I have heard from Tom Bisio ( Tooth from the Tiger's Mouth ), and some other sources relating to eastern medicine that icing injuries to reduce inflammation is bad for the long term health of your soft tissue, and can add pain and stiffness to the injury years after it heals. The types of injuries that Bisio talks about ice being no good for are tears, sprains, pulls, etc. Would love to hear some responses from both sides ( pro-ice, ant-ice ).
From what I understand, you are supposed to ice it when the injury first occurs, for no more than 20 minutes at a time. The length of time you keep ice on it is what will damage the skin tissue. After the first couple days, you want to use heat because the injury needs blood to heal. Again, only heat for about 20 minutes at a time.
I have wondered about this myself. I have tried the icing of injuries. As best as I can tell, I never notice any improvement or benefit from icing vs doing nothing. I have often wondered what research is behind it and how much it really helps, if any. Here is an interesting synopsis of current research that seems to suggest that not much decent reearch has really looked at the main issue which is, does icing (cryotherapy) really speed overall recovery? http://www.ncbi.nlm.nih.gov/pmc/articles/PMC522152/
New study about this released this month: http://www.themedguru.com/20101027/newsfeature/ice-prevents-healing-case-injury-study-86141266.html
After reading a lot about this subject, I think people's confusion has to do with when they are icing. Icing is not bad for you. It is only bad if you ice for more than 20 minutes at a time, or put ice directly on your skin. Ice is not meant to heal the injury but to provide immediate relief from pain and swelling.