By Emma Maaranen
My reply to this question is, “do you want a flood or a swamp?” First, a little physiology.
At various times each of us has been told to ice an injury. Maybe a soccer coach sent you to the locker room to ice a sprained ankle, or a co-worker recommended it to treat a stiff neck. Usually the ice treatment helped. Why? When you experience a soft tissue injury (muscle strain, joint sprain, bruise, muscle spasm, etc.) cells are damaged and leak their contents into the surrounding tissue. These bits of cellular debris and chemicals irritate healthy cells and stimulate nerve receptors to illicit a pain response, as well as to call in your immune system to start cleaning up the mess. When you ice an injury, making sure you do not frostbite the area and create a bigger problem, the tissue cools to a point where the blood vessels constrict, preventing blood to perfuse the injured area. Then, after the ice is removed and the tissue rewarms, there is a moment where the blood vessels dilate and flood the injury site with blood. This flood not only pushes out the bits of damaged cells and chemicals that are causing pain and slowing healing, but bathe the area with fresh white blood cells and nutrients to repair the damage and decrease the pain. Although the brief numbing may be relief in itself, note that the most important part of this process is not cooling the area for a long period of time, but the rewarming phase. I recommend applying ice (direct ice massage, insulated chemical ice pack or bag of frozen carrots) as long as it takes to make the area numb.
Heat on the other hand acts more like a swamp at the injury site rather than a flood. Heat will increase circulation to the injured tissue bringing in white blood cells and nutrients to heal tissue, but does not pack the punch of a flood to push out irritants. However, in the middle of winter after a long day of skiing in a snowstorm, heat really does feel nice on that aching low back.
So what should you do? During the first 72 hours of an injury damage may still be taking place from the assault. Swelling, if excessive, will hinder circulation to the injured area, and ice will do a better job or reducing swelling. Heat causes fluids to expand. If cells are delicate, the increased pressure on their walls may cause them to rupture. For this reason, ice is almost universally recommended for the first three days of an injury to prevent further damage. After this phase, there is little empirical data to support greater benefit of ice over heat. I personally believe ice does a better job, but if you simply won’t do an ice treatment, heat is a great alternative. Another option is to use heat to amplify the flood event of icing by applying heat after the tissue is numb, and go back and forth between ice and heat. I typically ice an injury in the evening, hop into a hot shower then go to bed and dream of speedy tissue repair!
Hopefully this makes the choice to flood or swamp for an injury more clear.