Motion ( gridiron football ) In gridiron football , motion refers to the movement of an offensive player at or prior to the snap . Motion and shift . There is a distinction drawn between a " shift " and " motion " in football . A shift occurs when one or more players changes their position on the offensive side of the ball " before the snap " , causing a change in formation . For example , players may line up initially in an I - formation and then shift the two running backs into wide receiver positions to put the offense in a spread formation . A team may shift any number of players into new positions , so long as they all come to a complete stop for a full second before the ball is snapped to start the play . Motion occurs when a player is moving " at the time of the snap " . While different leagues have different rules regarding motion , most mandate that no more than one player may be in motion at the time of the snap , and that only players who start in " back " positions ( running backs , fullbacks , quarterbacks , flankers , H - backs , etc . ) may be in motion at the snap . Additionally , the NFL ( professional ) , NCAA ( college ) , and NFHSAA ( high school ) require that they must be moving laterally or backwards , and are not allowed to move towards the line of scrimmage . The Canadian Football League and the Arena Football League allow for motion towards the line of scrimmage . The National Football League defines all motion and shift penalties as " illegal motion " , while both the NCAA and NFHSAA make a distinction between an " illegal shift " and " illegal motion " ; an illegal shift refers to players shifting and not coming to a complete stop before the snap while illegal motion refers to a player who is in motion towards the line of scrimmage , or a player who is not a " back " in motion . In both leagues , however , the penalty for illegal motion / illegal shift is five yards from the previous spot and replay the down . Additionally , the offensive team may be charged with the penalty of a " false start " if a player on the offense jumps or moves abruptly , simulating the start of the play . This movement is not normally considered a subset of the " motion " or " shift " rules , as the player is not judged to be moving into a new pre - snap position ; they are merely starting the play too soon . This is also a five yard penalty . History and purpose . In the earliest days of American football , offenses were allowed to shift and assemble themselves as much as they wanted , much as defenses do . The famous Notre Dame Box relied heavily on these shifting motions . However , rule changes were eventually implemented that prevented offenses like the Notre Dame Box from ever occurring again . The motion rules seen today resulted from these rule changes . Currently , wholesale formation shifts can only occur before the offensive formation is set , and said formation must be in place for at least one second before a snap or motion can occur . The purposes of motion are to allow the offense to change formations and , in leagues that allow forward motion , a chance to gain momentum on the defenders . Requirements . In all forms of football , only players in the backfield and not on the line of scrimmage may be in motion at the time of the snap . Prior to starting the motion , all players on the offensive side must be in a set formation for a minimum of one second . In most versions of American football , only one player may be in motion at one time , and the player must not move toward the line of scrimmage in his motion ( in other words , he can only move laterally or backward ) . In no situation may the moving player begin on the line of scrimmage when he moves ( in other words , offensive linemen are prohibited from motion prior to the snap ) . Any player who shifts from a lineman position to a back position must set in position at least five yards behind the line of scrimmage before going into motion . Exceptions are as follows : In leagues that allow forward motion , the moving player ( s ) cannot cross the line of scrimmage , or else it is a false start .