We, as primates, spend the majority of the day upright. Whether sitting or standing, our feet are usually below our waist. This creates a number of unique situations for our bloodstream. Mainly, the heart has to put enough pressure behind the blood flow to ensure it can make its way back up after being cycled throughout the body. If something affects that blood flow, then the blood cannot do its job in that part of the body and causes issues elsewhere.
One recommendation physicians make when faced with some blood flow problems are a special pair of long socks known as compression stockings. Compression stockings are designed specifically to be very tight on the leg, squeezing the veins and arteries of the leg. Some stockings are knee height, and some, used in some extreme cases, can include the thigh.
The point of compression stockings is best compared to a running hose of water. Known as the Venturi effect, when pressure is pressed on the hose—but not enough to block it off completely—the water moves faster through it. Similarly, when a compression stocking is put on, the arteries and veins have added pressure from the compression. The blood flows faster, putting less pressure on the walls of the veins and arteries themselves. In addition, there is less room for overall blood content in the legs. This causes a rise in the pressure to volume ratio, causing the blood to be pumped through the body faster with less collecting in the legs and feet.
The benefits of these stockings are many. First off, those people who are prone to swelling legs will benefit from the increased blood flow: less blood will be in the legs to collect and swell. Those with CVI (chronic venous insufficiency—the inability to pump the deoxygenated blood back to the heart) benefit from the stockings as more pressure is put on the valves of the bloodstream to open and allow blood to pass through. CVI left untreated can lead to very serious problems, resulting in less overall good blood to be shared amongst the rest of the body. Skin conditions can occur. CVI has been recognized since the beginning of medicine, extending back to the Greeks.
Overall, compression stockings are necessary components worn by those with blood flow issues or those prone to clotting. While self-prescribing compression stockings is usually safe, it is best to check with a doctor and other health resources before usage, as some minor conditions exist that can cause dangerous conditions in conjunction with compression stockings.