Preacher Hammer Curl

The preacher hammer curl combines two constraints that each solve a different problem. The preacher pad fixes the upper arm, so there is no way to swing the torso or help with the shoulder, and the muscle receives exactly the load on the dumbbell. The neutral hammer grip shifts a large share of that load onto the brachialis, the muscle underneath the biceps that pushes it upward and adds visible thickness to the arm, and onto the brachioradialis along the forearm. Together they produce a curl with nowhere to hide. Expect noticeably lighter weights than on a standing hammer curl, which is the honest consequence of removing the cheating rather than a sign of weakness. Straighten the arm fully at the bottom without bouncing out of the stretched position, since that is where the pad is least forgiving.