Why is Michael Phelps covered in purple circles? We've got the answer

The ancient practice seems to be very popular with athletes.

What in the world is going on with Michael Phelps skin? If you asked yourself that question as you watched the 31-year-old Olympian compete in the men's 4x100m freestyle relay during the 2016 Summer Games in Rio de Janeiro, you were certainly not alone.

The Google search for "what are those purple spots on Michael Phelps" must have been through the roof on Sunday, August 7, when Phelps removed his shirt and revealed a torso covered in large, dark purple spots that made the Olympic champion look like he took a beating on a paintball field.

No, Phelps hadn't wound up on the receiving end of a few punches or fallen asleep on one of his son's toys. Those marks are the result of an ancient Chinese healing practice called "cupping."

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If that sounds vaguely familiar, it's because cupping had a moment a few years ago when celebrities like Jennifer Aniston and Gwyneth Paltrow were photographed with similar marks on their bodies as a result of the therapeutic practice.

Now cupping is once again in the spotlight thanks to a totally different group of high-profile clientele. The process is fairly simple: glass cups are applied to the skin along the meridians of the body, creating suction as a way of stimulating the flow of energy. Either heat or an air pump create suction between the cup and the skin, resulting in the dark, circular bruising, like that seen on Phelps' body. According to WebMD, "Cupping therapy dates back to ancient Egyptian, Chinese, and Middle Eastern cultures. One of the oldest medical textbooks in the world, the Ebers Papyrus, describes how the ancient Egyptians were using cupping therapy in 1,550 B.C."

Though this may be the first time most people noticed the hickey-like bruises on Phelps' body, he certainly isn't new to the practice. Almost a year ago, Phelps posted this Instagram photo of him receiving a cupping treatment. Additionally, he appeared in a short clip for Under Armour just today during which he is actually in the process of receiving a cupping treatment.

The benefits of cupping, however, are still frequently debated. There is not much scientific fact to support the physiological benefits of the practice and many doctors and scientists believe that what most people experience from cupping is a placebo effect.

As noted by The New York Times, a placebo effect can still be immensely beneficial, especially for athletes looking for legal ways to improve their performance. Sometimes a positive state of mind can make all the difference in a high-pressure situation like the summer games.