It is illegal for an offensive player to aid a runner in advancing the ball forward. An offensive player may block for the runner, but may not push them forward. If an offensive player is deemed to have helped a runner advance the ball, a 10-yard penalty will be assessed.
This rule was implemented to prevent teams from lining up their biggest players behind their running back or tail back, and helping them move the pack. No offensive player may lift a runner to his feet or pull him in any direction at any time, nor push or throw his body against a teammate to aid him in an attempt to obstruct an opponent or to recover a loose ball. The foul for assisting the runner is a ten-yard penalty. Prior to the rule being implemented, a running back stopped by the opposing team would sometimes get an assist from behind.