Starting Position: Stand holding dumbbells in your hands with a closed, neutral grip (thumbs around the handles with your palms facing your body). Position the dumbbells alongside your thighs with your elbows fully extended. Assume a split-stance position to stabilize your body, stiffen your torso by contracting your abdominal and core muscles ("bracing"), and depress and retract your scapulae (pull your shoulders down and back). Maintain these positions throughout the exercise. Your head and neck should be aligned with your spine.
Upward Phase: Exhale and slowly shrug your shoulders upward, avoiding any shoulder rotation or elbow flexion (bending). Maintain an erect torso (no arching in your low back) and neutral wrist position (wrists held straight without any bending).
Downward Phase: Inhale and gently lower the dumbbells back towards your starting position keeping your elbows extended and neutral grip position. Maintain your split-stance, torso, shoulder and wrist positions.