As a chiropractor, I am asked this question a lot. Should I use ice or heat for a bad back?
The use of temperature to mediate pain and influence recovery from an injury has been commonplace since the times of Hippocrates.
But despite this, a quick google search today will reveal how much conflicting advice exists, and not just on what to apply, but how long for and how often as well.
Before trying to answer this question once and for all, it is worth mentioning that there are certain caveats. Not all types of pain require the same approach, and what eases symptoms may not be the best thing for aiding long term recovery, for instance.
The general rule of thumb is that ice is better for symptom management than heat.
Cryotherapy, as the use of ice is called, causes temporary narrowing of blood vessels, which reduces the potential for inflammation or bruising.
Cooling can also decrease nerve conductivity, lowering the number of pain signals transmitted to the brain.
For superficial injuries, cold should be applied for a maximum of 15 minutes. For deeper injuries, 20-30 minutes is best.
A layer of cloth must be placed between the skin and the cold pack.
Heat is only used infrequently, either prior to sporting activity, to increase the pliability of muscles before use, or in cases of ligament/tendon tear where inflammation is desirable to improve the rate of tissue repair.
Contrast therapy, using ice and then heat in quick succession, is not beneficial.
There are also some circumstances when using either heat or ice is not a good idea. People with a history of circulatory disorders, heart disease, as well as the very old and very young, should not use any form of thermotherapy.