What will be if to take an ice shower? Learned from walruses, for which water in lakes while too warm (Special project)

Our joint from Bionorica SE "The autumn marathon against colds" proceeds. We already learned that is not to ache, and collected personal stories of our readers about immunity strengthening. We sort all these subjects in a marathon telegram-chat in more detail — subscribe, we wait your comments! And today we will discuss a hardening and cold treatment...