The bench press is known for being a compound chest exercise. Find out if it also works your shoulders and if so, what parts to what extent.
Regular bench presses work the front parts of your deltoids (main shoulder muscle) a good amount. Potentially up to the point of being challenging enough to grow and strengthen this part of your shoulder muscles.
Additionally, you engage your middle deltoids to a small extent to control the angle of your upper arms throughout the exercise.
That being said, this only requires a small amount of effort and is likely not enough to see actual growth and strength progress.
The back parts of the deltoids do not really work during bench presses since gravity takes over the job of the muscles.
Additionally, your chest muscles and triceps are still heavily involved in the bench press exercise too.
Lastly, incline, narrow-grip, and wide-grip (generally not recommended) bench presses will generally work your shoulders more than the regular version.
Parts of the deltoids and whether the bench press works them
The deltoids are the main shoulder muscle. These muscles have three different parts/muscle heads that each have their own movements where they really work hard.
You do work your deltoids during the bench press but not all parts have to work to the same extent.
The front deltoids, also known as the anterior deltoids mainly help you raise your arms forward/upward. This is also called shoulder flexion.
An isolation exercise for this part of the deltoids would be a front raise. This is basically the movement described.
That being said, the front deltoids also have to work a good amount during certain compound movements like a regular bench press.
Together with your chest muscles, this part of your shoulders raises your upper arms in the lying position.
The middle deltoids are also known as side/lateral deltoids. These are responsible for moving your arms sideways/upward in a standing position. This movement is called arm abduction.
When you lie down on a weight bench, engaging your middle deltoids would make your upper arms go “back” to the direction of your head.
During the bench press, the middle deltoids work to a small extent together with the latissimus dorsi and lower chest muscles to keep your upper arms at the right angle in relation to your sides.
That being said, you will not experience too much resistance in these correction movements.
So you can say that the bench press engages the middle deltoids but generally not enough to see actual muscle growth and strength progress.
Something else to note is that your equipment choice for the bench press influences to what extent you work your side deltoids.
A dumbbell bench press will require a lot more stabilizing and in turn, muscle engagement in this area than a machine bench press where the trajectory of your hands is fixed.
The rear/posterior deltoids are mainly responsible for moving your arms backward in a horizontal position in relation to your shoulder blades aka horizontal arm abduction.
When lying down on a bench this would mean lowering your upper arms.
Gravity is responsible for this movement. Your rear deltoids should not work at all during the bench press.
Incline vs flat vs decline bench press for shoulders
An interesting aspect of the bench press exercise is that you can do it in many different ways.
The first example of this is that you can use a flat, incline, and decline bench to do the movement with your upper body tilted at different angles.
This changes what direction you push in relation to your body and in turn, in what ratio you work the muscles involved in the exercise.
At some angle, your side deltoids will start to work a good amount too.
On the flip side, decline bench presses where your shoulders are positioned lower than your hips will work your shoulders a lot less than flat bench presses.
Close vs regular vs wide grip bench press for shoulders
Another factor that influences what parts of your shoulders you work to what extent during the bench press is how wide your grip is in a barbell bench press and more specifically, the angles of your upper arms.
First of all, a “normal” bench press grip would be at a distance where it feels natural to keep your upper arms at about 45-degree angles to your sides.
In a close-grip barbell bench press, your upper arms will generally be closer to your sides.
This will require more work to lift from your front deltoids and less work from your chest muscles than the same weight in the regular-grip version.
You can also get a similar increased focus on the front deltoids during dumbbell bench presses by keeping your upper arms close to your sides.
Wide-grip bench presses are typically not recommended to do because of concerns about shoulder injuries. That being said, in theory, these would generally also work your front deltoids more than the regular grip.
Similarly to the narrow grip variation, you could get a similar effect in dumbbell bench presses by adjusting the angles of your upper arms.