The Press: Muscles Worked

The human eye is a keen observer of movement, and people tend to be impressed by athletic feats for their displays of gracefulness, power, or strength without needing to consider the internal complexities of the act itself. We do not require an understanding of the history of dance, for example, to appreciate the aesthetics of a well-executed performance. What makes us appreciate one’s smoothness, control, and balance and what makes uncoordinated movement cringe-worthy is somewhat of a mystery. It is as if we are wired to appreciate coordination, strength, and athleticism—things which would have been useful survival traits in our ancestors. (The same may be said of other classic sensory observations such as music, color, feel, and taste.) That which is pleasing often aligns with something we want to emulate. Feats of strength are no different.

Historically, spectators have been more impressed by feats in which something (or someone) is hoisted overhead. Classic stage acts included a lot more overhead pressing and supporting that anything that looked like a basic deadlift, squat, or bench press. And, as is always the case, the stage influenced popular strength training practices:

That part of the public which patronizes the theaters has very little interest in bar-bell and dumbbell lifting. They enjoy seeing “Strong acts”; but their preference is for marvelous and seemingly miraculous feats of strength. Therefore, professional lifters cater to the taste of their audiences. Instead of lifting bar-bells, they lift and support enormous quantities of live and dead weight. They try to make their acts spectacular. (Alan Calvert, “Super Strength” (1924).)

The mass-produced barbell was built, in part, to allow people at home to mimic the feats of stage strength performers. As a result, a lot of older forms of barbell training came from what people saw on stage. The bent press, for example, was a popular training and performance lift. Popularized by strength performers who essentially dueled to see who could support more weight overhead. The bent press is rarely used to train for strength today as it is more of a skill of support than a builder of strength. And, it fell from popularity in favor of what were considered better tests of athletic strength.

Le Miroir des sports / Public domain

That the first internationally recognized tests of strength were single and two-handed, ground-to-overhead lifts: the one-handed and two-handed snatch, the press (cleaned first from the floor), the clean and jerk, and the snatch. These five lifts were the original iteration of traditional strength feats and stage performances, adapted for 20th-century sports contests. In the same way that we appreciate fine dancing, people are drawn to overhead strength, being something that seems to fit the human design well. We stand on our feet and move things with our hands. Training to lift heavy things at arms’ length above the head is both recognizably impressive and a valuable as a training tool.

Function from Stability

The overhead press is a functional movement in that it trains the whole body in ways that apply to the use of general strength—strength for life and the many obstacles it may present. This is so even though the prime movers of the press are smaller than the prime movers involved in our other mains lifts.

The press is a lift that prioritizes stability, moving weight through a large range of motion around the most mobile (and unstable) major joint in the body. At the top of the press, a heavy load is balanced on the stacked bones of your arms, connected by a hinge joint at your elbow, and ending in a round bony head of your humerus, which sets in a bowl-shaped cavity at your shoulder joint. If you have any question as to the need for stability in this position, try balancing a mortar inside a pestle. These shapes (the shoulder being known as a ball and socket joint) are built for movement, not stability.

The muscles and tendons around the shoulder joint act constantly to keep your arm in your socket, as well as to press and secure a load overhead. Four muscles and their tendons form a cuff around the humerus to hold it in place. These rotator cuff muscles, starting from the anterior side of the scapula and going counterclockwise—as viewed from a person’s side—are the subscapularis, the supraspinatus, the infraspinatus, and the teres minor.

The Rotator Cuff Muscles

Public domain

Subscapularis: The subscapularis originates on the medial front side of the scapula (known as the subscapular fossa) and inserts on the anterior, medial aspect of the humerus (the lesser tubercle). Its primary functions are to medially, or internally, rotate the arm at the shoulder and adduct the arm, bringing it closer to the body.

Supraspinatus: The supraspinatus originates on the posterior aspect of the scapula at the supraspinatus fossa, located above (superior to) the spine of the scapula. This relatively small muscle inserts on the lateral aspect of the head of the humerus (greater tubercle) outside and slightly behind where the subscapularis inserts. The main function of the supraspinatus is the abduction of the arm, pulling the humeral head toward the glenoid cavity of the shoulder.

Infraspinatus: The spine of the scapula separates the supraspinatus and the infraspinatus origins. As their names suggest, the supraspinatus lies above the spine of the scapula, and the infraspinatus originates below the spine of the scapula at the infraspinatus fossa. The infraspinatus is a triangular muscle that attaches to the humerus at the middle facet of the greater tubercle of the humerus, posterior and inferior to the supraspinatus’ insertion. The muscle’s primary function is to externally rotate the humerus, but its relatively small size suggests that its most common role is one of stabilization, holding the joint stable against the bigger torques produced by larger muscles of the shoulder.

Teres Minor: Located inferior to the infraspinatus, the teres minor originates along the lateral border of the scapula. The muscle runs posterior to the shoulder joint, attaching at the inferior facet of the greater tubercle of the humerus, just lower than the attachments of the supra- and infraspinatus muscles. While the concentric contraction of the teres minor is part of the external rotation of the humerus (along with the infraspinatus), its primary role is to prevent the head of the humerus from sliding upward the arm is abducted.

Each of the rotator cuff muscles pulls the humeral head into the glenoid cavity of the shoulder, acting to keep your arm in its socket through the wide ranges of motion the shoulder is capable of performing. As the shoulder reaches its end range of flexion, the lifter must stabilize the shoulder in 360 degrees of motion, requiring the active engagement of the rotator cuff. Recall our mortar and pestle example; it takes stabilization in all directions to keep the ball in the socket of the joint in this position. The rotator cuff muscles get more thoroughly trained in their stabilizing functions during the overhead press, working together as they are intended to, suggesting that the overhead press promotes shoulder health, requiring and training stability of the joint. In this, the press accomplishes something neglected in the bench press. The shoulder, being built for incredibly versatile movement, requires versatile stabilizing structures. The press trains these structures in their main function, making the press essential to long term shoulder health and doubly important for anyone trying to build a big bench or anyone involved in athletics. No other basic barbell lift and certainly no isolation exercises train the shoulder for such widely applicable strength and stability as the overhead press.

Prime Movers

OpenStax / CC BY (https://creativecommons.org/licenses/by/4.0)

At the top of the press, the humerus sits in the glenohumeral joint, attached to the scapula. The scapula connects the humerus to the clavicle but has few bony articulations considering its wide range of movement. It can be elevated, depressed, retracted, protractive, rotated upward and medially, and rotated downward. It is a mobile bone by virtue of being covered in muscle attachments. Muscle and soft tissue are keeping the bar aloft and your shoulder secure during the lift.

The basic movement of the press starts with elbows flexed and shoulders extended, the lifter holding the bar in a front rack position. Different styles of overhead presses will have the lifter either carrying the bar “floating” in front of the body or resting it on the meat of the deltoids. Either way, the press ends with the arms fully extended at the elbows and fully flexed at the shoulders. The scapulae move from their normal anatomical position, getting elevated and rotated medially until the socket of the ball and socket joint is facing upward. The deltoids elevate the arm and the scapula. The trapezius muscles elevate and hold stable the scapula. These function as prime movements and stabilizers at the top of the movement.

Deltoids

“Whether or not broad shoulders have anything to do with one’s ability to survive the cares and worries of this earthly existence, as you will hear some folks say, we cannot properly decide. Nevertheless, we are certain that the broad-shouldered man should have the edge on the majority of his fellow men so far as health, strength, and personal appearance is concerned.” (Mark H. Berry, “Physical Training Simplified,” (1930))

When most people think of the human shoulder, they picture the deltoid muscles. It covers the shoulder joint from front to back, giving it the rounded appearance. Old-time bodybuilders believed that if someone who trained with barbells had big strong-looking deltoids, they would undoubtedly also have full-body strength.

The deltoid muscle has three sections with distinct origins and actions: The anterior part of the deltoid originates along the inferior lateral aspect of the anterior clavicle. The acromial part originates at the top of the scapula—the superior surface of the acromion process. And, the posterior part of the deltoid originates along the inferior edge of the spine of the scapula. Each of these origins’ muscle fibers inserts at the deltoid tuberosity of the humerus, located on the front-side, middle of the humerus.

The anterior deltoids flex the arm at the shoulder, as you would in a press or if you try to extend your arm forward against resistance. The acromial part of the deltoid abducts the arm, as you would if your arms were being pressed down to your sides, and you were trying to extend your arms out Vitruvian Man style. The posterior deltoids extend the arm, in the same manner as your lats, or as if you are paddling a boat with your hands. The many different functions of the deltoids mean that physical therapists and bodybuilders have a slew of isolation exercises to try and train every aspect of the shoulder musculature. However, these muscles are meant to work together, and when you press overhead, they do. With the anterior deltoids being most heavily recruited, the acromial section a little less so, and the posterior deltoids contributing even less. The press, along with your deadlift, will lead to strong, well developed, functional shoulders.

Triceps Brachii

The triceps brachii is a three-headed muscle, primarily responsible for elbow extension. The heads of the triceps attach at the lateral part of the scapula below the glenoid cavity of the shoulder (the long head) and on the humerus (the lateral head on the upper half of the humerus and the medial head below it and mostly covered by the long and lateral heads). Each of the three heads inserts at the olecranon process of the ulna—the pointy part of your elbow. The long head, by crossing the shoulder joint, has a proximal function of stabilizing the head of the humerus when the shoulder is adducted (pulling the humerus into the joint) and extending the arm at the shoulder.

Pectoralis Major

The pectoralis major plays a larger role in the bench press, but one of its primary functions is to flex the shoulder, making it a primary mover in the overhead press as well. A large, fan-like muscle, the pectoralis major originates along the medial side of the clavicle (collar bone) then down, attaching to the upper two-thirds of the sternum with tendinous connections to those ribs that also attach to the sternum. The muscle’s fibers insert at the outer (lateral) lip of the humerus’ bicipital groove. The pectoralis major flexes, adducts, and medially rotates the humerus and aids in the stability of the shoulder joint. As a prime mover of the overhead press, the pecs aid in shoulder flexion.

Traps and the Shrug

We talked about the trapezius muscles and their role in the deadlift. The trapezius is one of the largest, most visible muscles of the upper back with origins going from the occipital bone down to the spinous process of the T-12 vertebrae. The muscle has three distinct segments defined by the orientation of the muscle’s fibers, from their origin along the posterior midline of the body to their lateral insertions.

Superior

The uppermost fibers of the trapezius muscle originate at the skull, from the occipital bone to C7 of the cervical spine. The fibers proceed downward and laterally, inserting at the posterior, lateral third of the clavicle. The superior fibers of the traps elevate the scapula in a shrugging motion.

Middle

The middle fibers of the trapezius originate at the spinous processes of C-7 down to T-3, are aligned roughly horizontally, and insert at the medial aspect of the shoulder blade, at the acromion. These middle fibers retract the scapula and pull it toward the body’s midline.

Inferior

The lower fibers of the trapezius extend from T-4 to T-12 at their origin and run laterally upward to insert at the spine of the scapula. These lower fibers depress the scapula.

When you press, your scapulae are elevated and rotated medially by the trapezius muscles. This movement allows the full flexion of the shoulder, making it possible for you to put your arms over your head. We will often cue an active “shrug” of the shoulders at the top of the press, making this automatic contraction a conscious and voluntary movement, accentuating the shrug at the top, bringing more active muscle mass into the movement, and helping to support the bar at the top of the movement.

A Fully Body Shoulder Exercise

As you lift the bar in the press, you are moving a large part of your overall lifter-barbell-system’s mass upward. The whole system’s average mass is also moving upward. Ideally, you remain in balance while you do this, but small movements in the barbell can cause bigger changes to everything below it. When your center of mass is moving upward, the potential lever between it and your base of support (which you can think of as a point of rotation existing right at the middle of your feet, when viewed from the side) is also getting longer. Movements in the bar will challenge your ability to keep your balance, requiring constant effort to stay tight and stable during the movement.

In addition, your arms are levers with points of rotation at the shoulder and elbow joints. As you extend your arms, the weight in your hands moves farther from the shoulder. Ideally, there is no moment force acting on your shoulder, but keeping the bar directly above the shoulder is not easy. It’s part of the challenge of the lift, a challenge of constant stabilization, requiring you to keep the barbell situated over the shoulder and your center of mass over the midfoot at the same time. Together, this requires the hard, isometric contraction of every major joint flexor of your trunk and lower body. Lifters will often remark at the benefit of wearing a belt during overhead presses, making the lift easier, attesting somewhat to the benefit of added trunk stability in the lift.

We’ve focused mostly on the prime movers and main stabilizers of the movement, but since the press takes place with your feet on the ground, it involves your entire body in the task of getting the bar overhead and maintaining balance while you do so. As you press the bar upward, your center of mass changes, requiring constant adjustments to maintain your balance. And, because the lift takes place on the feet, the more weight you press overhead, the more equal and opposite force must be pushing against the ground. The heavier the press, the more your trunk and lower extremities are involved in the transfer of force throughout your system, keeping your joints locked, your back extended, and your skeletal system rigid, allowing for the transfer of force through a large kinetic chain. Any weak link usually means a missed rep.

While overhead strength is visually stunning, aesthetically pleasing, and universally impressive, training for overhead strength with the most basic press is perhaps the most functional lift for training real-world-applicable upper body strength.