The biceps brachii muscle is the most recognizable muscle of the upper arm. While it is impossible to isolate a single portion of this muscle complex completely, strategically adjusting exercise selection and body position can place greater mechanical tension on specific regions. Modifying the angle of the arm relative to the torso effectively shifts the load emphasis, helping to develop the distinct characteristics of the bicep.
Understanding the Bicep Muscle Group
The biceps brachii is a two-headed muscle comprising the long head and the short head. The long head originates above the shoulder joint. Because this attachment crosses the shoulder joint, the long head is highly influenced by shoulder position and contributes significantly to the height of the bicep’s peak when flexed.
The short head originates closer to the body on the coracoid process of the scapula. This head contributes more to the width and overall thickness of the upper arm, as its origin does not cross the shoulder joint. Both heads merge into a common tendon to insert near the elbow.
Additionally, the brachialis muscle lies beneath the biceps brachii, acting as a pure elbow flexor without the supination function. The brachioradialis is a prominent forearm flexor that originates higher up on the humerus and is highly involved in elbow flexion, especially when the hand is not supinated.
Targeting the Long Head for Peak Development
To specifically target the long head, the muscle must be placed into a pre-stretched position by extending the shoulder, positioning the arm behind the torso during the curl. Placing the long head on a greater stretch increases its initial mechanical tension.
The Incline Dumbbell Curl is the most effective exercise for this mechanical advantage. The individual sits back on an adjustable bench set to a 45- to 60-degree angle, allowing the arms to hang fully extended behind the torso, ensuring the palms face forward.
Allowing the arms to hang completely at the bottom maximizes the stretch on the long head. The supination component further biases the biceps brachii. Lift the dumbbells upward with control, focusing on keeping the elbows stationary.
Drag Curls
Another method for emphasizing the long head involves minimizing the short head’s involvement by restricting shoulder movement. Drag Curls accomplish this by having the individual “drag” the bar up the front of the torso while keeping the elbows pushed back. This technique ensures the long head is fully engaged. The elbows must remain fixed behind the bar path to maintain the long head’s mechanical leverage.
Maximizing the Short Head for Bicep Thickness
Developing the short head requires a mechanical setup that minimizes the long head’s contribution. This is accomplished by placing the arm into shoulder flexion, positioning the arm in front of the torso. Supporting the elbow on a fixed pad during the curl shortens the effective length of the long head.
The Preacher Curl, performed with a straight or EZ-bar, is the primary exercise used to achieve this effect. The upper arm should rest firmly on the pad, and the shoulders must remain down to prevent them from lifting off the support and re-engaging the long head.
Grip Width
Using a slightly wider grip when performing preacher curls or standard standing barbell curls increases the activation of the short head. This wider hand position externally rotates the shoulder slightly, providing a minor mechanical advantage to the short head’s line of pull.
Focusing on the peak contraction at the top of the range of motion is important for maximizing short head development. The movement should be controlled on both the concentric and eccentric phases, avoiding the tendency to bounce the weight off the bottom. Keeping the tension constant ensures the short head remains the primary mover throughout the set.
Developing the Brachialis and Forearm Connection
Arm development includes the underlying and adjacent flexor muscles. The brachialis muscle, situated beneath the biceps, is a powerful elbow flexor that does not contribute to forearm supination. Targeting the brachialis is important because its growth pushes the biceps upward.
The most direct way to activate the brachialis is by using a neutral grip, with the palms facing each other, as seen in Hammer Curls. This grip position largely removes the supination function of the biceps, forcing the brachialis to take on the majority of the lifting load. Maintain a neutral wrist position throughout the movement to keep the tension focused on elbow flexion.
The brachioradialis, a prominent muscle of the outer forearm, also plays a significant role in elbow flexion. This muscle is primarily engaged when the forearm is in a pronated, or palms-down, position. Reverse Curls are the exercise of choice for developing the brachioradialis, as the pronated grip minimizes the mechanical advantage of the biceps brachii. Because this muscle is smaller than the biceps, lighter weights should be used, focusing on a slow and controlled eccentric phase.