For you eagle-eyed spectators out there, you may have noticed some athletes at this year's Olympics have red dots on parts of their body.
Michael Phelps, the most decorated Olympian of all time, was seen with three large red circular dots on his shoulder during his swimming event yesterday, and it has now been revealed what they actually are.
The red dots seem popular on swimmers and gymnasts, in particular, on athletes representing Team USA.
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Several possible reasons have been suggested, but it's actually because of a technique called 'cupping', an ancient therapy where you put heated cups on your skin.
The therapy is a form of acupuncture, and it's done by lighting flammable liquid in a glass cup. During the process, the flame will go out and the temperature will drop, resulting in the cup sucking to the Olympian's body, eventually leaving a red mark on them.
The suction then pulls the skin away from the individual and promotes blood flow, leaving the red marks on their skin. The marks usually stay visible for three to four days.
But why are Olympians using this ancient therapy and what does it do for them?
Well, it's believed they do cupping as it eases aches and pains in their muscles. It also helps them recover from the consistent training and the intense workload.
Of course, there are more traditional methods of recovery, and more up to date methods, but it seems Team USA are more than happy to stick with cupping.
US gymnast Alex Naddour was speaking about the therapy with USA Today, and he admitted that it was the best method he's used in terms of recovery.
"That's been the secret that I have had through this year that keeps me healthy," Naddour told the paper, adding that it had saved him from "a lot of pain".
Naddour isn't the only one though. His team captain Chris Brooks added that many of the athletes have started doing their own cupping that can be suctioned with a pump rather than a flame.
"You're like, 'OK, I'm sore here,'" said Brooks. "Throw a cup on, and your roommate will help you or you can do it yourself."
Despite the marks looking like they could cause pain to the athletes, The British Acupuncture Council are adamant that the treatment doesn't hurt.
However, Phelps and Natalie Coughlin, two swimmers, have both said that the therapy can sometimes hurt, with The BAcC eager to warn people that it can cause burns, but only on 'rare occasions'.