I found this wonderful article explaining the importance of minimizing swelling. It was written by verycoolrunner at coolrunning.com.au and it goes like this.
One of the main reasons for using ice post-injury is to slow down the metabolic rate of the cells in the area (like a vet putting a lizard in the fridge before surgery, you know...). By doing that, you can temporarily decrease the cells' requirements for oxygen, and hopefully fewer cells in the area of your injury will suffer damage related to lack of oxygen, in the acute phase of your injury. (A complete aside, here - the rooms used for heart surgery and the like are also cooled, for the same reason as the lizard going into the fridge - to decrease the metabolic rate, and decrease cell damage as a result. Neat, huh - but VERY cold for the theatre staff)
The reason that your tissues in the injured area are at risk of damage from lack of oxygen, is due to THE SWELLING, because swelling increases the pressure surrounding the cells in the injured area. That makes it harder for the blood supply containing oxygen and nutrients to battle (or diffuse) their way into your cells. Like trying to pump up a bike tyre with a fat guy sitting on the bike - it's a pressure thing, you know? (and thank you to my spouse for that particular analogy).
The reason that the swelling is there in the first place, is because when you injured yourself (and damaged some of your tissues - you reckless maniac!), the damaged tissues called for their own ambulance - and a fleet of them arrived. This is the response we know as inflammation, and it involves an increase in blood flow to the area, an increase in the permeability of the walls of your capillaries, so lots of fluid leaks into the space in your tissues surrounding your cells, and often clots there (read - stacks of ambulances parked all over the place), and the cells themselves swell. The effect this inflammation is intended to have, is to put up a barrier around the injured area (read - police roadblocks), to slow the passage of any bacteria or toxic products that may be in the injured tissue, into the surrounding healthy tissue (read - quarantine).
So the swelling does have a purpose, but it also comes at a cost to the tissues in the "quarantined area" - with all those ambulances parked all over the place, it's hard to get on with things. Then, when the quarantine period (read - acute inflammatory phase of injury) is over, the tissues have to repair their damaged lives. This includes rebuilding and remodelling, and this is where your friendly physio will start raving on about collagen fibres in disarray, and scar tissue in abundance. To avoid this (both the scarring and the raving, I mean), most people set out to minimize the inflammatory response as far as possible, when they get injured.
Now Macattack may get hot and bothered when I type this, and demand to see references (sorry, Macca) - but when I was a student, there was more evidence to suggest that the best way to prevent swelling, was to elevate the affected part, and put a pressure wrap on it. The wrap increases the pressure from outside the body, and makes it harder for the extra fluid to leak into the tissues etc., as part of the inflammatory response, while the elevation serves to make it an uphill drive all the way for those darned inflammatory ambulances to get into the tissues. Meanwhile, the rest and ice part of the RICE equation, are meant to decrease the metabolic rate of the cells in the injured area, to hopefully minimize the damage to those cells, and therefore lessen the rebuilding and remodeling that will be required.
I am not a physician and the above is in no way to be taken as medical advise. This is my interpretation of what I have been told by my physicians and from what I have read. Always consult with a professional for case specific accurate information.
