If you refer back decades and even well over one hundred years ago you will notice that pretty much every culture practiced some form of cold water immersion therapy at one point or another. Aside from making you feel much more alert and invigorated, there is definitive evidence that shows submerging in a painstakingly cold ice bath or dousing yourself under freezing cold water, or exposing yourself to very cold temperatures outside with light clothing will effectively boost your metabolic rate and allow you to burn more calories, among many other things. Here is an article from world famous trainer Ben Greenfield that covers everything you literally need to know in regards to various levels of cold water therapy:
In this article Ben talks about two very potent hormones (i.e. adiponectin and irisin) involved in health and longevity, body composition management, and performance as it relates to cold therapy. It’s easily the best article written on the subject too date, so any feeble attempt from me to re-invent the wheel here wouldn’t do justice and I would just be repeating what Ben already wrote. I just want to take a moment in this short article to outline some of the surface level benefits associated with cold water therapy so you can appreciate the modality's value.
First, there is a very apparent increase in energy utilization from exposing yourself to ultra-cold showers for a short duration (1-2 minutes) at repeating intervals. Cold therapy is a form of hormetic stress, meaning that too much of a good thing can be bad and any benefit that you encounter from cold training can be restricted if you try and push the temperatures too low for too long at the beginning. A greater starter method for this type of therapy would be cold exposure for 1-2 minutes followed by a minute or two of hot water, and repeat the sequence for 4-6 rounds. I can tell you firsthand that any intolerance that you feel at the start of cold therapy will be diminished once your body builds up a safeguard against the extreme temperatures for whatever reason.
The next benefit of cold water therapy is a boost in testosterone levels! With testosterone’s very direct control on muscle exertion levels, this benefit is great for anyone regardless of your age or training objective. A research study performed in England during the early 90s showed that plunges in cold ice baths and exposure to extreme cold weather and water sources yielded an increase in testosterone production in the human body. 1 Moreover, there is a potent immune response that occurs as well which give you the added benefit of an increase in white cell production to help combat disease and increase your immunity!