One of the most common questions that patients ask in the chiropractic office is when to apply heat or cold to help an injury heal.
There is certainly a lot of varied advice available, and often the advice seems very contradictory.
What does cold do?
When cold is applied to an area for 15 minutes or less the immediate response is vasoconstriction (decreased size) of the blood vessels in the skin and reduction of blood flow.
What are the benefits?
Cold is often the temperature of choice for up to the first six weeks following an injury. During this period the cold will help to decrease swelling, inflammation and pain. Cold also decreases the metabolic rate of the tissue to which it is applied.
A reduced metabolic rate is important because it will help to lessen the secondary injuries to the area from a lack of oxygen due to the injury. Cold has also been found to decrease nerve conduction speed. By reducing nerve conduction speed the sensation of pain can be decreased or even blocked.
How do I apply cold?
The cold source should be placed in a wet towel and left on the skin for 10 to 15 minutes. It is important that the ice pack is not left on the skin for longer than 15 minutes.
The effects of ice on the body are reversed after 15 minutes of treatment. The benefits of ice occur because of the vasoconstriction of the blood vessels. After 15 minutes of cold application the blood vessels will dilate rather than constrict.
Dilation of the blood vessels will cause the inflammation to worsen. The ice pack can be applied as often as necessary throughout the day; however there should be at least 30 minutes between applications.
After the ice pack has been applied for five minutes the skin should be checked for excessive redness, or discomfort. If these symptoms are present the ice pack should be removed.
Cold therapy is also not recommended over areas of the body that have poor circulation, or for individuals that have conditions that affect their ability to feel temperature.
What are the benefits?
Elevating the tissue temperature has many therapeutic advantages. Chemical reactions in the cells within the body are influenced by temperature. An increase in the chemical reaction allows for an increase in oxygen uptake, therefore more nutrients will be available to help the tissues heal more quickly.
Heating an area is also associated with an increased blood flow to the area. With increased blood in the injured area, nutrients are delivered and wastes are carried away from the area more effectively.
Therapeutic heating has also shown to decrease pain and to help reduce muscle spasms. These positive benefits are due to the changes heat causes on the body; an elevation of the level where pain is felt, a change in the speed of signal conduction along a nerve and a decrease in the rate of activation of the muscle fibers.
Temperature elevation in combination with stretching will also help to alter the length of different types of tissue.
Following an injury many tissue structures will progressively shorten due to limited movement. Adhesions may develop between the tissue layers and scar tissue may form at the site of injury to further limit mobility.
Heat and stretching in combination can result in decreased joint stiffness and increased tissue flexibility, which will help to increase ease of movement and gains in range of motion.
How do I apply heat?
Moist heat penetrates the skin and reaches the muscles, ligaments and joints better than dry heat. It is the moistness that helps heat to penetrate to the deep tissues. Heat can be applied to an area for 15 to 20 minutes maximum.
The following conditions indicate it is not safe to use heat as a treatment option:
? Inability to distinguish between hot and cold sensation.
? Poor circulation in the area of heat application.
? Recent or potential hemorrhage in the treatment area.
? Cancer in the treatment area.
? Acute (recent) inflammation of the treatment area.
? Local infection.
? Presence of liniments or heat oils on the skin.
In order to achieve the maximal therapeutic effect of the heat the tissue temperature should be increased to between 104° F and 113° F. Tissues heated to temperatures above this level have the potential to burn.
Hot or cold?
So with all this information, how do we answer our original question?
When deciding to use heat or cold it is best to follow these simple rules:
? If there is swelling and pain use ice.
? If there is no swelling, but stiffness is present use heat.
? If this is a recent injury, use ice.
? When in doubt – use ice.