Cold Exposure Secrets (Science & Benefits Explained)
Your friends are probably doing it. And if they are, you definitely know about it.
That’s right - we’re talking about the cold plunge trend that has taken over the world.
They’re everywhere.
They’re transforming routines and people swear by them.
There have been countless claims of reducing stress, giving you more energy, improving your sleep, strengthening your immune system and lots more.
But, hold on - is this just a passing trend, or are there actual benefits beyond the hype?
Today we're diving headfirst into the world of cold immersion.
We’ll break down the science behind what happens to your body, we’ll explore the potential benefits as well as shedding light on the dangers you should be aware of.
What is cold exposure?
It can mean a few different things but generally speaking, it’s exposing the body to the cold temperatures intentionally.
This can be as simple as ending your shower with cold water or by having an ice bath, right the way through to getting whole body cryotherapy.
Some of the earliest recorded benefits of cold water therapy dates back thousands of years in the times of Hippocrates’ and the Ancient Greeks.
Fast forward to the present day and it seems like everyone’s doing it.
What happens to your body?
Your body uses a couple of key strategies to maintain a stable temperature, which is also known as thermoregulation.
The two primary responses are vasoconstriction and shivering.
One of the first things that happens is our blood vessels in the skin get narrower.
This process is called cutaneous vasoconstriction.
The cold is detected by receptors in the skin. This signal is then relayed to the hypothalamus - which is basically the information inbox of the brain.
The hypothalamus receives this signal and decides to reduce blood flow to our skin. This is because it wants to prevent heat loss and by doing this, we’re trying to limit the amount of heat that escapes from the core of your body to the outer parts like the skin, fat, and muscles.
This vasoconstriction helps keep the warmth inside and prevents our core body temperature from dropping too much.
The other main strategy is that the body increases metabolic heat production, mainly through muscle activity.
This can be broken down into shivering and non-shivering thermogenesis. Thermogenesis just means making heat.
Shivering is when your muscles contract continuously, prompted by thermal receptors in different parts of the body. It can be quite intense and widespread, think about when you’ve been outside in the freezing cold.
The process is controlled by the hypothalamus, which leads to increased muscle activity, higher energy usage, and an elevated metabolic rate.
The body can produce up to five times more heat through shivering than at baseline.
In cold water immersion situations, shivering is particularly effective because it keeps the you relatively still, reducing heat loss through convection. Even though exercise generates more heat overall, shivering is more efficient in cold water.
Non-shivering thermogenesis involves brown adipose tissue or (BAT), which can produce extra heat without the need for muscle movement. BAT achieves this by burning a type of fat called triglycerides in the mitochondria and then releasing this heat directly into the bloodstream.
Now, we have another type of fat called white adipose tissue, or WAT. Unlike BAT, this is more like an insulator, helping to keep your body warm. But when it gets chilly, BAT steps up.
It actively produces heat in response to the cold, a bit like turning on a small heater in your body.
But its role in adults has been debated for years because the actual amount of BAT in adult humans is pretty small.
Recent research suggests that the contribution of BAT to daily energy consumption is relatively modest, equivalent to just a couple of minutes of moderate-intensity running. On the flip side, BAT is important for babies because they can't shiver effectively to stay warm like we can.
So instead, their abundant BAT stores produce heat, without the need for muscle movement. This is one of the reasons babies often feel warm and cozy, especially in cooler environments. BAT helps them maintain a stable body temperature.
It's like they have built-in blanket.
Now, I wan’t you to picture that time when you decided to challenge yourself with a cold shower or take a plunge into an icy cold pool.
The anticipation built as you prepared for the shock that awaited your body.
You took that initial step, and as the cold water hit you, a cascade of sensations rushed through.
In that split second, the shock of the cold hit you like a wave, catching you off guard.
The water felt like a thousand icy needles penetrating your skin.
And then without warning, your body responded with uncontrollable gasping. It was as if your body, in that very moment, tapped into a survival instinct.
The gasp was your body's way of getting oxygen in, preparing for the potential challenges of the cold.
In the biting cold, every inch of your body seemed to tighten, creating a sensation of an intense full-body shiver. This is the cold shock response and it happens over a few minutes usually.
Your body detects the sheer cold and goes into overdrive.
It reminds you that you’re alive.
Your heart rate climbs dramatically. You start gasping for air.
You begin hyperventilating. You a vasoconstriction response and your blood pressure rises as well.
This response can have a major impact on your body and has actually been connected to increasing your risk of drowning.
One particular study found that the initial sharp inhale and rapid breathing were connected to a decrease in blood flow to the brain. This drop in blood flow was associated with confusion and loss of consciousness in the participants.
Let’s talk about benefits of cold water immersion.
1. Improved circulation.
When exposure to cold water stops, the body initiates self-warming mechanisms, leading to increased blood flow as blood vessels expand through dilation.
This is called vasodilation and some researchers believe this process could actually improve your circulation.
One study explored how regular endurance training and post-exercise cold water immersion impact the tiny blood vessels in our muscles. Nine men did endurance training three times a week for four weeks
After each session, one leg was immersed in cold water (10°C) for 15 minutes while the other leg served as the control. They used a special technique to measure changes in blood flow.
The results suggested that regular cold water immersion after exercise might enhance the way these tiny blood vessels adapt, potentially improving overall muscle function.
2. Improved recovery.
One group looked at 21 male athletes and how they recovered after competing.
They compared those who used cold water immersion after exercise with those who didn't. They checked things like sprint performance, muscle function, soreness, and certain markers in the blood related to muscle damage and inflammation.
The group that used cold water immersion showed faster recovery in sprint speed 24 hours after exercise and they also released less called creatine kinase in their system, which is a marker of muscle damage.
Cold water immersion after exercise is thought to enhance recovery through various theories. It’s thought that it can help flush waste products like lactic acid out of muscles.
The cold temperature can also reduce metabolism as well as minimising swelling and tissue breakdown.
3. Improved mood & less stress.
One study looked at 26 people with anxiety and depression and subjected them to whole body cryotherapy.
This is different to cold water immersion because in cryotherapy you have specialised chambers where temperatures can drop well below freezing.
In this study they used questionnaires like the Hamilton depression scale to assess the participants before therapy and a few weeks after.
After three weeks, about one-third of the treated group saw a significant 50% or more reduction in their initial depression rating scores.
Cold water immersion can also lead to an increase in two chemicals in your body—dopamine and noradrenaline.
These are signalling molecules that play a role in how your brain and body function. The cold exposure triggers your body's stress response, leading to the release these neurotransmitters.
This can have several benefits, including improving your mood, boosting alertness, and enhancing focus.
One experiment looked at cold water immersion and blood levels of these neurotransmitters in 10 men who had an average age of 22.
They found that cold water immersion at 14 degrees celsius increased blood dopamine by 250% and noradrenaline by 530%.
This suggest that the shock of cold water activates the release of these neurotransmitters, creating a kind of natural energy and mood lift.
Interested in learning more about dopamine? Watch this:
Totally BS?
We can't talk about cold immersion without mentioning Wim Hof.
He is a huge advocate for cold therapy and the idea that prolonged exposure to cold is associated with increases in brown fat activation.
What most people don’t know is that Wim Hof has an identical twin brother, who doesn’t do cold exposure.
So what they did was they compared brown fat content in both of them when they were exposed to mild cold conditions of about 13 degrees and then at more normal temperatures.
Interestingly they found no significant differences in their brown fat activity or the levels of cold induced thermogenesis.
What temperature should you plunge in?
There’s no set figure but having looked at the literature online, a temperature of 10 to 15 degrees celsius or 50 to 60 degrees fahrenheit seems to be optimal.
As for the length of time, this varies with some people suggesting a couple of minutes at a time ranging up to 15 minutes. If you’re just getting started it might be sensible to not stay in for too long.
What are the risks of cold water immersion?
- The risk of hypothermia.
This occurs when your body loses heat faster than it can produce it, leading to a dangerous drop in your core temperature. It's really important to be mindful of the duration you spend in cold water to avoid this risk.
- Cardiovascular Stress.
Cold water can prompt a shock to your cardiovascular system. The sudden immersion can cause blood vessels to constrict, increasing blood pressure and putting extra stress on the heart. People with heart conditions should be mindful of this.
- Drowning risk.
And while it's a natural reaction, the cold-shock response can pose risks, especially if you're not prepared. Uncontrolled hyperventilation can lead to difficulty in breathing and loss of overall control, so it might be better to ease into cold water slowly.
On top of this, the shock of cold water immersion can induce stress and anxiety in some individuals especially if you’re new to it. It can leading to panic reactions which is far from ideal if you’re doing cold exposure in an open water lake.
- Injury risk.
A key risk is injury because cold water can numb your senses, making you less aware of your surroundings. Make sure you always choose a safe location for cold water immersion.
So, should you should get a cold plunge tub or not?
Before we answer this, there are a few issues with the data.
I don’t know if you noticed but the majority of the studies on cold water exposure are on groups of male adults which are generally quite athletic and young.
And this isn’t representative of the wider population.
On top of this, the studies are quite small in their sample sizes and they don’t tend to have robust control groups.
Another problem is that the studies vary in their immersion techniques.
Some use cold tubs and plunges, some immerse the whole body whilst some leave the hands and head out of the tub, some use cryotherapy chambers, some use cold showers and some are open water swimming studies.
You can see how the variety of methods and durations of immersion can be an issue.
Despite this, some people swear along the common narrative that; "it’s really good for you, it gives you more energy, it helps you sleep better sleep and it improves your immune system".
It may sound fantastic but the majority of these claims haven’t actually been studied extensively.
You'll find plenty of stories online and in the news singing the praises of cold plunges.
People share their positive experiences, and it all sounds amazing. But the reality is, the scientific community hasn't delved deep into a lot of these claims.
Most of what's out there leans heavily on personal anecdotes.
Now, don't get me wrong – personal stories can be insightful, but they're not a substitute for solid scientific research.
And here's the catch – positive stories tend to grab the spotlight, creating a bit of a one-sided view of the benefits of cold water exposure.
You don’t really hear about the millions of people who hate cold water exposure and couldn’t think of anything worse.
But if you do want to give it a go...
How do you get started?
First, you should probably consider your own tolerance for cold.
If you're someone who hates cold weather or finds the idea of a chilly shower unbearable, jumping straight into an ice bath might not be the best starting point. You might want to start with shorter exposures, like ending your shower with a quick blast of cold water.
As you get used to it, you can always extend the duration or explore other methods.
Safety is really important - always be aware of your physical condition.
If you have pre-existing health issues, especially heart concerns or conditions affecting your blood circulation, you should consult this with a healthcare professional beforehand.
As you experiment, listen to your body.
If you experience prolonged discomfort, shivering, or any adverse reactions, you should reassess and maybe alter your approach.
Remember that what works for one person may not be suitable for another.
If you want to jolt yourself to the core, just hop in the shower or take an ice cold bath.
You probably don’t need to buy a really expensive cold plunge tub.
I actually found one for nearly $30,000. (I think you can get one off Amazon for like 50 quid). Or just use your wheelie bin.
Ok so to finish - is cold water immersion a fad?
I don’t think it’s a fad. Cold exposure can be quite a powerful thing.
I just think that we try to over science lots of things and then use the science to justify it’s importance to everyone.
Of all the fads and experiments I’ve seen people do, ice baths are relatively benign and chilled. (Pun not intended).
So if you like it, great. If you don’t, it’s all good.
A quote from a great
Hope you have a chilled day,
Z
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