Using a neutral grip (palms facing each other), hold a dumbbell in each hand and lie on your back on a flat bench.
Raise the dumbbells vertically above your body, towards the ceiling.
Keeping your upper arm still, inhale as you bend one elbow to lower the dumbbell to the side of your head.
Exhale as you straighten your elbow and push the dumbbell back to the starting position.
Repeat with your opposite arm.
Repeat for the prescribed number of repetitions, alternating between sides.
Comments and tips
Only your forearm should be moving. Do not lock out your elbow.
When bending your elbow, keep it pointed up towards the ceiling in order to emphasize your triceps. If you find that your elbows flare out or turn in when lowering the dumbbell, the dumbbell may be too heavy.
For the safety of your back, keep your back flat on the bench.