Why does Michael Phelps have purple spots on his back?

Olympics

RIO DE JANEIRO, BRAZIL – AUGUST 07: Michael Phelps of the United States competes in the Final of the Men’s 4 x 100m Freestyle Relay on Day 2 of the Rio 2016 Olympic Games at the Olympic Aquatics Stadium on August 7, 2016 in Rio de Janeiro, Brazil. (Photo by Al Bello/Getty Images)

After the American men’s 4×100-meter relay team won gold, Michael Phelps reached down to help anchorman Nathan Adrian out of the pool.

While he did it, millions of Americans watching at home saw several purple dots on his back and shoulder.

Some kind of new tattoo? Did he take a nap on a bed of tennis balls?

United States' Michael Phelps competes in the final of the men's 4x100-meter freestyle relay during the swimming competitions at the 2016 Summer Olympics, Sunday, Aug. 7, 2016, in Rio de Janeiro, Brazil. (AP Photo/Matt Slocum)

United States’ Michael Phelps competes in the final of the men’s 4×100-meter freestyle relay during the swimming competitions at the 2016 Summer Olympics, Sunday, Aug. 7, 2016, in Rio de Janeiro, Brazil. (AP Photo/Matt Slocum)

No, the circles are the result of cupping, a traditional Chinese therapy technique that athletes use to help their muscles recover and perform at their best. It involves a therapist heating small glass cups, then placing them on the skin and pulling them from the body to loosen and relax the muscles.

Michael Phelps has been using it regularly for a while.

 

Thanks @arschmitty for my cupping today!!! #mpswim #mp ? @chasekalisz

A photo posted by Michael Phelps (@m_phelps00) on

Cupping therapy dates back centuries and has enjoyed a bit of a renaissance over the past decade after athletes like Phelps and NFL star DeMarcus Ware and actresses Gwyneth Paltrow and Jennifer Aniston started touting its benefits.

Researchers have traced cupping’s origins back to China and Greece somewhere around 1500 B.C.

Team USA gymnast Alex Naddour was among other Olympians who have been seen with the purple marks in Rio. And it’s not just for star athletes. Health spas often offer the service for a few hundred dollars and the cups can be purchased online for as little as $15 and applied at home.

Alexander Naddour has been seen with the purple marks in Rio. (Photo by Alex Livesey/Getty Images, via VCG)

Alexander Naddour of the United States has been seen with the purple marks in Rio . (Photo by Alex Livesey/Getty Images, via VCG)

 

This is my treatment today…. Not sure if it’s a trick or a treat? #halloween #otc #weneedkeenan

A photo posted by Michael Phelps (@m_phelps00) on

“I’ve done it before meets at pretty much every meet I go to,” Michael said.

The treatment involves applying glass or plastic cups to the area of discomfort and either applying heat or suction to create a vacuum. The suction pulls the skin away from the muscle and draws oxygenated blood to the area. The suction also is what causes the bruising, like a giant hickey without the fun that comes with it.

RIO DE JANEIRO, BRAZIL - AUGUST 07: Michael Phelps of the United States competes in the Final of the Men's 4 x 100m Freestyle Relay on Day 2 of the Rio 2016 Olympic Games at the Olympic Aquatics Stadium on August 7, 2016 in Rio de Janeiro, Brazil. (Photo by Al Bello/Getty Images)

RIO DE JANEIRO, BRAZIL – AUGUST 07: Michael Phelps of the United States competes in the Final of the Men’s 4 x 100m Freestyle Relay on Day 2 of the Rio 2016 Olympic Games at the Olympic Aquatics Stadium on August 7, 2016 in Rio de Janeiro, Brazil. (Photo by Al Bello/Getty Images)

Steve Hamilton, a massage therapist for the Denver Broncos, has used the technique for years in working with players. He said the biggest benefits include increased circulation, decreased muscle tension, decreased inflammation, increased range of motion and improved blood flow.

“Its effectiveness is because it’s all part of the body’s natural healing process,” Hamilton said. “But cupping helps the body recover faster by keeping the process moving forward. It’s awesome because it’s all natural,” he said, “it helps enhance the body’s natural neurological and circulatory function, thus allowing the body to be pushed and perform at a higher competitive level.”

Phelps even included the process, which can be painful, in a commercial he did for Under Armour on the rigorous training he puts his body through to get ready to compete. When he is competing in an event where victory is measured in fractions of a second, any little edge could make the difference.

Photo: CFP

Photo: CFP

Photo: CFP

The traditional way of cupping uses fire to create the vacuum. Photo: CFP

Like many forms of manual therapy, the effectiveness of cupping has been hard to prove from clinical evidence. Though a research in 2015 showed cupping therapy may be beneficial for pain-related conditions, such as acne or facial paralysis. However, a firm scientific conclusion could not be drawn due to the insufficient number of included reviews and low quality of the original studies.

Story from the Associated Press.