Our body operates at 37° C as long as the blood flow functions at a normal rate. The flow rate depends on temperature and pressure. It is highest in the body core (40cm/sec) and up to 1/1000 times lower (0,4mm/sec) when it finally reaches the most distant extremities (fingers, toes) and before it pushes back to the core. The blood has now reached its lowest speed, is the coldest and uses additional energy to keep flowing. This process can result in cold pain or even hypothermia (undercooling). At an outside temperature below 0° C, the hands and feet can reach levels as low as 28° C.

The skin is a complex organ with 93% cold sensors and 7% warm sensors. The sensitive structure consists of two mutually dependent layers, the outer epidermis and internal dermis, which rest on a thin brown fat layer serving as insulation. The functionality of the hand is ensured when the blood circulation works at a normal rate. At the hands and feet, and especially in the case of women, the skin surface is disproportionally larger compared to the overall volume and the thickness of fat insulation, causing an exceptional sensitivity to cold and deceleration of the blood circulation.