Performing the: A Step-by-Step Tutorial Dumbbell One Arm Triceps Extension
Raise the dumbbell above your head until your arm is fully extended, keeping your elbow close to your head and perpendicular to the floor.
Slowly lower the dumbbell in a semicircular motion behind your head until your forearm touches your bicep. Make sure to keep your upper arm still and your elbow fixed in place.
Use your triceps to return the dumbbell back to the starting position, fully extending your arm above your head.
Repeat the exercise for the desired number of repetitions and then switch to the other arm.