What Are Those Purple Circles on Michael Phelps' Back?
The circles are the result of cupping, a therapy technique that athletes use to help their muscles recover and perform at their best.
After the American men's 4x100-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?
No, the circles are the result of cupping, a 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.
Some experts are skeptical of the treatments effectiveness, but Phelps has been using it regularly for a while. And the 31-year-old, swimming in his fifth Olympics, delivered on Sunday night.
With infant son Boomer watching from the second deck, the American superstar summoned a performance for the ages to propel Team USA to gold — the 19th of Phelps' career.
Phelps was swimming in his traditional second leg, and it was that swim that gave the Americans a commanding lead. His turn helped him finish his leg in 47.12 seconds, the second-fastest time on the team behind Adrian.
When the race was over, Phelps looked into the crowd to find Boomer and mother Nicole Johnson, waving and pointing with a golden smile on his face.