Holding a dumbbell in each hand then bring yourself to the ground and enter a high plank position with your hands directly under your shoulders and your legs extended directly behind you. This is your start position. Keeping your core braced and hips still, pull your left elbow back and up towards your hips, bringing the dumbbell level with your chest. Squeeze your back muscles as you do and exhale. Return the dumbbell and your hand to the floor with control. Repeat this movement on the other side. Keep alternating sides for the required number of reps (or time).