Extend your arms completely so that the barbell is directly above your head.
Slowly bend your elbows to lower the barbell behind your head, keeping your upper arms stationary and close to your head with elbows in and perpendicular to the floor.
Lower the weight until your forearms touch your biceps, ensuring that only your forearms move and not your upper arms.
Finally, use your triceps to return the barbell to the starting position above your head, repeating the movement for the desired amount of repetitions.
Pro Tip
Controlled Movement: It's important to move in a slow and controlled manner. As you lower the barbell, breathe in and keep your upper arms stationary, only moving your forearms. Lower the barbell until it is about level with the base of your skull, then use your triceps to return the barbell to the starting position as you breathe out. Keep Your Elbows Close: A common mistake is to let the elbows flare out to the sides. Keep them as close to your head as possible throughout the exercise for maximum triceps engagement and to avoid shoulder