In this video, Milo Lines demonstrates how to maintain proper posture through impact by keeping the 'butt back' against a wall. He explains how keeping the tailbone back while the lead hip rotates prevents early extension, creating the necessary room for the arms to stabilize the clubface and generate lag.
Start lowering and pushing the glutes back during the second half of the backswing.
Keep the tailbone against the starting wall line while pushing the left cheek further through it during the downswing.
Create 'stretch' by landing into the left foot while the hands are still high in the transition.
Maintaining this posture allows the right arm to stay on or under the shaft plane, which stabilizes the clubface through impact.