The Research-Based Guide to Boulder Shoulders

Boulder Shoulders (The Exercise Selection)


Lateral Deltoid

The outside head of the deltoid. Get this part of your shoulders well developed and your entire physique will look better.

  • Shoulder abduction (draw your arm out to your side. Like a lateral raise).
  • Helps with shoulder flexion (raise your arm directly out in from of you).
  • Shows the most activation between about 60 and 90 degrees of abduction. The rotator cuff drives the first 60 degrees of a lateral raise and anything above 90 degrees.

Posterior Deltoid

The posterior, or rear, delts should be second on your list of importance when it comes to shoulder aesthetics.

Also,  frequently training your rear delts will, probably, be enough to keep your shoulders healthy. 

  • Shoulder horizontal abduction (stick both arms out in front of you, now draw both of your elbows backward while keeping your elbows on a similar plane as your ears).
  • Shoulder extension (pulling your elbows backwards. Any pulling movement achieves this).
  • Shoulder external rotation (put your right arm out in front of you and point your thumb to the right, or vice versa with your left arm)

Anterior Deltoid

Also known as the front delt. Usually, the anterior deltoid would be one of the first things to come up when discussing the shoulder muscles.

So why do I save it for last?

Well, the vast majority of people who train their pecs do not need to do any isolation work for their front delt.

"Why shouldn't I do isolation exercises for the front delt?"

Because there is heavy involvement from the anterior deltoid in every pushing motion that you do. That includes the bench press, all overhead pressing, dips, pushups, and even pec flys. In fact, it’s nearly impossible to get a good chest workout without heavily involving your front delts.

So, doing isolation exercises for the front delt is redundant. Also, research shows that bodybuilders typically have overactive front delts, which can lead to injury. 

I’m still going to give you the functions of the anterior deltoid and an exercise to properly train them.

But, this is specifically for those who do not do much in the vein of pec work or pushing movements.

  • Shoulder flexion (raise your arm directly out in front of you).
  • Shoulder horizontal adduction (put your arm directly out to your side, now bring your arm forward. Think of a pec fly).
  • Shoulder internal rotation (put your right arm out in front of you, now rotate it until your thumb is facing downward).
  • Helps with shoulder abduction (raise your arm directly out to the side)

How to Manipulate The Angles to Target The Delts

Angles are everything in weight training. Angles are what differentiate one exercise from the next. The angles created by your body and the line of resistance will largely dictate where on your body the tension is.

So how does this concept apply to the shoulders? Well, each head of the deltoid is quite small when compared to some of our other muscles. Therefore, we must take extra care with form while trying to build the delts. A slight shift in the angle between your body and the line of resistance can turn a lateral deltoid exercise into an anterior one. 

If you’d like to find out more about manipulating angles on an exercise click here.

Gripping The Weight

Manipulating the way you grip a dumbbell or cable is a powerful way of transforming a good exercise into a great one. Manipulating grip is especially important in shoulder training. 

Because of the relatively similar functions the three heads of the deltoids share it is difficult to isolate one from the other. Finding the correct grip can help with that.

I go into far greater detail on the subject of manipulating grip – here.

Shoulder Health

You can’t get big and strong if your shoulders are busted. Not only will a shoulder injury keep you from training your shoulders, but it will also keep you from training just about every other muscle.

Don’t believe me? Ask someone with chronic shoulder pain how squatting feels for them.

*Spoiler alert, it doesn’t feel good.

“Ok, you’ve appealed to my vanity. How do I keep my shoulders healthy?”

Glad you asked. You’ll be happy to know for those who have yet to suffer an injury, maintaining shoulder health is not that complicated. You don’t need to do a ton of goofy exercises from a "mobility" exercise blog, and you don’t need a degree in physical therapy.

My two step process for maintaining healthy shoulders is as follows:

  • Give your rear delts the attention they deserve.
  • Limit the amount of pressing that you do. Or try to maintain an even amount of pushing and pulling.

Number one probably came as no surprise to you. But number two may have sent you into a frenzy. “Limit the amount of pressing that I do!? I’m a man dammit!”

Chill. Hear the reasoning behind my point. Overhead pressing, in all its’ forms, and I do mean all, mostly stimulates the front delt. There is this notion that overhead pressing is best for all three parts of the deltoid, which may or may not be true (not enough research to say either way).

P.S. I did my best to explain my reasoning here. Hopefully, I did a good job. But even if I do a perfect job of explaining my point I know people are still going to want to debate this with me. So please leave a comment down below and we can talk out our differences.


  • Escamilla, R. F., Yamashiro, K., Paulos, L., & Andrews, J. R. (2009). Shoulder muscle activity and function in common shoulder rehabilitation exercises. Sports Medicine, 39(8), 663-685. Retrieved from Google Scholar.
  • McGinnis, Peter Merton. Biomechanics of Sport and Exercise. Champaign, IL: Human Kinetics, 2013. Print.
  • Nanba, Y., Miyamoto, S., Takemasa, S., Uesugi, M., Inoue, Y., Ootani, Y., . . . Tanaka, H. (2015). Effect of exercise at light loads with manipulative resistance on infraspinatus, trapezius (upper fiber) and deltoid (middle fiber) muscle activities in shoulder joint elevation. Journal of Physical Therapy Science,27(3), 627-9. doi:10.1589/jpts.27.62
  • Reinold, M. M., Wilk, K. E., Fleisig, G. S., Zheng, N., Barrentine, S. W., Chmielewski, T., . . . Andrews, J. R. (2004). Electromyographic analysis of the rotator cuff and deltoid musculature during common shoulder external rotation exercises. Journal of Orthopaedic & Sports Physical Therapy,34(7), 385-394. Retrieved from Google Scholar.