The bicep curl is a foundational exercise for developing the muscles of the upper arm, and the wide grip curl offers a strategic variation that subtly shifts the muscular focus. This exercise involves taking an underhand grip on a barbell or similar equipment with the hands positioned significantly wider than shoulder-width. By altering the position of the hands relative to the shoulders, the wide grip curl changes the biomechanical leverage, influencing which parts of the arm musculature receive the greatest stimulus.
The Primary Target Muscles
The biceps brachii, the muscle on the front of the upper arm, is composed of two distinct sections: the long head and the short head. The short head is located on the inner side of the upper arm, closer to the body, and it contributes significantly to the width of the bicep when viewed from the front. The mechanical change introduced by the wide grip position places the short head at a distinct biomechanical advantage over its counterpart.
When the hands move wider than shoulder-width, the upper arms are forced into a slight degree of external rotation. This rotation alters the angle of pull for the two bicep heads during the lifting phase of the curl. The wide grip effectively reduces the distance between the origin and the insertion point of the short head, enabling it to generate force more efficiently throughout the movement. This increased mechanical advantage means the short head is preferentially recruited to perform the majority of the work.
The goal of emphasizing the short head is to increase the overall size and thickness of the bicep, particularly the inner portion. Developing this head is what gives the bicep a fuller appearance. While no exercise can completely isolate a single muscle head, the wide grip is one of the most effective ways to shift the emphasis toward this inner section.
Secondary Muscles and Stabilizers
While the short head of the biceps is the primary focus, the wide grip curl engages several other muscles that assist in the movement or stabilize the body. The brachialis is a deep muscle that lies directly beneath the biceps brachii, and it is a powerful elbow flexor. This muscle works synergistically with the biceps and is recruited heavily during the curl, contributing significantly to overall arm thickness.
The brachioradialis, a prominent muscle in the forearm, also functions as an elbow flexor, particularly when the hand is in a neutral or hammer-style grip. Although the underhand grip of the wide curl reduces its primary role, the brachioradialis is still actively involved as a secondary muscle to assist in pulling the weight upward. Additionally, the muscles of the forearm are recruited to maintain a secure grip on the weight being lifted.
The movement requires a stable torso to prevent momentum from assisting the lift, which engages the core musculature, including the abdominals and lower back muscles, as stabilizers. The shoulder muscles are also engaged isometrically, meaning they contract without changing length, to keep the upper arm in a fixed position against the body.
Proper Execution and Form
To maximize the activation of the short head, the execution of the wide grip curl must be precise, beginning with the hand placement. The grip should be slightly wider than shoulder-width, typically about 1.5 times the width of the shoulders, with an underhand (supinated) grip. Stand with feet shoulder-width apart, keeping a slight bend in the knees and the chest upright.
The movement should be initiated by curling the weight toward the shoulders while keeping the elbows pinned close to the sides of the body. Avoid letting the elbows flare excessively outward or shift forward, as this can reduce the targeted tension on the short head. The weight should be curled until the biceps are fully contracted, aiming for a peak squeeze at the top of the movement.
Controlling the speed of the lowering phase, known as the eccentric portion, is equally important for muscle development. The weight should be lowered slowly and deliberately over two to three seconds, resisting the pull of gravity. Maintaining this controlled tempo prevents using momentum or swinging the body, often referred to as “cheating,” which would shift the workload away from the targeted bicep muscles and onto the back and shoulders.