There is quite a “buzz” about the round marks evident on the worlds’ best swimmer, Michael Phelps, as he participates in the Olympics in Rio.
He is practicing an ancient therapy called “cupping” where by cups are place on the skin to produce a local suction on the skin. This is believed to assist the flow of blood in order to promote healing. The “suction” can be created by placing heated cups on the skin—or in modern times by using mechanical suction.
This technology was actually used by the Greeks as far back as the Hellenistic Period as the above statue base gives evidence! The above object dates to the 3rd or 2nd century B.C. and is located in the National Museum in Athens.
See Here for a good article on modern “Cupping.”