If you have watched legendary Olympian Michael Phelps in Rio Olympics, you must have noticed several purple dots on his back and shoulder.
Millions of people around the globe saw it when Phelps reached down to help anchorman Nathan Adrian out of the pool after helping his team win gold in 4x100-meter relay.
People wondered the origin of these purple dots. Many thought it was some kind of new tattoo. People, who had not seen Phelps or his picture before, thought it was some kind of birth mark. Some even joked if Phelps had taken a nap on a bed of tennis balls.
As it turns out, 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 treatment's 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.
Phelps made the world aware of cupping by showing his marked muscular shoulders before diving into the pool at the Rio games recently, but cupping, and a similar treatment known as coining, have been practiced in East Asia for centuries.
Phelps clinched his 20th gold by winning the 200-meter butterfly Tuesday night, a victory that sent him climbing into the stands to kiss his 3-month-old son Boomer. An hour later, he returned to take what amounted to nothing more than a triumphant victory lap in anchoring the 4x200 freestyle relay, the crowd's deafening roar growing louder with every stroke.
"That was probably one of my most challenging doubles," the 31-year-old Phelps said. "Doing a double like that is a lot harder than it once was."
It was another performance for the ages, but Phelps has done it so many times that nothing else would have been fitting. It came on a night that American teammate Katie Ledecky picked up her second gold of the Rio Olympics on the way to what could be a historic run of her own in the pool.
Phelps now has 25 medals in all, 21 of which are gold.
