The How and Why of Ice

We’ve all heard, over and over again, that for sore and strained muscles we should apply ice, but I know you’re all wondering: Why is icing good for sore muscles? When should I ice? How long? Can I use heat? Is heat bad? But ice is so COLD! Today I’m going to try and unravel a little bit of the mystery and explain why ice is good for you and when it is appropriate to use it instead of heat.

Your body and pain

 First and foremost, it helps to understand your body’s biological response to pain and injury.
When our bodies sustain an injury (and that injury can be sudden and painful or chronic and slow onset – such as from repetitive use) it produces inflammation and a spasming designed to act as a “splint” for the injured muscle, by restricting movement to allow the muscle to heal. This spasm and consequent tightening of the surrounding muscles produces more pain. More pain causes more spasming, more spasming causes more tightness and more pain. To a point this is effective by allowing an injured muscle time to rest and heal and preventing sudden movements that could cause further injury. But often this cycle keeps repeating and the body gets caught in what is called the pain-spasm-pain cycle causing chronic pain and discomfort and eventually loss of range-of-motion.

How do ice and heat work?

Now, you should know how ice and heat work. Ice operates in the following beneficial ways to help speed the recovery of strained muscles:

  • By slowing the inflammation and swelling that occurs in injured or overused muscles
  • By numbing sore tissues (providing pain relief like a local anesthetic)
  • By chilling and slowing the nerve impulses in the area, which interrupts the pain-spasm reaction and prevents the surrounding muscles from tightening
  • By decreasing tissue damage from internal bleeding and swelling

Because ice is a vasoconstrictor (it reduces the size of the veins, thus decreasing the amount of blood flow to the tissues) applying ice reduces circulation to an injured area. When the ice is removed the veins then overcompensate and dilate bringing blood flowing back to the area at a quicker rate. This blood contains nutrients that the soft tissues need to repair and heal.

Heat operates in a different beneficial way:

  • Relaxes and loosens tissues
  • Stimulates blood flow to an area

Ice or Heat?

In general ice should be used for acute, immediately painful injuries in which swelling, bleeding and inflammation are a concern. Ice is most effective if applied within the first 72 hours after an injury occurs. It should be applied for 10-20 minutes (or until the area is numb – for maximum benefit) at a time and repeated every 2 or 3 hours. (Don’t apply directly to the skin) However after the initial 72 hours of icing and once the swelling has gone down, you may choose to alternate ice and heat. (10 minutes of ice followed immediately by 10 minutes of heat) this has the effective of constricting the blood vessels and reducing circulation (with the ice) and then hyper-dilating the blood vessels and rushing blood and nutrients to the affected area (with heat). You want to be sure not to apply heat before this time period though as heat applied to an injury too early on will actually increase swelling, bleeding and pain, despite the fact that it “feels” better.

Conversely, heat should be used for chronic injuries in which the goal is to relax tight and stiff muscle fibers. You can apply heat before any activity that irritates a chronic condition to relax the muscles and increase blood flow. However, even for chronic injury ice is recommended after activity  or any time that inflammation is a concern. Never ice any muscle before activity as this can lead to much worse injury!

Generally speaking, whenever you are inflamed and in pain whether from a tough workout at the gym, too much time at your computer or a jarring slip and fall you should turn to ice first. It not only reduces inflammation and promotes tissue healing, but the cold on your skin acts as an anesthetic breaking the pain-spasm-pain cycle. On the other hand, think of heat more as a way to head off pain in the first place. For example a hot pack around your neck while you work before you even get that pulsing pain in the base of your skull.

And now you know the basics of ice therapy versus heat therapy. Are we cool?


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