Cold Exposure & Other Mild Stressors for Increased Health & Longevity

[Todd Allen]

4 hours ago, Sibiriak said:

allow me to post a long quote from the murdered journalist Paul Klebnikov

Sibiriak, thanks for posting Klebnikov's piece.  While we fret about longevity perfection debating the uncertainty underlying our beliefs of optimal diet, supplements and lifestyle factors it is good to be reminded that societal, environmental and other factors outside our individual control deserve utmost respect. 

Living in Chicago I can't help but wonder how much of Russia's suffering was instigated by the celebrated Nobel prize winning free market economists of the University of Chicago.  One thing your article didn't mention is that despite so much poverty Russia is the largest nation by land and perhaps wealthiest nation with respect to natural resources but during that period the wealth was increasingly extracted into the pockets of a small elite.

The pendulum between public and private wealth and power also swings in the US and it isn't unimaginable we might spiral into an extreme situation not so unlike what Russia has been through.  Also concerning is the likelihood in periods of increasing instability the hawks find less resistance to the options of belligerence and war.  With so many  potential catastrophes such as hundreds of nuclear reactors accumulating decades of nuclear waste all out war could make our pursuit of ideal diet and factors such as cold exposure somewhat irrelevant to our common goal of longevity.   Despite the ongoing escalation of demonization of Russia and Putin in our popular media I'm impressed and thankful for Russia's fairly competent handling of the unending series of provocations in places such as the Ukraine and Syria by the US and the lackeys of NATO.  

[Gordo]

While I'm quite interested in discussing how to prepare for and survive economic collapse and what can cause it (socialist governments and out of control debt and/or corruption for example) I vote for moving off topic discussion to a new thread "Doomsday Preppers"

[Dean Pomerleau]

CR Extends Life More In Rodent Strains that Maintain Higher Body Temperature

The last time I discussed this study [1], I failed to notice or mention a very interesting finding related to the combination of CR and CE.

In [1], researchers tested 32 different strains of mice to determine how much their longevity benefited from 40% CR. They found that strains that benefited the most from CR had the least drop in body temperature when subjected to CR at normal (chilly-for-mice) housing temperature. The strains that most benefited from CR were also the ones that maintained the most body fat. They didn't report how much of the retained fat was thermogenic (i.e. brown or beige), but given that rodents preferentially retain brown (vs. white) fat when subjected to CR and the longer lived strains on CR were better able to maintain their body temperature, it seems a pretty safe bet that much of the retained fat was thermogenic.

Here is the way the authors put it in [1]:

Interestingly, reduction of body temperature was also a negative predictor of life extension in this study (r = −0.47, P = 0.008, n = 31 strains; females; males were not studied in the earlier report): strains with the greatest reduction in body temperature were at greatest risk for life shortening and those maintaining higher body temperature were more likely to have extended lifespan under [C]R. 

This would seem to support the idea of a synergy between CR and an effective response to cold exposure. When subjected to the combination CR and chilly housing conditions, those mice that were best able to maintain their body temperature lived the longest. This jibes with the fact that longest lived of all mice strains (the dwarfs) are BAT and thermogenic superstars, leading to metabolic advantages that are erased in thermoneutral housing conditions as discussed here and here.

--Dean

-------

[1] Aging Cell. 2011 Aug;10(4):629-39. doi: 10.1111/j.1474-9726.2011.00702.x. Epub

2011 Apr 25.

Fat maintenance is a predictor of the murine lifespan response to dietary
restriction.

Liao CY(1), Rikke BA, Johnson TE, Gelfond JA, Diaz V, Nelson JF.

Author information: 
(1)Department of Physiology, University of Texas Health Science Center, San
Antonio, TX 78229, USA.

Dietary restriction (DR), one of the most robust life-extending manipulations, is
usually associated with reduced adiposity. This reduction is hypothesized to be
important in the life-extending effect of DR, because excess adiposity is
associated with metabolic and age-related disease. Previously, we described
remarkable variation in the lifespan response of 41 recombinant inbred strains of
mice to DR, ranging from life extension to life shortening. Here, we used this
variation to determine the relationship of lifespan modulation under DR to fat
loss. Across strains, DR life extension correlated inversely with fat reduction, 
measured at midlife (males, r= -0.41, P<0.05, n=38 strains; females, r= -0.63,
P<0.001, n=33 strains) and later ages. Thus, strains with the least reduction in 
fat were more likely to show life extension, and those with the greatest
reduction were more likely to have shortened lifespan. We identified two
significant quantitative trait loci (QTLs) affecting fat mass under DR in males
but none for lifespan, precluding the confirmation of these loci as coordinate
modulators of adiposity and longevity. Our data also provide evidence for a QTL
previously shown to affect fuel efficiency under DR. In summary, the data do not 
support an important role for fat reduction in life extension by DR. They suggest
instead that factors associated with maintaining adiposity are important for
survival and life extension under DR.

© 2011 The Authors. Aging Cell © 2011 Blackwell Publishing Ltd/Anatomical Society
of Great Britain and Ireland.

DOI: 10.1111/j.1474-9726.2011.00702.x 
PMCID: PMC3685291
PMID: 21388497  [Indexed for MEDLINE]
 

[Gordo]

https://selfhacked.com/blog/12-reasons-embrace-cold/#comments

 

12 Proven Benefits of Cold Exposure & Cold Showers

By Josh Finlay

 

Reviewed By Joe Cohen, BS

 

Last updated: July 10, 2019

 

 

Evidence Based

4.5/5

8

 

From freezing showers to cryotherapy tanks, cold exposure is in vogue amongst health-conscious people. And rightly so; simple practices that can enhance nervous system health, decrease inflammation and promote longevity are rare.

In this article, we will explore the scientific research to uncover the many benefits of getting cold. We will also touch on the best ways to approach cold exposure as, whilst we should embrace the cold, we need to be aware of its power.

 

What is Cold Therapy?

Cold therapy is not a new invention; it is among man’s earliest medical treatments. The Edwin Smith Papyrus (3500 BC), the most ancient medical text, repeatedly mentioned cold therapy [1].

However, until the late 1980s, cold exposure remained relatively unappreciated by modern, allopathic medicine [1].

More recently, cold therapy has been increasingly used to prevent or mitigate various types of neurologic injury [2].

Even so, the numerous benefits of cold therapy remain relatively untapped by conventional healthcare practitioners. Hopefully, this article will give you an insight into how you can leverage cold exposure to optimize your health and performance.

Benefits of Cold Exposure

1) Aids Fat Loss

Location and control of brown adipose tissue [3].

Humans have stores of active brown fat tissue (BAT). Unlike white fat, which stores energy and comprises most body fat, brown fat is active in burning calories and using energy [4].

BAT can essentially turn calories from food into heat. It generates heat by uncoupling proteins, particularly UCP1, within the mitochondrial membrane [5, 6].

Indeed, studies show that cold exposure increases BAT activity which leads to increased calorie expenditure. Researchers concluded that frequent cold exposures might be an acceptable and economical way to address the current obesity epidemic [7].

In fact, a lack of BAT has been linked with obesity [8].

Cold exposure increase shivering and non-shivering thermogenesis. These processes increase calorie expenditure [9].

One study exposed one group of mice to cold temperatures and the other to normal temperatures. The cold-exposed mice ate far more calories but weighed less [10]. This goes against the prevailing view that increased calorie consumption shortens lifespan.

Exposure to cold temperatures leads to increased levels of adiponectin, a protein that increases fat burning. Low levels of which are associated with obesity [11, 12, 13].

In one study, subjects who were exposed to cold stress had an 80% increase in their metabolismover “warm” levels [14].

If you want to maximize your brown fat levels you should take things with capsinoids, like chili extract. The bitter melon extract also works synergistically with the cold to create more brown fat [15].

2) Fights Inflammation

Exposure to cold temperatures raises adiponectin, a protein that helps prevent inflammation [16].

Another study found that exercising in the cold reduced the inflammatory response seen in regular temperature environments [17].

This same study found that exercising past a certain time in the cold can actually increase the inflammatory response [17]. The dose is important! More on this below.

Cold exposure can lower pro-inflammatory TNF-α, IL-6, and IL-8.

3) Increases Lifespan

A study found that flies lived twice as long when kept at 21°C than 27°C [18].

Similarly, research on worms found that a 5 °C drop in temperature increased lifespan by 75% [19].

A number of studies on insects have also found a negative relationship between temperature and lifespan [20, 21, 22].

Fish also seem to live longer at lower temperatures [23]. For example, one study showed that 6 °C drop in temperature increased average fish lifespan by 75 % [24].

In 1986, one researcher immersed his lab rats in shallow, cool water for four hours per day. The rats burned so many extra calories that they ate 50% more than control rats. The cold-exposed rats weighed less than the control rats and lived 10% longer [10]. This goes against the prevailing view that increased calorie consumption shortens lifespan.

Another study lowered the core temperature of mice by 0.3 °C (males) and 0.34 °C (females), resulting in an increase in the average lifespan of 12 and 20 % respectively [25].

Increased longevity via cold-exposure could be due to hormesis. Hormesis refers to the paradoxical adaptation that makes animals stronger and more efficient if they are exposed to environmental stresses [26].

Other researchers prefer the ‘rate of living hypothesis’. This theory suggests that lower temperature promotes longevity by slowing down the rate of reaction of various metabolic processes. This means fewer by-products of metabolism, such as reactive oxygen species (ROS) [6].

Alternatively, increased longevity from cold exposure may be due to a modulation of genes, such as TRPA-1 and DAF-16 [27].

4) Strengthens the Nervous System

The increase in fat burning during cold exposure is modulated by the sympathetic nervous system [28, 29]. Cold temperatures act as a mild workout for the nervous system, which adapts and strengthens.

Wim Hoff (“the Iceman”) has been instrumental in showing the world that, through specific training techniques using cold exposure and breathwork, a person is able to control their autonomic nervous system. Before this research was done on Wim, the autonomic nervous system was largely thought to be beyond conscious control.

5) May Heal Injuries and Speed Recovery

The physiological effects of cold therapy include reductions in blood flow, swelling, inflammation, muscle spasm, and metabolic demand [30].

There is some evidence that ice plus exercise is effective at increasing healing speeds after an ankle sprain or surgery [31].

Cold exposure has a positive effect on muscular enzymes linked to muscle damage (e.g. creatine kinase and lactate dehydrogenase) [32].

One meta-study looked at 360 people who either rested or submerged themselves in cold water after resistance training, cycling or running. 24-minute cold water baths (50 – 59 °F) prevented sore muscles after exercises [33].

6) Regulates Blood Sugar Levels

Exposure to cold temperatures can increase levels of adiponectin. One study found adiponectin levels increase by 70% after cold exposure. This is important as adiponectin is a protein involved in blood glucose regulation, with low levels found in insulin resistance [12, 13].

In rat studies, cold exposure increases glucose uptake in the peripheral tissues – (by enhancing glucose oxidation via insulin-independent pathways). Thus, cold exposure may be beneficial during a fast, as fasting can cause peripheral insulin resistance [34].

Cold exposure can enhance the body’s response to insulin, allowing glucose to be cleared from the blood quicker [35]. A cold bath is one of the quickest ways I have found to lower my blood glucose and increase insulin sensitivity.

7) Improves Sleep Quality

Natural daily temperature fluctuations are an important regulator of sleep cycles [36].

A Dutch study found that by cooling core body temperatures, participants achieved double the restorative, slow wave sleep [37]. (**Gordo NOTE: Maybe he accidentally linked to the wrong study?  Not sure, but I don't come to his conclusion from this study.  They didn't really change core temps, they only very lightly manipulated outer skin temps but found sleep quality was improved with an increase in temps and worsened by cooling.  Its a very odd study though because they were cycling between cooling and heating, I don't think the quality of this study is very good.  In my own anecdote - I find that by cooling the core body temp before going to bed then just sleeping in normal conditions sleep improves, but for me anyway, doing cold exposure while trying to sleep reduces quality of sleep which I guess is inline with the cited study.  That said, I find sleeping in a very cold room, but with blankets, gets me the best sleep of all, which I guess is in line with the reference below)

The nonprofit National Sleep Foundation recommends keeping bedroom sleeping temperatures between 60 and 67 degrees F [38].

8 ) Strengthens the Immune System

Studies have shown that cold exposure increases natural killer cell count and activity.

Cold exposure also increases levels of white blood cells and circulating IL-6.

One study looked at the effects of 6 weeks of cold water immersion (14C for 1hr) on the immune system. Participants had increased levels of IL-6, CD3, CD4, CD8, activated T and B lymphocytes, suggesting a more active immune system [39].

Engaging in exercise before cold exposure enhances the immune stimulating effects of cold therapy.

Increased immune system function could be due to increased levels of adrenaline from cold exposure.

9) Enhances Detox Pathways

One study found that people who regularly swim in ice-cold water had relatively high levels of reduced glutathione, an antioxidant that’s vital for detoxing [40].

Cryotherapy can enhance antioxidant status, allowing the body to deal with free radicals more effectively [32].

10) Reduces Pain

Blasts of cold significantly improve the quality of life for patients suffering from phantom limb pain [41].

Cold compression therapy provides more pain relief than popular, alternative interventions [42].

Cold application alone may be effective in reducing pain associated with migraine attacks [43].

11) May Increase Bone Health

Some researchers have suggested that age-related decline in bone health is attributable to a loss in brown fat (discussed above). Thus, it stands to reason that regular cold exposure could be an important tool for maintaining bone health as we age [44].

12) Increases Will Power

This benefit is anecdotal and not backed by scientific research*

Many of my clients and I have noticed a huge increase in will-power from taking regular cold showers.

Nobody wants to get in a cold shower. Getting under freezing cold water every morning trains your brain to do things it doesn’t want to do if the rewards are big enough. This attitude then translates to other areas of your life.

Cold Therapy Suggestions

It is best to build up cold exposure gradually.

Start by turning your central heating down, and going for minimally (but legally) clothed walks. Then move on to cold showers. When comfortable with these you might be ready for cold baths and, finally, ice baths.

Cryotherapy (brief exposures to air temperatures below -100°C) is becoming more mainstream and, as a result, more affordable. However, at the moment there is insufficient evidence to suggest it offers advantages over traditional methods of cold exposure [32].

Edited July 19, 2019 by Gordo

[Sibiriak]

Quote

Todd Allen:  One thing your article didn't mention...

Actually,  that was just a small excerpt I copied from his book,  which covers many more topics.   You make a lot of good points and ask some important questions,  but of course this forum is not the place to discuss such issues.

[Dean Pomerleau]

Gordo wrote:

13 hours ago, Gordo said:

12 Proven Benefits of Cold Exposure & Cold Showers

https://selfhacked.com/blog/12-reasons-embrace-cold/#comments

Thanks Gordo. Nice summary, although it looks to me like they got one of the "proven benefits" backwards. The article says: 

A Dutch study found that by cooling core body temperatures, participants achieved double the restorative, slow wave sleep [37].

But reference [37] seems to say just the opposite. Namely:

By employing a thermosuit to control skin temperature during nocturnal sleep, we demonstrate that induction of a mere 0.4 degrees C increase in skin temperature, whilst not altering core temperature, suppresses nocturnal wakefulness (P<0.001) and shifts sleep to deeper stages (P<0.001) in young and, especially, in elderly healthy and insomniac participants. 

Looks like they need a bit more careful editing.

--Dean

----

[37]

1. Brain. 2008 Feb;131(Pt 2):500-13. doi: 10.1093/brain/awm315. Epub 2008 Jan 11.

Skin deep: enhanced sleep depth by cutaneous temperature manipulation.

Raymann RJ(1), Swaab DF, Van Someren EJ.

With ageing, an increasingly disturbed sleep is reported as a significant

complaint affecting the health and well-being of many people. The available
treatments for sleep disturbance have their limitations, so we have adopted a
different approach to the improvement of sleep. Since in animal and human studies
skin warming has been found to increase neuronal activity in brain areas that are
critically involved in sleep regulation, we investigated whether subtle skin
temperature manipulations could improve human sleep. By employing a thermosuit to
control skin temperature during nocturnal sleep, we demonstrate that induction of
a mere 0.4 degrees C increase in skin temperature, whilst not altering core
temperature, suppresses nocturnal wakefulness (P<0.001) and shifts sleep to
deeper stages (P<0.001) in young and, especially, in elderly healthy and
insomniac participants. Elderly subjects showed such a pronounced sensitivity,
that the induced 0.4 degrees C increase in skin temperature was sufficient to
almost double the proportion of nocturnal slow wave sleep and to decrease the
probability of early morning awakening from 0.58 to 0.04. Therefore, skin warming
strongly improved the two most typical age-related sleep problems; a decreased
slow wave sleep and an increased risk of early morning awakening. EEG frequency
spectra showed enhancement of low-frequency cortical oscillations. The results
indicate that subtle feedback control of in-bed temperature through very mild
manipulations could have strong clinical relevance in the management of disturbed
sleep especially in the elderly, who have an attenuated behavioural response to
suboptimal environmental temperature, which may hamper them from taking
appropriate action to optimize their bed temperature.

DOI: 10.1093/brain/awm315 
PMID: 18192289  [Indexed for MEDLINE]
 

[Sibiriak]

The Temperature Dependence of Sleep

Edward C. Harding, et al.

Front Neurosci. 2019; 13: 336.

PMID: 31105512

Full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6491889/

 

 

Quote

Abstract

Mammals have evolved a range of behavioural and neurological mechanisms that coordinate cycles of thermoregulation and sleep. Whether diurnal or nocturnal, sleep onset and a reduction in core temperature occur together. Non-rapid eye movement (NREM) sleep episodes are also accompanied by core and brain cooling. Thermoregulatory behaviours, like nest building and curling up, accompany this circadian temperature decline in preparation for sleeping. This could be a matter of simply comfort as animals seek warmth to compensate for lower temperatures. However, in both humans and other mammals, direct skin warming can shorten sleep-latency and promote NREM sleep. We discuss the evidence that body cooling and sleep are more fundamentally connected and that thermoregulatory behaviours, prior to sleep, form warm microclimates that accelerate NREM directly through neuronal circuits. Paradoxically, this warmth might also induce vasodilation and body cooling. In this way, warmth seeking and nesting behaviour might enhance the circadian cycle by activating specific circuits that link NREM initiation to body cooling. We suggest that these circuits explain why NREM onset is most likely when core temperature is at its steepest rate of decline and why transitions to NREM are accompanied by a decrease in brain temperature. This connection may have implications for energy homeostasis and the function of sleep.

 

Quote

[...] One mechanism by which mammals, and small rodents in particular, generate heat is through brown adipose tissue thermogenesis (BAT). This is also a key mechanism in regulating energy homeostasis. Uncoupling protein 1 (UCP-1) is a key component of thermogenesis in brown adipose tissue (BAT). It decouples the electron transport chain from the ATP-synthase, facilitating heat production through proton gradient dissipation, without ATP production, and compensatory metabolism (Cannon and Nedergaard, 2004). UCP-1 knockout mice have weakened homeostatic rebound following sleep deprivation. They also show a blunted sleep induction effect of warmer temperatures observed in control mice (Szentirmai and Kapas, 2014). Similarly, the β3-adrenergic receptor agonists, which activate BAT thermogenesis, usually induce sleep in control mice but this response is ablated in mice with chemical deafferentation of the BAT (Szentirmai and Kapás, 2017). These data suggest that UCP-1 mediated BAT thermogenesis is helpful in both recovery sleep (sleep following sleep deprivation) and NREM sleep induction. UCP-1 may also have a role facilitating NREM sleep during systemic inflammation (Szentirmai and Kapas, 2018). The heat generated by these mechanisms could activate the sensory receptors in the skin and so trigger NREM sleep (Harding et al., 2018).

 

Edited July 19, 2019 by Sibiriak

[Ron Put]

On 7/16/2019 at 7:02 PM, Gordo said:

So the non-human data carries no weight for you?  And the fact that we can observe the relationship between cold exposure and improved biomarkers in humans means nothing to you?

You keep going back to the fact that more people have heart attacks in the winter, which is true, but do you understand why?

... At this forum, we are a bunch of health fanatics (for the most part).  Vasoconstriction is not a problem if you don't have heart disease.  You too can avoid heart disease by eating a diet that isn't atherogenic.  If you have heart disease, don't do CE, but instead try to reverse it though diet (which can be done to some extent).

CE has been shown to improve/activate many biomarkers/pathways in humans: Adiponectin, Irisin, insulin sensitivity, mTOR, AMPK.  You don't think any of this can lead to better health or longer life?

Regarding temps in Austrailia, here's today's forecast for Sydney....

I am fully aware of many of the non-human, as well as human studies involving cold exposure. I am also aware that BAT is new and exciting shiny object, which draws all the attention in lab results.

What I am suggesting is that for me at least, the shine of these short term results is not quite enough to silence all the other questions about cold exposure and general health, and longevity in particular.

There are some clear negative consequences of cold exposure, including vasoconstriction and the resulting increase in blood pressure.

One may be healthy, but there is still a question of the wisdom of regularly causing arterial constriction, increasing blood pressure and circulating lipid particles and some proinflammatory cytokines, for hours at a time.

Yes, some of it may be offset by corresponding beneficial processes involved in thermogenesis in brown adipose tissue, but to me, it's a really mixed bag and it is far from clear that cold exposure benefits longevity in humans.

This is why I keep bringing up the fact that population studies do not support increases in longevity in  human populations in colder climates (arguably the opposite is seen). Such studies show clear evidence for CE benefits in certain other species, like mollusks, but not in humans. We can see longevity benefits in population studies for caloric restriction, plant-based low protein diets, smoking abstinence, moderate alcohol use, etc.. But generally, we see evidence that people die when it gets cold, at significantly higher rates than when it gets hot.

The reason I keep bringing this up is not to convert you, or Dean, into abandoning your cold vests, but because I am under the impression that this is a place for discussion and learning. I have learned from posts and studies I found here and adopted a number of behavioral changes in the few months I have lurked here, as I am certain others have.

Perhaps others can benefit from an open discussion on this topic, too.

On 7/17/2019 at 1:01 AM, Sibiriak said:

... Why are you repeating the joke? 

On a serious note,  in 2015, "the OECD [ Organisation for Economic Co-operation and Development ] attributed Russia's slow increase in life expectancy to 'the impact of the economic transition in the 1990s and a rise in risk-increasing behavior among men,' such as drinking and smoking. "....

Because while it was a quip about the longevity of Siberian construction workers, it is nevertheless valid, since in this case I compared it to a corresponding population (construction workers) in the warmer parts of Russia (some of which are poorer than Siberia).

Funny enough, I am familiar with both Russia and Australia. Believe me, Sydney is overall much warmer than Siberia, even though I am sure you can find the occasional day when the opposite is true. But this, or the economic and political woes of Russia, are hardly the point of this discussion. See above for what I consider to be the point.

Cheers.

Edited July 19, 2019 by Ron Put

[Gordo]

Ron, you know what else raises blood pressure and puts strain on the heart? Exercise!  Yup, people dropping like flies from it:

https://www.health.com/heart-disease/cardiac-arrest-gym-aed-bob-harper

 

Edited July 20, 2019 by Gordo

[Ron Put]

Gordo, I don't have to guess, I am well aware that during exercise the force of your heart's contractions increases in order to increase the supply of oxygen and your blood pressure elevates.

But I am also well aware that during exercise, your blood vessels dilate significantly (and more so in healthy people).

Cold exposure does exactly the opposite, it constricts and stiffens your blood vessels, while at the same time increasing blood pressure, the flow of lipids and inflammatory agents.

Add to this the generally greater length of cold exposure by CE aficionados, and you'll see why I am not convinced that CE offers long term health or longevity benefits in humans, despite the otherwise beneficial impact of thermogenesis in brown adipose tissue.

"Cardiovascular disease (CVD) is considered the primary cause of death in the developed world. Large scale epidemiological studies indicate that prevalence of hypertension along with adverse cardiovascular events peak during the winter months. Moreover, during the winter months outdoor activities and physical stressors such as exercise have been associated with higher cardiovascular mortality when compared to other periods of the year. Although low environmental temperatures have been implicated as the triggering factor for cardiovascular complications, the mechanisms on how cold exposure increase cardiovascular morbidity and mortality remain to be elucidated. However, new research suggests that cold exposure may induce increases in cardiac sympathetic activity, endothelial damage and increased arterial stiffness of central arteries."
https://clinicaltrials.gov/ct2/show/NCT01462591

Edited July 20, 2019 by Ron Put

[Gordo]

Exercise actually causes vasoconstriction as well.  If you've got plaque build up, that can be deadly, so a person should get that taken care of before doing CE or vigorous exercise.  For the rest of us, vasoconstriction (from exercise or CE) is probably a benefit as it likely helps prevent the accumulation of cholesterol or other substances that potentially compromise cardiovascular function.  It's like power-washing a dirty hose. But the first step is to fix the diet so you don't have plaque build up in the first place.

Edited July 20, 2019 by Gordo

[Ron Put]

Gordo, we are discussing healthy people without CVD here, right?

The redistribution of blood flow during exercise does result in vasoconstriction affecting non-exercising organs like your your gut, sexual organs or kidneys (normally those receive about 10-20% blood flow, but during strenuous exercise can drop as low as 1%), but it dilates your systemic vasculature (including arteries) to maintain mean arterial pressure and the vastly increased blood flow to your skeletal muscles (which goes from as low of 10% blood flow at rest to as high as 85% during exercise). 

But this constriction (non-exercising organs)/dilation (systemic vasculature) balance is very different than than the arterial constriction and stiffening during cold exposure.

Which is why believe in the long-term health or longevity benefits of (moderate) exercise, but am not convinced of the long term health or longevity benefits of CE.

Edited July 20, 2019 by Ron Put

[Ron Put]

My response to Gordo immediately above was a bit convoluted (I just reread it, since I was reading something else, which brought me back to this topic).

To summarize my argument: 
Cold exposure appears to have beneficial health effects, mainly as a result of thermogenesis in brown adipose tissue.
But when looking at the whole picture, the negatives of CE practiced for hours per day, even in healthy persons, may outweigh or at least negate such benefits.

Here are two studies which help explain what I see as fundamentally different effects exercise and cold exposure have on one's cardiovascular system, which I tried to summarize for Gordo above.

EXERCISE (in healthy subjects and smokers):

"Conduit arteries react with a flow-mediated dilation in response to whole-body exercise. The impairment of this vasodilation observed in smokers was strongly related to a decrease of endothelium-dependent dilation induced by forearm ischemia, indicating that endothelial dysfunction represents the underlying mechanism."
https://www.sciencedirect.com/science/article/pii/S0735109701015753

 

COLD EXPOSURE (in healthy subjects):

In summary, we have demonstrated that AI, a measure of wave reflection and indicator of systemic arterial stiffness, was significantly elevated after acute cold exposure. Brachial and central systolic pressures increased with cold exposure; however, the magnitude of the cold-induced change in central systolic pressure was greater than the change in brachial systolic pressure. This is attributable to cold-induced increases in wave reflection and stiffness of the arterial system and suggests that the magnitude of the hemodynamic response to cold exposure cannot be determined with traditional brachial cuff measurements. Cold exposure may increase myocardial oxygen demand through an increase in central systolic pressure secondary to increased arterial stiffness and wave reflection."
https://www.physiology.org/doi/full/10.1152/japplphysiol.01154.2005

[Gordo]

I did find some other studies that discuss CE damaging the cardiovascular system:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2826836/

Cardiovascular responses to cold exposure

Quote

Chronic or intermittent exposure to cold causes hypertension and cardiac hypertrophy in animals

Quote

 Therefore, it is important to study how cold temperatures cause cardiovascular diseases. Studies from our laboratory have shown that chronic exposure of rats to cold (5°C) for 1–3 weeks is accompanied by a significant elevation of resting (systolic, diastolic and mean) blood pressure (BP), tachycardia and cardiac hypertrophy (19–23). These signs characterize the development of the syndrome of hypertension during chronic exposure to cold, namely cold-induced hypertension (CIH). Chronic exposure to cold also induces hypertension in dogs, rabbits, sheep, and young oxen (24,25). The elevated BP of rats after 7 weeks of exposure to cold did not return to pre-cold exposure level even after discontinuance of cold treatment for 4 weeks (26). Thus, an elevation of BP induced by a longer period of cold exposure might not be reversible after return to a thermo-neutral temperature. Intermittent exposure of rats to cold also induced hypertension, with a sigmoid relationship between the hours per day exposed to cold and systolic BP (27). 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648808/

The years of life lost on cardiovascular disease attributable to ambient temperature in China

Quote

The change of ambient temperature was associated with human blood vessels’ contraction and may cause fluctuation of blood pressure. Literature has shown the rapid changes of blood pressure are likely to cause cardiovascular disease

 

I do think CE could be taken too far, certainly monitoring one’s blood pressure on a regular basis is a good idea. I actually haven’t checked mine in a while, after a day of my usual CE:

 

Edited July 22, 2019 by Gordo

[Ron Put]

 

54 minutes ago, Gordo said:

...

I do think CE could be taken too far, certainly monitoring one’s blood pressure on a regular basis is a good idea. I actually haven’t checked mine in a while, after a day of my usual CE:

 

Thanks for those, Gordo. Your blood pressure is enviable :)

But note this sentence in the second study I posted above:

"This is attributable to cold-induced increases in wave reflection and stiffness of the arterial system and suggests that the magnitude of the hemodynamic response to cold exposure cannot be determined with traditional brachial cuff measurements."

Edited July 22, 2019 by Ron Put

[Dean Pomerleau]

Thanks Ron and Gordo. Those are interesting studies, and are definitely a reason for caution against extreme forms of cold exposure.

All of the animals studies cited in those papers involved long-term exposure to very low temperature, i.e. 40F/5C continuously for 1-5 weeks at a time. 40degF is a full 40degF colder the thermoneutral temperature of the mice involved in the study. This is opposed to the 10degF below thermoneutrality (~70F) that appears beneficial for rodent health and longevity in combination with CR.

The human study you cite Ron exposed healthy young men to even colder (38F/4C) with a 14 mph wind blowing on them. All the subjects started shivering within 5min and continued shivering throughout the experiment. This is much more extreme CE than I would recommend and it isn't surprising their cardiovascular system responded with vasoconstriction, elevated BP and arterial stiffening.

Like with both CR and exercise, it is possible to go too far with CE. Shivering is a sign of going too far. My recommendation remains to engage in incidental cold exposure (e.g. cold showers and not over dressing on mildly cold days) and/or a couple/few hours per day of controlled exposure to the equivalent of 10deg below human thermoneutrality (i.e. ~62 deg lightly dressed, or wearing a cold vest) to maximize the potential benefits and minimize potential risks.

--Dean

[TomBAvoider]

OMG, people! I feel like a broken record: the dose makes the poison! This has been known for hundreds of years! This is why (I'm relating this for about the 100th time), whenever I hear about a drug or an intervention, my first question is - "dose and protocol?" It is completely worthless without that. You can overdose on water and die, it doesn't mean water is bad for you. 

It's great to cite studies for and against CE, but unless we fully understand dosing/protocol, interpreting the study is impossible. And again, that goes both ways - for the proponents of CE as much as for the sceptics of CE. That's one of the reasons why I am so deeply suspicious of animal studies when it comes to applying to humans - even if a given, very particular and specific physiological reaction is exactly the same between a mouse/rat/animal and a human (pretty rare), you still cannot be confident about how to convert a dose/protocol from animal values to equivalent human values. Parenthetically, that's one issue I'm facing now with rapa which I am getting ready to try - one of MR's objections to humans taking rapa is that the doses in mice are not practical in humans (of the studies showing beneficial effects of rapa in mice); my response is: I don't accept such mechanistic dose calculations - a given dose in a mouse might not translate at all into human doses no matter what the math translational factor is - weight, age, whatnot. Mice and humans have different physiologies, and a drug may work at an utterly different point and manner than just straight weight/dose translation, so telling me that the mouse doses in those studies are different from what the few humans out there are trying, tells me absolutely nothing (sorry, MR!); it's not a useful objection to my mind.  

Same for studies in mice (or broadly animals) when it comes to CE - for or against. I read these studies and always wonder - "and we translate this to humans how? What exact dose/protocol?" and I don't have much confidence in any particular answer. I much prefer even marginal human studies. YMMV.

[Ron Put]

Here is something I just ran across, which might of interest. It would appear that being too cold or too hot negatively affects REM sleep.

Scientists Determined Why Room Temperature Is So Important for Sleep

"Schmidt hypothesized that there are mechanisms in the brain that regulate the amount of REM sleep you get depending on the room temperature, like increasing REM sleep when the room is comfortable and sacrificing REM sleep when it's too hot or cold."
https://curiosity.com/topics/scientists-determined-why-room-temperature-is-so-important-for-sleep-curiosity?utm_campaign=daily-digest&amp;utm_source=sendgrid&amp;utm_medium=email

[mccoy]

Even though, according to Matthew Walker, the body core temperature drops during sleep, so a relatively colder environment temperature is ideal, while keeping teh extremities warm.

[Gordo]

Makes sense, too cold definitely disrupts sleep in my experience.  You also have to consider that most people are more comfortable sleeping with sheets and/or blankets, even weighted blankets are trending. I love a cold room coupled with heavy blankets.  Those are going to significantly raise your actual "under the covers" temperatures which is probably why many sources report the best sleep temp is on the cool side.

[mikeccolella]

On 7/20/2019 at 4:34 PM, Ron Put said:

Gordo, I don't have to guess, I am well aware that during exercise the force of your heart's contractions increases in order to increase the supply of oxygen and your blood pressure elevates.

But I am also well aware that during exercise, your blood vessels dilate significantly (and more so in healthy people).

Cold exposure does exactly the opposite, it constricts and stiffens your blood vessels, while at the same time increasing blood pressure, the flow of lipids and inflammatory agents.

Add to this the generally greater length of cold exposure by CE aficionados, and you'll see why I am not convinced that CE offers long term health or longevity benefits in humans, despite the otherwise beneficial impact of thermogenesis in brown adipose tissue.

"Cardiovascular disease (CVD) is considered the primary cause of death in the developed world. Large scale epidemiological studies indicate that prevalence of hypertension along with adverse cardiovascular events peak during the winter months. Moreover, during the winter months outdoor activities and physical stressors such as exercise have been associated with higher cardiovascular mortality when compared to other periods of the year. Although low environmental temperatures have been implicated as the triggering factor for cardiovascular complications, the mechanisms on how cold exposure increase cardiovascular morbidity and mortality remain to be elucidated. However, new research suggests that cold exposure may induce increases in cardiac sympathetic activity, endothelial damage and increased arterial stiffness of central arteries."
https://clinicaltrials.gov/ct2/show/NCT01462591

 

I know this is true first hand. My father died at 44 from atherosclerosis due to familial hypercholesterolemia. For years he-had angina symptoms which were greatly exacerbated by cold weather. No doubt about it cold effects our arteries otoh exercise would also cause angina and as we all know exercise is generally a good thing.

Edited August 2, 2019 by mikeccolella

[Todd S]

Thanks Dean for your detailed review of the water-cooled CompCooler UniVest. This influenced me to get a beige one (what was available at the time in M/L size) a couple of weeks ago. It was delivered by Amazon from vendor CompCooler for $219. My order also included the spare 3 L reservoir, which cost an additional $42.99. I agree with you that this product is well made. I've found it very comfortable to wear in the house all evening on hot days. I've also worn it on a couple of weekends so far when experimenting with Nordic Walking on San Francisco Bay trails on hot days -- and found that it helps to reduce fatigue by keeping front and back upper torso cool.

[Todd S]

Gordo,

I can confirm that plugging the USB connection from the CompCooler UniVest into an Apple 5 V charger instead of the 7.4 V battery still works for running the water circulation pump.

[Dean Pomerleau]

Todd S, 

Glad to hear you are having good luck with CompCooler vest. I continue to use mine for a couple hours each day and it is holding up very well. One thing I learned to do is to blow out any remaining water in the female couplers on the ice bag before putting it back in the freezer after a cooling session. Otherwise it freezes inside the coupler and makes it hard to attach next time. 

--Dean 

[Gordo]

12 hours ago, Todd S said:

Gordo,

I can confirm that plugging the USB connection from the CompCooler UniVest into an Apple 5 V charger instead of the 7.4 V battery still works for running the water circulation pump.

That is great to know, I may get one of these eventually.  The one and only review on amazon though, is pretty underwhelming.  I am wondering if it cools any better than the Techkewl vest I already own...