself, then there’s your answer. If you notice it helps you in some way, then there’s your answer. Weigh out the pros and cons for yourself and you decide. But please, don’t start parroting potential benefits to others like cold water immersion is the secret source to life.

References:

Brazaitis, M., Eimantas, N., Daniuseviciute, L., Mickeviciene, D., Steponaviciute, R., & Skurvydas, A. (2014). Two strategies for response to 14 °C cold-water immersion: is there a difference in the response of motor, cognitive, immune and stress markers?. PloS one, 9(9), e109020. https://doi.org/10.1371/journal.pone.0109020

Didrik Espeland, Louis de Weerd & James B. Mercer (2022) Health effects of voluntary exposure to cold water – a continuing subject of debate, International Journal of Circumpolar Health, 81:1, DOI: 10.1080/22423982.2022.2111789

Espeland, D., de Weerd, L. and Mercer, J.B. (2022) “Health effects of voluntary exposure to cold water – a continuing subject of debate,” International Journal of Circumpolar Health, 81(1). Available at: https://doi.org/10.1080/22423982.2022.2111789.

Moore, E., Fuller, J.T., Buckley, J.D. et al. Impact of Cold-Water Immersion Compared with Passive Recovery Following a Single Bout of Strenuous Exercise on Athletic Performance in Physically Active Participants: A Systematic Review with Meta-analysis and Meta-regression. Sports Med 52, 1667–1688 (2022). https://doi.org/10.1007/s40279-022-01644-9

Šrámek, P., Šimečková, M., Janský, L. et al. Human physiological responses to immersion into water of different temperatures. Eur J Appl Physiol 81, 436–442 (2000). https://doi.org/10.1007/s004210050065