But for days after Michael Phelps’s first appearance at the games, it seemed all anyone could talk about was cupping. It’s an ancient therapy that left multiple circular discolorations on his skin.

During dry cupping, suction is applied to the skin for several minutes; sometimes it is combined with massage, acupuncture, or other alternative therapies. Wet cupping is similar except that blood is removed by making small cuts in the skin.

Cupping is supposed to draw fluid into the area; the discoloration is due to broken blood vessels just beneath the skin, much like a bruise.

Cupping has been popular in Egyptian, Chinese, and Middle Eastern cultures going back thousands of years, but increasing numbers of people worldwide have been adopting it.

Celebrities and athletes have popularized it in the U.S. in recent years.

What Is Cupping Supposed To Do?

According to its advocates, cupping is supposed to promote healing and has been used extensively for sore muscles. But that’s only the beginning. Cupping has also been used for;

• Back and neck pain
• Skin diseases such as acne and hives
• Lowering cholesterol
• Migraines
• Knee arthritis
• Improving immune function

And there are many others. If cupping does help with these problems, it’s worth asking: How?

From a biological perspective, it’s not clear how the application of suction and drawing blood into an area under the skin would provide all these benefits.

A recent review of the treatment describes cupping as a treatment that can strengthen the body’s resistance, restore balance between positive and negative forces, remove disease-causing factors, and promote blood circulation. But exactly how is unclear.

Does Cupping Work?

A number of studies have examined this question, but unfortunately don’t seem to have convincingly answered it. In fact, a 2015 review of the evidence found that cupping provide some relief for chronic neck or back pain, but that the quality of the evidence was too much to draw firm conclusions.