This exercise requires the use of the triceps of the upper arm.Hold a dumbbell in your straight arm above your head. Stand straight. Let the dumbbell go down in a semicircle until you reach the shoulder blade on the same side, in the meantime hold your elbows closely next to your head. Lift the dumbbell into the starting position on the same arch. The exercise can be performed in sitting position as well for the sake of greater stability.