Lie on your back with your legs bent and feet on an unstable surface.
Keeping your legs hips width apart, lift your unaffected leg off the bosu.
Cross your arms over your chest, and tighten your buttock muscles, lifting your hips up off the floor.
Aim to achieve a straight line from your shoulders to your knees, and do not allow your hips to rotate.
Hold this position, then lower your hips back down to the floor before you repeat the movement.
