Shoulder in (click to read more), is an excellent lateral movement, helping to develop engagement and suppleness.  A common rider mistake, is to bring their inside leg too far back and push the quarters out rather than move the shoulders across to the inside.

To help reduce the risk of this happening when teaching either a horse or rider shoulder in, start off in a school with a high fence around the school, or for those lucky enough, an indoor school.  In this way it will be more difficult for the horse to swing his quarters out as there is nowhere for them to go.  The rider must keep their inside leg well forward and think about moving the horse's shoulders across.

Riding up the centre line from A and a mirror at C will clearly show whether the quarters are being pushed out or the shoulders moved across.
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