Register for free
Ball Bridge Position
Position yourself where you are crouched down behind the ball with your upper back leaning against it. You feet are flat on the ground but your glutes are not touching the ground.
With your arms crossed across your chest, keeping your feet stable, extend your back / raise your hips until your back is parallel to the floor.
Hold for a second or two, squeeze your glutes and then return back down to the starting position.
This is an excellent core and glute exercise, take your time and really feel the muscle contract.
Search on FreeTrainers.com