The application of cold water produces a greater stimulation of the skin and a more intense reaction of the body. There are two well-defined stages.

1- The first stage is a direct, local response to the application. When exposed to cold the blood vessels in the skin contract, reducing the flow of blood through the skin.


2- The second stage is a general, reflex-type action, which consists of reactive vasodilation (dilation of blood vessels), which increases the flow of blood through the skin, giving it a reddish appearance.

In hydrotherapy treatments it is important to always favor this second, reactive phase by:

> Covering up in bed as soon as the application has finished,
> Taking physical exercise, or
> Applying friction to the skin.

"Never apply cold water to a cold body"