Current Theories on Ice vs. Heat for injuries

Question

So I will preface this by saying I've heard a couple of things that I will list out for legibility:

• "Ice should be used for Acute injuries and Heat for Chronic injuries"
• "Ice restricts blood flow therefore slows healing while Heat enhances blood flow and immune response."

For the sake of argument lets say an Acute Injury is defined by the following:

• Sharp well-defined pain upon using or pressing area
• Constantly present
• Possible bleeding/bruising
• Occurred within the past week

Lets also say a Chronic Injury is defined as:

• Dull pain upon using or pressing area that becomes sharp with prolonged agitation
• Lasting longer than a week
• Comes and goes depending on activity
• No bleeding/bruising present

Looking at such cases what has research shown is the most effective way of tackling such injuries? I would guess that they are treated differently seeing as they are considered different types of injury.

If two patients sprained their left ankle in the exact same manner I imagine the one who sprained his yesterday will be treated differently than the one still experiencing problems from a month old sprain.

Since this is something that does cover a broad spectrum of issues I will coalesce it into four relatively specific questions of what I am looking for.

Are there studies/data showing that:

1. Heat improves healing response for injuries, while Cold reduces it.
2. Icing acute injuries gives better outcome than heating or doing nothing at all.
3. Heating chronic injuries gives better outcome than icing or doing nothing at all.
4. The RICE method is truly effective.

For simplicity sake consider the question of this post to be: "Are there any conventional theories/study/data that prove whether Ice or Heat is better for injury treatment?"

EDIT: For clarity I should note I am not asking if pain is reduced but the underlying issue causing the pain. I am looking for studies/data showing what is the best treatment for enabling recovery.

Answer 1

There is only marginal evidence of RICE (rest, ice, elevation and compression) improving recovery in injuries.

For example, in a review of 22 studies of ankle injuries, ice and elevation had only marginal effects on recovery.

In another review of six studies in soft tissue injuries, there was no evidence that ice was effective.

In a review of 45 sports medicine textbooks, the advice on the use of ice varied in the textbooks.

Some individual studies such as this one do show evidence for decreased pain and some increased range of motion earlier for ice used in the first 72 hours.

Importantly, studies don't seem to suggest there is a harm. The short answer, which we often use to guide decisions in medicine, is "Can't hurt. Might help."

The "can't hurt" is conditional as only if done properly: don't ice directly on the skin as that is known to have caused frostbite. Wrap the ice in a cloth. Don't ice longer than 20 minutes. (Some studies say 10 minutes.)