I first read about this technique in "the 4 hour body" by Tim Ferriss, one of my all time favorite fitness books. So much incredible mind-boggling info on quirky ways to get fit quicker.. He pretty much ignores the good old fashion way of committing to a healthy lifestyle which is what I usually recommend. But anyhow..for those of you who'd prefer to cheat the system this book is for you. 

And for more info on the Cold water therapy and it's benefits check out this article by Mark Sisson