Cold baths stimulate brown fat, which increases metabolism and helps digest white fat stores.
They also boost neurovegetative function.
Beware of thermic shock!
Go little by little and slowly in your cold bath!
One body part after the other, before plunging the whole body in it.
Vigorous rubbing of every part with a glove of rough natural material, for instance hemp, activates circulation, is very healthy, and permits you to stay longer in icy water.
Besides, it maintains your skin always clean, and clears any dandruff.
The organism of elderly people needs a long period to be accustomed to low temperatures, months and even years, so take your time!
Conditioning is a very slow process.
Exposition should be limited in duration, and you must dress with appropriate clothing afterward, and be able to warm-up quickly in a cozy environment.
Monitoring bath temperature with a thermometer, for progressive conditioning, is a useful method. This one should stay above shivering level.
Previous physical training and preparation of the cardio-vascular system for years is essential.
The origin of the thermic shock is probably a “heart attack” with normal coronary arteries, like Takotsubo cardiomyopathy.
As proteins possess a higher thermogenic action than starches, and much more so for lipids, brown fat also consumes muscle.
Shivering is a natural protection response, which consists of tiny muscular contractions, and protects thus this noble element from burning.
That is why it is important to combine such a practice with preceding and following physical activity.
Remember to make a pause before washing.
For Anaerobics an interruption of a few minutes is probably sufficient, pondering its intensity, while for Cardio you would need a longer lapse of time.