Heat vs Ice: Which One and When?

When it comes to injuries, there seems to be a lot of confusion about when to use ice rather than heat.  I often see patients after they’ve experienced an acute injury due to sports or a car accident. Many times the pain from the incident isn’t felt for days or sometimes weeks.  And here’s why.

As a response to any tissue damage in the body, pain signals are sent to the brain over afferent nerves.  Afferent nerves carry information TO the brain.  There are 2 kinds of afferent nerves. There are Type A and Type C fibers.  Type A fibers have a larger diameter and are covered with a conductive sheath which allows the messages to get to the brain much faster. These are called myelinated nerve fibers.  Type C fibers are smaller in diameter and have no myelin. Therefore the messages over these nerves travel much slower. Pain chiefly travels on type C fibers in order to reach the brain.  Temperature on the other hand travels primarily on Type A fibers. So why is this all important?

Heat and ice are generally used as an analgesic, or pain killer. One works equally as well as the other in this regard. The reason for this is called the “Gate-Control Theory”. It’s a simple concept.  By applying heat or ice over an injury, your brain will perceive the temperature more than the pain since it travels on faster nerves. Either one will reduce the amount of pain you feel, but that is where the similarities end.

Any time there is tissue damage in the body, the blood vessels in that area become more permeable to water. This means that water can now seep out of the bloodstream in to the surrounding tissues. We commonly refer to this as swelling.  Swelling takes up space and can create pressure on nerves, including those that carry pain. 

So, if you injure your neck in a car accident and decide to apply heat to it, this will naturally speed up the blood flow to the damaged area. In turn, this will allow more water to escape the bloodstream and as a result create more swelling.  More swelling will not only create more pressure and pain, but it will also extend the amount of time it takes your body to heal the injury.

Ice, on the contrary, will slow down the blood flow to the damaged area and relax the nerves. This gives your body a chance to reabsorb the water and reduce the swelling. Once the swelling has receded and the blood vessels are back to normal, heat can then be applied. This is typically around 3-10 days after the injury, but can sometimes be longer. The heat will then bring more blood to the area with the nutrients needed in order for it to heal.

This chart can be used as a quick reference as to which one to use and when:

Atlanta Chiropractor, Chiropractor Atlanta

Next time you wonder whether to apply heat or ice, remember “When in doubt, ICE!” It could make a big difference in how fast you heal and how quickly you get back to your life.