Begin on hands and knees (“all fours”) with a dumbbell in one hand. Knees should be directly under the hips, about shoulder width apart. The hands and dumbbell should be directly under the shoulders. Engage abdominals and pull navel in to stabilize your core. Maintain a neutral (flat to normal) spine. Exhale and pull the dumbbell back to the side of your ribcage. Pause then slowly extend arm back out straight. Repeat using other arm.