Muscle Group: Forearms
Here we work the forearm extensors in isolation.
Kneel down on the ground, right in front of the middle of a bench. With a barbell in hand and palms down, rest your forearms on the bench so that they go across it and also so that the edge of your wrist is at the end of the bench and the barbell hang in the air off of it.
Now lower barbell all the way down so that you get a stretch in your forearm extensors. Moving nothing but your wrists, curl it upward until you get a peak contraction in your forearm extensors. Pause for a peak contraction and then lower slowly under control.