Start: Ball in curve of lower back, feet slightly forward, hips aligned under shoulders. Sitting bones sink straight towards the floor until hips and knees are bent to prescribed angle. Pressure is maintained in midline of each foot. Knees aligned with ankles.
Movement: Keeping shoulders and hips in line, move your weight so that it is centred securely over one leg. Pause, then return to the centre.
Return: Roll straight back up to start position as if sliding up a vertical pole.
