This is a single-joint isolating exercise that targets the back of the upper arm while developing stability throughout the hand and wrist region.
Kneel over one side of a weight bench by placing one knee and one hand on the bench. Position the standing leg slightly back and to the side with the foot firmly planted on the floor. The torso should be parallel to the floor. Grab a dumbbell with the free hand with an overhand grip and position the elbow at your side so the upper arm is parallel to the floor.
Keeping the upper arm stationary, extend the arm behind you by contracting the triceps. Pause for one second at the top and then return to the start position.
Avoid using a swinging motion to lift the weight. Instead, use a slow, controlled motion throughout.
Make sure to extend your elbow all the way at the top of the movement.
Choose the appropriate weight for your skill level. A lighter weight can still be very effective.