I'm of Russian heritage. I know of the crazy habit they have of plunging themselves bare naked into a hole in a frozen river or lake in the winter. I don't think they do it for health reasons. My guess is something atavistic and also lots of vodka in their systems to gather courage to do this crazy stuff. The way I see it, using the Russians as an example is a good example of bad science, cause there is nothing to corroborate the fact that the Russians do this for health reasons. To me, this is a huge red flag in the assumptions made on the subject of cold water being beneficial for our health.