The single-arm machine preacher curl is a popular exercise to build size and strength in the biceps. It approximates the motion of a free-weight preacher curl, but uses a selectorized weight stack or plate-loaded machine. Many such machines offer different grips and grip widths. Machine biceps curls are often done for moderate to high reps, such as 8-12 reps per set or more, as part of the upper-body or arm-focused portion of a workout.
