SuppVersity EMG Series - M. Deltoideus, M. Infraspinatus, Supraspinatus and Teres Minor: The Very Best Exercises for Broad Shoulders and Capped Delts
|Image 1: The muscles of the deltoids (red) on the
front (left) and back (right) of the body and the
rotator cuff (violett), the group of muscles
and tendons that stabilize the shoulder.
- the anterior, lateral and posterior part of the m. deltoideus, also known as the pars clavicularis, which attaches to the clavicle, the pars acromialis attaching to the acromion and the pars spinalis that is directly attached to the spina scapulae,
- the rotator cuffs, which comprise the m. infraspinatus, which arises from beneith the scapula at the fossa infraspinata scapulae and facilitates internal rotation, the m. supraspinatus, which is situated right above the former and is involved in the lateral adduction of the arm, and the m. teres minor, which is attached laterally to the scapula at the margo lateralis scapulae and figures in the abduction of the arm; the m subscapalaris, which completes this commonly overlooked muscular quartet attaches to the inner part of the scapula and facilitates internal rotation, abduction and adduction of the shoulder.
|Navigate the SuppVersity EMG Series - Click on the desired body part to see the optimal exercises.
I. The Best Exercises for the Anterior, Lateral and Posterior Parts of the Delts
|Image 2: Turns out the injury-prone neck
press is the most versatile delt-exercise as
it hits both the anterior, as well as the lateral
part of the delts about as hard
(image from sportkrachtfitness.nl)
* BB = barbell; DB = dumbbell
|Figure 1: EMG activity of anterior, lateral and posterior part of the m. deltoideus during selected exercises relative to the military press (anterior), the DB lateral raise (lateral) and the DB reverse fly (posterior); calculated based on data from from Boeckh-Behrens & Buskies (2000)
|Image 3: With its naturally arched
movement, the DB shoulder press
may be a viable, if not preferable
alternative to the BB military and
BB neck press (image everkineti.com)
That being said, the DB overhead press is also a viable alternative for the BB neck press as the position center of gravity is more in line with your head throughout the movement. It may thus be assumed that the the stimulus shifts away from the front and towards the lateral deltoid, as it is the case with the neck vs. the military press.
|Figure 2: Reduction in EMG activity of selected variants of the DB lateral raise and the reverse fly relative to lateral raises with external rotation, DB raises with 90° arm/torso angle and internally rotated machine reverse flys; calculated based on data from from Boeckh-Behrens & Buskies (2000)
Dessicating the Lateral Raise
If you make good use of what you have learned at the end of the previous paragraph, you can improve the load on the target muscle, while handling lighter weights and decreasing your risk of injury - I know, the big weights are more impressive, but after all what's the use of using the biggest weights, if you are not making progress, both strength- and size-wise, because of improper form? I mean, it is one thing to cheat on the last 1-2 reps of a set in order to squeeze out the very last drops of gasoline from your muscular tanks, it is however something completely different to compromise form, just to be "the guy who lifts the heavy weights". There is hardly any movement, where this becomes so obvious as with the DB lateral raise. If you do not do it yourself, you certainly know someone who grabs the 50lbs dumbbells, holds them vertically before his groin and then powers, or I should say, "rips" them up to his sides, lets them bang down and starts all over again until, after he eventually racked the weights, he grabs his shoulder or wrist in agony, yet not without the pride of having used a heavier weight than the guy next to him.
Note: The following analysis is based on a VERY simple mechanical model and does not consider factors such as increased load per square area of muscle fiber in the stretched position, effects of static or complete contraction etc... Notwithstanding, if you like the following part of this write-up, please spread the word (via Facebook, Twitter, etc.) and let me know (in the comment section or the SuppVersity Facebook page) that it would be worth the effort to do similar and even more depth analysis in the future!You already know from the previous paragraphs and the EMG data in figure 2, that it is imperative to keep the arms externally rotated, i.e. to pretend you were trying to pour out an imaginary liquid from the dumbbell at the top of the movement, if you do not want to lose 16% of the muscle tension in the first place... Well, but what about the aforementioned guy who does not even get the chance to think about pouring out any liquid other than that in his shaker bottle, when he is performing his ballistic weight exercises? Which of his mistakes, do you think compromises the effectiveness of the lateral raise most?
- Flexing the elbow too much (often up to 90°) and thus reducing the lever? Or,
- Not raising the dumbbells to shoulder height, i.e. keeping the angle between arm and torso <<90° (often <<70°)
|Figure 3: Effects of arm/torso angle and elbow flexion on torque during the DB lateral raise
(data calculated based on a very basic physical model)
II. The Best Exercises for the Rotator Cuff
I hope that, over all that you have learned about delt-training by now, you did not forget, what I mentioned at the very beginning of this installment of the SuppVersity EMG Series: Rotator cuff training equals active injury prevention. While most trainees do not even feel them working, the muscles of the rotator cuff are crucial for the stability of the most flexible and volatile joint in your whole body, your shoulder. It is imperative for these largely overlooked and often undertrained muscles to hold the ligaments and bones of your shoulder in position so that your other muscles such as the deltoids or the pectoralis can do their job. To build a strong m. infraspinatus, m. supraspinatus and m. teres minor, is thus also the foundation of building a "bigger bench" to impress your bros at the gym. If you don't believe that, you may listen to strength coach Charles Poliquin, who has the following anecdote to tell:
One of my pro hockey players, Jim McKenzie, improved his 14-inch, close-grip bench by 51 pounds in 12 weeks, from 280 to 331 pounds, by focusing on rotator cuff strength.And though I doubt the universality of Poliquin's "research", as far as the non-athletic regular gym-goer is concerned, it is certainly noteworthy that his years of experience in working with athletes have told him that "rotator cuff strength should be about 9.8 percent of what you can lift in the bench press [for] pain free bench pressing". That means, if you are benching 200lbs you should not wonder if your shoulder begins to hurt, if you are not able to use 20lbs dumbbells when doing external rotations lying on a mat on the floor ...
|Figure 4: EMG activity of the major muscles of the rotator cuff during selected exercises relative to the DB external rotations done lying sideways on the floor; calculated based on data from from Boeckh-Behrens & Buskies (2000)
|Image 4: DB lateral raise with
arms 30° horiz. adducted for the
m. supraspinatus (Jobe. 1986)
III. Conclusion- Three Plus One Equals Injury-Free Strength and Size
An imperative prerequisite for building impressive deltoids and thus broad, rounded shoulders is a stable foundation in form of strong rotator cuff muscles, if you neglect the latter you will either plateau or - even worse - injure yourself sooner or later. That being said, especially your front delts are hit very hard during pretty much all pressing movements for chest and triceps, it is thus neither really necessary nor advisable to do more than one (if any) "isolation" exercise in the form of a compound movement like the barbell or dumbbell military press, a movement, which by the way will also greatly help to bring up "the upper chest" many bodybuilders feel they are lacking. If you complement this basic "mass builder" with some lateral raises and reverse flys, the one and only thing that is really left to do on "delt day" is a rotator cuff exercise of your choice and you are ready for some highly anabolic rest and recovery ;-)
An EMG-Optimized Routine
|Image 5: You can rotate in some
Arnold Presses, if you feel you did
not hammer your front delts heavy
enough with the military press
- Military Press - BB or DB seated, 6-8 reps
- Lateral raise - DB elbow-flexion <15°(!), 10-12 reps
- Reverse fly - machine or DB, internal rotation, 10-12 reps
- External DB rotations - lying on the floor, 12-15 reps