Sit on a bench with your back straight and feet flat on the ground. Hold a dumbbell with an underhand grip and extend your arm straight up overhead. Lower the dumbbell behind your head by bending your elbow, keeping your upper arm stationary. Pause for a moment, then extend your arm back up to the starting position. Repeat for the desired number of repetitions, then switch arms.
1. Sit on a bench with your back straight and feet flat on the ground.
2. Hold a dumbbell with an underhand grip and extend your arm straight up overhead.
3. Lower the dumbbell behind your head by bending your elbow, keeping your upper arm stationary.
4. Pause for a moment, then extend your arm back up to the starting position.
5. Repeat for the desired number of repetitions, then switch arms.