Gophers offensive lineman Caleb Bak announced on Twitter Tuesday afternoon that his college football career is over.
Bak missed the last four games of the 2013 season dealing with the after effects of a concussion.
According to the Pioneer Press, he is the third Gophers offensive linemen in three years to quit because of a concussion. Tackles Jimmy Gjere and Brooks Michel are the other two.
Bak started the first nine games for the Gophers last season, before he was replaced by Foster Bush on the depth chart for the final three regular season games and the Texas Bowl.
The injury snapped a string of 20 straight starts for Bak.
Bak earned All-Big Ten honorable mention honors last season for the Gophers, despite missing the time.
The Gophers return seven offensive linemen with starting experience to the team.