Pouring Cold Water on Cryotherapy

One of our most abundant renewable resources is bogus medical therapies. About every day, someone thinks up a new one: sometimes invented from whole cloth, sometimes extrapolated from a real therapy, sometimes tweaked from an old tradition. Today we're going to look closely at one such spin-the-wheel-and-create-an-alternate-therapy: cryotherapy.

Don't confuse this with medical cryotherapy, the freezing off of tissue, usually called cryoablation. Alternative cryotherapy is a hijack of an actual medical term repurposed to refer to the use of what they call a cryosauna, the opposite of a regular sauna. Rather than applying ice to a specific body part, a cryosauna is used for what they call Whole Body Cryotherapy. It's a small room for one or more people, cooled by liquid nitrogen to extreme temperatures, usually about -125°C/-200°F but sometimes advertised as low as -170°C/-275°F. You have to wear special slippers to protect your feet since you can't touch anything in there, and you have to wear a mask to avoid frostbite to your pulmonary system. You stay in for no more than three minutes.

What is the medical claim? Unfortunately, as it is with so many alternative therapies, cryosaunas are claimed to cure just about anything the proprietor says, and they all have different spiels. Most all of them say it treats inflammation, skin conditions, and aids in workout recovery. There are several spas, plus chiropractors and other alternative practitioners near me who offer cryotherapy, according to Yelp.

Almost all of the customer reviews are raving. Here are some samples:

"My inflammation almost immediately decreased and I felt a huge wave of euphoria similar to a runner's high."

"Felt great afterwards. Will try again to see if I have any lasting effects."

"I feel euphorically energized after each session and I have noticed that my tendinitis has gotten better after 2 sessions."

"I feel so good afterwards. I can tell this cryotherapy is helping to heal my body!"

Why do these people feel so good unless there's something to cryosauna therapy? Is it possible their reaction comes from something other than genuine treatment of some medical condition? The evidence shows that it probably is.

If you're like me, you've done the polar bear plunge a few times. In my case it's skinny dipping into a High Sierras lake with a big iceberg floating in the middle at 3,500m. I've also jumped out of the hot tub in mid-winter in Lake Tahoe and plunged into the powder snow. It's quite a shock and gives you a real rush. But that's not just me saying so; that's real science. When we jump or fall into very cold water, our bodies go into the cold shock response. This is what causes most drownings in extremely cold water. It is an uncontrollable gasping that often causes you to gulp in water. A sudden plunge into any massive temperature change also triggers the acute stress reaction, known as the "fight or flight" response. Among its numerous physiological changes throughout the body are the production of dopamine in the brain and a great dump of adrenalin into the bloodstream, which produces endorphins. Yeah baby, those Polar Bear Club nuts are onto something.

It is, for real, a rush. You will walk out of the cryosauna ready to rock and roll, shouting something like "Wow! That was incredible! Let's do it again!" But before you pull out your wallet and start throwing money around, note that you can also get the same result at home, for free, by simply getting into the shower and turning on the cold water.

But wait, you say: a cold shower is water that may be only 15°C/60°F, which is not nearly as cold as the cryosauna. This is true, but it's also true that these two different environments will indeed extract heat from your skin at about the same rate. Air is a terrible heat conductor, while water is an excellent heat conductor. Water can remove heat some 25-30 times more efficiently than air can, so cold water is just as effective as a hyper-cold cryosauna.

Some athletes have been doing the cold-water version for some time: ice baths, literally a bathtub full of water and ice. This is great for orthopedic sore spots like shoulders and knees that might need an ice pack after a workout, combined with the rush from the shock response. You would come out of an ice bath numb and euphoric.

At least, you would at first. Testing done in 2005 showed that sudden immersion in cold water is something we adapt readily to. Depending on time of exposure, having just six such immersions under your belt gives you resistance to the cold shock response, with the increase in respiration reduced by 20-50%. Your brain learns "Oh, I guess this is not going to kill me after all," and the rush you get from an ice bath — and presumably from a cryosauna, though this was not in the study — will diminish once you've done it a few times. In short, you get used to it, and won't get as much out of it after a few visits.

So this leaves us with the amazing medical claims made by some of the proprietors of these cryosaunas. Here's a short snippet from a much longer Yelp review from someone that I'm pretty sure was a plant:

"There is also a bunch of studies around using cold therapy for many other health benefits including helping men with fertility issues, mental health issues, as well as helping with long term pain relief, arthritis, and depression."

The owner then replied, possibly to himself:

"I have seen cryotherapy provide very positive responses for psoriasis and eczema. It is interesting to see how skin health improves by reducing systemic inflammation."

"There exists a holistic solution to replace NSAIDs and medications. Cryotherapy can be very effective at treating fibromyalgia, chronic fatigue and other inflammatory conditions."

None of those claims are supported by evidence, and few of them have any plausibility. We can assert this as a fact, because whole body cryotherapy has been studied for a few such conditions. It's a certainty that no body of evidence supports the claims of cryotherapy for most of the conditions just listed — those appear to be nothing more unadulterated salesmanship — but what about treating inflammation, the most often cited benefit? Well, that's not very specific; all kinds of bits of anatomy can become inflamed for all kinds of reasons. Athletes who turn to cryotherapy often do so to treat chronic joint pain or to help muscles recover from exercise; exactly what we typically use ice packs for. Since the ice pack is in direct contact with your skin, it can conduct the heat away far more efficiently than a cryosauna, and is way more convenient and affordable.

But the question is whether the cryosauna can be as effective. Well, it may be, we don't know, because as of yet there has not been enough testing done. Thickening the plot of this question is the fact that reducing inflammation with an ice pack also has not been sufficiently tested, despite its nearly ubiquitous acceptance in sports medicine. Icing is a very effective treatment for pain, but the proof that it actually reduces inflammation is, surprisingly, minimal. Cryosauna has even less evidence, so right now, anyone selling you a treatment claiming otherwise is wrong. I'm not saying he's lying; most likely, he's been honestly misinformed by his company or by the cryosauna manufacturer, or simply by the massive pop-culture machine that drives industries such as this.

Here's a customer comment that represents yet another widely-held belief in the abilities of cryosaunas:

"The cold bumps up my metabolism so, over the next couple of days, I appear to drop weight."

There's one undeniable health effect of being in a cold environment for an extended period, and that's to put your metabolism into overdrive. Fighting off the cold puts your whole system to the test. If we take a look at one group who tried this, albeit unwillingly, for a long time — the Shackleton expedition, stranded in Antarctica for more than two years with almost no shelter — we can see how many calories it took just to stay alive. They were fortunate to have excellent food stores, and were able to keep up their diets with their primary food source, a concoction called hoosh. The ingredients for Shackleton's hoosh recipe were lard, oatmeal, animal protein, vegetable protein, sugar, and salt. Each man's daily ration of half-pound blocks provided an estimate 6,000 calories. That shows how much energy the cold sucked from their bodies.

But before we make the leap to assuming that a quick visit to a cryosauna will do the same thing, we have to understand what was happening to Shackleton's men. Their bodies burned that many calories because they were on the verge of hypothermia, almost all the time. Their core body temperatures had dropped, and that's a dangerous thing. It's different from your skin being cold because you go into a cold room for a few minutes. Most people have more than enough biochemical energy stored up to handle that easily, without kicking in the body's long-term preservation mechanisms.

You're in the cryosauna for three minutes. Your body's core temperature is unaffected. Your heart rate does increase, but that's due to the adrenalin from the cold shock response. If your visit to the spa is in the hope of burning calories, you could probably get better results by simply jogging for two minutes or running up two flights of stairs. It just isn't enough to make any noticeable difference.

Everyone wants a miracle treatment. Everyone wants to spend three simple minutes to gain radical health benefits and an edge in their sports performance. It's perfectly natural and normal to want such things. It's just, sadly, not very realistic. Visit a cryosauna in the hope of obtaining a medical benefit, and the chances are that you're going to be disappointed. But mix a little science literacy into your visit and understand what you actually will receive, and the prospect gets a whole lot cheerier. If you're into adrenalin rushes, a visit to -170°C/-275°F in your skivvies might be just the thing for you. It's not free like a jump into a snow bank or an icy mountain lake, but if you've got the $50-100 to spare, why not get your rush from standing in the coldest freezer you'll ever see? Keep up your guard and your skepticism, beware the red flags of sciencey-sounding claims, and get cold. Really, really cold.

By Brian Dunning
Follow @BrianDunning