Lying on the ball face down, head up and chest touching the ground. Your legs are straight and toes pointed upwards, with your core on the ball. Moving the ball towards you into a pike position, core is stabilised and posture is correct.
Its getting a little harder with the terms, and I hope your imagination are working in overdrive. Lying on your back on the floor, with your feet on the ball, hips are up. Then comes the hard part, with one leg raised, bring the ball inwards, the raised leg of course is moving towards your head and the ball is moving closer to you.
Easy huh?? Wrong, you really need to focus since the ball is not static, engaging the core is vital, your arms and shoulders start to burn with this one.