Cryotherapy the cold, hard facts on the world's coolest spa trend

Having worked for a spa magazine in my formative years, I've become pretty au fait with obscure treatments over the years. I've been pummelled with sticks of bamboo in the name of tension relief; I've had salt thrown at me to cleanse my aura; I've had tiny carp nibble away at my dead skin. I've even had a facial that utilised bird droppings. But I had never been frozen – until I signed up for whole-body cryotherapy in Finland, that is.

The philosophy behind cryotherapy – or cooling therapy – is not, however, as obscure as its name suggests. For centuries, doctors and sports therapists have favoured the technique of "chilling" various parts of the body to reduce injury through the constriction of blood vessels. Think, applying an ice pack to reduce blood flow, alleviate pain, swelling and inflammation after a fall, bump or scrape, or taking an ice bath after serious athletic training. Doctors also use localised cryotherapy, such as applying small amounts of liquid nitrogen to destroy abnormal skin tissue.

Today's whole-body cryotherapy – cryo comes from the Greek word for "icy" or "cold" – takes things a step further, with willing participants who are not necessarily injured to begin with signing up (and then signing a lengthy non-liability form) to endure very, very sub-zero temperatures. Potentially for the health benefits; definitely for the bragging rights.

My experience at Haikko Manor in Porvoo, a pretty spruce-laced spa town just outside the Finnish capital of Helsinki, begins with rules and instructions: I'm to shower, get completely dry, don my bikini, pull on felt booties and mittens, and step into an oversized vertical cylinder. Said cylinder is then chilled to -120Celsius – mine actually floats down to -138. A cool cloud forms as the cylinder's door opens; I shed my gown and step inside as liquid nitrogen (some chambers use refrigerated cold air) envelops me. The unit rises, and my head pops out the top of the cryo chamber – everything below my chin is treated to an icy blasting.

It's cold, really cold – colder than the coldest naturally occurring temperature recorded on Earth, in fact, which was -89.2C at the Soviet Vostok Station in Antarctica in 1983. Satellite recordings show there were absolutely, positively no people hanging around outside in their bikinis when that record was reached.

But it's not painful or unbearable. And, surprisingly, it's not the coldest I've ever felt – the next day, in local tradition, a dip in the Gulf of Finland after a sauna at Loyly proves a far more bone-chilling experience. In fact, I feel colder most days just walking the streets of Porvoo thanks to icy winds and a severely wanting winter wardrobe.

The first minute is the worst. My teeth chatter uncontrollably, the skin on my legs burns, goosebumps pimple my entire body. But thankfully I'm distracted by a gaggle of onlookers snapping photos of me – well, of my head, appearing to "float" in a nitrogen cloud shrouding the top of the sci-fi-like cryo contraption. During minute two, my therapist (let's call him Sulev) tells me that we've hit – 120 in the chamber; my skin temperature, however, will only be brought down to about 5 to 12C. By the end of minute three, I'm feeling numb enough to I think I could stay in longer. But Sulev has stopped the clock as I've reached the maximum treatment time.