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Tricep Kickback Muscles Worked: The Lateral Head

tricep kickback muscular recruitment

Tricep kickbacks are an arms isolation exercise specifically targeting the three-headed triceps brachii muscle present along the back and sides of the upper arm.

Because the humerus is positioned parallel to the side of the torso as elbow extension is performed, the tricep kickback will primarily target the lateral head of the triceps. 

While this doesn’t quite mean that the remaining two are left unactivated, it does mean that the triceps kickback may be used for greater inter-muscle emphasis if so needed.

Apart from the triceps themselves, triceps kickbacks will target no other muscle group and can be safely performed as an isolation accessory exercise without the interference or limitation of other muscle groups.

The Triceps Brachii: Long Head

The long head of the triceps brachii is located along the inner side of the upper arm, featuring an origin attachment point at the scapula and an insertion at the olecranon of the elbow joint as it runs along the length of the humerus.

triceps brachii long head

As its name suggests, the long head of the triceps is the largest among the three muscles, and as such will contribute the most to overall triceps muscle mass as a whole.

Function

The triceps brachii’s long head primarily works to extend the elbow by shortening along the humerus, exerting pulling force from its origin along the infra-glenoid tubercle of the scapula.

elbow extension

Apart from this, due to its position within the shoulder joint, the long head also plays some small part in stabilization of the humeral head and the shoulder joint itself during movements involving arm adduction or humeral extension at the shoulder.

Role

The long triceps brachii head is one among the three primary mover muscles of the triceps kickback. Being an isolation exercise, no muscles other than the triceps are dynamically contracted.

Function During Tricep Kickback Repetition

Because no significant arm adduction or arm extension at the shoulder joint is present during a triceps kickback, the long head solely acts to straighten the arm at the elbow.

The Triceps Brachii: Medial Head

The medial head of the triceps brachii is perhaps the hardest to visually identify, and is located along the posterior section of the humerus beneath both the lateral and long heads respectively.

location of the medial head of the triceps brachii

The medial head features an origin point at the dorsal section of the humerus bone, specifically beneath the radial groove located across the posterior side of the bone. 

Like the remaining two triceps heads, the muscle inserts into a large tendon located at the olecranon of what is essentially the elbow joint.

Function

The medial head’s rather short length and deep positioning, it does not actually display any significant action outside of extension at the elbow joint – so long as the forearms are held in a supinated or pronated orientation.

Role

Much like the lateral head, the medial head holds the role of primary mover during tricep kickbacks. All three heads of the triceps feature significant dynamic contraction at a (relatively) large range.

dumbbell tricep kickback muscles being worked

Function During Tricep Kickback Repetition

The medial head does not display any significant activity outside of extension of the elbow – an action it fulfills during tricep kickbacks.

The Triceps Brachii: Lateral Head

The lateral head of the triceps is the most visible section of the muscle group when viewed from the side, encompassing much of the lateral and posterior section of the upper arm.

The muscle features an origin along the dorsal side of the humerus bone, attaching above the radial groove and inserting into the olecranon of the ulna at the elbow joint.

lateral head of triceps

Tricep kickbacks will target the lateral head to the greatest degree in terms of pure range of motion and actual EMG activation data. 

If the majority of the “burn” of the exercise is felt along a different section of the triceps, it is possible that the upper arm is positioned too far from the shoulder joint or that the wrist is rotating as the elbow extends.

Function

Despite being considered the strongest of the three tricep heads, the lateral head solely acts as an extensor of the forearm at the elbow joint when in a pronated or supinated orientation.

Role

Like the two previous muscles, the lateral head is also considered a primary mover muscle during tricep kickback repetitions. 

Function During Tricep Kickback Repetition

The lateral head plays the most significant role among the three triceps heads due to its positioning and relative force output.

dumbbell tricep kickback movement

Although the entire triceps brachii muscle recruits as a single unit, the lateral head is emphasized the most by kickbacks.

Tips for Better Muscular Contraction During Tricep Kickbacks

To ensure proper muscular contraction, tricep kickbacks must be performed with a focus on a full range of motion and proper elbow positioning. Avoid terminating the concentric phase early, instead seeking to reach nearly full elbow extension at the height of each repetition.

Furthermore, keep the elbow as close to the torso as possible, squeezing the triceps brachii against it for greater leverage.

References

1. Tiwana MS, Sinkler MA, Bordoni B. Anatomy, Shoulder and Upper Limb, Triceps Muscle. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK536996/