Cryotherapy simply means the use of cold as a therapy. When a person is injured, the most common response by the body is pain or muscle spasms. Tendons and ligaments connect the muscles and bones to each other. The basic building material of these is collagen, which stretches and returns to normal depending on the tension that is applied to it. Stretched too far, collagen tears, and this tears blood vessels, allowing blood cells and fluid to escape into the spaces amongst the muscle fibres. Applying cold to the area reduces the amount of fluid flowing into the tissues and also slows the release of chemicals that cause pain and inflammation. It also decreases the sensation in an area by reducing the ability of the nerve endings to conduct impulses. Cold also decreases the activity of cells in order to reduce the amount of swelling and internal bleeding at the injury site. Cooling the tissues reduces muscle spasms. This is done by reducing the muscle’s ability to maintain a contraction.