Thread by @stevemagness

Ice baths, cold plunges, cryotherapy seem all the rage. Everyone’s jumping into freezing water.

But do they work?

Let’s look at the science from an athletic, health and well-being standpoint.

Lots of debate here we come:

1st: Athletic performance

Athletes use ice baths to enhance recovery.

The simple theory is they reduce inflammation, aid recovery, & get you back to normal soon.

Great! The research is a bit all over the place, but some say it actually works. Inflammation goes down.

But wait…inflammation isn't all bad.

Do ice baths aid recovery & performance? They actually may do the opposite.

Inflammation can be good. When we work out, the damage (whether physical or physiological) is often the trigger that leads to adaptation.

We get microtears in our muscle, our body says “crap, repair, get stronger!” Or we experience oxidative stress, and our body says 'make sure our mitochondria can deal with this next time!'And it does.

Reducing inflammation (and other damage) can INHIBIT positive adaptation

It’s why taking anti-inflammatory pills can lengthen injury time.

Dampen inflammation at the wrong time, you impair the building up/repair cycle.

For a nice review on this and the importance of timing of NSAIDs and the impact, check out this paper: journals.physiology.org/doi/full/10.11…

With ice baths, it’s not just theoretical. It is real.

Taking ice baths post-training, impairs strength training adaptations: pubmed.ncbi.nlm.nih.gov/24552795/
A review found ice baths likely blunt pathways that lead to strength training adaptations:
pubmed.ncbi.nlm.nih.gov/29627884/

Another found a decrease in anabolic signaling, protein synthesis, and muscle size, power, peak force, and more
pubmed.ncbi.nlm.nih.gov/33898988/

There’s lots of research in this area in strength training. The endurance data is a bit more mixed and nuanced.

But the principle holds.

I call this the disease of over recovering.

We don’t want to get in the way of adaptation. The damage, the inflammatory response, the fatigue is the signal that tells us to get stronger!

Turn that signal off too soon, and you just wasted part of your workout.

So what?

Save it for when you need it.
Ditch the ice bath if getting stronger/fitter is the goal of the training. Fatigue is the point.

If you like ice baths, if they make you feel better... Great, use them when competition is king. When adapting to training isn’t as important

What about Health?

All these people on social media tell me to jump into an ice bath first thing in the morning. Let’s evaluate.

What's going on when we take a plunge? Let’s focus on 3 things:
1. Hormonal surge
2. Immune System
3. Metabolism- Brown Fat

1. Hormonal Surge- It’s true. We get a surge of hormones.

One study found 1 hour in 14deg C water led to a massive surge in Dopamine and Noradrenaline.

Great! But…so what?

Playing slots triggers a similar response, as does sprinting up a hill, playing video games, etc.

Hormonal surges look great on Twitter: "X increases dopamine by 200%!"

But they mean nothing without context

What we’re seeing here is a specific stress response. We increase arousal, and we feel energized. So all the people saying they feel great. They probably do….for a bit

Increase arousal first thing in the morning and we feel energized.

Same thing if you go for a run, walk, dive into a creative pursuit, or jam out to music in your car.

Just about anything somewhat hard that forces us to be engaged will see a similar hormone boost.

The questions we need to ask are… So what?

Does it matter?
Is it better than the other things that we can do?
Is there a functional change?

Shifting mood is good, but simple. You want to ask about long-term shifts in measures that matter.

Take the data that shows ice plunges may help with feelings of depression.

It works via the release of noradrenaline and beta-endorphins.
pubmed.ncbi.nlm.nih.gov/17993252/
casereports.bmj.com/content/2018/b…

In other words, if it does work, it's in a similar fashion as exercising.

Which is great.

It’s another tool in the toolbox to shift mood. A little bit of stress is a good thing.

But it’s not magic. The research is small and limited

The research in other areas that do the same thing: Exercise, talking to friends, walks in nature, is much more robust

2. Immune System
Sitting in 14deg C water for an hour does activate the immune system
pubmed.ncbi.nlm.nih.gov/8925815/

Shorter but slightly colder plunges can too

Why? It’s a stress response. Again, go for a jog, lift some weights, go stand on stage for a presentation. Same immune boost

Ask, does it matter? And does it work better than those other things we do?

Does it matter?

Doing something that activates stress response (and shuts off quickly) consistently does seem to help. It's why exercise works. So, yes, activating immune system can reduce illness

But with cold, the data is mixed.

Most show a short-term increase in immune system markers, but little long-term data on whether this matters.

In one review, they point out in some cold water swimmers it leads to a disruption of daily cortisol response: physoc.onlinelibrary.wiley.com/doi/full/10.11…

Again, it’s a tool. It may be useful. We've got short-term data focused on immune system markers.

That tells us only a little. Many things 'enhance' the immune system acutely. Hyperventilating, for example

Does it work better than things like exercise? Doubtful.

3. Brown Fat/Metabolism

1st, jumping in an ice bath can boost your metabolism via shivering & activating brown fat.

We could get into the details of cold shock proteins, brown fat activation, hormones, but let's not get lost.

Activation of stuff is simple and easy.

Does it matter? Does it lead to a functional change? And if so, how much over the long haul?

The real answer at this point: We have no idea. We have a theory and a story.

Let's explore:

Take for example, athletes…

Did you know athletes generally have LOWER brown fat than regular people?

Did you know endurance athletes often have even lower brown fat?
journals.plos.org/plosone/articl…

Wait a minute…I thought brown fat was what we wanted?

The body adapts to the demands put upon it.

Endurance training actually seems to reduce the activation of brown fat in the cold.
journals.biologists.com/jeb/article/22…

Here’s my point: It’s not an easy straight forward answer. Individuality matters here.

If you are an athlete, I wouldn’t be worrying about brown fat activation…

If you are struggling with being overweight/obese, I still wouldn’t worry...

Yes, cold can activate and may even shift things. There is data on that.

It may turn out to matter and help a lot. But the hard data right now is lacking.

Is it better than a good healthy diet and exercising? Doubtful.

Will a few ice baths help over the long haul, or would you need to go back to a world without a heater? We don’t know.

We know it shifts metabolism. We know shivering can increase metabolic rate, but is shivering for 30min for ~10 extra calories in that time worth it?

We’ve got a good theory and story, but all the reviews say the same thing.

Interesting, not yet viable. No one has seen a functional change.

A few reviews on the topic:
journals.physiology.org/doi/full/10.11…
nature.com/articles/nrend…
link.springer.com/article/10.100…

It’s complicated.

The few studies that have looked at cold & weight loss, haven’t been promising: onlinelibrary.wiley.com/doi/abs/10.111…

That doesn’t mean we give up or that you don’t try it out. There’s little harm.

Just don’t jump in ice baths and neglect what we know actually works!

So what?

Why do ice plunges sometimes ‘work’??
-They are somewhat hard and force engagement.

They can make you temporarily feel better. Why? It increases physiologic arousal. A stress response. Just like so many other things.

Is it a cure-all? Nope.

Does it work better or even at the same level as other items we’ve mentioned? Doubtful

Going for a walk, jog, creating or crafting something, having a good conversation, hiking in nature, all do the same thing. Many much better. And with other added benefits that are proven!

The point is: Don’t get caught up in the activation of pathways, the release of hormones, etc. Lots of things do that.

Does it lead to a functional change? If it makes you feel better with little downside? Great. go for it. Take a cold plunge.

Please, make sure you are doing the big bucket items.

It’s better to go for a hike than sit in a cold tub. If you like both, great. But if you are jumping in a tub, and not exercising, reading, having deep conversations with friends, or whatever, you’re missing the boat.

Doing hard things is great…

But hard things take effort. Is the effort worth the outcome?

If I want to add another hard thing to my life, it either has to have a large benefit or be better than the other hard things I do in my life.

If it’s simply another thing that is hard, increases arousal, and demands focus, I’ve got enough of those things in my life that I like more.

Running, working out, coaching, reading, going on long walks with my dog.

Shivering for 10min adds little I don't get elsewhere.

For you, that calculus might be different. But don’t get lost in the hype, the science at the pathway/hormone level.

Keep ice plunges/baths in their rightful spot. They are a tool. They can ‘work.’ Many things can.

They aren’t magical.

Thanks for taking the time to read this very deep dive. It's a fascinating topic.

If you're interested in performance, I go deep on topics weekly, consider following along.

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