( Originally Published 1938 )
Let us first consider the effect of full immersion cold baths. If you are brave enough and hardy enough to enjoy such a bath, you'll be wise if you take the precaution of sponging your neck, head and chest with water of a temperature below that of the bath if possible. This mitigates the initial shock. If the immersion lasts more than a few seconds, rub your body vigorously the whole time. But under no circumstances remain in the tub more than three minutes.
The action of a cold bath depends upon the mode, length and intensity of the application. With short moderate immersions the blood vessels of the skin are at first contracted, the skin pales and roughens. Since the surface vessels are contracted, there is a rise in blood pressure. The pallor leaves after a short time and is replaced by a redness due to the relaxation of the vessels. The more intense the cold, the greater the reaction. This is also true in the case of a cold shower which has the added effect of mechanical stimulation.
With the initial constriction of the surface vessels and the inhibition of sweating, heat elimination is greatly diminished. However, when the reaction takes place, the heat of the body escapes through the skin and the temperature is lowered. The drop in temperature lasts for only a short time, since the voluntary and involuntary or "shivering" movements result in an increased production of heat. In fever conditions there is a more lasting fall in temperature.
The cold bath also has a combined effect of both resting and exercising the heart, but such a bath should never be indulged in if a person has a weak heart.
Cold water at first produces deep inhalation with a momentary arrested respiration at the height of inhalation, followed by deep exhalation. This effect is usually known as gasping. If the application is prolonged, the respiratory movements continue to remain deeper and frequency is inereased. The excretory function is affected in still another way diuresis or excretion by the kidneys is increased.
Cold water tends to prevent muscular fatigue and to restore normal tone to fatigued museles. Mechanical stimulation, such as vigorous rubbing of the body or applying the water in the form of a shower, tend to heighten this effect.
Most of the reactions which we have just described are brought about through the nervous system. Cold baths of short duration tend to increase the sensibility of the nervous system. The central nervous system, too, is decidedly influenced, as witnessed by the feeling of refreshment and heightened vigor after a brief cold bath.
Cold baths are used to reduce temperature in feverish persons but in normal individuals they are largely confined to use after a hot bath in order to tone the skin. It is an excellent form of stimulation for healthy persons and is efficacious in cases of obesity where it is used to increase metabolism or the burning up of tissues for energy. Highly irritable, nervous individuals respond irregularly to cold water. For the most part they respond poorly, although some have an excessive reaction. Cold baths should not be used in the case of the very young and the very feeble. They are also contraindicated in febrile conditions which are due to inflammation of internal organs, arteriosclerosis and kidney disorders. And remember, even if you are in the very prime of health, if you have an unfavorable reaction, or no reaction after a cold bath, that is, if your skin isn't pink and smooth and supple, if you have no increase in perspiration and above all, no sensation of well-being, warmth and renewed vigor, by no means even think of indulging in this type of bath, despite the advice or proud boastings of friends. Hot baths are equally beneficial, and most of the effects resulting from a cold bath can be obtained through some form of the hot bath.