Sit on a bench holding a dumbbell in one hand.
Keep one foot on the floor and place your other foot on the bench with the knee bent.
Support your elbow on your knee, with your elbow bent and your hand pointing upwards.
This is your starting position.
Keep your shoulder down and your neck long throughout.
When ready, keep your elbow in place and lower the weight down towards the floor, with your palm facing down.
Return to the starting position and repeat.