Starting Position: Holding a dumbbell in each hand, kneel down in order to rest your elbows and forearms on a bench. Forearms are turned so that the palms face one another and the dumbbells are vertical to the floor. Elbows should be bent to about 90-degrees and the dumbbells/hands should hang freely off the edge of the pad. Wrists are in line with the forearms (neutral).
Downward Phase: Inhale and slowly rotate your forearms so that the palms are angled toward the floor. Keep the wrist in neutral throughout the exercise. Do not release your grip, straighten your elbows, or lean forward / backward. Hold this position briefly.
Upward Phase: Exhale and slowly rotate your forearms so that the palms turn toward the ceiling. Keep the wrists in neutral throughout the exercise. Do not release your grip, straighten your elbows or lean forward / backward. Hold this position briefly and repeat the entire sequence.
Exercise technique is important to avoid potential injury, control the movement of your dumbbells by slowing down the movement speed at the end ranges of motion in each direction. For additional strength gains, think about squeezing the handle of the dumbbell as hard as possible during both phases of the movement.