For athletes, wellness enthusiasts and even casual gym-goers, the idea of plunging into an ice-cold bath after an intense workout has become increasingly popular. But beyond post-exercise recovery, the practice of cold immersion has deep roots in winter traditions.
Each February, thousands of thrill-seekers participate in polar plunges—braving freezing waters for charity events, personal challenges, or simply the rush of the experience. While some claim these icy dips boost circulation, reduce inflammation, and even strengthen mental resilience, others question whether the benefits outweigh the shock of submersion.
To better understand the physiological effects of cold exposure, The Daily spoke with Julian E. Stelzer, a professor in the Department of Physiology and Biophysics at Case Western Reserve University School of Medicine. Stelzer’s research focuses on the molecular mechanisms that regulate cardiac muscle contraction, exploring how contractile proteins influence force generation and cross-bridge kinetics in the heart.
His expertise in muscle function and adaptation provides a unique perspective on what happens when the body is suddenly exposed to extreme cold—whether through an ice bath or a full-body plunge into an icy lake.
Read on to discover the science behind cold exposure and Stelzer’s take on whether these wintertime rituals offer real benefits or just a brief, frigid thrill.
Can you explain what happens to the body and organ systems during a polar plunge or ice bath?
The cold water plunge causes a sudden and significant increase in heart rate, breathing and blood pressure. This is typically called the cold shock response. The hyperventilating can last several minutes as the body tries to adapt to this extreme environmental stress. Blood vessels in the periphery and limbs of the body constrict and shunt blood toward the vital organs. A second heat defense system is activated by inducing shivering through contraction of skeletal muscle to generate more heat.
What are the potential health benefits of cold water immersion?
Most potential benefits or claims are mostly anecdotal with no randomized large-scale studies in normal populations. Some studies on athletes have shown some benefits, but it depends somewhat on the type of exercise. However, potential benefits can include:
- Regulating blood sugar and increasing weight loss: Cold water exposure can activate your muscles through shivering, similar to exercise, and that can improve glucose uptake in muscle tissue, which helps clear sugar from the blood stream and improves insulin sensitivity. It can also increase your metabolic rate several fold, at least temporarily, which may help burn more calories.
- Boosting your immune system: This can happen potentially by increasing your white blood cell count (unclear how). However, prolonged exposure to very cold water can risk hypothermia and impaired immune capacity.
- Reducing chronic inflammation: This may be helpful in many diseases like autoimmune diseases, diabetes, arthritis, or inflammatory bowel disease. Cold tends to reduce inflammation in an acute injury setting, but if it can help chronic inflammation is completely unclear.
- Helping anxiety and depression: Some studies have found that cold water plungers and swimmers experience elevated moods immediately after the activity, although it’s not clear how long the effects last. The acute effects could be physiological through release of hormones like adrenaline and noradrenaline, or dopamine. The other aspect could be social, as most cold-water plungers are part of polar-plunging groups.
- Assisting with workout recovery.
Are there risks associated with polar plunges, especially for people with certain medical conditions?
The cold shock can be dangerous for anyone who is not accustomed, but particularly for individuals with a history of heart problems, poor circulation, stroke, or high blood pressure. Those individuals are often on drugs such as beta blockers that reduce heart rate and blood pressure, which makes it more difficult to adapt to a surge of adrenergic activity that produces the increases in heart rate and breathing rate in response to the cold shock.
The result can be a heart attack or an arrhythmia. In some individuals, the cold shock can cause panic and fear, which may lead to cognitive impairment and bad decision making, increasing the chances of drowning.
How does cold water immersion compare to other forms of cold exposure, like cryotherapy or cold showers?
The main difference between the three is likely how much your body temperature drops. A cold shower can range from 50 to 60 degrees (cold tap water is ~55°F, may be slightly colder in the winter), a polar plunge in icy water can reach temperatures just above freezing 35–40°F, and some forms of whole-body cryotherapy can reach as low as -200°F for a few minutes.
The other difference is that polar plunges and whole-body cryotherapy submerge your whole body in cold, whereas a cold shower is mostly a peripheral effect and affects your core less.
What does research say about the effectiveness of polar plunges for muscle recovery and immune function?
We are all familiar with the pictures of athletes fully submerged in ice-cold baths after training or games. The idea behind it is that this can help muscle recovery by reducing body temperature, blood flow, and inflammation in the tissues. Is it true? Probably not.
Although the evidence is not strong for either case, reducing blood flow could slow down protein synthesis, and at least some inflammation is also a trigger that helps muscle recovery. Whether inflammation is decreased with acute exposure to cold is not clear for athletes, and is unlikely to happen in non-athletes. The conclusion is that for long-term muscle health, a polar plunge serves no benefit.
What about immune function? There is some evidence that cold plunges may increase white blood cells, which may boost the body’s ability to fight infection. However, those studies were mostly conducted on cold-water swimmers, so it could have been the exercise and not the temperature of the water. For the average once-a-year polar plunger, there is little evidence that there is any effect on the immune system.
What precautions would you recommend for someone trying a polar plunge for the first time?
The shock of the cold-water response can be mitigated by acclimating the body slowly to cold water. This can be done by taking cooler showers at home. Also, placing cold water on your back or on your neck before heading in may better prepare your neurological system for the shock that is coming. Exercising in cold weather will also condition your lungs to cold air so you can better maintain your breathing in the cold water.
Aside from the physical preparation, the mental preparation can be just as important. By understanding how your body will react to the cold shock and how it may feel, you will be less likely to panic when it happens. The initial few seconds in the water are the most dangerous when people try to get their breathing under control, and those who panic are in danger of drowning.
Citation:
The science behind ice baths and polar plunges—are they truly beneficial? (2025, February 25)
retrieved 25 February 2025
from https://medicalxpress.com/news/2025-02-science-ice-polar-plunges-beneficial.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
For athletes, wellness enthusiasts and even casual gym-goers, the idea of plunging into an ice-cold bath after an intense workout has become increasingly popular. But beyond post-exercise recovery, the practice of cold immersion has deep roots in winter traditions. Each February, thousands of thrill-seekers participate in polar plunges—braving freezing waters for charity events, personal challenges, or simply the rush of the experience. While some claim these icy dips boost circulation, reduce inflammation, and even strengthen mental resilience, others question whether the benefits outweigh the shock of submersion. To better understand the physiological effects of cold exposure, The Daily spoke with Julian E. Stelzer, a professor in the Department of Physiology and Biophysics at Case Western Reserve University School of Medicine. Stelzer’s research focuses on the molecular mechanisms that regulate cardiac muscle contraction, exploring how contractile proteins influence force generation and cross-bridge kinetics in the heart. His expertise in muscle function and adaptation provides a unique perspective on what happens when the body is suddenly exposed to extreme cold—whether through an ice bath or a full-body plunge into an icy lake. Read on to discover the science behind cold exposure and Stelzer’s take on whether these wintertime rituals offer real benefits or just a brief, frigid thrill. The cold water plunge causes a sudden and significant increase in heart rate, breathing and blood pressure. This is typically called the cold shock response. The hyperventilating can last several minutes as the body tries to adapt to this extreme environmental stress. Blood vessels in the periphery and limbs of the body constrict and shunt blood toward the vital organs. A second heat defense system is activated by inducing shivering through contraction of skeletal muscle to generate more heat. Most potential benefits or claims are mostly anecdotal with no randomized large-scale studies in normal populations. Some studies on athletes have shown some benefits, but it depends somewhat on the type of exercise. However, potential benefits can include: The cold shock can be dangerous for anyone who is not accustomed, but particularly for individuals with a history of heart problems, poor circulation, stroke, or high blood pressure. Those individuals are often on drugs such as beta blockers that reduce heart rate and blood pressure, which makes it more difficult to adapt to a surge of adrenergic activity that produces the increases in heart rate and breathing rate in response to the cold shock. The result can be a heart attack or an arrhythmia. In some individuals, the cold shock can cause panic and fear, which may lead to cognitive impairment and bad decision making, increasing the chances of drowning. The main difference between the three is likely how much your body temperature drops. A cold shower can range from 50 to 60 degrees (cold tap water is ~55°F, may be slightly colder in the winter), a polar plunge in icy water can reach temperatures just above freezing 35–40°F, and some forms of whole-body cryotherapy can reach as low as -200°F for a few minutes. The other difference is that polar plunges and whole-body cryotherapy submerge your whole body in cold, whereas a cold shower is mostly a peripheral effect and affects your core less. We are all familiar with the pictures of athletes fully submerged in ice-cold baths after training or games. The idea behind it is that this can help muscle recovery by reducing body temperature, blood flow, and inflammation in the tissues. Is it true? Probably not. Although the evidence is not strong for either case, reducing blood flow could slow down protein synthesis, and at least some inflammation is also a trigger that helps muscle recovery. Whether inflammation is decreased with acute exposure to cold is not clear for athletes, and is unlikely to happen in non-athletes. The conclusion is that for long-term muscle health, a polar plunge serves no benefit. What about immune function? There is some evidence that cold plunges may increase white blood cells, which may boost the body’s ability to fight infection. However, those studies were mostly conducted on cold-water swimmers, so it could have been the exercise and not the temperature of the water. For the average once-a-year polar plunger, there is little evidence that there is any effect on the immune system. The shock of the cold-water response can be mitigated by acclimating the body slowly to cold water. This can be done by taking cooler showers at home. Also, placing cold water on your back or on your neck before heading in may better prepare your neurological system for the shock that is coming. Exercising in cold weather will also condition your lungs to cold air so you can better maintain your breathing in the cold water. Aside from the physical preparation, the mental preparation can be just as important. By understanding how your body will react to the cold shock and how it may feel, you will be less likely to panic when it happens. The initial few seconds in the water are the most dangerous when people try to get their breathing under control, and those who panic are in danger of drowning. Citation: This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
Can you explain what happens to the body and organ systems during a polar plunge or ice bath?
What are the potential health benefits of cold water immersion?
Are there risks associated with polar plunges, especially for people with certain medical conditions?
How does cold water immersion compare to other forms of cold exposure, like cryotherapy or cold showers?
What does research say about the effectiveness of polar plunges for muscle recovery and immune function?
What precautions would you recommend for someone trying a polar plunge for the first time?
The science behind ice baths and polar plunges—are they truly beneficial? (2025, February 25)
retrieved 25 February 2025
from https://medicalxpress.com/news/2025-02-science-ice-polar-plunges-beneficial.html
part may be reproduced without the written permission. The content is provided for information purposes only.
