When To Apply Heat Or Ice To An Injury

A question that I often get in the clinic is whether a patient should be applying ice or heat to an injury. Although the answer isn’t always straight forward, there are a few basic principles that will guide you well when you’re dealing with an injury.

Both heat and ice may have a role in your recovery depending on the nature of your injury and its stage of healing. Knowing what exactly is happening when you’re applying either ice or heat will help you to understand why you’re applying one or the other.

Deciding which of the two may be more appropriate at any given time might seem like a daunting task.

Just remember that as a general rule, if something is red, swollen and inflamed, then ice will likely be of benefit. On the other hand, if the issue is more chronic in nature or the result of stiffness, then heat may be appropriate.

How Does Ice Reduce Inflammation?

When you apply ice to an area, the end result is cooling of the area. The response of the body to that cooling is to constrict or tighten blood vessels, effectively decreasing the amount of blood flow to the area.

The cooling action of ice will also slow down the activity of any inflammatory cells in the area, which means they won’t be producing as many of their potentially harmful by-products. It’s the action of these inflammatory cells that cause the symptoms that we see with inflammation – swelling, heat, redness and pain.

Ice can also numb the area where it is applied, which may provide you with some temporary pain relief.

When to Use Hot Compress

Of course, applying heat has the opposite effect. When you apply heat to an area, the blood vessels dilate or expand to bring more blood to the area. This can help to decrease the tension in muscles.

The increase in blood flow can help to bring more nutrients to a healing area and can also help to clear away waste products.

When To Apply Heat or Ice To An Injury

Now we know what ice and heat each do when we use them. But, how do we decide which to use?

Applying Ice To An Injury

The general rule of thumb is that ice is usually the best bet for an acute or recent injury. But how long ago is considered ‘recent’? Some people stick to the old rule of 72 hours. That is, within the first 72 hours of sustaining an injury, apply ice.

However, ice can often be useful beyond this 72 hour period. Remember the signs of inflammation discussed above: swelling, heat, redness, and pain. In general, while there are still signs of active inflammation, ice will still be helpful. This may mean that you are icing an injury well beyond 72 hours after it has occurred.

Applying Heat To An Injury

But what about heat? When should I apply heat instead of ice? Heat is useful when the cause of the pain is due to muscle stiffness or tightness. Stiff and sore back or neck muscles will almost always feel better with heat application.

Heat can also be helpful in areas of chronic injury (for example, in tendinopathy) because it can help increase the nutrients being brought to the area, which can help with healing.

Talk To An Expert!

An accurate assessment of the injury can be integral to deciding whether an injury would benefit from either heat or ice. Or potentially both!

Christina Mattiello, MPT BSc. Kin.
Registered Physical Therapist, Trailside Physio New Westminster