In the cold winter days, air conditioning systems help create an atmosphere in the room is warm and pleasant. Similarly when you are in a car, air-conditioned offices or bedrooms. However, the fact that some people have a cold this time more.

"Our bodies are pampered," Ulrich Betz, director of the Institute for Rehabilitation, prevention, and treatment of the body at the Johannes Gutenberg University Medical Center (Germany). "Over time, the lack of exposure to natural stimuli will weaken the immune system."

Betz has compared this with the athletes still have to "self-deportation" in the extreme workout to enhance the activity of the immune system.

"The more often exposed to the cold, the less likely a cold. Otherwise, the body has become adapted."

According to the German press and the China Daily, a doctor at the same time as the German naturalist Georg Kruenitz 18th century by defining "forged body", according to which "create the body to adapt, so that will withstand factors and external hardships, so that the body does not even feel the obstacles. "

Annealing methods include sunbathing, cold shower, barefoot, sauna, have become highly developed in Europe and became a part of natural therapies. Explanation of this effect, the experts say it is because of the body, hot or cold state are the stress. As soon as the body realizes the difference between body temperature and the outside temperature, it will try to pull the normal level.

"This will stimulate the blood flowing and whole body becomes energetically".

The result of this practice is a body full of life and more stable.