IntroductionSince centuries, people have been practicing cold exposure. In Scandinavia, for instance, the practice of winter swimming is very popular since many years. Athletes have, for years, taken advantage of the benefits of cold exposure for recovery after training and competition. But, is cold exposure an esoteric tool to be used by a select few? Or can everyone partake of the benefits of cold exposure?This article will attempt to simplify some of the concepts of deliberate cold exposure. In addition, It will try to distill some of the available evidence and suggest some strategies that could help us all in optimising this concept for improving health.Cold wars at home!Let me begin with a war that each of us have fought again and again. This war is on our home turf. Yes, in our home! It relates to the speed of the ceiling fan. Family members don't agree on a lot of things, including room temperature. Some always want the ceiling fan at the highest speed- but others feel cold and need to wear sweaters even as the former bask in the fastest-swirling-fan and its air current.That this is a common phenomenon. It turns out that men are more comfortable at 21°C, while a thermo-comfortable environment of women is around 24°C. Thus the temperature and our adaptation to it is a real and relevant phenomenon.Is temperature adaptation important?At this point, it might be important to look at the phenomenon called "hormesis", which can be simply described as" what doesn't kill you only makes you stronger", as the adage goes. This has been noted in a variety of settings. A minor stress, and overcoming the same helps one to be ready when a major stress occurs.During medical school, for instance, periodic tests are used to prepare would-be doctors well when the final examination comes. Another example is the heart. In the heart small, frequent, minor blockages to blood vessels open up alternate channels blood supply (called collateral supply) to improve the blood supply to the heart. This phenomenon, referred to as" ischemic preconditioning" protects people from a major catastrophe when a sudden blockage to a major blood vessel occurs, reducing mortality in this setting.Similarly, when we are exposed to fluctuation in atmospheric temperature, it has been argued that our system emerges stronger.What happens during cold exposure?When our body is suddenly exposed to cold, there is a release of noradrenaline which is a stress hormone. What are stress hormones? These hormones alert us about danger-and increases our blood pressure, heart rate, focus and mental alertness. Part of the benefits of cold exposure come from this stress response. However-prolonged stress can be exhausting. Hence it is important to restrict the duration of cold exposure.But the most important benefit of cold exposure is because cold exposure can activate and increase" brown fat". This type of fat is beneficial because it helps release of energy as heat.Brown fat is associated with weight-loss and better metabolic health, as well as a reduction in insulin resistance. Insulin resistance has been associated with Type 2 Diabetes and cardiovascular disease and therefore improving insulin resistance is beneficial.In addition to all this, exposure to cold can release dopamine-a molecule that increases happiness and combats depression. Hence the benefits of cold exposure could benefit mental health as well.Is your internal suit brown?To understand cold exposure better, it is important to know about 3 types of fat: white, brown and beige.White fat: as adults, most of the fat in our body is white fat, so called because of its color under a microscope. While white fat insulates us from cold, too much white fat makes us obese. Storage is the main function of white fat.Brown fat: children have more of this type of fat, which looks brown under a microscope. We adults have it at specific sites, like around the neck. Brown fat is smaller, but burns more energy. Brown fat helps in maintaining the body temperature by dissipating energy as heat. Brown fat also improves blood glucose control and regulates fat in the body. The main function of brown fat is temperature regulation.Beige fat: beige fat is a combination of white fat and brown fat. It regulates temperature but also aids in" browning" of the white fat.A common question that is asked is: why does fat appear white or brown? The answer is probably that brown fat contains a lot of mitochondria, which are the energy producing subunits of the cell. Mitochondria contain iron which impart a brown color.Thus, brown fat is a healthier type of fat- and we can increase brown fat by adding cold exposure. Brown fat is activated by cold, just before we start shivering. Taking a cold shower can also activate brown fat..Science behind cold exposureIt is said that cold exposure can increase the levels of norepinephrine-a stress hormone and a brain neurotransmitter. Norepinephrine can increase the production of mitochondria-and thus help in brown adipose tissue, which helps in glucose control and weight management. In addition, cold exposure provides a minor stress to the body making it eventually stronger.Thirdly cold exposure reduces inflammation- which is well known to be deleterious. By lowering the temperature, muscular recovery after injury improves and muscle pains reduce. The release of norepinephrine and dopamine in the brain improves mood and boosts focus.Finally, the body, on exposure to cold, creates methods to produce heat via both shivering and non-shivering mechanisms to improve body temperature and raise it to normal.Clinical research evidence for deliberate cold exposureSome of the critically important studies of cold exposure in humans have come from Scandinavia, where winter swimming is part of the culture. Critical work in this regard has been carried out by Dr Susanna Soberg and team.Soberg and colleagues studied the classic Scandinavian swimming tradition, which combines hot sauna sessions with brief dips in very cold water. The researchers found that brief exposure to cold about 11 minutes per week has benefits on activation of brown fat as well as blood glucose and metabolic health.Winter swimmers had a lower body fat percentage too. In an article in the Journal of Sports Medicine (2022), researchers Emma Moore and colleagues report that cold exposure provides substantial recovery for athletes after training or competition. Exposure to cold facilitated recovery from pain as well as muscle soreness and helped in rejuvenation..Concerns about cold exposureFrom Norway, Espeland and colleagues have extensively reviewed the benefit and risks of cold exposure. A major, albeit rare side effect is the occurrence of a sudden cardiac shock on exposure. Overall the acute(immediate) response to cold is called cold shock response and varies in severity- bearable to most people.Another side effect is that of hypothermia which is a dangerously dipping body temperature. Hypothermia could result in loss of consciousness or even death.In addition to cardiac and respiratory effect of cold-sometimes cold exposure can lead to sudden even narrowing of blood vessels to the legs and toes. These parts of the body may turn black and even wither away. This is referred to as frostbite causing gangrene.In people with Diabetes, who already may have a compromised blood supply-there may be a special risk of frostbite and gangrene. Changes in blood pressure could also occur and could have adverse health consequences.Benefits of cold exposureIn addition to the metabolic benefits, cold exposure may have beneficial effects on immunity, reducing inflammation and on the gut microbiome. Cold exposure may also function as an antioxidant and antidepressant.Modalities of cold exposureCold water immersion: this involves submerging one's body in water, typically at or below 15°C or 59°F.Local cryotherapy: this involves placing ice packs on inflamed/ painful areas of the body specially joints and muscles.Whole body cryotherapy: this modality involves exposure to cold air for a few minutes at -178°C or 289°F wearing protective garments in the extremities.Cryotherapy chambers are usually colder than water because the rate at which temperature is transferred is higher in air than in water: the thermal conductivity of air is 25 times lesser than water. The simplest method of cold exposure, that everyone can do is taking a very cold shower. Cold water swimming is another alternate method.To concludeConsider doing cold exposure for about a total period of 11 minutes/week. Two to four such sessions can be distributed over a week with a total duration of 11 minutes. The water should be uncomfortably cold yet should be safe for the body.If you are alternating between a hot and a cold shower, then it is better to end with a cold shower. Allowing the body to shiver may enhance the metabolic benefit of cold exposure according to Prof. Huberman of Stanford university. Shivering not only releases energy, but can also lead to brown fat thermogenesis.After the cold shower, it is important not to cross arms or immediately use a towel to water off, so that the body can reheat naturally. Also, after training, wait for 6- 8 hours before cold exposure.Early morning cold exposure is an ideal time. Short burst of cold showers (3-5 minutes) are better.Cryotherapy and cold plunge are relatively newer methods of cold exposure. Studies on the same are limited. Both are technologies that look at giving a short period of cold exposure to maximize benefits.In a study from France, Hausswirth and colleagues reported that whole body cryotherapy was associated with a quicker recovery from athletic-induced muscle damage in runners.Cold plunge tubs and cold plunge pools are a fad in some parts of the world. Both allow cold immersion with clean water and require very little day to day maintenance. Cold plunge technology is not available in IndiaSummaryWhile the benefits of cold exposure are wide ranging and exciting, at present much more needs to be done to generate scientific evidence. If the benefits are proven in more extensive studies then cold exposure might become a more important tool against obesity, Diabetes, inflammation, depression and other diseases.
IntroductionSince centuries, people have been practicing cold exposure. In Scandinavia, for instance, the practice of winter swimming is very popular since many years. Athletes have, for years, taken advantage of the benefits of cold exposure for recovery after training and competition. But, is cold exposure an esoteric tool to be used by a select few? Or can everyone partake of the benefits of cold exposure?This article will attempt to simplify some of the concepts of deliberate cold exposure. In addition, It will try to distill some of the available evidence and suggest some strategies that could help us all in optimising this concept for improving health.Cold wars at home!Let me begin with a war that each of us have fought again and again. This war is on our home turf. Yes, in our home! It relates to the speed of the ceiling fan. Family members don't agree on a lot of things, including room temperature. Some always want the ceiling fan at the highest speed- but others feel cold and need to wear sweaters even as the former bask in the fastest-swirling-fan and its air current.That this is a common phenomenon. It turns out that men are more comfortable at 21°C, while a thermo-comfortable environment of women is around 24°C. Thus the temperature and our adaptation to it is a real and relevant phenomenon.Is temperature adaptation important?At this point, it might be important to look at the phenomenon called "hormesis", which can be simply described as" what doesn't kill you only makes you stronger", as the adage goes. This has been noted in a variety of settings. A minor stress, and overcoming the same helps one to be ready when a major stress occurs.During medical school, for instance, periodic tests are used to prepare would-be doctors well when the final examination comes. Another example is the heart. In the heart small, frequent, minor blockages to blood vessels open up alternate channels blood supply (called collateral supply) to improve the blood supply to the heart. This phenomenon, referred to as" ischemic preconditioning" protects people from a major catastrophe when a sudden blockage to a major blood vessel occurs, reducing mortality in this setting.Similarly, when we are exposed to fluctuation in atmospheric temperature, it has been argued that our system emerges stronger.What happens during cold exposure?When our body is suddenly exposed to cold, there is a release of noradrenaline which is a stress hormone. What are stress hormones? These hormones alert us about danger-and increases our blood pressure, heart rate, focus and mental alertness. Part of the benefits of cold exposure come from this stress response. However-prolonged stress can be exhausting. Hence it is important to restrict the duration of cold exposure.But the most important benefit of cold exposure is because cold exposure can activate and increase" brown fat". This type of fat is beneficial because it helps release of energy as heat.Brown fat is associated with weight-loss and better metabolic health, as well as a reduction in insulin resistance. Insulin resistance has been associated with Type 2 Diabetes and cardiovascular disease and therefore improving insulin resistance is beneficial.In addition to all this, exposure to cold can release dopamine-a molecule that increases happiness and combats depression. Hence the benefits of cold exposure could benefit mental health as well.Is your internal suit brown?To understand cold exposure better, it is important to know about 3 types of fat: white, brown and beige.White fat: as adults, most of the fat in our body is white fat, so called because of its color under a microscope. While white fat insulates us from cold, too much white fat makes us obese. Storage is the main function of white fat.Brown fat: children have more of this type of fat, which looks brown under a microscope. We adults have it at specific sites, like around the neck. Brown fat is smaller, but burns more energy. Brown fat helps in maintaining the body temperature by dissipating energy as heat. Brown fat also improves blood glucose control and regulates fat in the body. The main function of brown fat is temperature regulation.Beige fat: beige fat is a combination of white fat and brown fat. It regulates temperature but also aids in" browning" of the white fat.A common question that is asked is: why does fat appear white or brown? The answer is probably that brown fat contains a lot of mitochondria, which are the energy producing subunits of the cell. Mitochondria contain iron which impart a brown color.Thus, brown fat is a healthier type of fat- and we can increase brown fat by adding cold exposure. Brown fat is activated by cold, just before we start shivering. Taking a cold shower can also activate brown fat..Science behind cold exposureIt is said that cold exposure can increase the levels of norepinephrine-a stress hormone and a brain neurotransmitter. Norepinephrine can increase the production of mitochondria-and thus help in brown adipose tissue, which helps in glucose control and weight management. In addition, cold exposure provides a minor stress to the body making it eventually stronger.Thirdly cold exposure reduces inflammation- which is well known to be deleterious. By lowering the temperature, muscular recovery after injury improves and muscle pains reduce. The release of norepinephrine and dopamine in the brain improves mood and boosts focus.Finally, the body, on exposure to cold, creates methods to produce heat via both shivering and non-shivering mechanisms to improve body temperature and raise it to normal.Clinical research evidence for deliberate cold exposureSome of the critically important studies of cold exposure in humans have come from Scandinavia, where winter swimming is part of the culture. Critical work in this regard has been carried out by Dr Susanna Soberg and team.Soberg and colleagues studied the classic Scandinavian swimming tradition, which combines hot sauna sessions with brief dips in very cold water. The researchers found that brief exposure to cold about 11 minutes per week has benefits on activation of brown fat as well as blood glucose and metabolic health.Winter swimmers had a lower body fat percentage too. In an article in the Journal of Sports Medicine (2022), researchers Emma Moore and colleagues report that cold exposure provides substantial recovery for athletes after training or competition. Exposure to cold facilitated recovery from pain as well as muscle soreness and helped in rejuvenation..Concerns about cold exposureFrom Norway, Espeland and colleagues have extensively reviewed the benefit and risks of cold exposure. A major, albeit rare side effect is the occurrence of a sudden cardiac shock on exposure. Overall the acute(immediate) response to cold is called cold shock response and varies in severity- bearable to most people.Another side effect is that of hypothermia which is a dangerously dipping body temperature. Hypothermia could result in loss of consciousness or even death.In addition to cardiac and respiratory effect of cold-sometimes cold exposure can lead to sudden even narrowing of blood vessels to the legs and toes. These parts of the body may turn black and even wither away. This is referred to as frostbite causing gangrene.In people with Diabetes, who already may have a compromised blood supply-there may be a special risk of frostbite and gangrene. Changes in blood pressure could also occur and could have adverse health consequences.Benefits of cold exposureIn addition to the metabolic benefits, cold exposure may have beneficial effects on immunity, reducing inflammation and on the gut microbiome. Cold exposure may also function as an antioxidant and antidepressant.Modalities of cold exposureCold water immersion: this involves submerging one's body in water, typically at or below 15°C or 59°F.Local cryotherapy: this involves placing ice packs on inflamed/ painful areas of the body specially joints and muscles.Whole body cryotherapy: this modality involves exposure to cold air for a few minutes at -178°C or 289°F wearing protective garments in the extremities.Cryotherapy chambers are usually colder than water because the rate at which temperature is transferred is higher in air than in water: the thermal conductivity of air is 25 times lesser than water. The simplest method of cold exposure, that everyone can do is taking a very cold shower. Cold water swimming is another alternate method.To concludeConsider doing cold exposure for about a total period of 11 minutes/week. Two to four such sessions can be distributed over a week with a total duration of 11 minutes. The water should be uncomfortably cold yet should be safe for the body.If you are alternating between a hot and a cold shower, then it is better to end with a cold shower. Allowing the body to shiver may enhance the metabolic benefit of cold exposure according to Prof. Huberman of Stanford university. Shivering not only releases energy, but can also lead to brown fat thermogenesis.After the cold shower, it is important not to cross arms or immediately use a towel to water off, so that the body can reheat naturally. Also, after training, wait for 6- 8 hours before cold exposure.Early morning cold exposure is an ideal time. Short burst of cold showers (3-5 minutes) are better.Cryotherapy and cold plunge are relatively newer methods of cold exposure. Studies on the same are limited. Both are technologies that look at giving a short period of cold exposure to maximize benefits.In a study from France, Hausswirth and colleagues reported that whole body cryotherapy was associated with a quicker recovery from athletic-induced muscle damage in runners.Cold plunge tubs and cold plunge pools are a fad in some parts of the world. Both allow cold immersion with clean water and require very little day to day maintenance. Cold plunge technology is not available in IndiaSummaryWhile the benefits of cold exposure are wide ranging and exciting, at present much more needs to be done to generate scientific evidence. If the benefits are proven in more extensive studies then cold exposure might become a more important tool against obesity, Diabetes, inflammation, depression and other diseases.
