Big Arms Builder / With preacher curls

The biceps is symbolic of upper-arm strength and power, and there isn’t a serious trainer alive who hasn’t longed for larger, thicker and harder upper arms. If your biceps represent the seat of stubbornness because they grow far too slowly and have little length or peak, then it’s time to become more creative with your arm work than just doing barbell and dumbbell curls and add in Barbell Preacher Curls.

ANATOMY LESSON

The front of the arm contains the biceps and brachialis muscles, and the nerves and blood vessels associated with these muscles. These muscles function primarily at the elbow joint, although parts of these muscles can also function at the shoulder joint.

The biceps brachii is a two-headed muscle. The long head of the biceps brachii muscle has its upper attachment on a bump over the shoulder joint called the glenoid tubercle. It sits on the lateral (outer) part of the arm, and its fibers intertwine with the short head of the biceps as it approaches the elbow. Because the long head of the biceps brachii crosses the shoulder, it becomes involved during shoulder flexion (i.e., bringing the arm forward). This anatomical positioning also means the arms and elbows need to be back to stretch the long head (such as in barbell curls) to maximize the stretch and activation of this muscle belly during elbow flexion.

The short head of the biceps lives along the inside (medial side) of the arm. At the top, it attaches to the coracoid process just below the shoulder joint. This is a beak-like projection on the anterior (front) part of the scapula bone or “shoulder blade.” The muscle stretches along the medial (inner) part of the humerus bone of the arm and it comes together with the long head of the biceps brachii muscle to form the strong bicipital tendon. The bicipital tendon crosses the front part of the elbow joint and attaches on the radius bone of the forearm near the elbow joint. Contraction of the biceps muscle can pivot the radius bone at the elbow joint and this supinates the hand (turns the palm toward the ceiling) if the hand begins in a pronated position. Because the short head of the biceps brachii doesn’t cross the shoulder joint, it’s activated just as strongly whether the shoulder and arm are forward (arm flexion) or pulled backward (arm extension) during elbow flexion (e.g., curls).

The brachialis muscle is a very important flexor of the elbow joint. It attaches along the anterior side of the humerus bone throughout its journey down the arm. It crosses the elbow joint anteriorly and attaches to the anterior side of the nonpivoting ulna bone of the forearm near the elbow joint. The attachment to the ulna prevents the brachialis from having any role in supination. As much as 60 percent to 70 percent of forearm flexion is thought to be due to the strength of the brachialis muscle.

The angle of the preacher bench puts the arm position somewhat forward (arm flexion), and this places an emphasis on the medially placed, short head biceps brachii muscles. The bench angle shouldn’t be too low (e.g., it should be 60º to 80º, not 30º to 45º). Otherwise, the arm will be too far forward and activation of the long head of the biceps brachii will be severely diminished. The brachialis muscle is active throughout the exercise. Although the exercise can be used with either a dumbbell or barbell, the barbell version will be described here.

THE EXERCISE: BARBELL PREACHER CURLS

1. Sit on the seat of a preacher bench so that your triceps sit along the top third of the bench. Don’t jam your armpits (axilla) into the top edge of the bench because it’s too easy to cheat from this position. Rather, your axilla should be above the edge of the bench and only your triceps should contact the bench. Grip the bar so that your hands are slightly narrower than shoulder-width apart.

2. Begin by flexing the elbow joint (i.e., curling the weight) so the barbell moves closer to your face. The bench will prevent you from pulling your elbows posteriorly into arm flexion, thereby concentrating the efforts on the biceps— particularly the short head of the biceps.

3. Curl the weight upward toward your face, as far as possible. Isometrically squeeze the biceps muscle at the top of the movement. This muscle “burn” will encompass the biceps and the brachialis. Because the hands are supinated throughout the exercise, the biceps will be strongly activated throughout the range of motion.

4. Slowly lower the weight toward the floor as your elbow joint straightens. It’s important to make this a slow descent and to control the lowering of the weight. A fast decent will, at best, reduce the effectiveness of the exercise; at worst, it will result in injury to the elbow joint and bicipital tendon, particularly as the elbow joint is straightened.

5. Stop the downward descent just before the elbow joint becomes completely straight. Then begin the curl back toward your face. This will maintain the tension on the biceps throughout the full range of motion.

RX TIP

If you can’t control the weight during the descent, you need to lower the resistance or stop the set to reduce the risk of becoming injured. If you need your workout partner to help slow the weight on the downward part of the lift, you’re using too much resistance in your set.

Preacher curls are much harder to complete than standing curls. They place stress on the biceps in both ends of the muscle and throughout the entire range of motion. In addition, there’s no way to pull your arms into extension to gain additional assistance from the long head of the biceps, or to do any “cheating” by swinging the weight up using your torso, as is often the case with barbell curls.

References:

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4. Kulig K, Powers CM, Shellock FG and Terk M. The effects of eccentric velocity on activation of elbow flexors: evaluation by magnetic resonance imaging. Med Sci Sports Exerc, 33: 196-200, 2001.
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