Heat or Ice? When to use which?
When should you use heat or ice therapy? The answer is – it depends. In general, heat therapy is for chronic conditions and ice is useful in acute situations.
If you recently sustained an injury or aggravated an old injury, ice should be applied for a period of 15mins each time for the first 3 days. If you feel your muscles are feeling tight and stiff, a hot pack on the muscles will help to relieve the tightness.
This spectrum of acute to chronic looks at the duration since injury. If the injury is sustained within 36 hours, it is considered to be in the acute stage. At this stage the inflammation process is ongoing. Ice will help to bring down the inflammation and swelling so that the injury can heal better. Note that applying heat to this stage will increase the blood circulation, inflammation and hence swelling.
There are 2 common scenarios that cause pain, making you reach for that heat/ice pack. One of them is the acute injury (for example a fall, twisting movement or direct blow that is immediately painful) and the other is the chronic injury (happened over a period of time or from an acute injury that failed to heal). Each scenario requires a different approach to reducing your pain and speeding up your recovery.
It might be that you have just sprained your ankle playing soccer, shut your fingers in the car door or fractured your hand. All these are examples of acute injuries and will show the following signs:
- Sharp, severe pain
- Increased warmth
- Restricted joint movement
- Unable to put weight through the structure (e.g. leg, ankle, wrist etc).
For these types of injuries, we recommend managing the pain, inflammation, and swelling immediately with the use of ice. The ice cools the tissues, reduces tissue metabolic rate and constricts the blood vessels helping reduce further damage from occurring.
There are many ways of applying ice like using an ice pack; wrapping ice cubes in a wet towel or using a bag of frozen peas (sometimes that is the only thing on hand!). The cold agent should be in contact with the area for up to 20 minutes at a time and re-applied every 2-3 hours for around 3-5 days or until the swelling settles.
How does ice work?
1. Decreasing the pain
There are a few proposed theories regarding how ice decreases pain and it is possible that a combination of some of them can cause pain relief.
- Decreased nerve transmission in pain fibres
- Cold reduces the activity of free nerve endings
- Cold raises the pain threshold
- Cold causes a release in endorphins
- Cold sensations over-ride the pain sensations
2. Reducing swelling
Ice cools the surface of the skin and its underlying tissues, causing narrowing of the blood vessels. This narrowing leads to a decrease in the amount of blood delivered to the area and subsequently reduces the amount of swelling. After a few minutes, the blood vessels re-open allowing blood to return to the area. The narrowing and opening repeat in cycles.
The decrease in swelling also allows more movement in the area and lessens the loss of function associated with the injury. Pain is also reduced as pressure from the swelling lessens. Chemicals that intensify the pain are released into the bloodstream when tissues are injured, thus the narrowing of the vessels help to minimize this release and pain.
3. Decreasing metabolic rate
Ice reduces the metabolic rate and oxygen requirements of the cells. Thus, even with the decreased blood flow and oxygen delivery that comes with narrowing of the vessels, the risk of cell death will be lessened. This prevents further injury.
A few days following an acute injury, the pain and swelling may have decreased so much that there may be no sign of the original injury. However, the tissues are still in the process of recovery and will still benefit from modifying your activities (less vigorous) as well as using both ice and heat alternatively. This means to apply ice for 10 minutes, followed immediately by 10 minutes of heat.
How does this work?
Doing this will cause massive increases in blood flow to the area as the narrowing caused by cooling is reversed when heat is applied, resulting in an influx of blood to the damaged tissues. The increased blood flow to the area provides proteins, nutrients and oxygen for better healing. It also helps remove the products of inflammation and reduce residual swelling.
An important point to note is to ensure that inflammation has stopped before applying this technique. That means that the area should not be red, and should not be warm to touch.
These are injuries resulting usually from overuse where some tissues are tight and inflexible causing aches. Examples include tennis elbow, golfer’s elbow, patella tendinitis and Achilles tendinopathy. Symptoms include pain when performing activities, a dull ache at rest and swelling. Occasionally, an acute injury is not allowed the time to heal properly and muscles spasm to protect it.
In order to treat these, heat should be used to help relax tight, aching muscles and joints, increase the extensibility of ligaments and tendons and promote blood flow to the area. Heat can also be used before exercise in chronic injuries to warm the muscles and increase flexibility.
Heat can be applied to the area in the form of heat packs, a warm damp towel, hot water bottles or heat rubs. If using a heat pack or hot water bottle, ensure a suitable layer of protection is placed over the skin to prevent burns. The heat should be applied for 15-20 minutes.
How does heat work?
Heat applied on the skin increases the temperature of the skin and the underlying tissues. This in turn opens up the blood vessels like your ateries, allowing more blood to flow into the area. This increase flow helps to remove waste products from cells and deliver more nutrients, relaxing tissues. The increased temperature of the blood also warms up surrounding tissues. Heat also has an effect of increasing flexibility of the soft tissues.
Both heat and ice are cheap, easy to use and effective ways of speeding up recovery when used correctly. Besides managing your injuries with these modalities, it may be a good idea to consult a physiotherapist in helping you rehabilitate and/or prevent the same injuries from occurring.