ICE -vs- HEAT
SOFT TISSUE BRUISING
BREAKING THE CAPILLARY BEDS
An important concept to remember is that you cannot injure the tissue without injuring the tissue's capillary bed as well. Because these capillaries are quite thin, they can be torn or broken relatively easily. Let's say that you were hit in the thigh by a line drive baseball while pitching to your son. As the tissue was impacted, it deformed / stretched. This is normal and good. Unfortunately, the blow by the baseball was too intense and occured too quickly for the soft tissues in your thigh to overcome the mechanical stresses / load placed upon it. In other words, the tissue tore.
Bear in mind that usually this "tissue tearing" is something that occurs microscopically. In other words, testing with advanced imaging techniques (MRI, CT, Diagnostic Ultrasound) might show some swelling, but are not likely to show the tissue damage itself --- even though it was the tissue damage that caused the swelling to occur.
When this happens, there are chemical mediators that are released (INFLAMMATION) which, while not to be considered swelling, attract swelling to them via vasodilation. In other words, these mediators we call Inflammation can actually make the blood vessel dilate to a larger size! As you can imagine, the worse the tissue injury, the worse the swelling. And the worse the swelling, the more things that can go wrong. Some of this is because the initial Swelling and Inflammation is the first step in forming SCAR TISSUE. This is why it is important to control swelling. Oh, and by the way, when the capillaries are torn enough, they can actually leak red blood cells into the fluid around the tissue (Interstitial Fluid). This is called a BRUISE.
My advice is to only use heat for old (chronic) injuries and then use it systemically ---- whole body heat in the form of a bath, shower, jacuzzi, etc. Local heat has the potential to cause lots of problems. Instead use ice. Just be smart about how you do it. No more than 10-20 minutes (depending on the area being treated) and never directly on the skin.
One more thing. Even though anti-inflammatories work, they have lots of potentially serious side-effects. This is why we recommend ice instead of drugs!