If you’ve been watching the Olympics in Rio, especially swimming or track and field, you’ve probably noticed dark red circles on many athletes. These circles are made by a traditional Chinese medical treatment called cupping, a technique that uses small glass cups or bamboo jars placed on the skin. Heat causes these cups to suction on to the skin, causing the skin and superficial muscle layer to be lightly drawn into the cup. Cupping is sort of like the inverse of massage–rather than applying pressure to muscles, it uses gentle pressure to pull them upward. For most patients, this is a relaxing and relieving sensation. Once suctioned, the cups are generally left in place for about ten minutes.

Generally, cupping is combined with acupuncture in one treatment, but it can also be used alone. The suction and negative pressure provided by cupping can loosen muscles, encourage blood flow, and sedate the nervous system. It’s also used to relieve back and neck pains, stiff muscles, anxiety, fatigue, migraines, rheumatism, and even cellulite. The treatment is also valuable for the lungs, and can clear congestion from a common cold or help to control asthma. In fact, respiratory conditions are one of the most common maladies that cupping is used to relieve. Three thousand years ago, in the earliest Chinese documentation of cupping, it was recommended for the treatment of pulmonary tuberculosis.