Extension dumbbell because of the head

Take the dumbbell. Sit on a bench with a back and place a dumbbell on upper thigh. You can also perform this exercise standing.
Raise the dumbbell to shoulder level, then straighten the arm, raising the dumbbell up above the head. Hand should be beside your head, perpendicular to the floor. The other arm relax it or put a belt or grasp a fixed surface.
Rotate the wrist so that the palm was facing forward, and the toe was pointing to the ceiling. This will be your initial position.
On the inhale slowly lower the dumbbell behind your head without moving your shoulder. At the end of the movement pause.
On the exhale, return to starting position, straightening the arm over the head. Tip: when performing exercises only the forearm moves, the hand piece from the shoulder to the elbow remains absolutely still.
Complete the required number of repetitions and change arms.

Variations: instead of dumbbells you can use a cable simulator.

exercises for the arms exercises triceps exercises with dumbbells