BBC on why so many Olympians are 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, the BBC  writes.

Swimmers and gymnasts, particularly from Team USA, are among those seen sporting the mysterious dots.

According to the source, they are the result of a practice known as “cupping”; an ancient therapy where heated cups are placed on the skin.

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.

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”.

An illustration from a medical textbook "Exercitationes practicae" published in 1694 shows a man undergoing cupping on his bottom