Updated: Jan 31, 2022
One of the most frequent questions I get as a physiotherapist. “Should I use heat or cold for my injury?” I will let you in on my thought process when answering this question, because it really is individual for each person. However, there are some basics rules. But first, I am going to talk pain. Image source
Types of Pain
Neurological pain or irritation of the nervous system.
Mechanical pain is the type of pain that is sharp and easy to localize. It occurs when something mechanical happens to the tissue, i.e. stub your toe. It is an immediate sharp, piercing pain that makes you catch your breath and try not let profanities leak out of your mouth. Another type of mechanical pain is a pinch. When this type of pain occurs my client usually starts their sentence with something like this, “ Every time I…”. There can be many examples, for the shoulder, the sentence could finish with “… lift my arm overhead, I get the pain” or for low back “…try to stand up straight after sitting for awhile, I get that shot of pain in my back”.
If the client does not do the movement, then they do not get the pain. That is how mechanical pain works. Mechanical pain can occur in the body when something gets pinched, say a capsule around a joint (they help to keep the fluid in the joint to lubricate it) or a muscle spasm (many people describe this as a shot of pain and think that they have pinched a nerve).
Inflammatory pain is a different type of pain. This type of pain is more difficult to pinpoint exactly what causes this pain. Inflammatory pain usually comes on 2-8 hours after you did “the something” to cause the pain. Let’s go back to the stubbed toe example, 3-4 hours after you stub your toe, you finally get a chance to sit down and take your shoe off. Your toe is just throbbing with pain. It seems to throb/ache with every heartbeat. That is inflammatory pain, a dull, ache, throbbing type of pain. It is difficult to locate where the pain is actually coming from, other than the general area (i.e. the entire toe). Another time that inflammatory pain shows up is first thing in the morning. You did something and you thought you were going to be sore that night but were not. You wake up the next morning and can hardly move because of the dull, aching sensation. That is inflammatory pain.
Neurological pain will bring on a totally different type of pain. We will not talk about this type of pain in this blog post.
How to Determine the type of pain.
In my mind, you should treat the different types of pain differently.
Let’s look at timing after an injury. When you get injured, enough to cause some either muscle or ligament tearing, the body goes to repair the damage. Step 1 = inflammation. Why inflammation? The body part gets red, hot, swollen, painful. Do you want to move the part of your body that meets the above? The answer should be no. That ‘no’ answer gives the body part some rest. Generally, the inflammatory process lasts about 24-72 hours. The really cool thing is that the body does not recognize the inflammatory process to start healing. However, the body recognizes ‘the end’ of the inflammatory process as the time to start rebuilding the body.
When to use cold on pain?
During the initial 24-72 hours, I recommend the use of cold to reduce pain and swelling. Cold packs, ice packs, resting your icy, cold beer containers or other cold items can be rested on the body part you just injured. Image source
You might remember a couple of years ago, in 2014 or 2015, I believe, there was a reporter that called into question the act of using ice or cryotherapy. They found that there was limited evidence. So they suggested not using ice as the evidence was limited. What a dumb thing to do! I have even had other, less experienced physiotherapists ask me about using ice/cold and then asking what evidence do I have for suggesting that someone put ice on the hot, red, swollen ankle. I usually say simply because it works! There are some people that cannot stand the immediate cold. I, personally, find the initial drop in temperature to be excruciatingly painful. So I will take my cold pack off whatever I hurt, for 10 seconds, until the sensation is only down to a low scream, then put it back on. I will repeat this process about 2-3 times, if needed. By that time, it is still really cold but it is much more tolerable.
So what do I recommend? Simple. Take a tea towel, get it wet, then wring it out so it is just damp. Then put a cold pack or some ice cubes or snow in the middle of the towel. Fold the towel in thirds, left side of the towel goes to the right side of the cold pack, then the right side of the towel goes to the left side of the cold pack. Fold up the ends to the middle. Turn over the towel and put it on your sore spot. How long? 10 minutes every waking hour, if possible. After 10 minutes put the tea towel and ice/cold pack/snow in the freezer. After an hour, take the towel out of the freezer, wet the towel again and put it on your ‘owie’. And repeat. I find this technique takes the inflammation down each time you do it.
WARNING! It is dangerous to put ice/cold on your skin for a long time!! After about 10-15 minutes of an ice pack on the body part, the body says “whoa, if this part of the body stays this cold, it is going to get frostbite”. Then the body actually increases blood flow to the area to stop from getting frostbite. Increasing the blood flow = more swelling. That is why I say 10 minutes every waking hour, if possible.
When to use heat on pain?
When do I recommend heat? Basically all the other times that are not mentioned in the ‘when to use cold’ section above.
Why heat? Heat increases blood flow to the area that is sore. Interesting fact is that the increased blood flow is only to the outer 0.5 – 1.0 cm deep. That is why when you remove your hot pack, you see a pink area of skin, the same shape as your hot pack. Heating with a hot pack heats from the outside inwards. While activity/exercise heat the body from the inside outwards. One of my profs at the U of A, Sandy Rennie, said something like this to our class. “A five minute walk will heat the body up more than 15 minutes on a hot pack”.
People tend to relax easier with heat than with cold, (both heat and cold can reduce muscle spasm). When people relax, then the muscle tension decreases and increased blood flow through the muscles. Why is it important to have increased blood flow? More blood to the area = more oxygen. The body uses the oxygen for energy to heal itself.
How long? Basically after about 15 minutes, there is minimal therapeutic effect of the heat. Other than continually stimulating the skin, giving you that sense of warmth. The stimulation of the skin can also stop some minor throbbing as well.
Summary of when to use heat or cold on an injury.
To recap my basic rules (remember you can always break the rules) are to use cold in the first 24-72 hours after an injury. Put the ice pack on 10 minutes every waking hour.
Other than that, use heat.
I did not talk about alternating hot/cold for a reason. There is some evidence out there that states it does not make swelling go away any faster.
My old running coach, Cliff Matthews, once said to try alternating cold and heat. Put the cold on for 10 minutes and let the body part warm back up to regular temperature, then put the cold back on for 10 minutes.
What do you think about this advice? Do you like to do something different? Let me know by commenting below!