Ice or heat to cure your pain?

Ice should always be your first line of defense against injury. If I notice the slightest little ache, I like to ice it after my run and a couple of other times during the day, too, if possible. A few minutes of preventative care can work wonders in keeping a little nagging pain from developing into a disruptive injury.
Why ice instead of heat? The reason is that most running injuries are a result of soft body tissues (muscles, tendons, ligaments) that have become inflamed. Blood vessels get damaged and swell; the greater the swelling, the worse the injury, and the longer recovery is going to take. Icing the inflamed area causes the blood vessels to constrict. This reduces the swelling because less blood flows to the injured area and the damaged tissue relaxes.
This not only reduces the pain you feel, but also speeds healing, because as the tissue’s metabolism is slowed, there’s less tissue breakdown. Heating an inflamed area worsens, rather than improves things. Heat has the opposite effect of ice, so the blood vessels of the injured area become that much more swollen. Heat is helpful when your inflammation has reduced, however. This reduction usually won’t occur for at least 72 hours. At this point, the increased blood flow that heating stimulates will speed delivery of nutrients to the damaged tissue, thereby speeding healing. Heat is also good if you have overall stiffness in an area. The general rule is to use ice on small, acute body aches because they are signs of damage to a specific body part and to use heat for more widespread stiffness. Always ice an injury for at least 5, but no more than 20 minutes. The area should become red and numb, not white and numb. After running is the best time to ice, because the tissues will be the most swollen, but you’ll speed recovery if you can find a few other times during the day to ice. Rub the ice in circular motions on the injured body part.
The best method of icing I’ve found is to fill a few paper cups with water and keep them in your freezer. When you need to ice an injury, just tear down the top of the cup until the ice is exposed and hold the cup from the bottom while icing. This method keeps your hands warm while you ice, so you’re more likely to stick with it for the proper amount of time. When you’re done icing your injury, just put the cup back in the freezer until you need it again. These cups can last for months and will ensure that you always have one handy.