For example, the dumbbell preacher curl Samuel demonstrates in the video above lets you stretch the muscle deeply by extending your elbow, and the dumbbell applies the most force in that position.

The 'Godfather of Bodybuilding' Charles Glass shared how to maximize arm gains with preacher curls and cable skullcrushers.

These are the main muscle groups in the upper arms ... when they’re stretched — at the bottom position of a preacher curl, for example. It’s best to start off with fairly light weights ...