The application of cold triggers three basic reactions.
Firstly, at a cellular level, the metabolic response of the cells is reduced, so the cells need less oxygen to function and thereby suffer less hypoxic injury.
Secondly, the permeability of the blood vessel walls is decreased, thus reducing the amount of fluid that accumulates in the injured area.
And thirdly, the cold numbs the area to a certain degree, acting as a topical analgesic.
One of the best things about cold is that it does not override the beneficial effects of the body’s natural healing process.