When to Use Heat or Ice, What Happens to the Body and Why
Using heat (thermotherapy) and cold (cryotherapy) are easy and effective means of treating pain at home. But how do you choose which one is best?
What happens to the body?
Both heat and cold work to change the blood flow to the affected area. When heat is applied to an area, the blood vessels will become bigger (vasodilation), allowing for an increase blood flow. When cold is applied, the opposite will occur – the blood vessels will become small (vasoconstriction), and the blood flow will be decreased. When trying to decide on using heat or ice, one must first determine whether they want more or less blood flow to the area in question.
When to use cold:
When you have an acute injury or wound, inflammation develops because that is the body’s way of beginning the healing process. Inflammation is characterized by redness, pain, swelling and heat. While we don’t want to eliminate inflammation altogether, decreasing the blood flow to the area will help to decrease some inflammation while also helping to decrease the pain, as it numbs the surrounding nerves.
When to use heat:
When you have tight muscles, stiff joints and old injuries that don’t seem to want to go away, using heat is handy in this situation. Blood contains oxygen and nutrients that is optimal for healing, so when heat is applied to the affected area, that increases the flow of oxygen and nutrients as well. Tight muscles are able to relax a little bit more, stiff joints begin to loosen, and scar tissue can start to break up.
For how long?
When you have a new injury, you want to make sure you use cold within the first 48-72 hours. Apply cold for 15-20 minutes at a time, with 2-3 hours in between. Any less than 10 minutes and it is unable to penetrate to the muscular levels, and any longer than 30 minutes, you are at risk for frostbite. Always remember to have a layer between the cold and skin.
For using heat, it can be applied for 15 minutes or up to 45 minutes (at a lower heat level), with 2-3 hours in between. Always ensure that there is a layer in between your skin and the heating device.
What happens if I mix it up?
If you apply heat to a new injury, or cold to an old one, it isn’t the end of the world. The cold will simply make muscles and joints more stiff, while heat will delay the healing process of an acute injury.
Check out this PDF below which shows what is best for what type of injury or pain!