The bench press is a recognized compound exercise for building upper body strength. While primarily known for developing the chest, the bench press definitively works the shoulders. The movement involves several muscle groups working together, and the shoulder muscles play a significant role in generating force and stabilizing the joint. The shoulder’s involvement makes the exercise highly effective for overall upper body development.
The Deltoids as Primary Movers
The primary pushing muscles in the bench press include the pectoralis major (chest), the triceps brachii, and the anterior deltoid (the front portion of the shoulder muscle). The anterior deltoid acts as a major agonist, directly responsible for generating force to move the weight. Its primary mechanical contribution is shoulder flexion (raising the arm forward) and transverse flexion (bringing the upper arm across the body’s midline).
This muscle is particularly active during the middle and upper portions of the pressing motion, assisting the pectorals and triceps. Electromyography (EMG) studies consistently demonstrate high activation in the anterior deltoid during a standard bench press. The sheer volume of muscle fibers in the anterior deltoid makes it an indispensable partner to the larger chest muscles throughout the lift.
Controlling Load Through Technique
Lifters can manipulate the degree of shoulder involvement by adjusting their grip width and elbow position. A wider grip places the hands farther apart on the barbell, increasing the degree of horizontal shoulder abduction required at the bottom of the lift. This wider arm position increases the mechanical leverage on the shoulder joint, which can raise the strain placed on the anterior deltoids and surrounding connective tissues.
Conversely, using a narrower grip and keeping the elbows tucked closer to the torso reduces the range of motion for shoulder abduction. This shifts the primary emphasis toward the triceps brachii and the clavicular head of the pectoralis major. A tucked elbow position is often recommended for individuals with shoulder concerns because it limits the horizontal extension of the shoulder, making the movement less aggressive on the joint capsule.
A significant elbow flare (near 90 degrees from the torso) is associated with the highest anterior deltoid activation but is generally considered less stable. Minimizing the flare by keeping the elbows at an angle closer to 45 to 60 degrees is a more balanced approach. This moderate tuck allows for efficient force transfer while distributing the load more evenly among the chest, triceps, and anterior deltoids, improving safety and lifting potential.
The Essential Role of Stability Muscles
Beyond the primary force-generating muscles, a group of smaller muscles must work constantly to maintain the integrity of the shoulder joint throughout the pressing movement. These muscles are the rotator cuff, a group of four muscles—the supraspinatus, infraspinatus, teres minor, and subscapularis—that surround the shoulder. The main function of the rotator cuff is to keep the head of the humerus centered within the shallow socket of the shoulder blade.
When the powerful pectorals and anterior deltoids contract, they generate a force that tends to pull the humeral head forward. The rotator cuff muscles, particularly the infraspinatus and subscapularis, counteract this force, hugging the joint tightly into the socket. This stabilizing effort prevents excessive movement and potential impingement.
The posterior deltoid also functions as a stabilizer during the bench press, though it is not a primary mover. Neglecting to train these stabilizer muscles can lead to muscular imbalances, increasing the risk of injury. Maintaining a retracted and depressed shoulder blade position against the bench helps engage these stabilizing muscles, creating a more solid base for the movement.