Cryotherapy simply means "Cold Treatment", therefore it can be used in many applications and medical procedures.
The Cryosauna is pumped with environmentally friendly gas nitrogen ( nitrogen composes 78.09% of the atmosphere), and is cooled to a temperature of approx.−110 °C. The patient is protected from acute frostbite with socks and spends up to 3 minutes in the Cryosauna. 

The sauna works by cooling the entire skin surface of the body in order to develop defensive reflexes and reactions such as stimulation of blood circulation, endocrine system, the immune system and the central nervous system. Such stimulation makes the therapy beneficial to a range of conditions. During the cooling effect your brain will trigger a spontaneous release of endorphins and adrenaline into your blood stream. 

Post treatment you will feel a tingling sensation over your skins surface together with a analgesic  effect, your capillaries will expand to around four times there natural diameter. This enables your white blood cells to access and heal your injuries up to 50% faster then the natural process. Therapy triggers the release of endorphins which also induce analgesia (immediate pain relief). 
Whole body cryotherapy originated in Japan in 1978. However, it was a group of Polish scientists who took the idea and made whole body cryotherapy the physical therapy it is today.
The lowest ever recorded temperature on earth was recorded in Antarctica on Aug 25th 1960, you will experience a temperature almost 110 degrees centigrade lower then this.