Originally Posted by SFrazeur
For myself I am not a fan of icing for an injury as I have never felt it benefited me. The only time I use heat is mildly when in the shower as I doi not want to inflame. The body is smart and largely able to take care of itself. There is some scientific evidence that icing is actually bad for healing /swelling. As well as some people who claim to know better: http://www.youtube.com/watch?v=0UmJVgEWZu4
The reason you ice a swelling injury is simple. Cells require oxygen. Swelling occurs when fluid floods an area due to inflammation or damage. So, what's the problem? This increase in fluid increases the amount of pressure in the injured area which makes it more difficult for the cells to receive the oxygen they crave. If the cells are oxygen deprived, then the tissue they are part of can become damaged. By icing, you are decreasing the metabolic rate of said cells and therefore lessen their oxygen requirements. If the pressure is high and the blood vessels are therefore less able to transport necessary nutrients to the site, the swelling itself can lead to surrounding tissue damage.
So then, why on earth would the body cause swelling? When the area is injured, the body requires an increase in blood flow to the area to begin repairing it. Along with this comes a huge amount of fluid which accumulates in the surrounding areas. This fluid can clot (scar tissue!) and serves only to slow the passage of bacteria and toxins into and out of the site of injury. So yes, the swelling does serve a purpose, but it is minor compared to what can happen since if you know the injury isn't at risk of infection. This is why for tendinitis and bursitis NSAIDs are administered so that blood flow can resume to the area while reducing the swelling response.
The reason why you NEVER want to heat a swollen area is because heating it increases the cells' metabolic rate, and if they're already not getting the oxygen they need, you're going to pretty much start manufacturing scar tissue without repairing anything. Heating ALSO increases blood flow to the area, and if you've damaged blood vessels in the area, you're going to increase the bleeding from these damaged vessels. You obviously do not want this. The argument against swelling treatment is for this: to allow increased blood flow to the area. Unfortunately, your body is not focused on what that fluid is doing to the surrounding tissue.