Herschel Walker is starting a new career in mixed martial arts.

The 47-year-old former NFL running back said Monday that he has signed a multi-fight contract with promoter Strikeforce. Walker will begin a 12-week training camp next month in San Jose, Calif.

"MMA fighters are said to be some of the best athletes in the world," Walker said in a release. "My plan at the age of 47 is to show the world I am still one of the best athletes as well."

The 1982 Heisman Trophy winner already holds a fifth-degree black belt in Tae Kwon Do. 

Said Walker, "I will go in there and test myself against any 20-year-old."