Whole-body cryotherapy is essentially a modern variation on an old idea. That idea is that cooling off is good for you. Athletes routinely use ice packs to bring down inflammation in sore or injured joints. Some also take dunks in ice-cold water based on the theory that the submersion speeds recovery from intense physical exertion.
The idea that freezing your rear has health benefits dates back at least as far as the late 1800s when one Professor Sugarman became world-famous as "the human polar bear" for his midwinter dips in an icy New York river [source: Fulton County Republican]. Sugarman was known as a health advocate, but it's not clear what benefits he claimed from the practice. At least one recent study has found that people who swim regularly in cold water report improvements in mood and reductions in chronic pain [source: Huttunen et al.].
Dr. Yamauchi's 1970s innovation of replacing water with nitrogen cooled to liquid form and released as a gaseous mist was designed to help people suffering from rheumatoid arthritis. The practice was picked up by athletes in the former Soviet bloc, and from there it spread. It was only a matter of time before whole-body cryotherapy crossed over from the world of elite athletics to trendy health spas.
While it's often referred to simply as "cryotherapy" in popular media, the practice should be called "whole-body cryotherapy" to distinguish it from "local cryotherapy," which is a much-used and highly effective medical application. When applying local cryotherapy, doctors use liquid nitrogen to freeze skin or organ tissue that needs to be removed.
Whole-body cryotherapy is a different animal altogether. At a cryotherapy center, you'll plunk down $40 or $50, strip to your undergarments, and walk into a "cryosauna" or cryotherapy chamber. The chamber looks a bit like a fashion-forward version of one of those barrels clowns sometimes like to wear. Or maybe it's a bit more like an expensive incarnation of the trash can Oscar the Grouch lives in. In other words, your body's in a tank while your head pokes out from a hole in the top.
Then liquid nitrogen is released into the chamber where it instantly gasifies, and you're enveloped in a freezing mist somewhere in the neighborhood of minus 256 degrees Fahrenheit (minus 160 degrees Celsius). Sessions usually last no more than two to three minutes. Using very cold, very dry gas rather than water reputedly cools the body more slowly, with the cold penetrating no more than half a millimeter below the surface of the skin [source: Robinson].
Proponents claim that the practice not only reduces inflammation, but also destroys toxins, increases metabolism, boosts the immune system and slows aging.
If that's what the enthusiasts say, what does the science tell us?