The application of cold to the tissues is a practice as old as medicine itself.
An ice pack, or more conveniently, a large bag of frozen peas wrapped in a thin, damp cloth may be used to:
a. reduce pain
b. reduce muscle spasm
c. reduce swelling
d. promote repair
The initial response of tissue to cooling is an attempt to preserve heat, and this is accomplished by an initial local vasoconstriction (narrowing of the blood capillaries) and reduction of blood flow.
Therefore in acute muscular strains or joint sprains apply ice for no more than 5 – 10 minutes at a time but apply frequently. This will have the effect of reducing blood flow from torn tissue. The precise time will depend on the area concerned and the individual but you should remove the ice before the area reddens.
This initial period of vasoconstriction is followed by vasodilatation with its corresponding increase in blood flow.
The ideal time for treating conditions that don’t involve torn tissue (the majority of back and neck problems) is approximately 30 minutes.
Physiotherapeutic uses of circulatory effect:
- The initial vasoconstriction is used to limit the extravasation* of blood into the tissues following injury, e.g. sports injuries. Ice therapy is then usually followed by some form of compression bandage, elevation and of course rest (R.I.C.E).
- >Alternate periods of vasoconstriction and dilatation affect the capillary blood flow, and it is across the capillary membrane that tissue fluid and metabolic exchanges take place. Consequently an effect is being produced at a very local level which can reduce swelling: excess tissue fluid can be removed from the area and returned to the systemic circulation. Increased circulation allows more nutrients and repair substances into damaged areas. Thus ice is very useful in removing swelling and aiding repair.
- >It is possible that the increased circulation could carry away chemical substances which are stimulating nociceptors** and producing pain, as in the case of local tissue damage.
* Extravasation is the leakage of a fluid out of its container. In this case the blood moves from the capillary (container) into the tissue.
** A nociceptor is a sensory neuron (nerve cell) that responds to potentially damaging stimuli by sending signals to the spinal cord and brain. This process, called nociception, usually causes the perception of pain.