A snowy weekend could lie ahead, so hopefully everyone is bundling up and staying warm. We definitely notice that when it is cold outside, people tend to come in and say, “Please tell me we are starting with the heat pack so I can warm up a bit,” and in the summer, “Boy it would be nice to cool down on some ice for a bit.” In addition to helping people warm up and cool down, hot and cold packs can have beneficial effects for people who have pain.
Many patients ask me, “which is better for what I have, hot or cold?” There are several answers to that question. The old school rules that nearly everyone still goes by are something like:
Heat before activity to warm up, ice afterwards to cool down.
Heat to loosen muscles, ice to reduce inflammation.
Alternate between hot and cold every few minutes when you are hurting.
To be honest, this basically how I use heat and ice most of the time, but that may be more from habit than anything. To know which you should use, and when, we need to know what is happening in the body, in response to heat or ice.
- Warmth causes blood vessels to dilate, increasing blood flow locally
- Connective tissues become warm and more pliable
- Nerves that detect temperature send signals to the brain and spinal cord that heat is present
- (Within the first 10 minutes) Cold causes blood vessels to constrict, reducing blood flow locally
- (After the first 10 minutes) Blood vessels begin to dilate increasing blood flow locally
- Connective tissues become cold and less pliable
- Nerves that detect temperature send signals to the brain and spinal cord that temperature is reduced
- Chemical processes in nerve endings begin to slow, reducing activity and causing numbness
- Metabolism of the local tissue and cells slows
So which is better? Well that still depends on a few factors. The important thing to remember with heat and ice packs is that most of the heat or cold will not penetrate below a level of 1-2 cm deep. As a result, most of the effects of heat and ice deal with the nervous system. Hot and cold signals travel on the same nerve pathways as nociception (danger signals). So if you are using a hot or cold pack, the temperature signal ties up the line and prevents some of the danger messages from getting through. As a result, muscles may get looser and pain may decrease.
When patients ask me which they should use my typical response is, “Whichever you like the best.” In reality both are good for most conditions because they both decrease pain and increase blood flow locally. There are a few caveats to this:
- Significantly inflamed tissues (swollen, red, hot) should not be heated as the heat could increase the inflammation.
- Ice should not be placed over inflamed tissues that have open sores or wounds because it could actually delay the healing of the wound.
- Some people may have an ice sensitivity called Raynaud’s phenomenon which actually causes an allergic reaction to cold. These people should generally never use ice.
- People with sensitive skin need to be careful with heat as many hot packs can burn the skin.
So, you don’t have to follow the old rules so closely. In reality, both heat and ice can help most conditions without significant side effects. So feel free to come in and warm up… or cool down if you prefer.