The Science of Training: Elbow Flexors

by Josh Bryant and Joe Giandonato

A big, strong neck can save your ass from hitting the curb a la a sucker punch to the head at 3AM from the drunker-than-Cooter-Brown Waffle House Patron.

But, well-developed “biceps” can stabilize heavy bench presses and earn you more right-swipes on Tinder.

Gym bros and long-unemployed authors of defunct, glossy bodybuilding magazines commonly refer to the four main elbow flexor muscles as the biceps.  Jailbirds in the clink call elbow flexors “knots”. Semantics aside, their development is critical for both performance and aesthetics. 

For maximal size, strength and functionality, you must train the entire continuum of elbow flexors. We are very thankful that we learned this important lesson early on from the legendary, late Charles Poliquin.  

The elbow flexors are the comprised of the biceps brachii both long and short heads, brachialis, brachioradialis, and pronator teres muscles.  

Anatomy

Visual Context

The long head of the biceps brachii originates from a bony notch known as the supraglenoid tubercle which resides above the glenoid fossa of the scapula, running along the intertubercular, or bicipital groove of the humerus. The short head of the biceps brachii originates from the coracoid process of the scapula, horned beneath the acromion process and resting below the clavicle. Together, both heads attach to bicipital tuberosity of the radius and blend into fibrous lacertus, a deep fascial sheath embedded within the musculature of the forearm.

Collectively, the long and short heads emit a pull on the bicipital tuberosity of the radius, which flexes the elbow and given the long head’s proximal attachment, is theorized as contributing to shoulder flexion and stabilizing the humerus. Additionally, the biceps supinate the radioulnar joint. Combining both elbow flexion with supination elicited near maximal electromyographical activity of the biceps brachii. A supinated grip with an extended elbow was shown to evoke greater elbow flexion moment, meaning that greater muscular force of the biceps is required to flex the elbow.

Here are the takeaways on how to train each.

Watch Josh Bryant put the legendary Nick Deltoro through the holistic arm ringer.

Biceps Brachii (Long Head)

Think long range of motion here because the long head of the biceps best responds to exercises where the elbows are behind the body; so, various forms of dumbbell curls that emphasize a stretch and drag curls.  

Key Points: Curls with the elbows behind the body or in line with it emphasize the longhead (particularly when elbows are turned out). Example exercises:

• Seated Incline Dumbbell Curls
• Seated Incline Hammer Curls
• Drag curls
• Girona Perfect Curls
• Wide Grip Barbell Curls
• Machines where the elbows are behind the torso

Biceps Brachii (Short Head)

Concentration, or Scott curls, are very effective for working the short head of the biceps because the elbow is forward to the body, the positioning you want to achieve maximal short head activation.

Key Points: Curls where the elbows are in front of the body. Example exercises include:

• Scott Curls
• One-Arm Eccentric Barbell Curls
• Concentration Curls
• Most Seated Machine Curls
• This is the least neglected area by gym bros

Brachioradialis

The longest of the elbow flexor muscles, the brachioradialis originates from the lower lateral half of the humerus, known as supracondylar ridge, and blends into the styloid process, a bony protuberance located on the lateral surface of the radius. The brachioradialis works synergistically with the biceps brachii in elbow flexion and assists with pronation, eliciting significantly higher EMG activity when elbow flexion is accompanied by a pronated grip (think reverse curls). Since the brachioradialis is composed mostly of fast-twitch muscle fibers (<60%) it is optimally trained via high velocities and against significant external resistance, long advocated by the late Master Blaster himself, who noted that this muscle responds best when trained in this fashion. Pronation, in conjunction with elbow flexion, elicited greater EMG activity versus supination

Key Points: Curls with appreciable loads performed with a pronated grip and quick cadence target the brachioradialis. Example exercises include:

• Reverse Barbell Curls
• Reverse Dumbbell Curls
• Reverse Cable Curls
• Reverse Preacher Curls
• Reverse Band Curls with Fat Gripz (performed explosively)

Brachialis & Pronator Teres

Not to be forgotten are the brachialis and pronator teres muscles. Gym bros, and, hell, even most pro bodybuilders, neglect these areas; so, regardless of increases in arm size in recent decades, potential inches are being left on the table.  

The brachialis rests below the biceps brachii and originates from anterior surface of the lower portion of the humerus and blends into proximal aspect of the ulna. Its sheath comprises much of the floor of the cubital fossa where it is anchored in opportune geographical position to supply the bulk of elbow flexion force, whether the palms are supinated, pronated, or neutral, since those motions bear minimal effect on its length, line-of-force, or internal moment arm.

Its featured role in elbow flexion is no more apparent among strength athletes who have suffered distal biceps injuries, yet remain able to maintain similar strength in curling movements.

The two headed pronator teres primarily serves as a forearm pronator, though, like the aforementioned groups, as its humeral head crosses the elbow — originating from the inferior aspect of the humerus and attaching onto the radius. Its ulnar head which attaches to the coronoid process of the ulna, imposes a twisting force, turning the thumb side of the hand towards the body’s midline.

As the forearm transitions from a supinated position to a pronated one, the biceps brachii begins to lose leverage, and with the forearms protonated in a curling movement, shifting the role of elbow flexion to the brachialis and pronator teres.

Key Points: Curls with a neutral or pronated grip,with isometric pauses at 90 degrees of elbow flexion, further activate the brachialis; these muscles do well with isometric pauses and slower movement velocities. Example exercises include:

• Zottman Curls 
• Zottman Curls (5 second negative)
• Hammer Curls
• Hammer Curls (Isometric pause on the negative) 
• Fat Bar Hammer or Reverse Curls
• Neutral Grip Pull-ups

Fiber Type

The fiber composition of the biceps brachii is quite balanced, as 50-60% are fast-twitch fibers. So, if you have been following this series you would know this means biceps react well to being trained with heavier weights in the five-to-eight range and with longer rest periods of one to three minutes.  However, since the remaining 40-50% fibers are slow-twitch, they also need metabolic stress stimulation such as extended sets, high reps and occlusion training.

Remember, the biceps are not the only elbow flexors!

Anecdotally, the brachialis and pronator teres react well to slower speed movements, higher reps, longer times under tension and isometric pauses.  Some reputable writers have asserted the brachialis is primarily composed of slow-twitch muscle fibers, while we have not seen sources cited, this makes sense based on in-the-field observations.

Final Thoughts

The GOAT of Powerlifting, Ed Coan, says, “Biceps are like ornaments on a Christmas tree.” And, if you want those ornaments to be fit for the Christmas Tree in the Ritz lobby, you better work the entire spectrum of elbow flexors.  

Chuck Sipes, arm training, adapted to hit holistic elbow flexor development. 

Sources

Basmajian, J.V. & Latif, A. (1957). Integrated actions and functions of the chief flexors of the elbow. Journal of Bone and Joint Surgery, 39, 1106-1118.

Boland, M.R., Spigelman, T., & Uhl, T.L. (2008). The function of brachioradialis. Journal of Hand Surgery, 33 (10), 1853-1859.

Jennekens, F.G, Tomlinson, B.E., & Walton, J.N. (1971). Data on the distribution of the fibre types in human limb muscles: an autopsy study. Journal of the Neurological Science, 14 (3), 245-257.

Levy, A.S., Kelly, B.T., Lintner, S.A., Osbahr, D.C., & Speer, K.P. (2001). Function of the long head of the biceps at the shoulder: electromyographic analysis. Journal of Shoulder and Elbow Surgery, 10 (3), 250-255.

Murray, W.M., Delp, S.L., & Buchanan, T.S. (1995). Variation of muscle moment arms with elbow and forearm position. Journal of Biomechanics, 28 (5), 513-525.

Srnivasan, R., Lungren, M., Langenderfer, J., & Hughes, R. (2007). Fiber type composition and maximum shortening velocity of muscles crossing the human shoulder. Clinical Anatomy, 20(2), 144–149.