Cupping is the use of glass, plastic or silicone cups or containers to create suction over an area of skin or muscle. In Traditional Asian Medicine this form of therapy has been used for thousands of years to help alleviate problems from coughs and colds to muscle trauma caused by stagnation.
When the cups are applied they lift and separate the layers of tissue below the cup (skin from the fascia, the fascia from the muscle, and the muscle from the bone), allowing a release of any stagnant blood or toxins that have built up in the area. The purple marks you can end up with are a result of that stagnant product being drawn up to the skin where it can be eliminated from your body through your lymphatic system.
Cupping is particularly beneficial for anyone, like athletes, who do lots of repetitive and intense actions and training. The act of intense exercise and repetitive actions causes not only tightness in the muscles and tendons, but also a buildup of lactic acid and other toxins. This tightness and build up can decrease your body's ability to properly oxygenate and repair the muscle tissue that is being continually damaged leading to prolonged recovery time, increased risk of injury and reduced performance.
The act of cupping can help relieve this build up in the muscles and tendons and encourage the flow of blood and oxygen to area allowing it to loosen and repair. This in turn can decrease your recovery time and injury risk while at the same time improving your performance by assisting your muscles to operate at their maximum capacity.