The preacher curl is a specialized variation of the traditional bicep curl that uses a support bench to isolate the arm muscles. This exercise involves resting the upper arms against a padded, slanted surface while lifting a weight, such as a barbell or dumbbells. The supported position prevents the use of momentum and torso movement, ensuring the biceps perform the majority of the work. This setup makes the preacher curl a highly effective tool for targeted muscle development in the upper arm.
Primary Muscles Targeted by Preacher Curls
The preacher curl directly targets the three primary muscles responsible for elbow flexion. The Biceps Brachii is the main mover, and its long head is stretched significantly when the arm is extended down the slanted pad. This lengthened position places a high degree of mechanical tension on the long head, promoting its development.
The second muscle, the Brachialis, is situated underneath the Biceps Brachii and is considered the strongest elbow flexor. Since it is not affected by shoulder position, the Brachialis is heavily engaged regardless of the arm’s angle on the bench. Developing this muscle can help push the Biceps Brachii outward, contributing to overall arm thickness.
The third contributing muscle is the Brachioradialis, which runs along the forearm from the elbow toward the wrist. While primarily a forearm muscle, it assists in flexing the elbow during the curling motion.
The Role of Isolation and Angle
The unique mechanics of the preacher curl stem from the fixed position of the upper arm against the angled bench. The bench is typically set at an incline between 45 and 60 degrees, which locks the shoulder joint into a degree of flexion. This prevents the recruitment of the anterior deltoids and minimizes the involvement of the torso, achieving a high degree of muscle isolation.
The fixed angle significantly alters the resistance curve compared to a standing curl. In a preacher curl, the point of maximum tension occurs earlier in the movement, specifically when the arm is fully extended or in the initial pulling phase.
This setup creates a challenging stretch on the bicep tendon at the bottom of the movement, where the muscle is at its most lengthened. As the weight is curled upward, the resistance often feels lighter toward the top, which is the opposite of a standard standing curl. This resistance profile is highly effective for stimulating muscle growth in the lengthened-to-midrange portion of the bicep.
Essential Form and Technique
Proper execution of the preacher curl begins with adjusting the bench height so the upper arms are fully supported on the pad. The grip on the bar or dumbbells should be set to approximately shoulder-width, using a comfortable underhand grip (palms facing up) to maximize Biceps Brachii engagement.
During the movement, the upward lifting phase should be controlled, focusing on squeezing the bicep. It is important to manage the lowering, or eccentric, phase by slowly resisting the weight back to the starting position. To avoid hyperextension and undue stress on the biceps tendon, always maintain a slight bend in the elbow at the point of full extension.