Injury Management

The Ultimate Guide to
Ice vs Heat for Injury

Mitchell Starkman, Physiotherapist, The Movement Centre

14 October 2017

Key Points

  • The body has an amazing way of regulating its temperature through increasing and/or decreasing blood flow to an area.
  • Cold therapy works by decreasing blood flow to the area of injury and can help manage inflammation.
  • Heat therapy works by increasing blood flow to the area of injury and can help to relax muscles and tissues.
  • As effective as ice and heat are for treating  injuries, there are risks so be aware of when applying either treatment.


Health care professionals get these all the time: “Should I put ice on this or heat?” “What’s better for a sprained ankle – hot or cold?” “My back is sore. What should I put on it?”

If this is the kind of question you find yourself asking then you’ve found the blog post to help offer you the appropriate answers. As a health care provider, this has to be one of the top questions I get so I decided to answer these age-old questions for you one and for all – right here!

In part 1 I am going to explain to you how temperature affects your body. In part two we describe heat therapy versus cold therapy specifically. Then to wrap up,  in part 3 I have broken things down into specific scenarios and the types of treatment that would work best in each.

So, let’s get things started ladies and gentlemen!

Part 1: Temperature and your body

First, let’s try to better understand the effect of temperature on the body. Humans are warm blooded mammals or at least most of us are! We have the ability to “thermoregulate” or regulate our body temperature through the power of a magical red fluid  also known as blood.

The human body likes to hang out at a natural temperature of around 37.5 degrees Celsius (to be exact)! As certain parts of our body change temperature, due to things like exercise and frigid outdoor temperatures, our body senses the change and send more or less blood to that part of the body in an attempt to naturally heat or cool it. When we’re hot, blood flow increases to our extremities in an to attempt to cool it by increasing heat loss through the skin. When we are cold the body does the exact opposite by decreasing blood flow to a region and thus reduce heat loss.

How does it do this you ask?

The body does this by increasing or decreasing the size of the blood vessels leading to that area and speeding up or slowing down the flow of blood to that area.

So why is this relevant to my injury or pain?

When we have a recent injury (i.e. “acute injury”) the body’s first response is to send blood to that area to help speed the healing process. Healing and clotting factors are needed to help reverse any damage that may be going on. When the body increases blood flow to an area in hopes of bringing the healing factors, it also heats the area. This  helps to relax the local tissues and helps to speed up and improve the healing process. Because of this heat, people can use something like ice on a hot and angry injury to cool the area. This helps to constrict the local blood vessels and slows down any potential swelling that may happen. You might be wondering, “Is swelling bad?”. Great question which we will be touching in on in a future post so stay tuned!

Part 2: Ice vs Heat

Let’s talk about “Ice, Ice baby”

For as long as most people can remember, tossing something cold on an injury has been the holy grail of treatments. “Your ankle hurts? Grab yourself a bag of frozen peas! You tripped on little Johny’s toy firetruck again? Go get some ice on that, stat!

Based on what we know about the body’s ability to thermoregulate, we can understand that if we use cold therapy over an injury it’s going to constrict the blood vessels in the area and direct blood away from it. If you have a hot or swollen joint, ice can be a great adjunct to help control inflammation and aid in the healing process.

Are you feeling “hot, hot, hot”?

Now that we know about what heat can do to the body, let’s talk about what adding a heat pack to your skin can do. Once you’ve added some heat on your body, we understand that it helps open up the blood vessels around the area. Your body senses the heat and thinks “hey, this isn’t 37.5 degrees celcius, so lets widen the blood vessels in an attempt to cool it down” – which helps to relax the tissues in the area. This can be great for a tight or stiff muscle but if you’ve got swelling in the area stay away from the heat!

Part 3: So When Do I Use Ice Vs Heat?

So, do I ice it or heat it?

This an interesting question … to keep it simple: if your injury is not hot, swollen or red either will actually work! Both heat and cold place a strong input onto the skin which the brain senses and feels. As a result, the use of treatment really comes down to your personal preference. Most people prefer the warm and soothing sensation of heat, but hey there are Dr. Freeze’s out there is well.

Inflammation and swelling of a fresh injury

Swelling brings healing factors to the area so we don’t want to completely diminish this process. As a general rule of thumb use cold therapy on an acute injury during the first 24-48 hours of treatment, but for no more than 10-15 minutes at at a time. The use of compression is often a helpful adjunct in this case.

Muscle tightness

If you have a tight muscle increasing blood flow to the area will have a relaxing effect on it. Now I know a tool that would work great for that. Don’t you? Heat! Apply heat to an area for 10-15 minutes  can really help to relax the muscles in the area and improve your movement.  Just remember to keep the temperature comfortable. Excessive heat doesn’t really speed things up or make them any better.


If you have a stiff muscle or joint we know that if we can find a way to increase the blood flow to the area we will have a relaxation effect over the area. Now I know a tool that would work great for that don’t you? Heat!

Now we have to be careful here because sometimes after an acute injury we can have swelling into joints and/or muscles areas which can also be perceived as stiffness. If this is the case, cold therapy would be your best bet. If you’re unsure check in with a health practitioner that your trust – e.g. doctor, nurse, massage therapist, physiotherapist.


As wonderful as cold and hot therapy can be it’s important to remember that any treatment used in the extreme can have adverse affects on the body.  For instance, both hot and cold can cause skin burns or tissue damage if you are extreme or excessive, so be careful! Ensure that the temperature of the modalities you are using are always comfortable and regularly check the area for signs of redness, changes in skin texture, or loss of  skin sensation.

Moreover, when you are modulating the blood flow of the body you are also modulating your heart rate. So keep an eye on this as well. If you have any concerns about this, follow-up with your family physician before proceeding.


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