Those dark circles all over Michael Phelps' shoulders and back have been getting a lot of attention, but the 19-time gold medalist isn't the only athlete using cupping therapy.
Vikings defensive tackle Linval Joseph posted a photo to Instagram showing what it looks like when you get cupped.
Cupping is a traditional Chinese therapy that CBS Health defines as "a glass that is heated inside using a flame and then placed on top of the skin, where it creates a vacuum and sucks the skin up into the cup."
The belief is that it releases tension in muscles.
Major League Baseball players have been using it for a few years now, according to USA Today's For The Win.