To utilise the energy developed by the kinetic chain rotations, the racket head is manoeuvred away from the body (racket head speed is rotational speed * distance from centre of rotation).  The ideal contact position for the shuttle and racket head is thought to be high above the player and out on the racket side.  To develop a downward trajectory for the shuttle, the impact should be slightly in front of the player when the racket head has begun to rotate downwards.

It is important that a player lines up correctly with the shuttle during preparation.  There is a risk of lining up the centre of the body with the shuttle (in the cross court axis) as visually this is most natural, i.e. you are lining up the trajectory with your line of sight.  However, as mentioned above, the shuttle should be finally hit out towards the racket side.  If the preparation lines up incorrectly, the arm must swing across above the head and the body may have to be arched to affect the contact.  This will compromise the shot.

To position themselves correctly the player should line up on the non-racket side of the shuttle trajectory, so that when they rotate onto the shuttle they will hit it on the racket side.

This court positioning is the first requirement of the legs.  The second requirement is that they are positioned so they can orientate the body for the shot and contribute effectively themselves to the shot.

The ideal base position for the ground smash has the body turned substantially towards the racket side of the court (instead of facing the net).  This means the non-racket foot is closest to the net.  This orientation allows the main body kinetic chain to rotate onto the impact point (when the body will be approximately parallel with the net).  The legs should be fairly wide apart to provide a solid balance and to maximise their contribution to the whole body kinetic chain (remember that the further away from the centre of rotation the more speed/momentum that can be produced).

In practice, the base position is often compromised because of time constraints.  Depending on the direction of movement prior to establishing the base, one or both legs may be in a non-ideal position.  If there is sufficient time to develop the ideal base position, there is probably time to perform the 'jump smash'.  However, the ideal base position is still relevant for the ground smash as it provides a useful starting point to interpret variations within play.