Brock Lesnar is back in WWE and he brought with him one of the most dangerous holds in all of sports – the Kimura Lock. Lesnar has already used the maneuver to break WWE COO Triple H’s arm on Raw SuperShow (WATCH) and injure John Cena’s arm at Extreme Rules (WATCH).

To learn more about the devastating hold, WWE.com spoke with jiu-jitsu expert Rener Gracie. (WATCH GRACIE EXPLAIN THE HOLD)

Rener is the second eldest grandson of Grand Master Helio Gracie, the creator of Brazilian and Gracie Jiu-Jitsu. (MORE ON RENER | MORE ON THE GRACIE JIU-JITSU ACADEMY)

The hold can cause injury to three areas – the elbow joint, the shoulder joint and the upper arm bone (humerus) .

"The hold goes as far back as early Japanese jiu-jitsu and judo," Gracie said. "People even trace Japanese jiu-jitsu back further to India thousands of years ago. So it has been around forever. It’s only recently becoming very popular because of its successful use by professional fighters."

"The Kimura is a shoulder lock, originally a Japanese arm lock called the Reverse Ude Garami, which means the reverse arm entanglement," he added. "A lot of people know the Key Lock. It’s an inverted version of that."

Gracie explained the technique came to be known as the Kimura Lock, after his grandfather fought Japanese champion Masahiko Kimura in 1951. It was the first time a jiu-jitsu world championship match would be held outside of Japan.

Although Kimura outweighed him by nearly 80 pounds, Helio lasted for 13 minutes, until Kimura locked in the hold.

“Fearing for injury, my great uncle Carlos, my grandfather’s older brother, threw in the towel, forfeiting the match,” Gracie said. “To honor the champion, at least in Brazil, under the teaching of my grandfather, they named the technique the Kimura.”

Citing a UFC fight pitting Frank Mir vs. Antonio Rodrigo "Minotauro" Nogueira, in which Mir broke Nogueira’s arm with the hold, Gracie said: “It goes to show how serious the move is. Even though you might feel the pain and you might not want to tap, you have to. Because if you don’t, you’re going to pay for it. We always say at the Gracie Academy, recovery time from that lock is six days if you tap, six months if you don’t.”