Holding a pair of dumbbells using a neutral or hammer grip (palms facing your body), sit on a bench.
Keeping your upper arms fixed to your sides, lean forward until your torso is almost horizontal. Your back should be straight.
Raise your upper arms a little higher until they become horizontal. Your elbows should be bent at 90 degrees.
Execution
Keeping your upper arms horizontal, exhale as you extend the dumbbells behind you until your forearms are horizontal.
Hold for a count of two.
Inhale as you slowly lower the dumbbells to the starting position.
Repeat.
Comments and tips
Only your forearms should move. Keep your upper arms horizontal and locked to your sides.
While the seated bent-over two-arm dumbbell kickback recruits no synergistic muscles, the muscles listed as stabilizers contract to keep your upper arm horizontal.
This exercise is essentially the same as the dumbbell kickback. As mentioned on the dumbbell kickback page, the dumbbell kickback is very effective at activating your triceps. In one study that compared triceps exercises for effectiveness, it came second, to be beaten only by the diamond push-up.
Keeping your upper arms horizontal when holding a heavy weight can be difficult. Therefore, if you want to lift heavy, use the cable kickback instead.