Using Ice and Heat

by John Howick
© 2003

I often get asked "When should I use ice and when should I use heat?" With a sprain or strain, collagen fibres are overstretched and torn. Tiny blood vessels are also damaged. This bleeding produces the bruising seen in a sprained ankle or torn hamstring. Even if no bruising is seen, there is bleeding inside. If enough collagen and blood vessels are damaged, swelling appears almost immediately. A large amount of swelling appearing within the first hour after an injury is a sign of excessive bleeding and a serious bone, muscle or ligament injury. In a less severe injury, swelling develops gradually. Often it is not noticed until the day after the injury. This swelling is primarily cellular fluid, not blood, and is related to inflammation.

What causes fluid to leak out? When body tissue is damaged, chemicals are released which attract white blood cells to the area to clean up the damaged and prevent infection. These chemicals also make the blood vessels and cells in the area "leaky" allowing fluid to slowly ooze out. The chemicals also cause the nerve endings to become hypersensitive which leads to pain. After a few days the damaged blood vessels begin to repair and regrow but they are very weak. If there is a sudden increase in blood flow to the area these blood vessels leak and sometimes blow apart!

So how does this relate to the use of ice? If we want to minimize the swelling we need to slow down the blood flow to the area. Ice causes a closing down of the blood vessels (vasoconstriction). Ice also decreases firing of the nerve endings (that's why it makes you feel numb) and thus decreases pain. Therefore you should always use ice when you want to minimize swelling and inflammation. Inflammation is most significant in the first 72 hours after an injury so you must always use ice in this time period. Never use heat or hot tubs in this early period. Heat causes a large increase in blood flow to the area(vasodilation). I often hear "I pulled my muscle so I went straight to the hot tub and my leg swelled up like a balloon." Just visualize those poor torn blood vessels getting blasted with blood rushing to the area like a fire hose turned on full blast. Fluid and blood pour out into the surrounding tissue.

What about after the first 72 hours, should you switch to heat? Inflammation is most significant in the first few days after an injury but it doesn't stop magically when it reaches the 4th. day. The inflammatory process gradually decreases over time as long as no further injury occurs and conditions are perfect for healing. We don't live in a perfect world and often as we begin to recover we overdo it. The inflammation, pain and swelling increase again. Ice is the right choice to treat this. In my practice, I often continue using ice for 6 weeks or more after a traumatic injury or with overuse injuries.

When is heat a good idea? Heat gets the body ready for activity and may prevent injuries. Heat is best used for chronic injuries where there are no signs of inflammation. After a muscle strain has healed it is often tighter than it should be. Heat can make muscles, tendons and joints more flexible and easier to stretch. Arthritis can make joints feel very stiff and heat works well to improve mobility. Other mild chronic injuries cause an annoying ache and heat can sooth this pain.

What about alternating hot and cold? In my opinion this is not as effective as using ice or heat by themselves. I have used it in select cases to decrease extreme swelling in the foot and ankle. This involved alternating between a very hot whirlpool and a bucket of ice water. In most cases I would say stick with ice alone.

How about those creams and lotions you can rub on that feel hot or cold. These do not change the temperature of the tissue under the skin so they do not replace the use of ice or heat. These lotions do stimulate nerve endings on the skin and can temporarily decrease pain. If they make you feel better go ahead and use them but don't forget to use actual ice or heat when necessary.

Quick rules to remember:

1. In the first 72 hours always use ice, never heat.
2. Continue using ice as the injury heals whenever you have signs of inflammation (swelling, heat, redness, pain).
3. Use ice to treat constant, sharp, intense pain and muscle spasm (when the muscle tenses up and won't release).
4. Use ice after activity if you think you may have strained or restrained something.
5. Apply ice for 15-20 minutes. It can be repeated every hour in the acute stages. Generally 3 times per day is adequate.
6. Always have a thin layer of cloth or paper towel between you skin and the ice to avoid "frost bite".

1. Use heat before activity to help "warm-up" and get ready for movement.
2. Use heat to make joints and muscle more flexible and easier to stretch.
3. Use heat for mild arthritis, achy muscles and general feelings of stiffness.
4. Apply heat for 20-30 minutes.
5. Check your skin frequently for any signs of burning. If your skin is too red, remove the heat immediately and apply ice or cold water to cool the skin.

If you have Raynaud's Disease or any other circulatory problems check with your physician before applying heat or cold.

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