A preacher curl is a biceps curl performed using a specialized weight bench. Known as a preacher bench, or alternatively, a Scott bench, the equipment is essentially a seat positioned behind an angled platform. During a bicep curl, the upper arms rest on the platform, eliminating any unnecessary movement that might take the focus off the biceps.
The exercise typically begins with the chest resting against the top edge of the platform and the arms straight, following the angle of the bench. Grasping a loaded barbell or pair of dumbbells in a medium underhand grip, the lifter exhales forcefully while curling the weight upwards. At the 'top' of the movement — the point at which the elbow joint is fully flexed — the weight can be held momentarily as the biceps are consciously contracted. The weight is then lowered in a slow and controlled manner to the starting point, and the motion is repeated for the desired number of repetitions.
Preacher curls were first brought to widespread attention by trainer and gym owner Vince Gironda in the 1950s. A proponent of unconventional training methods, Gironda found the preacher bench to be the most effective way to isolate his biceps. The exercise did not achieve true popularity, however, until championed by Larry Scott, the first Mr. Olympia. Scott credited the preacher curl for his 20 inch (50 cm) biceps, an enormous measurement for the time.
Simple preacher benches will usually hold the upper arms at a 45° angle during a biceps curl. More complex benches have adjustable platforms that allow the angle to be altered, usually within a range of 35 and 90°. A preacher curl performed at a lower angle will concentrate the stress on the lower portion of the biceps, whereas higher angles work the muscle closer to the shoulder. The development of a biceps peak is a goal of many weight trainers, and a preacher curl performed at a high angle is generally considered to be one of the most effective exercises to meet that end.
For the preacher curl to be truly effective, the arm pad should be a good fit for the person using it. Women especially, might find standard gym equipment too large for the arms to rest comfortably on the platform. In this case, an adjustable platform that can be raised or lowered as needed, or a preacher bench specifically designed for women might be a better choice. For both men and women, the bench should be well-padded, enough to allow the arms to rest on the platform without any pinching or discomfort to the upper arms.
The choice between a barbell or dumbbell preacher curl is largely one of personal preference. Either option will require a slightly lighter load than is normally used for seated or standing curls. Many enthusiasts find alternating between barbells and dumbbells allows enough subtle differences in angle and resistance to maximize muscular response and prevent stagnation.
Preacher curls are one of the few biceps exercises with built-in controls for good form. Many of the problems associated with other biceps exercises, such as swinging the arms or leaning the torso to move the weight, cannot occur with preacher curls. In terms of injury prevention, the primary issue associated with the preacher curl is the tendency to use too much weight and try to bounce the barbell or dumbbell up, during the concentric phase of the motion. Doing so can result in a torn biceps muscle, a painful condition that will set training back considerably and, if severe enough, may even require surgical repair.