The benefits of cold therapy include pain relief, reduced inflammation, swelling and muscle spasm and metabilix rate. It is important for treating sports injuries. Here we explain the benefits and effects of cold therapy.
Why does ice reduce pain? The reason behind pain relief is a cold therapy benedit is not completely clear. There are many theories and it is possible that a number of the proposed mechanisms in combination have an anaesthetic effect. Some of the possible mechanisms include the following.
- Decreased nerve transmission in pain fibres.
- Reduces the activity of free nerve endings.
- Cold raises your pain threshold.
- It causes a release of endorphins. These are the bodies feel good chemicals.
- Cold sensations over-ride the pain sensation. This is known as pain gate theory.
Cold therapy reduces bleeding and swelling
By cooling the surface of the skin and the underlying tissues, ice causes blood vessels to narrow. This is known as vasoconstriction. Vasoconstriction therefore leads to a decrease in the amount of blood delivered to the area. As a result, it reduces swelling.
Hunting response & vasodilation
After a number of minutes, the blood vessels re-open (dilate) allowing blood to return to the area. This phase is followed by another period of vasoconstriction. This process of vasoconstriction followed by dilation is known as the Hunting Response.
Although blood still flows into the area the amount of swelling is significantly less than if ice is not applied. This decreased swelling (edema), allows more movement in the muscle and so lessens the functional loss associated with the injury.
Inflammatory response & cold therapy benefits
The swelling associated with the inflammatory response also causes a pressure increase in the tissues. This leads to the area becoming more painful. Pain is intensified by certain chemicals that are released into the blood when the tissue is damaged. Hence, vasoconstriction from applying ice also decreases pain.
Reduce muscle spasm
Another benedit of cold therapy is reduced muscle spasm. This is often a response to pain as muscles surrounding the injury contract to protect it. This is known as muscle guarding and it aims to prevent further damage. Because ice has a pain killing effect, the muscle relaxes as a result of decreased pain.
However, it is also thought that muscle spasms which are overuse related (not acute) can also benefit from applying cold therapy. This is not fully understood but is thought to be due to ice slowing the conduction velocity of sensory and motor nerves. Also, the activity of muscle spindle cells is decreased. Muscle spindles are sensor in the muscle which sense muscle tone.
Decrease metabolic rate
By reducing the cells metabolic rate, ice reduces the cells oxygen requirements. Therefore, when blood flow is limited by vasoconstriction, the risk of cell death (called secondary cell necrosis) is reduced.
References & further information
- Updates on PRICE – Br J Sports Med 2012;46:220-221 doi:10.1136/bjsports-2011-090297
- What is the evidence for PRICE? – J Athl Train. 2012 Aug; 47(4): 435–443.