Overhead Dumbbell Extensions
Sit down with a dumbbell in hands. Take one side of the dumbbell with both hands (pointing finger and thumb of one hand over the other). Lift the weight over your head by flexing your triceps. Inhale when you lower the dumbbell. Exhale when you raise it.
Exercise Type: Isolation
Primary Muscle: Triceps Brachii
Overhead dumbbell extension is another great isolation exercise for developing triceps brachii. Try to use a bench with lower back support to reduce pressure on your lower back. You should also flex your core muscles as you lift to keep your back straight.
The overhead dumbbell extension is a great exercise partially because it maintains constant pressure on the triceps. The full range of motion extends from fully flexed position to the point until the dumbbell is lower for a full stretch. Fully flexed means your triceps are at peak contraction, arms extended over your head, but elbows not locked out. Locking elbows may lead to tendonitis. Full stretch means the dumbbell has been lowered as far as you can lower it without actually moving anything but your elbow joint. Your upper arm should remain stationary for the duration of the exercise.
Be careful not to overdo the negative phase of the exercise and overstretch your triceps. Lower control the weight as you lower it. Dropping and jerking the dumbbell could easily lead to muscle tears.
A hint for all you heavy lifters: the best way to get a heavy dumbbell up to do the overhead dumbbell extension is by first placing it on your knee. Then take the grip with one hand and the end with the other. Then place the dumbbell on your shoulder. Finally, lift the weight over your head from your shoulder to perform the exercise.
Overhead dumbbell extensions could also be performed with one hand. The set up and the motion is the same.