Get Shapely and Sexy Shoulders

It is effortless to keep areas like thighs and hips in mind when you are exercising because they are easily seen from the front and in any mirror. However, unless you position yourself between a couple of mirrors, even areas that are in view to others – like your upper back and rear shoulders – are difficult to for you to see. Sometimes that translates into “out of sight, out of mind” when it comes to planning your exercise routine. If that is you, then your upper back and shoulders may be somewhat neglected; they may be a little weaker and have less shape than you’d like. If you want to look your best in your sleeveless and/or off-the-shoulder holiday clothes, you may want to spend a little time training these “out of sight” muscles.

The shoulder is a complex structure and that makes it harder to deal with. That’s because the deltoid muscle of the shoulder is not content with moving a bone in a single direction. Instead, it selects fibers from different regions of the muscle to move the humerus bone of the upper arm forward (flexion of the shoulder), backward (extension of the shoulder), up to the side (abduction) and back toward the body from a starting position with the arm raised. It’s amazing that one triangularly shaped muscle can do all those functions (and combinations of functions). Nevertheless, the very structure that was designed for maximum mobility also provides us with very poor stability. Also, it ‘s a rather poor mechanical lever, so tremendous amounts of force have to be generated within the muscle fibers even before the smallest loads can be lifted.

Structure and Function

The deltoid is usually described as having three “heads.” Although they are not truly separate heads, the deltoid muscle does originate from three regions on the bony portions of the shoulder. The anterior part of the deltoid is primarily involved in shoulder flexion (e.g., raising the arm forward), the medial deltoid is responsible for raising the arm laterally to the side of the body (abduction of the arm at the shoulder joint), and the posterior deltoid is largely involved in shoulder extension (pulling the arm backward like setting up for a backstroke in the pool). Exercises like pressing overhead involve all three regions of the deltoid, but this preferentially activates the anterior fibers and the posterior fibers are only minimally affected. If one were only to do overhead presses for your shoulders, for example, the posterior fibers would not receive much direct work at all, and this would eventually result in poor muscle strength balance around the very delicate shoulder joint. Strength and development in one region (e.g., anterior shoulder) but not another (e.g., posterior deltoid) can increase the risk of a shoulder injury even when doing simple things like a tennis stroke or picking up a bag of groceries.

The machine rear lateral raise preferentially activates the posterior (rear) part of the deltoid muscle, and therefore the anterior and medial fibers of this muscle will not be discussed further. The posterior fibers of the deltoid attach along the spine of the scapula (shoulder blade), a bony ridge located on its upper and posterior side. They anchor on the lateral side of the humerus about one-third of the way from the shoulder toward the elbow. These fibers produce strong extension (bringing the humerus bone posteriorly) and this is the primary function in machine rear lateral raises. The posterior fibers also contribute to lateral rotation of the humerus at the shoulder joint. Lateral rotation turns the medial side of the arm out and away from the body (e.g., counterclockwise rotation of your arm).

The shoulder joint is formed between a very shallow plate on the scapula called the glenoid cavity, and a rather large ball on the head of the humerus bone of the upper arm. The ball-and-socket arrangement makes this the most mobile of joints in the human body, but it’s also the most vulnerable to injury. It is therefore common to find that a high percentage of injuries around the home or in recreational activities are shoulder-related. Many injuries can be avoided if all three regions of the deltoid are stressed and proper exercise technique is employed.

The rhomboids – major and minor – deep muscles of the back that lie medial to the scapula, are also activated by machine rear lateral raises. These muscles add tone to the upper back and help improve your posture. The rhomboid muscle fibers begin along the midline of the back at the thoracic vertebrae and attach on the medial border of the scapula (the side closest to the vertebrae). The larger rhomboid major muscle sits just below the smaller rhomboid minor muscle, but both have similar functions. The rhomboid major and minor muscles adduct the scapula (squeeze the shoulder blades together) and rotate the scapula upward (as when you raise your arms over your shoulders). The medial part of the large trapezius muscle is positioned over the rhomboids. The medial sections of the trapezius are attached to the vertebrae medially and to the scapula laterally. The medial fibers of the trapezius assist the rhomboid major and minor during scapular adduction during the pull backward in machine rear lateral raises.

Machine Rear Lateral Raise

The deltoid works closely with other muscles (e.g., upper back, arms, middle and superior trapezius and pectoral muscles) in most shoulder movements. This makes it difficult, although not impossible, to isolate regions within the shoulder. As it turns out, the machine rear lateral raise provides an excellent means for isolating the posterior fibers of the deltoid and the middle and deep fibers of the upper back from anterior or medial fibers of the deltoid.

1. Position yourself in a seated chest (flye) machine, but instead of facing away from the back pad, your face and body should be positioned toward it.

2. The handles of the machine should be in front of you at the same height as your shoulders. You will know your arms/elbows are in the correct position if they are parallel to the floor when your hands grab the handles of the machine. If this is not the case, adjust the height of the seat on the flye machine before proceeding.

3. Take one handle in each hand. Your elbows should be pointing toward the rear of your body and away from the machine. If you have a pec deck that has pads instead of handles, simply place the back of your arms (triceps) into each respective pad. You will do the exercise identical to the version in which your elbows and triceps are pushing into a pad rather than pulling back on the handles.

4. Bend your elbows slightly and keep them at this position. Pull your hands backward as far as possible. Keep your arm abducted (out to the side) and do not let your elbow drop and point toward the floor. The trajectory of your arms and elbows should be directly posterior, but the movement should be at the shoulders and not the elbows. Concentrate on moving your arms and your posterior deltoid fibers as you use them to pull your hands backward and you squeeze your shoulder blades (scapula) together.

5. Hold the position for a count of two before slowly lowering the resistance back to the starting position. This will increase the activation of both the rear of the deltoid and the deep fibers of the middle back muscles. Do not let the weight rest on the stack before starting back out again. Rest only after you have completed at least 12 repetitions in your set.

Important Tips

You can increase the difficulty of the exercise by placing the seat lower so your arms begin above a position that is parallel to the floor. This will raise your elbows so they will be pointing slightly toward the ceiling as they move posteriorly. This will increase the stretch for the fibers of the posterior deltoid from the beginning and throughout the exercise, which will enhance the activation in this muscle.

If you find that your hand grip is giving out before your shoulders and middle back, you might want to switch to the seated pec deck machine. By pushing your elbows into the pads of the pec deck machine, and pushing them backward, you will eliminate grip strength fatigue and you will still get a great workout. On the downside, you lose a little range of motion with the pec deck, while the machine rear lateral raise will give you more movement and a slightly fuller contraction.

It’s not necessary, or even desirable, to try to use a heavy weight with this exercise. The shoulder joint, perhaps more than any other, should be worked with relatively strict movements. Thus, if you work carefully and with smooth, strict movements, your shoulders will respond, strengthen and firm. The added benefit is that the muscles in your middle back (between your shoulder blades) will be strengthened and toned by this exercise. You might also want to show those firm and toned shoulders off a bit more, as well. After all, your hard work deserves the attention!

References:

Cools AM, Witvrouw EE, De Clercq GA, Danneels LA, Willems TM, Cambier DC 2002. Scapular muscle recruitment pattern: electromyographic response of the trapezius muscle to sudden shoulder movement before and after a fatiguing exercise. J Orthop Sports Phys Ther, 32:221-229.

Gagey O, Hue E, 2000. Mechanics of the deltoid muscle. A new approach. Clin Orthop, 250-257.

Halder AM, Zhao KD, Odriscoll SW, Morrey BF, An KN, 2001. Dynamic contributions to superior shoulder stability. J Orthop Res,19, 206-212.

Moore KL. Clinically oriented Anatomy. Second edition. Baltimore, Williams & Williams, 661-672, 1984.

Roman-Liu D, Tokarski T, Kaminska J, 2001. Assessment of the musculoskeletal load of the trapezius and deltoid muscles during hand activity.  Int J Occup Saf Ergon, 7, 179-193.

Uhl TL, Carver TJ, Mattacola CG, Mair SD, Nitz AJ, 2003. Shoulder musculature activation during upper extremity weight-bearing exercise. J Orthop Sports Phys Ther, 33:109-117.

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