The big story from the Olympics last night was undoubtedly Michael Phelps‘s 19th gold medal win.
The 31-year-old swimmer put the U.S. men’s team in the lead during the 400 freestyle relay, marking the first time they’ve won gold at the event since 2009.
It was also the first time Phelps’s adorable 3-month-old son Boomer was in the stands while his dad stood at the Olympic podium, which was undoubtedly an emotional moment for Phelps and his family.
Still, with all of that going on, people still couldn’t help but wonder: “What are those circular bruises on his shoulders?”
The purple marks are apparently a result of a therapy technique called ‘cupping,’ which “releases the tendons and muscles by pulling them up rather than having them pressed as they would be in a massage,” according to USA Today.
And Phelps certainly isn’t the only Olympian sporting those round bruises:
Alex Naddour of the U.S. men’s gymnastics team also says that cupping relieves his soreness better than hot tubs, massages or cortisone shots.
“That’s been the secret that I have had through this year that keeps me healthy,” he told USA Today of the therapy. “It’s been better than any money I’ve spent on anything else.”