Gua Sha (pronounced gwah SHAH) is a neat technique for ridding the body of toxins as well as relaxing muscles. Gua Sha translates to "scraping sand" in English. Gua Sha is extremely good at getting muscles that have been tight for a long time to relax. It can also be used for more recent injuries, under the right conditions.
According to Chinese medical theory, when our muscles get tight and crampy, the Qi does not flow properly through the area, so toxins will be trapped in the area. These toxins contribute further to the muscle tightness and cramping, continuing the cycle.
From a biomedical standpoint, these "toxins" are the natural byproducts of normal muscle action. When a muscle cramps, these byproducts are unable to be flushed from the area due to a decrease in blood flow.
If Gua Sha is the right technique for you, your acupuncturist will use some sort of a tool such as a coin or a Chinese soup spoon to quickly and repeatedly scrape your skin that has been lubricated with some sort of greasy ointment (usually a Vaseline-type product). Because your skin has been lubricated, the scraping isn't painful.
After several minutes of Gua Sha (the repeated sensation can be annoying to some people, so tell your acupuncturist if you need a little break occasionally), your skin will begin to get a "sandy" texture to it (hence the "sha" part of "Gua Sha"). This is the reaction of your pores opening to let the toxins out that have been locked away in your muscles. Many people will also get some bruising which is another indicator that the toxins are being released. These bruises aren't painful, merely colorful.
After a Gua Sha treatment, make sure to drink lots of water. The toxins that have been released from your muscles can bring on flu-like symptoms if they're not flushed from your system. Also make sure to keep the area covered, as your skin will be more sensitive than usual to temperature changes and the sun.
Make sure to take into consideration who may be seeing any bruising from the Gua Sha. Always tell your partner that you've had it done, so there won't be any surprises. And if you're going to be wearing a fancy evening gown, where the bruises might show (and you care if people think you've been in a bar brawl!), you can always put off a Gua Sha treatment until a later date!