There are four different positions on the offensive line. One is the center. Another is the guard. Third is the tackle and fourth is the tight end. The offensive line is really busy between plays. In a little over 30 seconds the offensive line plans with the quarterback and the other part of the offense for the next play. Even though the offensive line is made up of big guys, they have to be quick and balanced. The offensive line has to stand perfectly still until the quarterback has the ball. If they don't the referees call illegal procedure. The average weight of a man on the offensive line is 300 pounds!!! That's a lot!! Even though there are tackles on the offensive line, they can not tackle the defense or the referees call a holding penalty.