The overhead tricep extension is a resistance exercise designed to isolate the muscles on the back of the upper arm. Unlike other triceps movements, this exercise requires the arms to be fully raised over the head. This unique positioning fundamentally alters the biomechanical stress placed on the three distinct segments of the triceps group. This analysis defines the specific head of the triceps brachii that receives the greatest stimulus during the overhead extension and explains the anatomical reason for this focused recruitment.
The Triceps Brachii Muscle Group
The triceps brachii is the muscle on the posterior side of the upper arm, composed of three distinct heads: the long head, the lateral head, and the medial head. All three heads converge into a single tendon that inserts onto the ulna bone at the elbow. The primary function of the triceps is the extension, or straightening, of the elbow joint.
The three heads are differentiated by their points of origin. The lateral head and the medial head both originate on the humerus. The lateral head originates superior to the radial groove, while the medial head originates inferior to it.
The long head is unique because it originates on the scapula, or shoulder blade. This means the long head is the only segment that crosses both the shoulder and elbow joints, making it a biarticular muscle. This anatomical difference explains why arm position significantly determines which triceps head is predominantly engaged during various exercises.
Targeting the Long Head Through Stretch
The overhead tricep extension specifically targets the long head due to the mechanical advantage of the overhead position. When the arm is raised overhead (shoulder flexion), the origin and insertion points of the long head are moved farther apart. This action forces the long head into a maximally stretched or lengthened position.
The lateral and medial heads are monoarticular, meaning they only cross the elbow joint. Therefore, their length is not significantly affected by the position of the shoulder. Training a muscle under load while stretched is an effective strategy for stimulating muscle growth. This biomechanical principle places the greatest tension on the long head, increasing its recruitment relative to the other two heads during elbow extension.
Scientific studies confirm that training the triceps in this lengthened, overhead position results in substantially greater muscle hypertrophy, especially in the long head. One investigation found that overhead elbow extension resulted in 1.5-fold greater growth in the long head compared to the same exercise performed with the arm by the side. The increased mechanical tension from training in a stretched state makes the overhead extension a superior movement for developing this triceps head.
Technique for Optimal Long Head Recruitment
Proper execution of the overhead tricep extension is necessary to maximize focus on the long head. The primary goal is maintaining the stretched position throughout the movement by lowering the weight as far as possible behind the head, ensuring a full range of motion.
Maintaining a stable shoulder and elbow position is crucial for optimal recruitment. The elbows must remain pointed forward and stay close to the sides of the head. Flaring the elbows shifts tension away from the long head and allows the lateral and medial heads to take over the load.
Control the weight on both the eccentric (lowering) and concentric (raising) phases of the lift. A controlled tempo ensures the long head manages the load, preventing momentum from assisting the movement. Engaging the core muscles helps stabilize the torso, preventing excessive lower back arching.