Fresh health concerns have been raised over slap fighting, after former UFC heavyweight champion, Tim Sylvia debuted in the sport, despite having his mixed martial arts career ended, due to blunt force trauma fears.
Sylvia was forced to end his MMA career in 2015 after failing to receive medical clearance to fight Juliano Coutinho.
His manager Monte Cox said at the time the Mohegan Athletic Unit had found signs of blunt force trauma in an MRI scan.
'Basically what they're saying is there's damage from blunt force trauma,' Cox told ESPN. 'He's got damage there. Does it affect his everyday life? Not so far.
'Not that he can tell - but it's certainly something to pay attention to.'
Despite the concerns, the 47-year-old has embarked on a career in the controversial sport of slap fighting, with the American beating 'the Bouncer' in the super heavyweight division in Oklahoma City.
Sylvia, known as 'the Maine-iac' during his MMA career, shared footage of him knocking out his rival on social media.
Footage showed Sylvia brutally slapping his opponent around the face, leading to him stumbling back and falling to the floor.
The blow led to Sylvia winning the contest in the fifth round to secure the super-heavyweight title.
Ben Rothwell, who previously faced Sylvia in the UFC heavyweight division, had questioned the American for competing in the Slap Fight Championship, citing the MRI scan Sylvia had in 2015.
‘The new MRI I took was clear with no problems,' Sylvia replied. 'But my knees don’t allow me to run and do cardio any longer so I could no longer make the weight.
‘Ben thx for your concern. Like I said there is nothing wrong with my brain. I am willing to bet our MRI would look the same.
‘Taking out of context, the MRI wasn’t clear and couldn’t be read, so I had to take another one.
'What they did see was what they thought was trauma from 16 years in a contact sport. Mine looks just like any other fighter competing that long.’
Neuroscientists have criticized the brutal sport due to the risk of brain injuries for its participants.