This is the bizarre, painful therapy Michael B. Jordan used for his boxing movie 'Creed'

The goal of "Creed" trainer Corey Calliet was to make actor Michael B. Jordan "action figure" fit for his lead role in the movie, a reboot of the "Rocky" franchise. Jordan didn't just feel the burn while training, but while recovering as well.

When the production began filming the fight scenes, to recover more quickly, Jordan underwent the painful Chinese medical treatment known as Gua Sha every two weeks.

This entails scraping the skin to produce light bruising so the areas stimulate blood flow and healing, according to practitioners of the method.

"We would go to this place in Philly and they actually had this thing that looked like a small shovel to scrape his back," Calliet recently told Business Insider.

Though there have been reports of injuries from having the practice done, Calliet did not mention Jordan getting injured from it. In fact, he said it helped his flexibility for the fighting scenes.

"It's the worst pain in the world," Calliet said. "I did it once and I told them to stop."

"Creed" is currently in theaters nationwide.