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Table of Contents
- What is a cold plunge?
- The difference between cold plunge, cryotherapy, winter swimming, and contrast bathing.
- How much of my body should I submerge when cold plunging?
- How long should you stay in a cold plunge for?
- How cold should a cold plunge be?
- How often should you cold plunge?
- When should you cold plunge?
- Can I take a hot shower after a cold plunge?
- Potential risks of cold plunge
- Summary
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
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
[1] An Evidence-based approach for choosing post-exercise recovery techniques to reduce markers of muscle damage, soreness, fatigue, and inflammation: a systematic review with meta-analysis
Cold exposure decreases DOMS (massage is most effective)
Cold exposure decreases inflammatory markers (creatine kinase, IL-6, C-reactive protein)
Massage was also effective
[2] Cold Water Immersion (cryotherapy) for preventing and treating muscle soreness after exercise
Cold-water immersion reduces DOMS
Data from 17 trials n=366
Some evidence that cold-water immersion reduces DOMS at 24,48,72,96hrs
[3] 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
Not sure if I agree with the methods they used to perform this meta (pooled counter movement jump and sprints lasting under 10s)
CWI improved:
-recovery of muscular power (but not strength) 24hr after high intensity exercise
-muscular soreness
-reduced circulating Creatine Kinase levels post exercise
-perceived recovery 24 hr after high intensity exercise (but not eccentric, even though perceived DOMS decreased?….)
Dose-response relationship indicating lower-temperature water and shorter duration may be more effective for clearing serum creatine kinase after high-intensity exercise
[4] Effects of Cold Water Immersion on Muscle Oxygenation During Repeated Bouts of Fatiguing Exercise
CWI attenuated a decrease in tissue oxygenation in the 2nd fatiguing bout by 4%
Decrease in perceived muscle soreness 1 day post testing in treatment group
No significant effect on muscle performance
Knee extensions
10 min recovery intervention (CWI or control)
Repeat knee extension
[5] Use of Cold-Water Immersion to Reduce Muscle Damage and Delayed-Onset Muscle Soreness and Preserve Muscle Power in Jiu-Jitsu Athletes
CWI 6℃ for 19 minutes
Significant decrease in Lactate Dehydrogenase in CWI group 24hrs post recovery (might not actually be a good thing though for adaptation)
Decrease perceived muscle soreness
Increased estimated muscle power (they did a weighted chin up – don’t love it) for upper and lower limbs
Higher perceived recovery
[6] The Effect of Different Water Immersion Temperatures on Post-Exercise Parasympathetic Reactivation
Cold Water Immersion improves post-exercise HRV recovery while Hot Water Immersion delays post-exercise HRV recovery
Cold Water Immersion is an effective recovery modality to re-establish a parasympathetic state – wait how does that work if CWI increases circulating levels of catecholamines which are a sympathetic response?
Cold Water Immersion accelerates post-exercise parasympathetic reactivation (as measured by HRV)
Hot Water Immersion blunts post-exercise parasympathetic reactivation (as measured by HRV)
[7] Stress and Heart Rate Variability: A Meta-analysis and Review of the Literature
Relaxed state = Low heart rate and high Heart Rate Variability (HRV)
Stressed state = Higher heart rate and lower HRV
[8] Effect of cold water immersion on repeat cycling performance and thermoregulation in the heat
CWI might be an effective way to maintain endurance performance if short rest interval (like same day)
Active recovery helped clear blood lactate but decreased performance
CWI did not clear blood lactate and helped maintain endurance performance
n=10
30 min exercise,
15 min of one of 4 different cold water immersion therapies, or active recovery,
Followed by 40 min passive recovery
Repeat 30 min exercise
Active recovery resulted in lower blood lactate concentrations but also 4.1% decrease in performance in second exercise bout
CWI effective in reducing thermal strain and maintaining performance on subsequent exercise bout
[9] The Acute and Longer-Term Effects of Cold Water Immersion in Highly-Trained Volleyball Athletes During an Intense Training Block
CWI did not have any acute effects on performance, trending positive effects over 16 day period
Variables (countermovement jump, squat jump height, medicine ball throw distance)
[11] Post-Exercise cold water immersion attenuates acute anabolic signaling and long-term adaptations in muscle to strength training
CWI may blunt anabolic signals for long term strength and hypertrophy
12 weeks of 2x/week strength training
Significantly greater increase in isokinetic work, type 2 muscle fiber CSA and number of myonuclei per fiber in active recovery group vs. cold water immersion group
Active recovery group saw the following increases
Isokinetic work (19%)
Type 2 fiber CSA (17%)
Number of myonuclei per fiber (26%)
2nd study (also in this paper)
Single bout of exercise on separate days followed by active recovery or cold water immersion
Significantly greater number of satellite cells, and myogenic kinases in active recovery group than CWI group
[12] The Influence of Post-Exercise Cold-Water Immersion on Adaptive Responses to Exercise: A Review of the Literature
Cold Water Immersion may blunt strength and hypertrophy both acutely and chronically
CWI may enhance endurance signaling pathways and genes related to mitochondrial biogenesis but it seems potentially only acutely, not chronically
[13] Adipose-tissue plasticity in health and disease – excellent review on adipose tissue
Chronic cold exposure can increase number of mitochondrial rich, thermogenic beige adipocytes – this process is reversible if cold exposure ceases
“Upon cold exposure, sympathetic neurons release the neurotransmitter norepinephrine, which activates the beta-adrenergic receptor-cAMP-PKA pathway in adipocytes. This signaling cascade induces lipolysis and thermogenesis and stimulates transcription of genes driving the thermogenic program in brown and beige adipocytes. UCP1 function and thus thermogenic respiration is acutely activated by long chain fatty acids (LCFA) and inhibited by purine nucleotides.” from (Bertholet and Kirichok, 2017; Fedorenko et al., 2012)
[16] Uric acid and glutathione levels during short-term whole body cold exposure
Increased endogenous antioxidants (glutathione) in winter swimmers vs. non-swimmers – may improve immune function
Increased baseline concentration of reduced glutathione in winter swimmers vs. non-winter swimmers
Significant decrease in uric acid during and following cold exposure, likely because of the increase in ROS which is hypothesized as coming from muscle shivering, or catecholamine oxidation
[17] Improved antioxidative protection in winter swimmers
Higher baseline endogenous antioxidants in winter swimmers than non-swimmers – this is known as “body hardening” – exposing oneself to stressful stimuli (not sure if it’s always hypothermic conditions or stress in general)
Baseline glutathione was higher and erythrocyte activity of superoxide dismutase (SOD), and Catalase (Cat) were higher at baseline in winter swimmers than non-winter swimmers
[18] Examining the benefits of cold exposure as a therapeutic strategy for obesity and type 2 diabetes
Improvement in glucose utilization is largely due to skeletal muscle thermogenesis, and in part due to Brown Adipose Tissue activation
Dose dependent response to cold exposure and energy expenditure
Major increase in carbohydrate utilization in response to cold exposure, fatty acid utilization and protein metabolism also increase
Cold increases blood pressure and decreases heart rate
[19] Short-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitus
Cold exposure may be an effective therapy for increasing insulin sensitivity in Type 2 diabetics
10 Day Cold air acclimation (14-15℃) increased peripheral insulin sensitivity by 43% in type 2 diabetes
n=8
Increased GLUT4 translocation
[20] The distribution of brown adipose tissue in the human
Brown Fat is located around the kidneys, aorta, neck and the mediastinum (between the lungs?)
–keep the most important parts of the body warm, kidneys, heart, cervical spinal column which is responsible for the contraction of the diaphragm
Distributed throughout the body when we’re younger
[21] Brown Adipose Tissue: Function and Physiological Significance
Chronic adrenergic stimulation is required to stimulate brown fat
Chronic cold exposure is required to recruit Brown Adipose Tissue (BAT)
Recruited by epinephrine which is released by activation of the sympathetic nervous system
Non-shivering Thermogenesis is due to the activation of BAT
Protein dilution hypothesis – a diet low in protein requires the animal to eat more food in order to meet the metabolic protein requirements which leads to obesity
Obesity causes decreased activation of BAT and UCP1 expression
Leptin activates BAT
Decreased leptin sensitivity with age = decreased BAT activation with age
Decreased activation of BAT during fasting
Polyunsaturated fatty acids result in greater BAT activation (than saturated/monounsaturated FAs)
Testosterone and Estrogen activate BAT
Serotonin activates BAT
Serotonin helps regulate satiety
Cold exposure results in marked glucose uptake in BAT via sympathetic pathway (especially norepinephrine I believe) and mediated by β-adrenoceptors and cAMP
Fatty Acids are main substrate (fuel) for BAT
BAT utilizes lots of oxygen
BAT secretes Nerve Growth Factor during perinatal stage
VEGF highly expressed in BAT
I don’t understand. Recruiting diets = higher calorie diets where more of the calories come from fat and carbs. It is said that this leads to obesity which decreases activation of BAT, but then it says under “Are diet-adapted animals hyperpyrexic?” that animals adapted to recruiting diets have increased body temps, so wouldn’t that indicate an increase in BAT activation?
Only one study has looked at recruiting diets and BAT in humans, apparently did not show any effect, but author of this review says the norepinephrine stimulus may not have been adequate to activate BAT.
Also if Leptin from White Adipose Tissue activates BAT through receptors in the brain shouldn’t obese people activate BAT more, not less since they have more WAT? Or do they not produce as much Leptin and that’s why they’re obese?
Cold exposure increases precursors of Nitric Oxide
BAT can release Nitric Oxide
BAT generates fatty acids when stimulated by nor-epinephrine
[22] Cold and Exercise: Therapeutic Tools to Activate Brown Adipose Tissue and Combat Obesity
Really good, extremely detailed, review.
Fuels of Brown Adipose Tissue:
Glucose
Fatty Acids
Glutamate (which can directly and indirectly stimulate thermogenesis)
Cold exposure increases mitochondrial content and function in Brown Adipose Tissue
Chronic cold exposure causes “beiging” of White Adipose Tissue (increasing the expression of UCP1, PGC1alpha and other thermogenic proteins)
May cause beiging effect through batokines
[23] Cold Water Swimming – Benefits and Risks: A Narrative Review
Really good recap on benefits of winter swimming, but unclear whether the effects are due to the exercise, the cold, or the combination of the two.
Cold water swimming improves
Insulin sensitivity (seems sex specific – improves for women)
Mood – may be a treatment for Major Depressive Disorder
Potential risks of cold water swimming
Abnormal daily cortisol cycles
May cause arrhythmias that result in cardiac events
May cause pulmonary edemas
[24]. What is the biochemical and physiological rationale for using cold-water immersion in sports recovery? A systematic review
CWI <5 min, lower than 15 Celcius – most common parameters
Evidence that CWI increases
Peripheral catecholamine concentration
Oxidative stress – possibly via shivering, possibly because catecholamines are being oxidized into superoxides
Potential increase in free-radicals
Magnitude of these responses may decrease with acclimatization
[25] Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men
2-3 CWI swims per week (they also did sauna)
Water 1-9℃
Winter simmers exhibited:
Lower core temperature at a “comfortable state” than controls
No BAT glucose uptake at thermal comfort state, (controls did)
Increased cold-induced thermogenesis than controls
Increase in skin temperatures around 4:30-5:30am interestingly enough
They say winter swimming might be a way to combat obesity but wouldn’t decreased BAT glucose uptake at rest indicate a decrease in basal metabolic rate which would have the opposite effect, even though they have an increase in cold-induced thermogenesis than controls?
I believe they did contrast? Since they altered between CWI and sauna?
Was it actually a swim since it was only 1.4 min in the water? Does exercise play a role?
n=7 for winter swimmers
n=8 for control
Winter swimmers averaged 2-3 swims per week
1.4 minutes in water per immersion
2.6 immersions per swim
Total CWI per week = 11 minutes
They also did sauna an average of ? per week
2 sessions per visit
11.1 minutes per sauna session
Total Sauna per week = 57 minutes
[26] Moving in extreme environments: open water swimming in cold and warm water
Cold water swimming, especially in competition may cause an “autonomic conflict” where the sympathetic nervous system is activated while the parasympathetic is also working, potentially causing arrhythmias
Paper states that anger may be what’s causing this conflict.
This may lead to a cardiac event
[29] Cold-water immersion blunts and delays increases in circulating testosterone and cytokines post-resistance exercise
CWI blunted T and cytokine (hypertrophic) response after a bout of resistance exercise
[30] Cold water immersion attenuates anabolic signaling and skeletal muscle fiber hypertrophy, but not strength gain, following whole-body resistance training
CWI blunted muscle hypertrophy but not 1RM
[31] Post exercise cooling impairs muscle protein synthesis rates in recreational athletes
Post exercise cooling decreased uptake of amino acids
Post exercise cooling lowered the rate of myofibrillar protein synthesis
n=12
[33] The Effect of Cold Exposure on Cognitive Performance in Healthy Adults: A Systematic Review
Processing speed and executive function were most negatively affected by cold exposure
Memory and attention showed conflicting results
Acute Cold Exposure showed impaired cognitive performance in 15/18 studies…
18 studies included
May be a difference between males and females
May be a difference in single vs. multiple (chronic) exposures
[34] Swimming Induced Pulmonary Edema
Cold water increases pulmonary blood flow, exercise increases cardiac output, this combination can sometimes cause excess pressure on the capillaries in the lungs causing them to leak fluid into the alveoli
Recovery was spontaneous and quick with no recurrence of symptoms (although pulmonary edema can be fatal in other circumstances)
[35] Immune changes in humans during cold exposure: effects of prior heating and exercise
Cold air exposure increased white blood cell counts increased in all protocols
Significantly more leukocytes were in circulation 1 hour into cold exposure in the pre-exercise in water treatment
Natural Killer cell activity increased significantly in response to exercise in water pretreatment
Passive heating in water + 2 hours of cold exposure also increased NK cell activity
Cold exposure significantly increased stress hormones (Epinephrine, Nor-epinephrine, and cortisol) within 60 min of passive heating or control water immersion pre-treatment, within 120 min of exercise pre-treatment
Increases in circulating norepinephrine may be the cause of the rise in immune response in comparison to the other treatment protocols
[36] Improved mood following a single immersion in cold water
Improvement in vigor and esteem related effects – this was the ocean
Decrease in negative emotion subset (including depression by 2.1 points in CWI)
n=64 (42 CWI, 22 control) about 18 min at (56 ℉ = 13.6℃)
Other studies, uncited in this article:
[37] Contrast water immersion hastens plasma lactate decrease after intense anaerobic exercise
Contrast bath (36℃ and 12℃) resulted in faster clearing of lactate after intense anaerobic exercise (I don’t believe this is a good thing because it blunts the training stimulus – think about BFR)
4 wingate tests separated by 30s rest…ouch – n=11 randomized trial
Other research papers used to gather information but not specifically cited in the article above.
Scientific Evidence-Based Effects of Hydrotherapy on Various Systems of the Body
Discusses both cold water and hot water immersion and a number of different styles of immersions
Lot of great citations in Musculoskeletal section, and the endocrine section for cold water immersion and contrasting
Leg Immersion in warm water, stretch-shortening exercise, and exercise-induced muscle damage
Leg immersion in warm water decreased markers of exercise induced muscle damage, including creating kinase activity in the blood, muscle soreness.
Effects of cold-water immersion and contrast-water therapy after training in young soccer players
Cold Water Immersion reduces perceived fatigue after training sessions
Cold water immersion did not change inflammatory or hematological markers
Alternating hot and cold water immersion for athlete recovery: a review – 2004 review
Not a ton of conclusive evidence
Water Immersion Recovery for Athletes: Effect on Exercise Performance and Practical Recommendations – good review
Contrast bathing using consists of:
Alternating 3-7 times between hot water (bath not shower seems more beneficial) and cold water
1-2 in both cold and hot water
Mixed results but the above protocol seems to yield significant results, especially when accumulated fatigue and muscle damage over the course of 2+ days are considered
Take home: it’s likely helpful for recovery – but again, do you want to blunt the stimulus?
The effectiveness of hydrotherapy in the management of fibromyalgia syndrome: A systematic review
Mostly water at or around 37℃
Also includes exercise and balneotherapy (bathing in thermal mineral water)
Hydrotherapy was associated with positive health outcomes for pain, health status, and tender point count
Sex-related responses of beta-endorphin, ACTH, GH and PRL to cold exposure in humans
Don’t love this study, small sample size, also unless the subjects have similar lean muscle mass and BMIs subjects with less muscle / less mass in general would likely get colder overall (aka women might see a greater decrease in core temperature and as a result increase in hormone release but men may not because of difference in core temperature change)
8 men, 8 women 30 min in 25℃ room, then 30 min in 4℃ room
Significant increase in beta-endorphin, ACTH, cortisol and GH levels observed in women
Non-significant increased of same hormones observed in men
Significant increase in blood pressure for men and decrease in HR for men, but not in women
Skin temp significantly lower in women but not men
Are beta-endorphins and thermoregulation during cold-water immersion related?
Beta-endorphins were significantly lower in the high fat group vs. the low fat group
Beta-endorphins did not increase in proportion ot level of heat loss (no dose-dependent relationship between heat loss and beta-endorphin release
Perfect study to discuss what I mentioned above
No significant relationship between beta-endorphins, tissues insulation, and core temperature
No significant relationship between changes in thermoregulatory variables and High fat vs. Low fat groups
This runs counter intuitive to the idea that CWI causes a stress response via the sympathetic nervous system
Heart rate variability is the fluctuation of the length of heartbeat intervals
Diving reflex effects respiratory, cardiac, and vascular responses – occurs when water contacts the face
Cold stimulation to the neck and cheek increases HRV
The importance of norepinephrine in depression – finish reading
Decreased levels of Norepinephrine, serotonin, and dopamine are associated with depression
Hormone response of normal and intermittent cold-preadapted humans to continuous cold
Cold increases epinephrine release in both acclimatized and non-acclimatized groups
Exposure to cold in Non acclimatized group resulted in increased urine volume, norepinephrine (+48%), epinephrine (+84%), and hydroxycorticosteroids
Prior cold exposure resulted in no elevation in metabolism (it may have already adapted to be higher metabolism and additional cold exposure did not further increase Basal metabolic rate) and decrease in body temp in response to cold exposure
Prior cold exposure still resulted in an increase in epinephrine (+65%)
Human physiological responses to immersion into water of different temperatures
CWI 14℃ resulted increased dopamine, noradrenaline, and metabolic rate
Metabolic rate increased by 350%
Noradrenaline increased by 530%
Dopamine increased by 250%
Cortisol levels tended to decrease (not sure if they were significant – also the opposite of the other studies I’ve read)
Plasma adrenaline levels remained unchanged
Thermoneutral water resulted in “strengthened” parasympathetic tone (decreased HR blood pressure, and cortisol by 34%) (aka had a relaxing effect) – not sure this is convincing enough that I would site it, but still cool
20℃ water decreased HR, BP (not sure if cortisol decreased significantly)
Increase in noradrenaline
No significant increase in adrenaline or dopamine
n=10
14℃
Effects of Temperature and Water Immersion on Plasma Catecholamines and Circulation
CWI at 6℃ caused increase in Norepinephrine (don’t believe it specifically talked about cortisol)
Once weekly winter swimming for 2-10 minutes at 2-6℃)
Acute effects
Increase in TSH and cortisol
Mild decrease in prolactin
No change in FSH, LH, growth hormone
Chronic effects
Increase of basal prolactin levels
Decrease in insulin serum levels
The Effect of Cold Exposure on Cognitive Performance in Healthy Adults: A Systematic Review
Processing speed and executive function were most negatively affected by cold exposure
Memory and attention showed conflicting results
Acute Cold Exposure showed impaired cognitive performance in 15/18 studies…
18 studies included
May be a difference between males and females
May be a difference in single vs. multiple (chronic) exposures
Cold Water Swimming Beneficially Modulates Insulin in Middle Aged Individuals
Increased insulin sensitivity mid way through Cold Water swim season – only in women (where were the leaner individuals in this study) and lean individuals
N = 30
Health Effects of Voluntary Exposure to Cold Water – a Continuing Subject of Debate
BAT is used to produce heat to warm the body
BAT can generate heat by “the action of free fatty acids in uncoupling mitochondrial electron transport” – aka BAT burns triglycerides to generate heat
And by “Noradrenaline-induced membrane depolarisation and sodium pumping”
BAT energy consumption is less than 20 calories per day – the equivalence of running for 2 min at a moderate pace
Adiponectin is a hormone produced by adipocytes
Adiponectin
Reduces inflammation
Reduces atherogenesis (buildup of fatty acid plaques in the arteries)
Improves insulin sensitivity
Regular Winter Swimming attenuates catecholamine response to cold water
I’m not familiar with generalized estimating equations and am thus tentative to cite these findings
Cold water immersion
Decreased pain
Decreased depression
Improved Joint mobility
Improved Quality of life
The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial
Finishing a warm shower with 90 seconds of cold water decreased number of self reported sickness days by 29% (but not a reduction in illness days – so I believe they only called in sick when they were actually sick)
Health Effects of Voluntary Exposure to Cold Water – a Continuing Subject of Debate
Brown Adipose Tissue at the Intersection of Sleep and Temperature Regulation
This is a hypothesis, not an experiment. Impaired brown fat activation may play a role in poor sleep and/or metabolic function
Endocrine Effects of Repeated Hot Thermal Stress and Cold Water Immersion in Young Adult Men
Contrast bath caused significant decrease in cortisol concentrations especially for young men with higher baseline cortisol concentrations
No change in Testosterone, DHEA-S or prolactin
4 x 12 min sauna at 90℃, 6 min CWI at 10℃
NSAIDs likely impair muscle hypertrophy by inhibiting cyclooxygenase (COX) activity
CO2 enriched water
increased cutaneous blood flow (peripheral vasodilation)
Decreased body temp
Increased HRV
Compared to freshwater
Adapted cold shower as a potential treatment for depression
Referenced a lot but not actually a research study….it’s just a hypothesis….
The Science & Use of Cold Exposure for Health & Performance – Huberman lab
Role of Norepinephrine in the Pathophysiology and Treatment of Mood Disorders – great review
Norepinephrine is important for attention and learning – especially for novel stimuli
NE is also important for consolidating memories & creating stronger associations in the limbic system
(I believe whether these associations are positive or negative depends on our perception of ability to handle the challenge in front of us – example: the rapid heart rate from NE when you get nervous before a speech and cause you to stumble over your words or deliver it flawlessly depending on your perception of the situation, your ability to handle it, and what that sensation (rapid heart rate) means.
Norepinephrine (NE) cells primarily located in the Locus Coeruleus (LC) of the brain stem – projections from the LC innervate cortical and subcortical as well as the spinal cord.
Synaptic control of LC firing is in part determined by glutamate and GABA
Norepinephrine potentiates the firing of Dopamine cells in the ventral tegmental area that project to the limbic forebrain
Firing of the LC is correlated with behaviorally orienting responses.
Highest spike occurs when an automatic behavior is interrupted (think if you’re driving and a car cuts you off)
New stimuli – especially new faces and other meaningful stimuli elicit a strong, phasic firing from LC
Repeated exposure to new stimuli rapidly desensitizes firing of the LC
Low firing rates and release of NE = behavioral sedation
Optimal firing rates = focused attention
Extremely high firing rates = hyperarousal and distractibility
Changes in neurotrophin levels may lead to target and NE neuron degeneration or axonal pruning
Free Radical Theory of Aging (FRTA) – increases in Reactive Oxygen Species (ROS)s and oxidative damage are correlated with aging.
There are studies however that show the opposite, and common sense, exercise, sauna, ice baths, all increase ROS (but also likely increase endogenous antioxidants)
ROS that are free radicals – have an unpaired electron in their shell and are therefore highly reactive
Superoxide (O–2),
Hydroxyl (HO),
Peroxyl (RO–2),
Hydroperoxyl (HO2),
Alkoxyl radicals (RO)
ROS that are not free radicals – more stable, able to pass through membranes but can still be reduced (and thus cause damage I believe)
Peroxide (H2O2)
Hydroxide Ion (OH–)
Organic Peroxides (ROOH)
Reactive Nitrogen Species (RNS) – can cause cellular damage, but also have functional roles in cellular signaling and pathogen defense. We don’t know how they impact longevity.
Nitric Oxide (NO) is produced from L-arginine by the enzyme nitric oxide synthase
Nitric oxide can then react with superoxide to produce peroxynitrite (ONOO–)
Peroxynitrite (ONOO–) can damage cells or form other types of RNSs
Free Radical RNSs
Nitric Dioxide (NO2)
Nitrate Radical (NO3)
Non Free Radical RNSs:
Peroxynitrite
Nitrous Acid (HNO2)
Nitrite (NO–2)
Nitrosyl cation (NO+)
Nitroxyl Anion (NO-)
Peroxynitrous Acid (ONOOH)
Dinitrogen Trioxide (N2O3)
ROS can damage:
1.) DNA – cause mutations in both nuclear and mitochondrial DNA
2.) Proteins – can cause protein carbonylation. Especially thiol-containing cysteine and methionine residues
3.) Lipids – can cause lipid peroxidation which can cause reactive by products
All of these are correlated with advanced aging
Mitochondrial respiration is a major source of ROS within the cell.
Electrons may leak out while being transported between the complexes, binding with oxygen and creating superoxide
Immune system uses ROS to attack pathogens in the body
Membrane Phagocyte NADPH oxidase and myeloperoxidase (MPO) help to attack pathogens ROS also play a role in signaling for growth, survival, and apoptosis
ROS-generating enzymes that play a role in cell signaling
Cytochrome P450 (CYP) – produce ROS in detoxification and excretion of xenobiotics
Xanthine oxidoreductase (XOR) – produces superoxide anions to break down purines to uric acid
Superoxide Dismutase (SOD) – converts dopamine after signaling occurs and produces hydrogen peroxide in neurons in the process
ROS are also produced during Beta Oxidation of Fatty Acids in the peroxisome – producing hydrogen peroxide
Peroxisome-generated ROS are thought to contribute to the regulation of NF-kB and MTORC1
(NADPH Oxidase generated ROS are also thought to contribute)
Doesn’t seem to distinguish between endogenous and exogenous antioxidants which is surprising given what I’ve heard / read about anti-inflammatory substances blunting the hypertrophy response)
Enzymatic Antioxidants
- Superoxide Dismutase (SOD) – converts highly reactive superoxide anion to a less reactive hydrogen peroxide
3 types of SOD
- SOD1 – located in the cytosol – active site is Cu/Zn
- SOD2 – located in the mitochondria – active site is Mn
- SOD3 – located extracellularly – active site is Cu/Zn
2.) Catalase (CAT) – converts hydrogen peroxide to water and oxygen (aka downstream of SOD)
Primarily located in peroxisomes where hydrogen peroxide can be high due to Beta oxidation of lipids
3.) Glutathione Peroxidase (GPx) – works with CAT to reduce hydrogen peroxide to water and oxygen
GPx is located in the mitochondria and the cytoplasm (as opposed to the peroxisomes like CAT)
Active site is Selenocysteine (an amino acid that has Selenium I believe)
GPx requires 2 Glutathione (GSH) molecules to return it to its functional state which is catalyzed by Glutathione Reductase (GR) and uses electrons donated by NADPH
4 subcellular compartments
- GPx1 – cytosol – hydrogen peroxide and organic peroxides
- GPx2 – cytosol – hydrogen peroxide and organic peroxides
- GPx3 – extracellular – antioxidants
- GPx4 – cell membranes and mitochondria – can metabolize phospholipid hydroperoxides
4.) Glutaredoxin (Grx) and thioredoxin (Trx)
Protect thiol-containing proteins by repairing damage caused by exposure to oxidants
Active sites consist of cysteine residues
Requires 2 Glutathione molecules to be reduced back
Both require electrons from NADPH
Play important roles in redox signaling pathways
Located in:
- Trx1 & Grx1 – nucleus and cytosol – can be secreted
- Trx2 & Grx2 – mitochondria
- Grx3 – nucleus and cytosol
- Grx5 – mitochondria
- Peroxiredoxin (Prx)
Cysteine containing enzymes that reduce peroxides including organic peroxides
Returned to their active state by either being reduced by Trx or Glutathione
Locations:
- Prx1 – nucleus and cytosol
- Prx2 – nucleus and cytosol
- Prx3 – mitochondria
- Prx4 – endoplasmic reticulum
- Prx5 – peroxisomes
- Prx6 – cytosol
6.) Glutathione S-transferase (GST)s
Linked to various stress responses.
Thought to help GPx in attenuating lipid peroxidation by reducing fatty acid hydroperoxides
Binds GSH
Active site is serine residue
GSTs may also help detoxify the end products of lipid peroxidation (which can be harmful to the cell)
Located in the cytosol, microsomes, and plasma membrane
Non-enzymatic Antioxidants
- Glutathione
Essential for the activity of GPx and Grx since it helps convert each enzyme back to its active state
GSH can act as an antioxidant by donating the electrons on the sulfhydryl group to reduce ROS
GSH levels are restored to its reduced state by GR and NADPH or dietary supplementation
- N-acetyl cysteine (NAC)
Precursor to Glutathione.
Also has its own thiol group, which allows it to reduce ROS and protect sulfhydryl-containing protein groups from oxidative damage
NAC levels are maintained by consuming high protein foods with cysteine
- Vitamin C
Water soluble antioxidant
Present intracellularly and extracellularly
Helps prevent oxidation of cholesterols (that’s interesting…)
- Vitamin E
Lipid soluble
Present in cell membranes and lipoproteins
Helps to mitigate lipid peroxidation from oxidative stress
Vitamin C can help convert Vitamin E back to its reduced form
Antioxidants can also repair oxidative damage
-glutaredoxins and thioredoxins reduce thiol-containing proteins
14kDa reduces cysteine residues
Methionine sulfide reductase reduces methionine residues
Cysteine and Methionine are amino acids most susceptible to oxidation by ROS
DNA repair mechanism can be triggered by redox sensors which signal to enzymes responsible for:
Base excision repair (BER)
Nucleotide excision repair (NER)
Mismatch repair
Irreversibly damaged molecules/organelles are metabolized by proteasomes (in the cytosol) or proteases (in the mitochondria)
Oxidative stress can cause autophagy of:
- Peroxisomes (pexophagy)
- Mitochondria (mitophagy)
Which removes the dysfunctional ROS generating organelles and synthesizes new ones
ROS can oxidize cysteine residues within proteins which can change that protein’s function
Those cysteine residues can be reduced to thioredoxin or glutaredoxin to restore their original function or be further oxidized (presumably to be metabolized?)
ROS can activate protein kinase signaling pathways by inactivating phosphatases or
ROS can inactivate protein kinase signaling pathways (not entirely sure how)
Protein kinases – transfer a phosphate group (usually from ATP) to a target cell to:
- Activate
- Deactivate
- Signal to other cells to interact with that cell
Phosphatases – remove the phosphate group from a molecule
Oxidation
Is
Loss (electrons)
Reduction
Is
Gain (electrons)
