Hot or cold, which should I use to relieve my pain?
This is not one of those questions that has a simple one word answer. I wish it was but it actually requires some thought and a bit of an explanation.
Let’s get started.
How does heat relieve pain?
When you place a hot pack on the sore area, you increase the energy to the area. The blood vessels dilate (become larger), this in turn brings more blood flowing to the area of pain. Blood carries oxygen and nutrients, so more blood means more oxygen to that area. Heat helps the body absorb more oxygen which helps with healing and affects the muscles ability to contract and relax.
Heat helps muscles to relax and become more flexible. Reduced tension in muscles often places less pressure on the structure around and results in reduced pain.
How does cold relieve pain?
When you place a cold pack on your skin, the blood vessels constrict (get narrower). This results in less blood flow to an area, which slows down metabolism and inflammation. The inflammatory response of heat and swelling after an injury is what causes a lot of pain. Reduce the inflammation, reduce the pain.
Cold also slows down the speed at which nerves send messages up to the brain. The brain is the part of the body that “feels” pain. If you slow down the message to the brain, you feel less pain.
How does the physio choose which to use?
Injury
If it is an injury such as an ankle sprain or a hamstring tear, we have to determine which phase of the healing process the injury is in.
Phase 1: Inflammatory phase
This is within the first 48-72hours after an injury. The site of injury is painful, normally swollen, feels hot and may even look red. We want to slow down the inflammation but not stop it, so we usually use ice for short periods, 5 minutes max and never directly placed on the skin. 5 minutes every 1-2 hours is a good measurement.
Phase 2: Proliferation phase
This is when the body starts to fix itself with scar tissue and new tissue. This requires energy, oxygen and nutrients so we normally go with heat. Also not scorching heat, it must not burn the skin. Minimum 20 minute application to make a difference.
Phase 3: Remodelling phase
This is when the new tissue and scar tissue gains strength and settles into being functional tissue. Heat can also be used at this time as it also requires energy.
Back and neck pain
Back and neck pain behave differently. Often back and neck pain is as a result of muscle spasm or pain causes the muscles to spasm around the injured structure.
Here we don’t look at the phases unless it is a torn muscle.
Cold will increase muscle spasm in many people, resulting in more discomfort whereas heat reduces muscle tension thus relieving pain.
In the back, the structure that has been injured is so deep under layers of muscle that ice therapy will not penetrate deep enough to have an affect on the inflammatory phase.
Not so simple but here are the rules of thumb.
Use cold during the first 48-72 hours after an injury.
Thereafter use heat.
Unless it is still very red, swollen and feels hot to the touch, then continue with ice.
With back pain, heat often relieves pain faster than cold.
Ice – 5 minutes every 2-3 hours
Heat – minimum 20 minutes
Never apply ice or heat directly to the skin, use a barrier such as a towel.
Never apply ice or heat on an open wound.
If you lack feeling/sensation in the area to be treated, don’t use heat or cold.
Disclaimer
Although this advice and information is based on sound knowledge, you follow it at your own risk. We cannot take any responsibility for injuries or health conditions that may arise after following this advice.
This answer is generalised and cannot replace the individual advice provided after a medical assessment by your local healthcare professional who understands your specific history and condition.