Ice Versus Heat

There is a lot of confusion about when to heat and when to ice an injury or a pain.  While there is no perfect simple answer, here is a good outline to follow.

First, it is important to understand the basic principles 

Ice is used to reduce swelling by causing vasoconstriction (clamping down of the blood vessels in an area).  Heat is used to increase the flow of blood through an area.  Both reduce pain most of the time, but for very different reasons.  Ice shuts off pain signals from an area by effectively turning off the nerve cells due to lack of ability to keep firing in the cold environment.  Heat increases the flow of blood and oxygen, both of which sedate pain fibers.

Of course, if an area gets too cold, it starts to hurt as a message to the brain that tissue damage from cold is about to occur.  With too much heat, as in acute burns, pain fibers are stimulated to initiate a reflex to move away from the source of heat.

In general, our bodies love heat and constantly work to stay warm.  That is why we shiver when we are cold.  Our muscles can generate a lot of heat by contracting repeatedly during shivering.  Bodies also hate to lose heat.  So when we apply ice to an area, the body immediately shuts down the blood flow through that area to reduce the amount of heat loss.  

How can we use this in figuring out whether to use heat or ice?

If there is a new injury that involves any amount of new fresh tissue damage, tearing, over stretching, or anything that can microscopically rip open the tiny capillaries, we want to stop the leaks from occurring by triggering that vasoconstriction effect with ice.  

If there is an muscle that has been working too hard for too long but that hasn’t been damaged or a body area that has been in one cramped position for a length of time, then we want to help it get more blood to replenish the oxygen and nutrient levels.  Also, if there is a body part that is arthritic, heat is very helpful for the same reason of helping to deliver needed oxygen and nutrients and therefore reduce pain.

Ice is best used for about 10 minutes at a time, repeated every 20 minutes.  Longer than 10 minutes can trigger the rescue vasodilation effect, and cause more swelling.  Following a new injury, it is best to use ice during the first 72 hours.  

Heat can be applied for 15 to 20 minutes, at a medium level, as often as desired.  Care must be taken with heating as area above a medium level as that initially shuts off the pain sensors and can result in serious tissue burns.  Also, NEVER bypass the “dead man switch” on heating pads that require you to continually hold down the “on” button.  NEVER sleep on a heating pad.  In either case you run serious risks of major second and third degree burns.  Bad idea. 

What if after all this discussion, you still aren’t sure which way to go?  

When in doubt, use ice.  If you heat an area that should have been iced, it will worsen the swelling and take longer to heal.  If you ice instead of heat, it will make it start to ache more.  No damage will have been done, and you can simply switch to heat and be fine.