In recent years, the interest in alternative health strategies has seen exponential growth. Among them, one intriguing practice that is gaining traction, despite limited and even contradictory clinical evidence, is cold exposure. Athletes, celebrities, and many individuals who aren’t squarely in either of those two groups have taken up the conviction that regular exposure to short-term, intense bouts of cold temperatures (either by taking a cold bath or shower, swimming, or undergoing any other method of suddenly cooling down the body) will benefit their health or performance in some or several ways. But what does the research actually say? Let's dive into the benefits of cold exposure.

What is cold exposure?

Cold exposure is not a new health fad. It has been practiced for centuries with a rich history dating back to ancient times. In ancient Rome, cold therapies were prevalent and an integral part of their medicinal practices. Similarly, the Finnish have practiced sauna cultures for thousands of years, which often involve periods of hot sauna followed by plunging into icy water,  an early form of contrast therapy (see section below). This practice is still a huge part of Finnish culture today. 

Cold exposure, as mentioned earlier, is the practice of subjecting the body to extremely cold temperatures for short periods of time either by taking a cold shower, cold bath, swimming in very cold water, wrapping parts of your body with cold, wet rags, or even just stepping outside in cold weather without adequate clothing. (Others may call it cryotherapy, but don’t confuse cold exposure with the medical term of cryotherapy, which refers to certain procedures such as the freezing of skin to remove skin tags or cancer, in dermatology; cryotherapy for treating prostate and other cancers; or nasal cryotherapy for treating rhinitis.) When water is involved, as is most often the case, those forms of cold exposure may be referred to as hydrotherapy.

Modern cold exposure techniques

While not an exhaustive list, the following are the more commonly practiced methods of undergoing cold exposure:

• Cold water immersion (CWI) is one of the most commonly practiced cold exposure methods, and is done in various locations such as indoor or outdoor tubs, specially designed tanks or plunge barrels, or in lakes or the ocean. Some studies suggest a temperature of 50-60ºF (10-15º C) for 3-5 minutes, but there really aren’t definite standard temperatures nor duration guidelines.
• Cold showers typically involve water temperature below 60ºF for two to three minutes at a time. (See our separate report: Benefits of taking a cold shower after a workout.)
• Whole-body cryotherapy (WBC) is a dry-air method using a cryogenic chamber technology to expose the body to extreme cold (below −100°C) for a few minutes. 
• Localized cryotherapy involves applying extreme cold to specific areas of the body, such as joints or muscles, using devices like ice packs or cryotherapy machines. 
• Contrast therapy consists of bathing alternately in warm and cold water.  

The science behind cold exposure

Overall, the science behind cold exposure is much more complex and multifaceted than most of us, physicians and athletic trainers included, realize. It involves various physiological responses that work together to bring about numerous impacts, some of which could be considered health benefits, while others could have no significant medical outcomes or even potentially deleterious ones. The effects of cold exposure depend on what type of exposure, what temperature, what duration of exposure, when in the day and after what (or no) activity it is administered, the subject’s age and health status, and frankly so many other variables. But speaking generally about the effects of cold exposure, akin to an immersion up to the neck in water that’s about 60 degrees Fahrenheit (or about 15ºC) for 3-10 minutes, the following physiological impacts are most notable: 

1. Adrenaline boost: The very first response is that, quite simply, you experience a shock. The cold stimulates the release of norepinephrine, a neurotransmitter, which then boosts adrenaline as well as certain other hormones. But does that adrenaline burst actually go on to produce a health benefit? Yes and no, but mostly no. More on that later.
   
2. Vasoconstriction: Another response to cold exposure is vasoconstriction, or a tightening up of your blood vessels. As a UCLA Health blog explains, when that happens, blood moves to your body’s core and vital organs. The blood naturally becomes oxygen- and nutrient-rich during the process. As your body heats up again, the blood vessels expand (vasodilate), bringing that oxygenated blood back to your tissues. As it flows back, it helps to flush out inflammation — a cause of delayed-onset muscle soreness (or DORM), which can occur a couple of days after exercise. However, as other researchers (notably Dr. Craig Heller, Stanford School of Medicine, a world expert on the science of temperature regulation) have noted, the vasoconstriction that occurs from whole-body cold exposure may actually make it more difficult for your body to get rid of heat, because the cold has shut off your avenues of heat loss. In other words, you could end up getting hotter, overall, from cold exposure, with downstream impacts such as muscle fatigue and overall poorer athletic performance. On a more positive note, if your body is totally submerged in cold water (see CWI section, below), the surface area of your body is so great that, despite vasoconstriction, you’re going to lose heat, so it does cool you down systemically at least in the short term. More on that later.
   
3. Increased metabolic rate: The shivering response that results from cold exposure coincides with an increase in your metabolic rate. However, this response (a) is short-term, so should not be confused with long-term metabolic change; and (b) it’s not nearly as large of a metabolic response as you get from exercise. In other words, is the short-term impact upon metabolism from cold exposure clinically meaningful? Probably not. And it’s not likely to be the kind of metabolic boost that will help you lose weight, despite claims to the contrary. More on that later.
   
4. Other significant physiological and biochemical changes in the body that have been observed with cold exposure include an increase in heart rate, blood pressure, and respiratory minute volume; and decreases in end tidal carbon dioxide partial pressure and a decrease in cerebral blood flow. Increases in peripheral catecholamine concentration, oxidative stress and a possible increase in free-radical-species formation have also been observed and reported. 

Likely and possible cold exposure benefits

While there’s a growing body of research on cold exposure, frankly the evidence around the health benefits is mixed, and much of it is largely inconclusive in part due to studies that are either small or have design flaws or both. However, a few very distinct benefits have become quite widely accepted: 

Relieves muscle soreness: Of all the possible benefits of cold exposure, soothing sore muscles has been backed with the most evidence, which is why it’s a common practice for professional athletes (e.g., top tennis players) to undergo CWI or WBC following an important event. After intense exercise, athletes may experience what’s known as DOMS: delayed onset muscle soreness. When you're in cold water, your blood vessels constrict so there's less blood flow to the area, reducing your swelling and inflammation and leading to less pain. Most recently, a 2022 meta-analysis (of 52 studies) concluded that CWI did reduce soreness following two types of exercise (eccentric and high-intensity), although “perceived feelings of recovery” only improved in the high-intensity group. Similarly, a 2022 review identified that the primary benefit of cooling was in the early recovery phase (< 1 hour post-exercise) in improving fatigue resistance in hot ambient conditions following endurance exercise and possibly enhancing the recovery of maximal strength following resistance exercise. A 2018 meta-analysis also showed benefits to muscle soreness, but no better (or not quite as good) as massage therapy. 

Analgesic effect: Relating to the muscle soreness relief benefit, cold exposure produces an analgesic effect that may reduce pain generally, if only temporarily.

Treatment for over-heating or heat stroke: Cold immersion clearly helps to arrest heat exhaustion or heat stroke, although practical logistics make it tough to time the administration of such a therapy, particularly during a sporting event or even training regimen. A 2015 meta-analysis concluded that contact with cold water (around 50°F) cooled off overheated people twice as fast as recovery without hydrotherapy. However, it’s important to note that heat stroke is a condition that comes on suddenly and is often misdiagnosed. When an individual is brought into an ER with symptoms, a bath of cold or ice water has been proved to be the most effective way of quickly lowering your core body temperature. The quicker you can receive cold water immersion, the less risk of death and organ damage.

“Pre-cooling” may be uniquely beneficial for endurance athletes: While research into this approach is scarce, initial evidence indicates that CWI before endurance exercise may improve endurance performance (especially in hot conditions), as concluded in this 2012 review. (Interestingly, cooling garments appear of limited efficacy, despite their frequent use. More on that later.) As expert Heller explains, during an aerobic activity, such as running or cycling, your heat gradually rises and spreads all over your body, eventually hindering your performance. A cold shower or bath prior to such activity could help increase the capacity of your body mass to absorb that excess heat, thereby elongating the time it takes you to heat up, potentially increasing your speed or your ability to continue the activity longer/farther or both. Pre-cooling does not appear efficacious in anaerobic activities (e.g., weight lifting), during which your individual muscles heat up far more than does your whole body. When that muscle-specific hyperthermia gets too great, that muscle simply can no longer perform adequately due to muscle fatigue.

Cooling during exercise/training, where and when feasible, holds distinct potential for many types of athletes: For example, a group at Stanford have determined that it’s the “glaborous” (non-hairy/furry) skin — which you only have on the palms of your hands and feet and on parts of your face — that can most rapidly cool athletes’ core temperatures and thereby dramatically improve exercise recovery and performance. So they’re developing a commercial version of their specialized heat extraction device, known as “the glove,” which has demonstrated an ability to reduce fatigue onset during resistive exercise, leading to improving strength and work volume training responses. The product is still in development, and logistically it may not have practical application (as currently devised) during certain live sporting events (e.g., where there are no “time-outs,” like in a marathon or a bike race). But it may hold potential in numerous training applications, and it could even be housed in golf carts during tournaments and on the sidelines during football and baseball games, as just two examples. Applications for individuals who are physically hindered, e.g., with multiple sclerosis, also appear promising.  

Improves mood: The intense physical response to cold exposure, including the adrenaline effect and the release of endorphins and other hormones, could boost your mood at least over the short term, and some small studies have found a correlation with cold immersion or regular cold showers with reduced symptoms of depression and anxiety, although the results to date are far from definitive. Bear in mind, too, that studies looking at cold exposure after exercise may have found mood improvements, but many scientists would argue that the endorphin rise, for example, may be more the result of the exercise than it is from the post-exercise cold therapy! But if the feel-good effect is even just short-term, or even if it’s only a placebo effect (“I did it, I went in cold water, I’m tough and resilient, I feel better about myself”), that could be a real positive for you, and beneficial if it improves your work productivity or motivates you to get back out and exercise some more. 

Other potential benefits of cold exposure, but of unclear value

Cold exposure ups your metabolism: While it’s true that exposure to cold increases the body's metabolic rate as it fights to generate heat, this does not mean that it helps you burn more calories than you take in. In other words, don’t count on it as an aid to a weight loss program. Cold immersion may boost your metabolic rate about 3-4x above your resting rate, but compare that with exercise, which boosts your metabolic rate by as much as 50 times (for a long cycle ride). Furthermore, as explained in a 2023 Nature study, it could be skeletal muscle thermogenesis, rather than the stimulation of thermogenic adipose tissue brought on by cold exposure, that elicits weight-loss benefits in humans.

Cold exposure amps up your circulation, i.e., stimulates blood flow, which is generally good for your overall health. However, a 10-minute walk does that, too.

Cold exposure may impact your immune system: But do these impacts translate into significant improvements in any medical outcomes? The research remains unclear. While many studies have shown that short-term stress reactions triggered by a single CWI can rapidly alter the numbers and proportions of leukocytes, others have not. A just-published 2023 study failed to find any relevant effects of 3-week repeated CWI on leukocyte counts in healthy men. In addition, several studies have pointed out the difficulty of separating the effects of swimming and/or exercise before, during or after CWI. Acute exercise and cold exposure are both complex physiological conditions that stimulate a stress response, and their combined effects may exceed the individual effects of either stimulus.

Cold exposure may improve short-term mood, but its impact upon major depressive symptoms and other, more chronic mental health or neurodegenerative disorders is far from clear.

Cold exposure may have certain positive cardiovascular implications, as it has been shown that those who engage in repeated CWI (like cold-water swimmers) “adapt” somewhat to the initial blood pressure response of cold exposure if they undergo it repeatedly. Other studies have shown benefits to lipoprotein parameters and antioxidative markers. However, the overall effects of repeated CWI and cold adaptation on cardiovascular health have not been clarified; and it also remains uncertain how much of an effect the movement (i.e. exercise!) in the water is producing the effects, rather than the cold temperature. 

Cold exposure has certain positive implications for glucose homeostasis in insulin resistant individuals: However, we’re going to say right up front that the jury is still out on cold therapy for those with diabetes, for several reasons. First, while cold exposure may be a potential therapy for diabetes by increasing brown adipose tissue (BAT) mass and activity (2015 Nature study), its contribution appears limited (2023 Nature review paper) and underlying mechanisms remain to be fully established. Furthermore, balancing the benefits and drawbacks for diabetics is a daunting task: While researchers have found that blood sugar levels can be reduced after 30 minutes of cold-water immersion, people with diabetes — if their blood sugars are significantly elevated at a given time — could be at significant risk of hypoglycemia from cold therapy and thus should not undergo it. On the other hand, cold water swimming can be good for diabetes as some symptoms of the disorder can be negated by swimming and other water sports. And yet, here, too, potential adverse reactions to cold water and ill effects from low blood sugar need to be considered and carefully monitored. In addition, while the analgesic impact of cold exposure therapies may benefit individuals with diabetes who are looking for another way to manage pain associated with diabetic neuropathy, that very neuropathy may impede a diabetic from objectively assessing cold-produced tissue damage, as we discuss in the Risks section, below. (Parenthetically, some research studies point to potentially safer benefits from heat therapy, including sauna or hot-tub bathing, for those with diabetes; a 2022 cross-sectional  study of nearly 1,300 subjects with type 2 diabetes who regularly underwent hot-tub bathing found slight improvements in glycemia, obesity and diastolic blood pressure.)

What can’t cold exposure do?

For athletes, the initial relief from muscle soreness that cold exposure does promote following athletic activities seems quite real. However, measurements of improved function and athletic performance relating directly to cold exposure have been a lot harder to prove. A 2014 study could not correlate the initial muscle soreness relief from WBC with enhanced functional recovery, noting that local ice-pack application or CWI may offer comparable physiological and clinical effects to WBC.

Of greater concern to athletes involved in anaerobic activities, such as weight lifting, a number of studies (such as this 2022 meta-analysis) have determined that chronic, repeated cold exposure can impair strength adaptations, meaning that while cold therapy may reduce initial muscle soreness, it ultimately may mitigate muscle growth and decrease fatigue resistance following resistance training. Researchers explain that the reduction in inflammation brought on by cold exposure, which is what relieves muscle soreness short-term, might actually hinder muscle growth over the longer term. This effect was also observed in a 2021 study, which found that the regular use of CWI associated with exercise programs has a deleterious effect on resistance training adaptations, but does not appear to affect aerobic exercise performance. Another 2021 study, similarly, determined that “although post-exercise CWI may enhance short-term recovery following resistance exercise, current evidence suggests CWI has either nil or detrimental effects on physiological adaptations to resistance training, including muscle hypertrophy and measures of maximal strength, strength endurance, and power/RFD, as well as the molecular responses that underpin adaptation to resistance training in skeletal muscle.”

Meanwhile, other scientists caution that even locally-administered cold on the specific muscles you may be using in an anaerobic activity, e.g., cold packs on your quads, can only do so much for performance (defined as the ability to continue to “work,” i.e. use your muscles effectively, or at all) because your body is such a good insulator. The only way heat can leave your muscles is via the blood. Furthermore, as Dr. Heller has explained, cold towels on your neck or near or on your head may be even less effective, as they just “cool the thermostat” that resides in your brain, tricking you (because it may feel good) into thinking that you’ve cooled down, when your core body temperature may have not, or not enough.

Athletes and exercise aside, as to potential health benefits for all of us, the jury really is still out on most of them. Some studies have found improved “biomarkers” or other such indicators of improved health metrics, but significant changes in actual medical outcomes have not been well documented. We’ve already discussed the questionable import of cardiovascular and metabolic impacts, and the debatable long-term impact upon immunity in general and cognitive/mental health generally. Some tout a link between cold exposure and improved sleep quality, but again the relationship is unclear. While a drop in external body temperature can initiate the body's natural preparation for sleep, leading to deeper and more restful sleep, remember also that your body actually starts heating up after cold exposure; and that heating-up process can keep you awake! (Thus, it is ill-advised to undergo cold exposure close to your bedtime.)

Risks associated with cold exposure

Always consult with a healthcare provider before you begin any new health regimen, including cold exposure. As Cedars-Sinai orthopedist Tracy Zaslow, MD remarks, “Cold-water immersion is not a completely benign activity. Talk to your doctor to make sure that no harm comes from a fun activity that is intended to help your health.” Risks associated with cold exposure include frostbite, hypothermia, heart arrhythmias and even heart attacks. Impaired cognitive function, such as clouded thinking and decision-making, can also result.

• Individuals with known cardiac or pulmonary disease should steer clear of cold water immersion, given the immense burden placed on these body systems.
• Individuals with diabetes may also want to consider avoiding cold plunging as diabetes can impact one’s ability to sense tissue damage, especially if there is a significant degree of pre-existing neuropathy (nerve disease) in the legs or feet. Furthermore, those with diabetes face unique risks of hypoglycemia that can be induced by sudden temperature changes.
• Individuals who are prone to allergy symptoms triggered by cold should also avoid cold exposure therapies.
• Additionally, experts recommend never cold plunging alone, as the rare but still possible loss of muscular control can potentially lead to drowning.

As to WBC, the dry-cold chamber therapy, escalating claims of its benefit and rising popularity has led the FDA to warn consumers that, "If you decide to try WBC, know that the FDA has not cleared or approved any of these devices for medical treatment of any specific medical conditions."

Some basic guidelines for starting the practice of cold exposure

If you get a green signal from your medical provider, start small. You could begin with cold showers, gradually reducing the temperature each day as your body adjusts to the cold. Remember, the idea is not to cause discomfort or pain, but to stimulate the body's response to cold. Listen to your body and do not push beyond your comfort levels.

If you're moving towards advanced techniques like ice baths or whole-body cryotherapy, follow proper guidelines and professional supervision. Limit your exposure time and always gradually acclimate your body to the cold temperature changes.

Key takeaways

Cold exposure is an area of therapeutic interest (particularly among athletes), and as a “recovery therapy,” cold exposure techniques have clear merit for reducing muscle soreness after extreme exertion. Whether those benefits translate into longer-term improvements in physical performance remains under study. For endurance athletes, the benefit of cooling down before lengthy aerobic sessions appears to promise distinct advantages. For athletes engaged in resistance training, or anaerobic activities, the short-term muscle soreness relief from cold exposure is also distinct, and yet studies have raised the issue of whether repeated cold exposure following exercise might hinder muscle building over the long term. Novel approaches to cold therapy during training or exercise, while logistically challenging, hold promise. Exercise aside, cold exposure is a wellness fad that appears to make some individuals more alert and in a better mood, although touted health benefits ranging from improved immunity to weight loss to a cure for depression seem quite far-fetched and unfounded.