The foot injury that sidelined Antonio Brown during his first training camp as a Raider was reportedly caused by frostbite. 

A source close to the Raiders disclosed to ESPN that Brown suffered "extreme frostbite" from a cryotherapy machine. Per the insider, Brown traveled to France last month to undergo cryotherapy. But, the wide receiver did not wear the proper footwear when he entered the machine. As a result, his feet were burned and left severely frostbit. During an appearance on Inside Training Camp Live, NFL Network's Ian Rapoport confirmed that the Raiders are still working through this issue with Brown.

"From what I was told, Antonio Brown is still day to day," Rapoport explained. "As far as the backstory—what led to this—what I was told, talking to a couple Raiders people, basically the story that they are saying is that Antonio Brown used a cryogenic chamber without proper footwear and that is why his feet ended up the way they did."

It was first revealed that AB would miss training camp in July, when he was placed on the team's non-football injury list. It was then reported by the Raiders that Brown would be seeing a foot specialist to treat a foot injury. Brown also shared pictures of his injured feet on Instagram.

Antonio Brown feet
Image via Instagram/AB

Despite missing practice, ESPN's Adam Schefter was told that AB's injury is not long term and he's expected to return to the field soon.