Round Out Your Shoulders

 With Incline Rear Lateral Raises

Great shoulders often find a home on guys who do a lot of bench presses and overhead presses. Nevertheless, without special attention, the medial and posterior heads of the deltoid will be underdeveloped and asymmetrical, as compared with the anterior head of the deltoid. Rather than decreasing the size or thickness of the anterior deltoids, the better strategy is to develop equal mass and depth as the anterior deltoid, on the lateral and posterior aspect of this muscle. A great way to do this is to do incline rear lateral raises.

ANATOMY LESSON

The three heads of the deltoid comprise a thick muscle, which caps the bony connections that make up the shoulder joint. The fibers of the deltoid converge on the humerus bone of the upper arm like an inverted triangle. Each side of this inverted triangle has a separate muscle region or head, each having different muscle attachments on the shoulder structures. As a result, the three deltoid heads all have different functions.

The anterior (front) fibers of the deltoid attach along the lateral part of the clavicle (color bone) above the shoulder joint to the acromion. The anterior fibers flex the humerus at the shoulder (bringing the humerus bone of the upper arm forward), and medially rotate the humerus at the shoulder joint.

In medial rotation, the humerus bone rotates at the shoulder so that the anterior aspects of the arm and palm of the hand are rotated toward the mid-line of the body. These fibers, as well as the fibers of the posterior deltoid, act as guide wires in directing the arm abduction of the medial deltoid.

The medial head of the deltoid muscle is positioned laterally on the body, but it is the middle of the three-headed deltoid muscle. The medial fibers of the deltoid circle around the lateral side of the shoulder by attaching across the acromion (point of the shoulder) of the scapula (shoulder blade). The medial fibers primarily abduct the humerus bone of the arm, by raising the humerus away from the side of the body. This is the primary activity of the incline bench lateral raise.

The posterior (scapular) fibers of the deltoid connect to the upper posterior side of the scapula (spine of the scapula). These fibers extend the humerus (pull the humerus bone posteriorly) and lateral rotation of the humerus. Lateral rotation occurs when the humerus bone is turned at the shoulder joint, so that if the palms were initially facing to the rear of the body, it would be rotated to the front, so that the thumb points laterally and away from the body.

THE EXERCISE: INCLINE REAR LATERAL RAISE

1. Lay face down on a 45-degree incline bench. Begin with a dumbbell in each hand, letting your arms will hang perpendicular to the floor in the starting position. Make sure that your bench is narrow enough so that when you raise the dumbbells, they will not hit the bench.

2. Your palm should face the floor at the start of the lift. Your elbows should be just short of straight, but the elbow joint angle should not change throughout the range of motion.

3. Keep the elbows slightly bent but locked, and raise the dumbbells out to your sides in a position that is just above eye level (i.e., abduction of the arm at the shoulder joint). The line of trajectory of the dumbbell should be slightly in front of your shoulder joint. The ending position is with the arms and hands in line with the shoulder joint and over the side of your chest. The arms and forearms will be at or just above a position that is parallel to the floor.

4. As the top position is approached, rotate the shoulder so that the knuckles of the little fingers point upward. This extra rotation at the top (medial rotation of the humerus) will also bring the anterolateral region of the deltoid into play (fibers between the lateral and anterior regions of the deltoid).

5. Hold at the top and squeeze for a peak contraction, then slowly control the descent of the dumbbell back to the starting position in front of your body and over the edge of the bench.

6. Do not pause at the bottom or between repetitions, but immediately continue upward. This keeps the deltoidfibers under constant tension from the beginning to the end of the exercise.

RX TIP

It is very important to rotate your arms (humerus bone) at the shoulder joint, rather than at the hand and wrist in the top portion of this movement. Simply supinating and pronating your hand involves movements in your forearm, but that will do nothing to help your deltoid. It is not wise to explode into this lift, especially during the rotation near the top of the movement. This is also not an exercise that you will be able to lift a lot of weight.

References

Ackland DC and Pandy MG. Lines of action and stabilizing potential of the shoulder musculature. J Anat, 215: 184-197, 2009.

Audenaert EA, De Roo PJ, Mahieu P, Cools A, Baelde N, D’Herde K and Verdonk R. Deltoid muscle volume estimated from ultrasonography: in vitro validation and correlation with isokinetic abduction strength of the shoulder. Med Biol Eng Comput, 47: 557-563, 2009.

Moore, K.L. and A.F. Dalley. Clinically-oriented Anatomy, Fourth Edition. Baltimore, Lippincott Williams & Williams, Kelly, P.J. Editor, 1992, pp. 690-698.

Rispoli DM, Athwal GS, Sperling JW and Cofield RH. The anatomy of the deltoid insertion. J Shoulder Elbow Surg,18: 386-390, 2009.

Ruckstuhl H, Krzycki J, Petrou N, Favre P, Horn T, Schmid S and Stussi E. Shoulder abduction moment arms in three clinically important positions. J Shoulder Elbow Surg, 18: 632-638, 2009.

Sakoma Y, Sano H, Shinozaki N, Itoigawa Y, Yamamoto N, Ozaki T and Itoi E. Anatomical and functional segments of the deltoid muscle. J Anat, 218: 185-190, 2011.