Effects of cold-water immersion on health and wellbeing: A systematic review | Hacker News Reader

Effects of cold-water immersion on health and wellbeing: A systematic review

journals.plos.org

65 pointsfallinditch86 comments

> including a 29% reduction in sickness absence among participants who took cold showers.

Reminds me of back when they claimed wine was good for your health

Turned out to be people affluent enough to drink wine regularly also had regular access to healthcare and were thus likelier to be healthy (for some definition of healthy)

Similarly here, I’m tempted to believe that anyone who does CWI regularly probably lives a healthier lifestyle in general and that CWI is just one element of a robust health routine.

It’d be pretty hard to tease out all this in a study like this. I think in situations like this the approach I’d take is:

See what the science says in terms of theoretical benefits, get some anecdotes from trusted sources, and when the stakes are low like this, give it a shot myself.

That said, noted that some of the other positives seemed to be a bit more directly measurable/observable, eg stress reduced after 12 hrs and things like that.

I have no idea why you're being downvoted; https://journals.plos.org/plosmedicine/article?id=10.1371%2F... is one of many good studies that show that the 'French Paradox' is little more than socioeconomic effect. The association with lower rates of cardiovascular disease among moderate drinkers shows an effect modification of 1.32 when comparing low vs mid socioeconomic position (SEP), 1.36 for mid vs high, and then unsurprisingly 1.63 for low vs high. This strongly suggests that socioeconomic position has a direct and confounding effect on the outcome measure (cardiovascular disease mortality). The alternative is that socioeconomic position modifies the effect of the treatment (moderate alcohol consumption) itself. This would be a sensible interpretation of an effect modification of a drug administered in the presence/absence of, say, grapefruit juice or DMSO, but severe mental gymnastics would be required to argue for the existence of a mechanism through which socioeconomic class could directly mediate the biochemical effects of alcohol on the body's cardiovascular system.

They're being downvoted likely because one study which missed a factor does not make personal anecdotes more valuable, or say anything about the reliability of the scientific method.

The irony of using one study...yeesh.

Also: science is iterative, people. Nobody in the scientific community looks at one study in a vacuum. Follow-up studies seek to confirm, efine, build off of, or come up with a different theory.

Only internet commenters who pride themselves in being "skeptics" do this - because they think skeptics are the smartest people, failing to understand that uneducated skepticism has little value.

When they hear the study had some flaw, they shout "AHA! RESEARCH IS BUNK!" and assume everything that came out of it was useless. Or, more commonly, they don't see some obvious potential flaw not specifically spelled out as being addressed just like a math paper wouldn't explain basic calculus - and assume they've found some flaw that somehow multiple people who have studied in their field for years - missed.

It's like looking at a bowl of cake batter and crying out "that's soup, you're incompetent!" to a chef who has a Michelin star, because it doesn't look or taste like a cake.

Wow you read way way too much into my comment

Sorry it got you bent out of shape

> Turned out to be people affluent enough to drink wine regularly also had regular access to healthcare and were thus likelier to be healthy (for some definition of healthy)

I'm curious to know about if/how much the positive effects of coffee are about people drinking it in social situations (at a café or after dinner with friends/family).

Actually socioeconomic status was controlled for. What was not controlled for was pre-existing conditions that might make people have 0 drinks like previous alcoholism, medical conditions where you can't drink, etc.

Here is a meta study debunking the myth that wine good for you was a myth.

https://pmc.ncbi.nlm.nih.gov/articles/PMC10507274/#:~:text=T...

The first time I took an ice bath after a 20 mile run, I was amazed. Not during the bath, but the next day. My legs could walk, hop and skip like it didn't happen.

I assume you meant like the run didn't happen, but it's funnier to interpret this as like the ice bath didn't happen.

Funny or not, that interpretation holds too.

There's a general principal that stressing the body and mind often begets strength.

Lifting heavy weights stresses your muscles and you get stronger.

Running long distances or short distances intensely stresses your heart and makes your heart stronger.

Doing something you're scared of (public speaking for example) stresses your psyche and makes you stronger.

So sauna and cold plunge both fall into this category of controlled stress that would unsurprisingly have some benefits.

Some of the best athletes of all time use it consistently in their regimen, including LeBron James (40+ and still one of the best players in the NBA).

Even if the cold water was nothing but a sort of pain-endurance test, that's good for your psyche in a similar way doing scary things like public speaking is good for it.

All these things together, I would bet cold plunge is probably good for you. Definitely that it is more likely good for you than bad for you. What do you have to lose? If there's a cold bath around, I'll jump in.

Cold water plunges or cold water immersion have conclusively shown to reduce anabolic signaling [1].

If you’re training to become fit and build muscles, there is definitely a downside. It has benefits in terms of recovery, but that comes at the cost of anabolic response. It makes sense for athletes who have consistent training and need to perform for games, but not for the average person who just wants to look more fit.

[1]: https://pmc.ncbi.nlm.nih.gov/articles/PMC4594298/

Interesting! Thanks for sharing this, made me revisit the huberman podcast on this topic:

https://www.youtube.com/watch?v=pq6WHJzOkno

He echoes what you said, summarizing: "If your goal is hypertrophy and strength don't do cold immersion until 4 hours or more after your workout".

If we can trust the studies Huberman cites, you can get many benefits from cold plunge and also avoid that post-workout caveat if it's relevant.

I personally would not trust Huberman. Just look at his blatant shilling of questionable products for sponsorship (AG1, being the best example). Look at the studies he cites, I suppose, but there’s plenty of low quality studies that can be cited to try to prove a bad opinion.

This is specifically about cold plunge immediately after strength training, there's no evidence this applies as a tradeoff in a more generic way.

Cold water immersion or whatnot immediately after training or exercise is generally when it’s used. Similarly, if you did it right before exercise it would hamper exercise and increase injury risk purely due to lower blood flow through muscles. Could be mitigated by extra warming up, but certainly a pain.

From a practicality standpoint, cold plunging and such are generally done at the same place (and coincident) where you exercise.

It’s similar to aerobic exercise immediately after strength training. Sure, you can do these things far away from each other (cold plunge in morning, train in evening)… but how much time are you going to dedicate to going to the gym?

I dont understand where your view comes from. I've never seen a gym with a cold plunge. I cold plunge in natural bodies of water or my back yard, and I do it whenever I want - intentionally separated from my strength training.

It's rarer, but it's the same type of amenity for a gym that has a sauna. Not all gyms have saunas either, but a certain type of gym does.

Frankly, I don't understand your view either. The vast majority of folks do not have access to a natural body of water that is cold enough, especially not year round. And having a plunge tank available at your home is a considerable expense, either in recurring ice cost or in the type of machine that can actively cool water.

The lowest barrier to entry is having access to it at an external facility. I lived in an apartment where that had a cold plunge next to the regular pool (which was also next to the apartment gym), for instance.

This systematic review suggests that CWI delivers time-dependent effects on inflammation, stress, immunity, sleep quality, and quality of life, offering potential practical applications for health practitioners considering CWI for stress management and wellbeing support.

Time-dependant is the key here.

> temperatures ranging from 7°C to 15°C and durations ranging from 30 seconds to 2 hours

Can we get some sort of chart or quick summary of results? Where's the line where temp+time translates to anything significant?

2 hours? There's an LD50 line in there somewhere.

Seems like some LLM could do this. If not a chart, at least some summary of the results.

I used to live in a beautiful valley in Wales. When I went jogging in the woods I finished off by jumping from a rock into a waterfall (it was in a wild place, nobody else about).

By first working up a sweat the CWI wasn't too shocking. But what a great feeling afterwards! It's like being high off the best possible drug. Good for your skin too.

Definitely a healthful thing to do if your heart is ok.

It should be noted here they're talking about cold water (above freezing) - not ice baths which is what a lot of people seem to think of and is quite a fad in the "sports medicine" industry.

It's a meta study that potentially includes these as well as other cold water exposure:

> undergoing acute or long-term CWI exposure via cold shower, ice bath, or plunge with water temperature ≤15°C for at least 30 seconds.

Yes, but also above 7°C

Yes, they could work on their grammatical ambiguity when using 'or'. From the studies list, it appears they found no ice baths to study perhaps due to safety concerns.

Anecdotal stuff is also useful when there is a lack of science. I hate it when HN people completely dismiss anecdotes and want research papers for everything. Even research papers are dubious.

Please share your personal experiences with cold water plunges! Was it good? Or was it bad? Where did you do it? How did you do it? Do you have a setup at home?

Tried it for 3 months, noticed zero difference, and stopped.

Now, do you know anything new? No, because anecdotes don’t actually provide meaningful information, we don’t know why we did or didn’t improve. Or in my case if there was some minor benefit or minor harm because I didn’t pay close enough attention etc etc.

Anecdotal results are highly dependent on the provider.

The scientific method is supposed to allow someone with no credibility to provide signal through >process< and then gain credibility.

Anecdotes from >a credible< person are very meaningful as they are often a high indicator of signal. A social heuristic outside of rigorous research.

Your results as an anon? Basically useless. On HN? Slightly better than on reddit or facebook. Provide your methodology? Better still, and now youre approaching a research proposal.

The meta discussion around anecdata being useful or not is silly.

If you want the protocol? Sure water temp 50-55f for 15 minutes 4-6 days a week (generally 5) for 3 months. Water chest height, arms generally above water.

How exactly does credibility matter here? Science is heavily reputation based because there’s so much at stake and so few experiments take place, but with anecdotal evidence I don’t see the credibility of individual datapoints mattering much.

I can’t tell if I minimally influenced my upper respiratory tract infection risk etc, all I can tell is the hassle wasn’t worth a benefit too small for me to notice. And that’s the issue, more than credibility if effect size was large enough to be noticeable to individuals you’d get extremely strong results from scientific studies. Conversely if it isn’t showing up as extremely effective in the literature that’s strong evidence individuals are misattributing their experiences.

how often did you get sick? weight? what season did you do it in?

what was your goal in the first place?

> you’d get extremely strong results from scientific studies

check population health data in countries where cold exposure is traditional.

science is cool, scientists are just regular ol' people and enough regular ol' people do a lot to look good, to not be unemployed and having to write applications again, to get their tap on the head and or a nice bonus. **regular in their little slices under the bell curve

It's strange to question the work of scientists in this way. Precisely because they are only human the studies are peer reviewed and the meta studies have the most explanatory value and weight.

Unless you are assuming there is some global conspiracy of scientists to have jobs the system it selfs manages it by it's transparency.

Simplifying it in a "check population health data in countries where cold exposure is traditional" way is exactly the wrong approach. How do you know what kind of diet, genome and culture they have? There are so many variables that the mere fact of whether one diverse group does something different than another doesn't really say anything. It's so difficult to try to isolate individual problems. That's why we have the scientists.

Don’t both things have value, when measured on different axes?

I think it’s just a bit more gray.

You haven't heard of the replication crisis?

Not till now. Thanks. But as weird as it can sounds. The failing and iterationg over and over is integral part of science. Which includes method itself.

The "method" was never fixed. It was identified but we have no way of correcting it. A ton of science is still completely dubious.

> check population health data in countries where cold exposure is traditional.

That tells you about those countries but very little about cold exposure specifically. One inherent difference is they lack a lot of tropical diseases because they aren’t in the tropics. You could still try and remove all those differences, but directly studying cold exposure itself is vastly more practical.

There are many things (I frankly don't think there's a more specific word for this) like diets and psychedelics where many of us (rigorously minded) are constantly seeking proofs within systems containing sufficient complexity to render conclusions nearly impossible.

> constantly seeking proofs within systems containing sufficient complexity to render conclusions nearly impossible

Language. Nothing is impossible.

Diet interventions aren't terribly hard to test, they just consistently tend to result in "as bad or worse than no intervention" (short of fixing the sort of malnutrition you rarely see in the contemporary developed world)

The rigorous result is right in front of us we just don't like the answer

I tried it for 20 seconds that was it

All five merchants who went to Opal City were never seen again, but don't let that stop you from going to Opal City because anecdotes don’t actually provide meaningful information.

if cold plunges either killed people or revived them from the dead, this would be a great analogy.

Another low stake option. 5 of your friends each say that restaurant A is horrible and restaurant B was great. You have to pick a restaurant. Are you going to throw dice because these are just anecdotes and don't matter?

Carful, now you’re leaving random antidotes.

A specific restaurant is an actual place so if someone describes the decor and prices yesterday it’s not going to be wildly different when you show up tomorrow.

Is there a paper supporting that position of yours? I would like to see a study highlighting that restaurants are unlikely to change in time.

I'm not eating anything till I see a peer-reviewed study demonstrating that the verbal reports about restaurant decor made by my family members or the guys I ride bikes with on weekends have any actual correlation with actual restaurant decor. Where is the hard, non-anecdotal evidence?

It also needs evaluation beyond subjective reports, as food taste is known to be highly prone to placebo. Until an objective device for evaluating the taste is found I believe it would be completely unscientific to take a bite or even smell the food since that is also known to affect taste.

Should you also not ask for restaurant recommendations from people? These are also anecdotes.

When someone records the height of a specific mountain we call that a measurement not an anecdote.

If I ask someone if this bar is good, and they say they went to a different unrelated bar and it sucked then I’m going to ignore that as a random anecdote.

What about if someone says that they felt a sauna session was good for them, or cold plunge benefited their health, etc?

I know far too many aging hippies and their kids who believe all kinds of nonsense to really care what kind of health claims they’re making. I just tune out.

One guy was saying you can replace sleep with LSD. He changed his mind, but would you believe it or just do what I did smile nod and move on?

I wouldn't believe that, but there are plenty of other activities that I do because people have anecdotally reported that they benefitted from them. In this case I would use my internal judgment and intuition to decide based on benefits vs cost/risk. Does it seem unlikely to harm me, but many people have suggested they benefit from it? Sure, I will try it. I will see if I feel better or notice anything. If I don't, that's fine. If I do, I wouldn't necessarily know if it is beyond placebo or not, but I could keep doing it to see how it affects my life and if it keeps seemingly positive I can decide to keep doing it even though I don't have scientifically unquestionable truth that it is actually helping me. People have survived generations and found things that work without needing everything to be scientifically verified.

When tested the overwhelming majority of things that “survived generations” didn’t work.

It’s amazing just how bad that stuff turned out to be. You personally can try whatever you feel like but the odds are just terrible that your going to find anything beyond mild pain relief and the risks can be go significantly beyond wasting time.

How do you pick the set from where you are picking the "overwhelming majority"?

I would argue that most things we use daily now started out as anecdotes rather than science experiments. Most of the food we eat, etc. The buildings we live in, being in the nature, exercise, sleep, etc.

They were all anecdotally described before we were able to run proper science on them.

> most things we use daily

Moving the goalposts a bit there, there’s no way in which wood’s utility depends on random peoples observations they can point to its actual use in a structure. We’re just talking about medicine here because we can’t see people’s past condition.

So the set includes all forms of historically practiced medicine from anywhere in the globe. From Chinese medicine to Voodoo, people did all kinds of things to dry to get better. Our ancestors didn’t use electronics, plastics, synthetic fibers, aluminum, etc which is a large fraction of what people interact with in a daily basis.

Western medicine kept a tiny fraction native from wound care via Honey to willow bark, the stuff that worked was either copied or refined when active ingredients were isolated. But when the actual useful techniques are under 1%, there’s hardly a reason for you to individually investigate people’s random claims.

Consider all of homeopathy is useless, for you to say test each individual treatment would be just as silly as individually testing each different prayer in faith healing.

I don't have a way to do "cold plunges" consistently, but cold showers have been great for me. I have ADHD and am quite anxious and highly sensitive. Whenever I make cold showers part of my daily morning routine, I feel much calmer. Very hard workouts also do wonders, especially if they involve combat sports, which I practice. There's something about overcoming fear of conflict. I guess exposing yourself to extreme cold is akin to that.

+1 for cold showers.

Excellent for several things. Personally I recommend them at the end of a normal shower, before bed, to drop your core temperature.

Takes a couple weeks to acclimate, but much easier afterwards, same benefits.

Anecdotal - according to the Huberman podcast, cold exposure is better practiced in the morning not before sleep due to its stimulating effect.

Same here, re: ADHD. The clearest my head ever is is after climbing at my very limit and then taking a cold shower.

Similar here. Although I’ve taken to just doing an occasional 30-60 seconds of cold water at the end of a regular shower.

Exercise wise, for me, it’s a solid pickleball session. Good intensity cardio, super fun, the competitive striving to win, as well as low stakes, meaningful social interaction, all combined together. Doing pickleball open play (pickup games) a few times a week has been huge for me.

I love a good yarn too! Hearing someone describe it can also help motivate you to try it in the first place

> Anecdotal stuff is also useful when there is a lack of science.

Yeah sure, but there is science, the link, and no one is arguing the opposite. The poster doth protest too much

these days anecdotal is better than "science"

Used to do them, and really want to start again. For me, felt more awake than I ever have been. And, your body feels like it's running at its best for a short while - think it's partially because, at least for me, I tense like every muscle in my body before that super cold water hits me. It's like a mini work-out.

I don't do plunges but do cold showers. They are not the same but cold showers do have one anecdotal benefit for me, I don't feel cold post the cold shower.

My immunity had been pretty good but am not sure if I can attribute that to cold showers. I moved to the bay area in August after nearly a 14 year stint in India. This winter the flu virus got me. I was able to fight it off without a lot of meds, I got sick after nearly 4 years.

So am not sure if my body has good immunity anymore. Overall, I have come to liking cold showers simply because of the post shower feeling.

A hot shower is great while in the shower, not so great afterwards. A cold shower is miserable the first 30 seconds, a pretty good feeling afterwards.

Given how absolutely trivial it is to do a randomized intervention study here (you can't do double-blind, but dose-response is easy enough) there's not a lot of reason to care about n=1 results except plausible reports of rare seriously negative outcomes.

If it works, it would be within the resources of an ambitious high school class to prove it. If it doesn’t, "more research will be needed"

> I hate it when HN people completely dismiss anecdotes and want research papers for everything.

You can point them to this: https://pmc.ncbi.nlm.nih.gov/articles/PMC300808/

That is absolutely fantastic and thank you for that.

Point them? Them is basically everyone on HN.

In my opinion anecdotes are extremely important to take heed of, especially if they are contrary to the prevailing model. I believe a lot paradigm shifts start out with anecdotal data. We need anecdotes to know where to start looking.

The problem with anecdotes is that the brain is a hell of a drug.

I work in clinical trials and it’s amazing at the list of side effects participants get when they are in the placebo arm.

And it’s not even small numbers. It’s not unusual for 20-40% to have side effects like drowsiness, tingling sensation, muscle pain, jitteriness, euphoria/dysphoria, feeling of being too hot/cold, headache, stuffy nose, tinnitus, frequent urination, diarrhea/constipation, etc.

Now layer that on top of cold plunges where people who do it already have an expectation based on others experiences and boom - you suddenly get tens od thousands of anecdotes about the effects that make it seem like it must be true.

(Note: I’m not making a judgement call on cold plunges, it’s just an example)

The person you replied to has such a fundamental lack of understanding of scientific method and logic, you're trying to make a horse drink.

Not true. I understand it quite well better then most people and most likely you as well.

You used the scientific method and logic in the same sentence. You're aware that they are completely different right? Science can never prove anything.

I do open water swimming through the winter in Melbourne with no wetsuit. Mid-winter it gets to about 8-9C, and I stay in about 20-30 minutes. There's definitely a mental health benefit, probably largely from doing the thing that seems difficult to do, but once you're started it fine. I also notice that at night, after such a swim, I run _really_ hot. Like, don't need a doona, even in the middle of winter in an un-heated and un-insulated house. Overall, I like it, but it's taken years of slow acclimation to get there.

> Anecdotal stuff is also useful when there is a lack of science.

There isn't...

https://www.google.com/search?q=science+direct+cold+water+im...

> e. I hate it when HN people completely dismiss anecdotes and want research papers for everything.

Then educate yourself on the scientific method, evidence, logic, and so on. Because "HN people" are right to dismiss anecdotes as being useful evidence of anything.

> Even research papers are dubious.

That some research papers are dubious does not make personal anecdotes more reliable.

https://pmc.ncbi.nlm.nih.gov/articles/PMC300808/

The above is an extremely true and reliable paper. Everything it talks about is true and reliable. But it illustrates the weakness with science. Something you don't understand.

Tried (completely) cold showers for a while.

anecdotally:

- the first 15 seconds are the worst, especially cold water on your back.

- it is invigorating. There is a feeling of "being present" that doesn't seem to happen with a hot shower.

- when you get out, the room and toweling off does not feel cold.

- the bathroom mirrors did not fog

I have no idea of the health benefits.

At some point I stopped doing it and then couldn't ever go back.

However, sometimes I do the "james bond shower", which is a hot shower that tapers to cold. mirrors fog, but still somewhat invigorating and easier to do.

I also once stayed in a hotel which had a dual shower stall. I put one to hot, one to cold and would go back and forth. That was very fun and invigorating.

More useful than anecdotes would be a theory(which put forths an explanation of why something might be so), which is interesting even in the absence of any experimental data.

It is incredibly challenging, but I feel absolutely amazing afterwards. Maybe because it's over lol. The difficulty and the high are both stronger when the water is colder, down to freezing.

45F with moving water feels WAY COLDER than 32F still water.

In my experience it causes excessive bragging. I had a strong urge to tell people as to assure them of my manly hood. I've seen these tendencies in others too!

My best version is to get in a hot bath, gradually make it even warmer, push it to the limit! Then stick your head over the railing and put a cold shower on it. Convection is a magical thing. It's like washing your brain.

I really couldn't care. I get cold easily in winter, and it chills me to the bone making me miserable all day, much less via a cold plunge. Not worth the (much needed) mental health benefits.

Sauna? Any day, any time!

Have you tried a cold plunge after a sauna? It’s a lot more bearable, borderline enjoyable I would say

I used to do it every morning in a cold city (water was around 10°C) and it made me feel less cold throughout the day, not more. That was one of the more obvious effects.

Exercise hard enough to start sweating and feeling hot. It won't necessarily be immediate, but your base metabolism will rise.

Nonsense.

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