Bring yourself to the ground in forearm plank position with your elbows directly under your shoulders and your feet directly behind you. Keeping your core braced and a neutral spine, twist your right hip towards the floor until it gently taps it. Reverse the movement and proceed to twist the left hip towards the floor. Make sure to keep your core contracted throughout, never letting your hips drop. Keep alternating sides for the required number of reps (or time).