What is a cold plunge?

Cold plunge goes by a couple of different names, in the scientific community it’s given the slightly stuffy title of Cold Water Immersion, for athletes it’s simply referred to as an ice bath. It usually consists of hopping into a cold tub or body of water usually up to the neck, and potentially dunking your head under as well if you are more focused on the health benefits side of the practice. Cold plunge has been used by athletes for decades to help with recovery and improve performance. In Scandinavian countries, like Norway and Finland, people enjoy (although that may be a strong adjective in this case) a similar ritual called winter swimming, which involves breaking the ice and taking a dip in a nearly frozen body of water as a way of improving one’s mood, and boosting one’s immune system.

We’ll take a look at these claims in the article below, explore their validity based on the current research, and speak to how cold plunge differs from cryotherapy, and contrast bathing and how it can be integrated to improve overall health and longevity. We’ll also examine the potential risks of cold plunge, determine who it is likely most beneficial for, and the specifics of when to do it, how cold the water should be, and how long to stay in for.

Get your parkas ready, this is going to be a chilly one folks.

The difference between cold plunge, cryotherapy, winter swimming, and contrast bathing.

Cold exposure is the big umbrella term under which cold plunge, cryotherapy, and winter swimming fall under. Cold plunge involves immersing oneself up to the neck in cold water, while cryotherapy rapidly cools the body through a room that is chilled to about -40℉ (-40℃) using liquid nitrogen. Lastly, there is winter swimming, which involves submerging oneself into near freezing water and often involves swimming (as the attentive reader may have inferred), although not always, and the distance and time spent in the water can vary greatly. All three of these practices increase circulating concentrations of stress hormones, which may improve your mood and burn more calories through increased brown fat activation. Since winter swimming also incorporates physical activity, which can work through other pathways, it makes it challenging to discern which benefits are from the cold water, and which are from exercise. In a perfect world there would be ample research on all 3, but at the moment, the largest body of research is on winter swimming so much of the proposed benefits in this article will be citing research papers that speak to this practice, so as always, take these benefits with a grain of salt.

Lastly, in some of the studies discussed below, winter swimming was performed in conjunction with traditional Finnish sauna bathing, in which one rapidly transitions from the cold water to the heat of the sauna, which is typically set to around 176-212℉ (80-100℃). This practice is sometimes referred to as contrast bathing, although this term can also mean going from cold water to hot water, instead of a sauna. Contrasting likely has some unique benefits that differentiate it from cold plunge [37].

Truly lastly, the information in this article is not meant to be a recommendation of any kind, and you should consult your doctor before integrating any sort of cold exposure routine into your health and wellness practice since there are some associated risks. With the disclaimers out of the way, let’s plunge into it!

6 Benefits of cold plunge

1. Decreased muscle soreness

As was mentioned before, taking ice baths has been commonplace for athletes for decades, and research has shown that it can decrease perceived delayed onset muscle soreness (DOMS) which is most often felt 1-2 days after a hard workout [1,2,3,4,5]

2. May improve short term recovery

There is research that suggests that cold water immersion after an exercise session slows the deoxygenation of muscles if a second exercise session is performed shortly afterwards, although in this study cold plunge did not have a significant effect on muscle performance, even though it slowed muscle deoxygenation [4]. Cold water immersion has also been shown to decrease inflammatory markers like Interleukin-6, C-reactive protein, as well as circulating Creatine Kinase levels, the last a marker of muscular stress, and cold water immersion may also help to get rid of lactate, one of the molecules responsible for “the burn” you feel when you push yourself to high number of reps in the weightroom, or to a new personal record in a 5k [1,3,5,8].

Taken in conjunction, these studies suggest that cold water immersion may help promote short term recovery on a cellular level [3,8]. That being said, studies are mixed as to whether or not cold water immersion actually enhances recovery or performance on a macro level [4,9]. It seems likely that cold water immersion may enhance recovery between athletic events, or endurance sessions if there is a short (less than 24 hour) amount of time between events [5,8]. So if you’re a weekend warrior with 3 soccer games in a single Saturday, your body may appreciate taking a cold plunge in between games to help promote recovery.

It should be noted however, research suggests that while cold water immersion may expedite short term recovery for some performance measures, it likely diminishes the hypertrophic response which signals to the body to build muscle.

3. Burn more calories

Cold environments cause a release in Norepinephrine which stimulates Brown Adipose Tissue, more commonly known as Brown Fat [13]. This is a special type of fat that is found in the neck, and upper back, as well around certain organs in the body [20]. Brown Fat helps keep these areas warm by burning fatty acids and carbohydrates [21]. Hopping in a cold plunge activates Brown Fat, and also causes a “beig-ing” of White Fat if done regularly, meaning that even the traditional fat found throughout the body begins to exhibit Brown Fat characteristics, like burning more calories than it normally would [22].

In addition to Brown Fat activation, cold exposure also results in skeletal thermogenesis (shivering) to help warm the body back up which requires calorie expenditure [18]. These two mechanisms, shivering, and Brown Fat activation, are the two primary ways in which cold exposure helps the body burn more calories than it would otherwise [18].

4. May improve immunity

Research has shown that Cold Water Immersion increases the level of Reactive Oxygen Species (ROS) [16]. While Reactive Oxygen Species can be harmful to the cells in our body, just like with exercise, small doses of Reactive Oxygen Species can actually improve the body’s ability to handle this kind of stress by increasing the number of natural antioxidants circulating at any given time, which may improve immunity and possibly decrease the chances of getting sick [16,17].

Additionally, cold exposure has been shown to increase the circulation of white blood cells that are important for fighting off infection and sickness [35].

5. May be a potential treatment for Type 2 Diabetes

This use of carbohydrates as a fuel source for Brown Fat helps to better regulate the body’s blood sugar by increasing its sensitivity to insulin, a hormone released in response to increases in blood sugar. If the body builds up a resistance to insulin, it can lead to Type 2 diabetes, thus cold plunge may be an effective way to help manage Type 2 Diabetes by helping the body increase its sensitivity to insulin, which allows it to more effectively manage blood sugar [18,19,23].

6. May improve mood

Hopping into cold water is certainly a shock to the system, and while most people find it rather unpleasant in the moment, there is some research suggesting that it can increase our feelings of vigor and esteem, which in layman’s terms mean that you generally feel better [36], however research on this specific topic is limited, and further research is needed to fully determine what effect, if any, cold exposure may have on mood.

How much of my body should I submerge when cold plunging?

Submerge your entire body up to your neck, and dunk your head underwater as well since this will likely create an even more powerful hormonal response.

How long should you stay in a cold plunge for?

A typical cold plunge lasts around 1-5 minutes [24]. The general rule of thumb is the colder the water the shorter the cold plunge should be.

How cold should a cold plunge be?

An ice bath or cold plunge is typically around 40-59℉ (5-15℃), although it can be just be just above freezing [24].

How often should you cold plunge?

2-3 times per week.

While there is no standard protocol to how frequently you should cold plunge, 2-3 times per week is a common practice [25].

When should you cold plunge?

In the morning.

Again, there is little research on when exactly is the most beneficial time to cold plunge, but since cortisol is naturally elevated in the morning, most people tend to start their day with a cold plunge [25], furthermore, since our core temperature decreases as we slip into sleep, it’s possible that cold plunge could negatively affect our sleep since cold exposure increases body temperature through Brown Fat activation [21].

Can I take a hot shower after a cold plunge?

Allow your body to naturally warm up after cold exposure.

Unless you are specifically doing contrast bathing [37], where you alternate between cold and warm water, you should allow your body to naturally warm up on its own after cold exposure since many of the Brown Fat activation benefits, like helping to regulate blood sugar and burning more calories, only occur when the body is trying to warm itself back up after a cold exposure .

Potential risks of cold plunge

1. Hypothermia

an obvious risk of cold plunge is hypothermia if you are not careful about how long you stay in the water for [26].

2. Cardiac event

cold plunge may cause arrhythmias of the heart which could potentially lead to a cardiac event [26].

3. Decreased muscle strength and muscle size

There is research that suggests that ice baths and cold plunge may have a negative impact on muscle strength and size, especially if done after training [1,12,27,29,30,31]. This likely occurs because cold exposure decreases the body’s natural inflammatory response [29]. While this may sound like a good thing, the goal of training is to stress the body enough that it has to adapt so that the next time it encounters this kind of stress, it’s better able to handle it. Cold plunge decreases this stress, meaning That the body doesn’t have to adapt as much, likely decreasing the benefits you are getting from your training sessions. Furthermore, cold plunge has also been shown to decrease amino acid uptake which could impact the recovery and repair of the damaged muscle fibers [31].

So if you’re looking to increase strength and muscle mass while still getting the health benefits of cold plunge, it’s probably a good idea to ice bath on a separate day or in the morning if you plan to train in the afternoon, so that the cold exposure does not negatively affect the training stimulus or your protein uptake.

4. Potentially decreases cognitive performance

while there has been a lot of talk on the internet of the benefits of ice baths on cognitive performance, current research actually suggests the opposite, with a 2021 meta-analysis concluding that cold exposure impairs cognitive performance, especially processing speed, and executive function [33]. Cold exposure also seems to negatively affect attention and memory, but there are conflicting results in this domain and further research is needed to draw firm conclusions. Only 1 of the 18 studies included in this meta-analysis showed an improvement in cognitive performance from cold exposure, with the other 17 showing a negative impact, or no impact on cognitive performance [33].

5. Pulmonary Edema

hopping into cold water causes an increase in blood flow to the lungs [34], especially when mixed with exercise, which can sometimes result in the capillaries in the lungs leaking fluid [34]. While pulmonary edemas can be fatal, in most cases of cold water swimming, patients recover quickly without a recurrence of symptoms [34].

Summary

Cold plunge is a practice in which you submerge your body up to your neck (even dunking your head if you can work up the courage) in cold water that’s about 40-59℉ (5-15℃), for up to 5 minutes, 2-3 times per week, while allowing your body to warm up naturally afterwards.

The 6 most notable benefits of cold plunge are the following:

Decreased muscle soreness
Improved short term recovery
Burn more calories
May improve immunity
Potential treatment for Type 2 Diabetes
May improve mood

The 5 biggest risks and drawbacks of cold plunges:

Hypothermia
Cardiac event
Decreased gains in muscle strength and size
Potential decrease in cognitive performance
Pulmonary edema

In conclusion, there are benefits to integrating cold plunge into your health and wellness routine, but it’s important to consult with a doctor to determine if the benefits outweigh the risks and the specific protocol that is right for you.

Stay cool my friends,

John

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