Antonio Brown practices with Raiders in certified helmet

ALAMEDA, Calif. — ALAMEDA, Calif. (AP) - Star receiver Antonio Brown practiced with the Oakland Raiders in a certified helmet.

Coach Jon Gruden said Brown participated in the team's first practice session back at team headquarters Tuesday, two days after being given an ultimatum by general manager Mike Mayock to be "all in or all out" after missing time fighting with the league and the union over his helmet.

Brown was not wearing a helmet during the open portion of practice and spent some of the time during stretch in the nearby weight room. But he walked off the field after practice holding his new helmet and Gruden says he's running well after also missing time with frostbitten feet.