After sending the City of Atlanta into full-fledged panic yesterday after injuring his arm in training and leaving the field with a freakishly large air cast on his left arm, Josef Martinez was back in training today:
April 12, 2018
The video in the tweet doesn’t show it, but he is reportedly working with a cast on the arm, according to Doug Roberson of the Atlanta Journal-Constitution. Clearly it is far smaller than the temporary air cast Martinez was placed in yesterday, but details of the injury and the nature of the cast have not yet been released.
Should he need to wear a cast for a while, it does not necessarily prohibit him from playing on Sunday. Law 4 covers player equipment and says this about protective gear:
Non-dangerous protective equipment, for example headgear, facemasks and knee and arm protectors made of soft, lightweight padded material is permitted as are goalkeepers’ caps and sports spectacles.
I would interpret that to mean that a fully rigid cast is acceptable if covered in some form of padding. There are of course plenty of other lower arm protection options that would be fully acceptable under this Law.