Short answer: The overhead press hits the entire shoulder girdle, and in some cases, it can be sufficient as a solo exercise. When done with proper form, the movement activates all heads of the shoulder, although the front deltoid is always doing the heavy lifting.
Using too much weight and turning the overhead press into a standing incline bench press is the most frequent mistake. In that scenario, the lifter overloads the anterior deltoids even more and robs the rest of the musculature of “gains” – all while placing needless stress on the lower back.
People who want to maximize their shoulder potential could benefit from experimenting with isolation exercises for the lateral and rear deltoids.
How Involved Are the Side and Rear Deltoids in The Overhead Press?
People think that the overhead press is all front delts, but that assessment is inaccurate. The front deltoids work heavily during the first 1/3 of the movement, but when the bar reaches the level of the forehead, the middle and rear deltoids kick in to help with the finish.
The Standing DB Overhead Press activates the side deltoids the most according to a Norwegian study published in 2013 which compared the activity of all three heads during the dumbbell and barbell overhead presses (both seated and standing versions). [source]
The following charts show some of the study’s findings:
- The Standing DB Press showed 7% greater mid-delt activation than the Standing Barbell Press.
- The Standing Barbell Press showed 7% greater mid-delt activation than the Seated Barbell Press.
- The Standing DB Press showed 15% greater mid-delt activation than the Seated DB Press.
- The Standing DB Press showed the greatest posterior deltoid activation.
- The Standing Barbell Press showed 25% greater rear deltoid activation than the Seated Barbell Press.
- The Standing Dumbbell Press showed 24% greater rear deltoid involvement than the Seated Dumbbell Press.
Judging by the findings of the study, the standing DB press (SDBP) should be the most optimal press for the shoulders. However, there’s more to the picture than EMG activity.
The SDBP may have the capacity to recruit a little more of the rear and side delts, but it loses to the barbell press when it comes to two crucial factors:
Convenience. Getting heavy dumbbells into position for a standing press is troublesome. You either have to clean them to your shoulders or grab them from a special rack that does not exist in most gyms. The barbell press fixes this problem by allowing you to comfortably unrack the bar from a set of upright supports, a squat rack or a power cage.
Programming. The press is dependent on many small muscles and joints which get stronger fairly slowly. The jumps between dumbbells found in commercial gyms are too big for linear periodization. Meanwhile, the barbell offers greater control over the increments and more flexible programming.
Those peculiarities and the fairly low differences in rear and middle deltoid activation between the standing presses make the barbell version the absolute overall winner.
Is It True That the Overhead Press Works the Rotator Cuff Muscles?
Yes. The rotator cuff works isometrically during overhead presses. You cannot support a heavy weight above your head without direct involvement from the rotator cuff.
Bench pressing with ego is the main source of rotator cuff injuries in the gym. If people weren’t so obsessed with reaching arbitrary bench numbers, most of us wouldn’t even know that the rotator cuff exists.
Unless you have a very specific reason to train the small shoulder muscles directly, a balanced program would take care of them all, and you wouldn’t have to perform isolation movements with cans promoted by various fear-mongering professors.
FAQ: What If I Make the Overhead Press My Only Upper Body Exercise?
An upper body routine comprised solely of overhead pressing is not complete because many primary movers are not heavily involved in the lift. However, a similar regimen wouldn’t be as dangerous as some may think. There will be weak points, but the shoulder girdle itself would remain fairly balanced. The chest, the latissimus dorsi and the biceps would be the muscles receiving insufficient growth stimulation.
Realistically, that level of minimalism is unwarranted. If you have the necessary equipment to perform an overhead press, you can easily incorporate a back exercise too.
What If I Really Want to Polish My Shoulders? Should I Add Isolation?
Let me ask you a question. If you wanted to develop the best biceps that you could, would you supplement your routine with curls or would you rely solely on chin-ups?
Isolation exercises have a bad reputation, but they are good at what they promise to do, namely to isolate. Compound movements are more fun, but if you are seeking maximal development of a muscle group, adding a few extra sets of direct stimulators shouldn’t be a big problem.
Nonetheless, it would be naïve to think that isolation exercises can trigger some insane growth. Don’t be surprised if you cut them out of your routine only to see that your shoulders look exactly the same.
Note: Isolation for the front deltoids is often “junk volume” since the muscle is getting plenty of stimulation from every pressing exercise. If you’re doing a lot of rowing with a wide grip, the same applies to isolation movements for the posterior deltoids.
Can a Natural Develop 3D Delts?
The 3D deltoids of roiders are the product of four ingredients:
- High concentration of androgen receptors in the shoulder area (more receptors equal a better response to steroids)
- Leanness – steroids allow bodybuilders to get brutally cut without losing muscle whereas naturals have to sacrifice noticeable mass to get from lean (10% body fat) to shredded (7% BF)
- Mass induced by anabolic steroids
- Dryness – some compounds dry you out the muscle and increase separation.
It’s impossible to naturally replicate the combination outlined above. Nevertheless, naturals can develop 3D deltoids but without the “Photoshop shine.”
Eugene Sandow and Arthur Saxon are two classic examples. They both lived before the invention of steroids and dedicated a lot of their time to the overhead press just like the rest of the strength athletes from that era. Their shoulders are as good as it gets naturally.