Swissball back extensions are a really useful exercise in order to build strength and stability across the core, through the lower back, glutes and hamstrings.
The set-up for Swissball back extensions involves kneeling on the floor with your feet pressed into the wall and toes pointing down. You can then place the Swissball against your thighs, pushing your hips down and towards your knees whilst your knees raise off the floor.
From there, you should place your fingers on your temples and pull your shoulders back lifting your chest up and away from the ball, holding this positions for a moment at the top and then coming down and rolling your chest back around the ball.
It is important to ensure that throughout the movement your weight is pushed back into the wall and between each repetition you come all the way back down rolling your chest around the ball.