dumbbell seated one arm kickback

Sit on a bench with your feet flat on the ground and hold a dumbbell in one hand. Bend your torso forward at the waist, keeping your back straight and parallel to the ground. Extend your arm straight back, keeping your elbow close to your body. Pause for a moment at the top, then slowly lower the dumbbell back to the starting position. Repeat for the desired number of repetitions, then switch arms.