Michael Phelps
Credit: Vaughn Ridley/Getty Images

When Michael Phelps got ready to conquer his 19th Olympic gold at the 4×100 free relay on Sunday night my eyes went straight to those purple circles on his upper back.

“What in the world are those things?” I wondered to myself. I turned to Google for a little digital digging and quickly realized I wasn't the only one wondering.

The circles have been spotted not just on Phelps, but also on some of his fellow US teammates, including some of the men gymnasts. The marks are not the result of some dramatic circumstances, like say, for example, a fight or a romantic encounter resurfacing in the form of a hickey.

Instead these bruises are the result of cupping, an ancient Chinese practice believed to speed the healing process of sore muscles. Though more research is needed, several US athletes are swearing by the technique in Rio.

In essence, the therapy involves small cups that are placed on the skin. With the use of heat or air pumps, suction is created, pulling the skin away from the muscle. The suction can cause small capillaries to break resulting in those bizarre looking circles.

Bruising is hardly the intended effect and quite frankly cupping looks that leans on the side of discomfort. But hey, if these Olympians believe is going to up their performance, so be it. Anything (legal) for the gold, right?

I say, keep calm and cup on.