There are many opinions regarding using ice as a therapy. Often time doctors, chiropractors, and physical therapists recommend using ice on an injury. They may tell their patient to use ice or alternate using ice and heat. Acupuncturists on the other hand don't recommend ice. Why? Ice is not a part of traditional Chinese medicine.
The theories of Oriental medicine go back thousands of years. Physicians at that time were great observers of nature and the cycles of nature. They noticed that during the winter, people were less active, animals hibernated or were very inactive, and plants looked dead. In the summer, when it was warm, plants looked alive and animals and people were active. They associated cold with inactivity or death and warmth with activity or life. They also noticed that people naturally gravitate to warmth. When it is cold people circle around the fire or source of heat. This was true since time began and is still true today. Heat was used as a therapy. Cold was not.
You should note that the word "acupuncture" is a Western description of the Chinese therapy of "Zhenjiu". "Acus" means "needle" and "punctura" means "to puncture". The Chinese word for this therapy is composed of two words "Zhen" meaning "needle" and "jiu" means "moxibustion". So the Chinese word for "acupuncture" is actually a reference to needling therapy and heat therapy. Moxibustion is the burning of the herb artemesiae vulgaris (Chinese: Ai ye) on the skin or over the skin. It provides heat and warmth to the body. The ancient Chinese must of thought highly of the use of heat in their treatment to make the word "jiu" a part of the description of what they were doing.
I think the Chinese realized that cold constricts the arteries and veins and impedes circulation. I often see people with chronic injuries and it just so happens that they've been told to ice the injured area which they do often. To me that is half of their problem. When I ask them if the the ice feels good the reply is that they don't like it but they are following the doctors orders. When I tell them to stop and use heat instead they often notice that their injury starts to feel better right away.
If you have an injury and want to use ice I suggest using it for 24 hours or less then use heat and of course liniments. There a good book about treating injuries called "A Tooth From the Tiger's Mouth" by Tom Bisio, L.Ac. I highly recommend the book. Mr. Bisio offers a good explanation of the reason ice is not used in Oriental medicine.
Remember, if you have a chronic injury or a recent injury don't use ice, use heat.