Oakland Raiders wide receiver Antonio Brown and his feet made headlines last week for a mysterious (and gagworthy) injury he showed off on his Instagram Story.
Brown, 31, shared a gruesome photo in which chunks of skin were visibly peeling off the bottom of his feet. Many originally thought they were large blisters.
On Monday’s episode of ProFootballTalk Live, co-host Chris Simms said that a source close to the situation said the NFL player reportedly burned his feet by not wearing appropriate footwear in a cryotherapy machine — which caused them to get frostbite.
On Wednesday, another source confirmed to ESPN that the injury was “extreme frostbite” caused by misuse of a cryotherapy machine. ESPN’s source also said that Brown did not wear proper footwear while using the machine last month in France.
The injury has caused Brown to miss some of training camp, according to ESPN.
Brown’s agent did not immediately respond to PEOPLE’s request for comment.
In 2011, Olympic sprinter Justin Gatlin also suffered frostbite on the bottom of his feet from using a cryotherapy machine with just wet socks.
Cryotherapy has become an increasingly popular treatment that exposes people to freezing or near-freezing temperatures and boasts a number of benefits including pain relief and muscle healing, reducing inflammation, and even weight loss, according to Medical News Today.
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The U.S. Food and Drug Administration, however, reports that it does not have any evidence of cryotherapy successfully treating or causing any of the benefits it claims.
“Given a growing interest from consumers in whole body cryotherapy, the FDA has informally reviewed the medical literature available on this subject,” Aron Yustein, M.D., a medical officer in the FDA’s Center for Devices and Radiological Health, said on their website. “We found very little evidence about its safety or effectiveness in treating the conditions for which it is being promoted.”