from Hydrothermic Remedies...
The modes in which water may be applied to the human body therapeutically are almost infinite in form and variety.
One of the most useful methods of application is the shower. Dr. John H. Kellogg has stated that the shower is the "the most powerful and valuable of all tonic measures. There is no drug known to man that is possessed of such marvelous renovating and permanently restorative properties."
In the therapeutic use of the shower, three factors are active:-
Due to the shortness of space, we will not discuss pressure of mass, except to say that the more forceful the pressure, the greater the effect will be; and that the mass you use will mainly be determined by whether the patient prefers a fine mist or a single jet (a jet will be more stimulating, but must be limited to the back and extremities). We will limit ourselves to the physiological effect of neutral, hot, cold, graduated, and alternate hot and cold showers. We will discuss the benefits to be derived from the various temperature and the conditions under which the shower might be discouraged. In this brief section we will not concern ourselves with the therapeutic applications which ought to be under the direction of a registered physiotherapist by physician's prescription.
Showers may constitute a treatment in themselves or be given as preliminary to, or as conclusion to another tye of hydrotherapy application (i.e: as a cool-down after a hot steam bath). Showers may be applied to the whole body or as local treatments. They may be given with good effect along with massage.