Arm development often involves choosing between the bicep curl and the hammer curl. Both exercises involve bending the elbow, but the subtle difference in hand position fundamentally changes the muscles emphasized. Understanding these biomechanical distinctions is necessary to maximize arm size and strength. Incorporating both variations ensures a complete and balanced approach to upper arm training.
The Supinated Grip and Targeting the Biceps Peak
The traditional bicep curl uses a supinated grip, where the palms face upward throughout the motion. This hand position maximizes the activation of the biceps brachii, the muscle responsible for elbow flexion and forearm supination. The supinated grip places the biceps in a mechanically advantageous position, directing work toward the biceps’ long head, the outer portion of the muscle.
The long head is the primary contributor to the visible “peak” that appears when the arm is flexed. To perform the exercise effectively, keep the elbows anchored close to the torso and avoid using momentum. Focusing on a full range of motion and achieving a strong peak contraction ensures the muscle fibers are fully engaged. This curl variation is the most direct way to enhance the height and shape of the upper arm muscle belly.
The Neutral Grip for Brachialis and Forearm Thickness
The hammer curl employs a neutral grip, where the palms face each other. This change in grip alters the line of pull, shifting muscle recruitment away from the biceps brachii peak. The neutral grip emphasizes two other elbow flexors: the brachialis and the brachioradialis. The brachialis is a deep muscle situated directly underneath the biceps brachii.
Developing the brachialis is important because its growth pushes the overlying biceps upward, contributing to overall arm girth and a thicker appearance. The neutral grip also engages the brachioradialis, a large muscle that runs along the outer forearm. Strengthening the brachioradialis contributes to forearm size and enhances grip strength. The hammer curl is effective for adding mass and density to the entire upper and lower arm structure.
Structuring Both Movements into a Comprehensive Routine
Performing both the bicep curl and the hammer curl is necessary for comprehensive arm development. Since the two exercises preferentially target different muscles, performing both ensures all major elbow flexors receive adequate training stimulus. A routine that only includes the supinated curl neglects the growth potential of the brachialis and brachioradialis. Conversely, relying solely on the hammer curl will not provide the targeted stimulus for the biceps peak.
These two movements can be incorporated into the same workout. One strategy is to perform the bicep curl first, focusing on 8 to 12 repetitions, to prioritize the biceps peak. Following this, the hammer curl can be performed in a similar rep scheme or with a slightly higher volume to focus on density muscles. Alternatively, they can be utilized as a superset, moving directly from one exercise to the next without rest, to maximize time under tension. This approach ensures that every muscle contributing to arm size is effectively trained.