Why are so many Olympians covered in large red circles?

 

A number of Olympians - including the most decorated Olympic athlete of all time, Michael Phelps - have been photographed with large red circles on their skin.

What are they, and why is everyone suddenly going dotty over them?

The mark of an Olympic athlete, at least at Rio 2016, seems to be a scattering of perfectly round bruises. Swimmers and gymnasts, particularly from Team USA, are among those seen sporting the mysterious dots.
No, not paintballing misadventures or love bites - they are the result of a practice known as "cupping"; an ancient therapy where heated cups are placed on the skin.

So how is 'cupping' done?

The technique, which is a form of acupuncture, is done by lighting flammable liquid in a glass cup.
Once the flame goes out, the drop in temperature creates suction which sticks the cups to the body.
The suction pulls the skin away from the body and promotes blood flow - and leaves those red spots, which typically last for three or four days.

Why are some Olympians using it?

Athletes say they are using it to ease aches and pains, and to help with recovery from the physical toil of constant training and competing.
There are plenty of other recovery techniques competitors use - including sports massage, sauna, ice baths and compression garments - but US gymnast Alex Naddour told USA Today that cupping was "better than any money I've spent on anything else".
"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".
His team captain Chris Brooks added that many on the squad had started "do-it-yourself" cupping, with cups that can be suctioned with a pump rather than with 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."
The marks visible on Michael Phelps as he competed in the men's 4x100m freestyle relay on Sunday had people on social media speculating what they might be, with some guessing he might have been playing paintball or attacked by a giant octopus.