Performing the: A Step-by-Step Tutorial Dumbbell Bench Supported External Rotation
Ensure your elbow is directly under your shoulder, and your palm is facing towards your feet.
Slowly rotate your forearm outward, raising the dumbbell until your forearm is perpendicular to your body, keeping your elbow and upper arm stationary.
Pause for a moment at the top of the movement, then slowly lower the dumbbell back to the starting position.
Repeat the exercise for the desired number of reps, then switch to the other arm.