According to the bending action of the dumbbell hammer, the arm only needs to droop naturally and does not need to cling to the side of the body deliberately. The specific operation steps are as follows:

1, back straight, sitting in the sports chair.

2. Hands droop naturally and hold dumbbells.

3. Use the biceps brachii of the arm to lift the dumbbell upward.

4. The dumbbell goes up to the chest position, and the arm is 90 degrees.

5, the force should be uniform, not explosive, and run to the end of the action for 2 seconds to make the muscles fully operate.