The triceps brachii is the large, three-headed muscle on the back of the upper arm, primarily responsible for extending the elbow joint. It consists of the long head, the lateral head, and the medial head. While all three heads work together, the long head is the largest and requires specific exercises to maximize its development due to its unique structure.
The Unique Anatomy of the Long Head
The triceps heads are differentiated by their origin points. The lateral and medial heads are single-joint muscles, originating on the humerus (upper arm bone) and crossing only the elbow joint to insert on the ulna in the forearm. These two heads focus primarily on elbow extension and contribute significantly to the triceps’ overall size.
In contrast, the long head originates on the scapula, or shoulder blade, specifically at the infraglenoid tubercle. Because it crosses the shoulder joint before inserting on the ulna, the long head is classified as a bi-articular muscle. This means the long head influences movement at both the elbow and the shoulder, assisting with shoulder extension and adduction. This dual-joint function requires a different training approach than the other two heads.
Biomechanical Principle: Maximizing Long Head Engagement
The most effective strategy for preferentially activating the long head relies on the length-tension relationship. This principle describes how the force a muscle can generate is dependent on its starting length. For the long head, moving the arm into shoulder flexion—raising the arm overhead—causes the muscle fibers to stretch.
By stretching the long head, the muscle is placed on the descending limb of its length-tension curve, increasing the mechanical tension during the subsequent elbow extension. This pre-stretched position forces the long head to contribute more significantly to the effort than the medial or lateral heads. Therefore, exercises that position the arm overhead are superior for stimulating this head, as increased muscle length correlates with greater potential for growth.
Primary Isolation: Overhead Extension Exercises
Exercises utilizing the overhead arm position are the most direct way to isolate the long head due to the biomechanical advantage of pre-stretching the muscle. The Dumbbell Overhead Extension is a highly effective movement that can be performed seated or standing. To execute this, hold the dumbbell overhead, then lower it behind the head by bending only at the elbow, keeping the upper arm close to the head to maintain the stretch.
The Cable Overhead Extension is another excellent choice, providing constant tension throughout the full range of motion. Using a rope or straight bar attachment, set the cable to a high pulley and face away from the machine, extending the arms from a fully flexed position overhead. Stepping slightly forward helps align the resistance with the long head’s fiber direction for optimal recruitment.
The EZ-Bar French Press, or a skull crusher variation where the bar is lowered behind the head, also targets the long head effectively. This involves lying on a bench and allowing the arms to drift slightly backward toward the head as the weight is lowered, increasing the degree of shoulder flexion. This adjustment in arm angle enhances the stretch and activation of the long head compared to a standard skull crusher.
Secondary Targeting: Non-Overhead Variations
While overhead movements provide the greatest stretch and isolation, non-overhead exercises still involve the long head as a secondary focus. The Triceps Pushdown, where the arms are kept at the side, primarily targets the lateral and medial heads, but the long head still contributes to elbow extension.
To increase long head involvement in a pushdown, the lifter can lean forward slightly or use a rope attachment and pull the ends apart at the bottom of the movement. Another option is the Close-Grip Bench Press, a compound movement that places significant stress on the entire triceps complex. Using a narrower grip than a standard bench press shifts the focus from the chest to the triceps, and the grip allows for a deeper stretch in the long head during the eccentric phase. These modifications allow for greater long head recruitment without requiring the full overhead position.