Mr Williams, who runs a gym and a security firm, said he came up with the idea after seeing Ringo play-fighting with another dog.
"All his strength seems to be in his legs," he explained. "I just thought about how I could develop that.
"I have only been training him for three weeks but he has picked it up really quickly and is incredibly strong.
"He can jump and kick to command with his two front feet at a punch bag or kick pad.
"It seems much better to teach a guard dog to do this than to bite."
Russian black terriers, also known as Russkiy Tchiorny terriers, were specially bred in the former USSR and originally used by the authorities for riot control.