kouhoutek: Because we have the option of taking it easy for a few days to let it heal.
Inflammation is kind of like a natural ace bandage. It immobilizes the joint and lets you know with pain if your movements are making it worse. This was really valuable if you had to keep up with your tribe as it migrated across the steppe. Today it is a lot easier to put your feet up for a few days.
the_deadcactus: Because the benefits to our comfort are immediately obvious to us but the repercussions of modifying the natural history of an injury are not as obvious or well understood.
4noop: Swelling and pain are body’s natural functions to protect the injured area by minimising the mobility that can aggravate the damage. Ice packs are used to reduce the swelling and thus numbs the pain. Basically you don’t want your body’s natural function to let you know by making you suffer that you need to rest that injured part, because you already know.
Sablemint: Your body tends to go a bit overboard with these things, because in general there’s no good reason not to. Using things that reduce swelling might slightly lengthen healing time, but not by that much really. Maybe if you kept it iced constantly it would have a negative effect, but doing that you’d get a much more negative effect from keeping it constantly iced than from any healing delay.