Lots of men who want bigger arms ask themselves: “How can I obtain a little more strength and shape in my biceps without adding another 45 minutes to my workout?” The answer lies in accentuating the natural shape of the biceps by challenging it to contract in the optimal positions in which it was designed to work – and one-arm cable curls will get the job done.

Muscle Structure and Function

The biceps brachii muscle has two (“bi”) heads (“ceps”). The short head of the biceps brachii attaches to the anterior part of the scapula (shoulder blade) near the shoulder joint and runs down the medial (inner) part of the humerus bone of the arm. It joins with the long head of the biceps brachii to form the thick bicipital tendon. This tendon crosses the elbow and attaches on the radius bone near the elbow. The long head of the biceps brachii begins on the scapula just above the shoulder joint. It has a very long tendon that crosses the shoulder joint, and therefore, the shoulder position will affect the function of the long head.

Most people will not realize that the biceps’ function is affected by shoulder position. This is because the long head of the biceps crosses the shoulder where it contributes to shoulder flexion (i.e., bringing the arm forward). However, the long head of the biceps is mechanically advantaged when stretched, as when doing a curl with the shoulders in slight extension (arms and elbows held slightly back). The long head of the biceps sits on the lateral part of the arm, and its fibers mesh with the short head as it approaches the elbow and attaches to the radius bone of the forearm. Because the muscle belly of the long head is actually rather short (it has a long tendon), thickening the muscle belly of the long head will improve your arm’s muscle shape more rapidly than thickening the longer-bellied, short head of the biceps. Strengthening the long head will also improve your ability to throw a ball (or any other object) because it will contribute to the forward movement of the arm at the shoulder joint.

Both heads of the biceps muscle are strong flexors of the forearm. However, because the biciptial tendon attaches on the radius bone, which is the most lateral forearm bone, the biceps (both heads) is a very strong supinator of the hand (turns the palm toward the ceiling) if the forearm begins in a pronated position. This is because when the hand is pronated, the radial bone of the forearm sits on top of the ulna bone. When the biceps muscle contracts, it pulls on the radius bone, and pulls it back into a position where the radius lies beside, and not on top of, the ulna. This moves the hand from a pronated to a supinated position. Thus, to fully activate both heads of the biceps, there must be a supination component as well as flexion of the elbow joint, with the arms pulled into extension. The one-arm cable curl fulfills all of these requirements.

One-Arm Cable Curls

This exercise will provide constant tension to your arms. This makes it difficult to use a heavy weight if you are utilizing all the suggestions below.

1. Position yourself so the cables of a high pulley station are behind you. Your feet should be shoulder-width apart or wider to maintain a stable and comfortable balance. If you will work the right biceps first, take the handle from the top right pulley in your right hand. The handle should have a rotational swivel on it so that you are able to pronate and supinate the hand during the exercise.

2. Your elbow will be straight or almost straight as you grab the pulley handle. Pull your right arm and elbow posteriorly (shoulder extension) to stretch the long head of the biceps brachii. Because you are facing away from the machine with the pulley behind your shoulder joint, you will likely feel some tension across your chest and shoulder. Lower your arms and forearms so that they are parallel to the floor (or slightly lower).

3. Move your wrist/hand position so it’s part way between pronation and supination. In this position, the thumb will be closest to your face and the little finger will be furthest from your face.

4. You might want to move a little to one side and hold on to one of the upright posts of the pulley station with your free hand to stabilize your upper body. This will add additional upper body stability if you need it. Begin to supinate your right hand as it moves closer to your left shoulder. By the time the elbow angle is 90 degrees, your hand should be fully supinated so the little finger is closest to your face and the thumb is furthest from your face.

5. At the top of the contraction when you cannot move your hand closer to your head, attempt to give an extra supination to get the little finger even higher. Hold this for three seconds while flexing your upper arm as hard as possible (isometrically “squeezing” the biceps). This will produce an unbelievably strong contraction, and if you are doing it properly, the long head of the biceps will feel like you have started a small torch in it. This effort will be soon rewarded by improved biceps strength, stamina and shape.

6. Keep your upper arm (humerus bone) parallel (or almost parallel) to the floor as you slowly extend the elbow joint. As you lower the pulley weight, move your hand toward the pulley from the super-supinated position to the semi-prone position. Just before reaching a position with a straight elbow, start the next repetition so you will curl the pulley back toward your shoulders while supinating your hands.

7. After completing your set with the right arm (usually 10-12 repetitions is sufficient if you have chosen a proper resistance), then work the left arm. You will grab the handle from the right high pulley station with your left arm, and repeat the position and sequence in an identical fashion to what you did for the right arm. Again, you may wish to stabilize your upper body during the exercise by grabbing a vertical pole from the pulley station with your right hand.

Important Tips

Your shoulder joint will be stretched posteriorly during the exercise because the pulley is behind your body. This position is important because it will stretch the long head of the biceps brachii and this will improve the mechanical efficiency and contributions to curling by the long head. If, instead, you face the pulleys so that your shoulders are pulled forward and the cables are to your front (and not to your back), the long head of the biceps would be somewhat slackened and this would reduce its mechanical contribution to the exercise. Therefore, stretching the shoulder joint, by having the cables behind you, greatly improves the focus on the long head of the biceps.

If you have previously injured your shoulder joint or rotator cuff muscles, you should face the pulleys so they are in front of you. This will reduce the effectiveness of activation of the long head of the biceps brachii, but the risk for the additional stretch/stain across an already injured shoulder joint is not worth the biceps benefit. In a further attempt to reduce rotator cuff strain, don’t hold your arms higher than 30 degrees from parallel to the floor.

Unlike free-weight biceps exercises, muscle tension is not reduced when the elbow is fully flexed in the high pulley cable curls. This results in a very intensive and fatiguing exercise, but very effective overload in the fully flexed position. This improves the efficiency of each contraction and nets more results in a shorter period of time. Make sure your form is perfect and each contraction is maximal before adding more resistance. In addition, since this is a rather intensive exercise, give yourself enough time to recuperate between biceps workouts before launching into these again.

References:

Basmajian, JV and CJ DeLuca. Muscles Alive, 5th Ed. Baltimore, Williams & Wilkins, 1985, pp. 285-286.

Ferrario, VF, Sforza, C, Serrao, G, Fragnito, N, & Grassi, G. (2001). The influence of different jaw positions on the endurance and electromyographic pattern of the biceps brachii muscle in young adults with different occlusal characteristics. J Oral Rehabil, 28, 732-739.

Gearhart, R F, Jr., Goss, F L, Lagally, KM, Jakicic, JM, Gallagher, J, Gallagher, K I, & Robertson, RJ. (2002). Ratings of perceived exertion in active muscle during high-intensity and low-intensity resistance exercise. J Strength.Cond Res, 16, 87-91.

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