Ultimately when coaching Rugby League, you want your players to create an overlap or to drag defenders out of position so that a hole is created in the defensive line for someone to go through!! Overs and Unders are a way of creating these holes for people to go through.
Both are coached in a very similar way, an unders line See's the support player run towards the ball carrier and overs the opposite way. The video below shows you the unders line being run twice and the overs line once.
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Set up 2 lines of players opposite tackle shields. The ball carrier runs into the middle of the drill and then steps away from the support runner dragging the defender away with him. The support runner suns straight at the other defender to get him to hold and then at the last moment steps inside into the gap created by both his and the ball carriers lines of running.
The overs is slightly different in that the ball carrier wants to stand the defender up by running straight at him whilst the support player runs into the middle to drag the 2nd defender towards the ball carrier. The ball carrier steps into the gap between the 2 defenders forcing both defenders to go for him and the support player steps outside of the 2nd defender whilst receiving the ball.
This one isn't really a drill as such but can be used to explain the concepts of overs and unders lines to players. What kind of drills can you use to practice this technique? Please tell us in the comments section