The triceps brachii is the large muscle on the back of the upper arm, composed of three distinct heads: the lateral, medial, and long head. All three work together to straighten the elbow. The long head is the largest of the three, making up a significant portion of the arm’s overall mass. For maximum arm development, specifically targeting the long head is an effective strategy that requires adopting specific training techniques leveraging its unique anatomical structure.
Unique Anatomy and Function
The three triceps heads converge into a single tendon that inserts onto the olecranon process of the ulna (the bony point of the elbow). The medial and lateral heads originate solely on the humerus, limiting their function to elbow extension. The long head is structurally unique because it originates on the infraglenoid tubercle of the scapula (shoulder blade). Because it crosses both the shoulder and the elbow joints, the long head is classified as a biarticular muscle.
This anatomical difference gives the long head a dual function. Its primary action, shared with the other two heads, is elbow extension (straightening the arm). Due to its attachment on the scapula, the long head also assists in shoulder extension and adduction (pulling the arm backward and toward the torso). This dual role determines how the muscle must be trained for optimal growth.
Maximizing Long Head Activation Through Shoulder Position
Targeting the long head effectively requires manipulating the muscle’s length across the shoulder joint. For optimal contraction and growth, a muscle must be placed at an ideal length, known as the length-tension relationship. When the arm is held close to the body (e.g., during triceps pushdowns), the long head is kept short at the shoulder, reducing its mechanical advantage. This position primarily recruits the lateral and medial heads for elbow extension.
To preferentially activate the long head, the arm must be moved into shoulder flexion, bringing the arm overhead. Placing the arm fully overhead creates a deep stretch across the long head, lengthening the muscle fibers. Training a muscle in this stretched position is a superior stimulus for hypertrophy compared to training it shortened. This deep stretch ensures the long head is highly recruited during the subsequent elbow extension.
Studies show that overhead triceps extensions result in a significantly greater increase in long head muscle volume compared to standard triceps pushdowns. This enhanced activation is due to the potent stimulus provided by stretch-mediated loading. Therefore, an effective long head training program must prioritize movements where the arm is positioned overhead to maximize this biomechanical advantage.
Essential Overhead Movements
The length-tension principle requires selecting exercises that force the arm into significant shoulder flexion. The most direct application is the Overhead Dumbbell Extension, performed seated or standing. Hold a single dumbbell with both hands or one in each hand and press it overhead until the arms are straight. Carefully lower the weight behind the head, keeping the elbows fixed and pointed forward. Achieve the deepest possible stretch before powerfully extending the elbows back to the starting position.
Cable Overhead Extension
A highly effective variation is the Cable Overhead Extension, typically performed using a rope attachment. The cable machine provides constant tension throughout the entire range of motion, unlike free weights where tension can drop off at the top. Stand facing away from the machine and pull the rope attachment overhead, ensuring the elbows are pointed forward and the upper arms are parallel to the floor. Extend the arms fully, focusing on squeezing the triceps, and control the weight back slowly to maximize the eccentric stretch.
Lying Triceps Extension (Skull Crusher)
The Lying Triceps Extension, often called the skull crusher, can be adjusted to target the long head. While lying on a bench, intentionally allow the weight to travel behind the head instead of only to the forehead. This slight adjustment introduces the necessary shoulder flexion to significantly stretch the long head. Keeping the elbows tucked and minimizing shoulder movement ensures the triceps is the primary muscle responsible for elbow extension.
For all these movements, maintaining a controlled tempo is beneficial, especially emphasizing a slow, deliberate lowering (eccentric) phase. Performing overhead movements early in a workout, when energy and focus are highest, allows for the greatest application of force and attention to form. Prioritizing a full range of motion that maximizes the stretch is the most important factor for stimulating long head hypertrophy.