Action: Sitting posture, holding the dumbbell with both hands to the side, elbow abduction, palm forward, pushing the dumbbell to the highest point in an arc, stopping for a moment, and slowly controlling the dumbbell to recover according to the original route (arc). Tip: You can also do it standing, with both arms at the same time, or with one arm. 2. Side lift: mainly practice the middle bundle of deltoid muscle. Action: Hold two dumbbells in front of your legs, lean forward slightly, bend your elbows slightly, lift the dumbbells to shoulder height on both sides, make the deltoid muscle in the "peak contraction" position, pause for a moment, and then slowly control the shoulder muscles. You can also do it with one arm and rotate with both arms. 3. Bend over and lift sideways: mainly practice the posterior deltoid. Action: Hold dumbbells with both hands, palms facing each other, bend over and bend your knees, stabilize your body, lift your arms to both sides, and then control them to decrease slowly. 4. Shrugging: Mainly practicing trapezius muscles. Action: Hold the dumbbell beside you, bend your knees slightly, lean forward slightly, fully lift your shoulders, try to touch the earlobe with the shoulder peak, pause for a moment, and then slowly control the lowering.