Both are well known and accepted, as safe, readily accessible, and cheap forms of therapy. Plus they have the added benefit of being self administered at home.

But which do we use and when?

I could just make a list of when to use heat (thermotherapy) or cold (cryotherapy), but it is way more useful to understand what effect these two modalities have on the human body.

Broadly, heat and cold therapy are valuable tools in addressing two common areas:

• Injury management
• Pain relief

Therefore, the most important questions to ask yourself when deciding which to use:

• Is this pain/ache a result of an injury?
• Was it the result of sudden force, where there is a likelihood of trauma to the tissues underneath the skin?
• Are there signs of an inflammatory response, such as swelling, bruising, increased redness or heat?
• Is there significant tenderness when you touch or move the painful area?

A typical example of this might be a sprained ankle.

If the answer is yes, then this should be regarded as an injury and your decision whether to use heat or cold is clear.

INJURY MANAGEMENT

In terms of treating an acute (sudden) injury, the most basic difference between heat and cold, is how it affects blood flow. Heat will open the blood vessels whereas cold tends to constrict (narrow) them.

Following an acute injury, the aim is to reduce the amount of bleeding and swelling under the skin by reducing the blood flow to that area by using cold therapy. Ice is an ideal way to do this and aiming to cover the injured area as completely as possible is advisable. For example, following a sprained ankle, immersing the lower leg in a bucket of iced water is ideal, as it will effectively slow the circulation down significantly, thus reducing the negative consequences of uncontrolled swelling and bleeding.

We can also use rest and elevation and compression to reduce the blood flow.

It is generally accepted that the blood vessels take between 24 and 48 hours to stop “leaking.” Then, the body will enter the next phase of healing, where it will begin to repair.

This is where heat therapy comes in. Now we need to increase the blood flow because that is how all the goodies, like oxygen and nutrients arrive, to achieve healing and repair. It is also how the waste products of injury are extracted from the site, so that repair can take place in the cleanest environment possible.

Heat can be used well into the healing and recovery phase of injury

PAIN RELIEF

This is where things get a little trickier.

When it comes to pain relief, ice is basically used for its ability to ‘numb’. In the example of an acute injury, ice not only helps to reduce blood flow and consequently unwanted inflammatory responses, it also helps to numb the pain. In fact many other types of more chronic (long lasting) inflammation, including that caused by arthritis, can respond well to the numbing effects of ice.

Generally, if inflammation is thought to be the cause of discomfort, it is worth giving ice a shot, to see if it does reduce your symptoms.

The great thing about using ice or heat for pain relief is that they are both very gentle, with very little risk of harm. Sometimes it is a matter of trial and error to see which one gives relief.

When it comes to muscular pain, things are quite different

If muscular pain is present with no outward signs of inflammation, heat can be extremely useful for pain relief. Muscle pain might result from strains, overuse, even just using a muscle in a way it hasn’t been used before. Muscle tissue can have painful ‘knots’ and trigger points, which can be responsible for quite severe and ongoing painful issues. Tightness and spasms can also cause pain.

When it comes to muscles, heat works to both increase circulation and to stimulate a complex neurological response within the nervous system.

Also, it is widely accepted that warming up muscles, prior to activity, helps with performance and to reduce the risk of injury. Similarly, applying heat to a painful muscle, encourages relaxation of the muscle fibres.

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