The biceps brachii is a two-headed muscle group located on the front of the upper arm, primarily responsible for flexing the elbow and supinating the forearm. Maximizing the growth of the entire structure can create the desired thickness and fullness near the elbow joint, often referred to as the “lower bicep.” While the ultimate length of the muscle belly is determined by genetics, this guide provides actionable training and anatomical strategies to maximize development in this specific area.
Understanding Bicep Anatomy
The biceps muscle is composed of two distinct parts: the long head and the short head, both originating from the scapula (shoulder blade). The long head runs along the outside of the arm and is largely responsible for creating the visible “peak” of the bicep when flexed. The short head is located on the inner side of the arm and is the primary contributor to the overall width and thickness of the upper arm.
Both heads merge into a single tendon that inserts distally into the radial tuberosity of the forearm, just below the elbow joint. The distance between this insertion point and the elbow crease determines the muscle’s visual length, a trait that cannot be changed through exercise. By prioritizing exercises that emphasize the short head, you can increase the muscle mass closer to the elbow, giving the illusion of a fuller bicep.
Exercises for Distal Bicep Development
To effectively target the short head and promote thickness near the elbow, select movements that place the elbow in front of the body or utilize a wider grip. These positions mechanically shift the emphasis away from the long head, forcing the short head to bear more of the load.
Preacher curls are highly effective because they lock the upper arm in a fixed position on a pad, preventing momentum and ensuring the elbow remains in front of the torso. This isolation places maximum mechanical tension on the short head, particularly at the bottom of the movement where the muscle is fully stretched. The fixed angle ensures a significant stretch and contraction.
Concentration curls further isolate the muscle by resting the elbow against the inner thigh, which eliminates assistance from the shoulder or momentum. This strict form allows for a powerful, focused contraction, maximizing muscle fiber recruitment in the short head. Performing these movements with a wide grip on a barbell or EZ-bar also preferentially activates the short head.
Spider curls, performed lying face down on an incline bench with the arms hanging vertically, are another excellent variation for targeting the short head. This movement positions the arms perpendicularly to the floor, ensuring the force vector is directed squarely against the bicep. Cable variations, such as the high cable curl, are also beneficial as they keep constant tension on the muscle throughout the entire range of motion.
Optimizing Training Variables
Effective training for hypertrophy in this specific area requires careful manipulation of training variables. Time Under Tension (TUT) is a crucial variable, focusing on the duration the muscle is loaded during a set.
Emphasizing a slow, controlled eccentric (lowering) phase of the curl is particularly beneficial for maximizing muscle damage and growth near the tendon insertion. A repetition tempo where the lowering phase takes three to four seconds is an effective way to increase TUT. This deliberate control also helps prevent the use of momentum, ensuring the targeted muscle fibers are doing the work.
For optimal muscle growth, a total training volume of approximately 10 to 20 direct sets per muscle group per week is generally recommended for trained individuals. Training the biceps at least twice per week has been shown to be more effective for hypertrophy than training once weekly.
Repetition ranges for arm growth often fall between 10 and 20 repetitions per set, though a mix of heavier and lighter work is ideal. Each set should be taken close to muscular failure, leaving only one or two repetitions left in reserve. Maintaining strict form and achieving a full range of motion is necessary to maximize the benefits of these variables.
The Influence of Brachialis and Forearm Growth
The appearance of a thick “lower bicep” is significantly enhanced by developing the adjacent muscle groups, particularly the brachialis. The brachialis muscle sits directly beneath the biceps brachii and is the strongest elbow flexor, regardless of forearm position.
As the brachialis grows, it acts like a foundation, pushing the biceps muscle upward and outward, which directly contributes to overall arm girth and a thicker look. Since the brachialis does not assist with forearm supination, it is best targeted using a neutral grip, where the palms face each other.
Hammer curls are the primary exercise for preferentially engaging the brachialis and the adjacent brachioradialis muscle. The brachioradialis is a prominent forearm muscle that runs along the thumb side of the forearm and assists in elbow flexion, especially with a neutral grip. Developing the brachioradialis adds mass where the bicep meets the forearm, further enhancing the perception of a full, thick lower arm.