A well-rounded shoulder workout includes both compound (multi-joint) and isolation movements. The basic compound exercise is the overhead press. But raising your arms overhead increases the likelihood of injury secondary to impingement (compression of the supraspinatus tendon of the rotator cuff under the bony acromial arch). Accordingly, overhead presses should be avoided if injury risk is high. If your shoulders are healthy, including presses in your regimen is a good strategy. But it is important to consider benefit-risk ratio when deciding how to perform this movement. The overhead position is particularly dangerous when the humerus (upper arm bone) is also externally rotated (turned rearward). This presents a problem when a barbell is used. Pure abduction (raising the arm directly to the side) is impossible with the bar because your head is in the way. Obviously, you have to either externally rotate to pass the bar behind your head or bring your elbows partially forward to allow it to pass in front. The former increases injury risk while the latter shifts emphasis to the anterior head of the deltoids, an area that is usually overdeveloped in relation to other parts to begin with.
This dilemma can be avoided by pressing with dumbbells or on a machine with split handles that allow you to lower your hands directly to your sides. But choose your body positioning on such a machine wisely. Many are made with handles situated in front of the body, causing a movement range that shifts involvement to the muscles of the front. By placing a pad behind you, the proper motion can be achieved. The correct range with dumbbells only requires paying attention to where your elbows point as you descend. If they are directly out to your sides, you are right on the money.
Effective shoulder training also includes isolation movements that stress the three distinct heads of the deltoids. Raising your arm to the front accentuates the anterior head so this movement is usually low on the priority list. Far more important are lateral raises, which emphasize the medial and rear portions. Any exercise that involves the arm being raised to the side (dumbbell lateral raises or upright rows) will target the medial head. On these, it is again important not to bring your arms forward. In addition, maintaining the humerus in an internally rotated posture as the arm is raised to the side becomes problematic when a 90 degree angle at the shoulder is approached. As a result, these movements should be terminated before the arm is parallel to the ground. The posterior head is targeted when the arm is drawn back against resistance. Bent-over dumbbell lateral raises and reverse flyes on a machine are examples of appropriate movements. It's important to minimize motion of the scapulae (shoulder blades) on these exercises. While all motions of the arm at the shoulder require a concerted effort of the muscles that act on the arm and those that function to move the scapulae (reposition the socket), minimizing this aspect of the motion will ensure that your deltoids are bearing the brunt of the effort.
In addition to the superficial deltoids, the underlying musculature that functions to stabilize the shoulder (the four muscles collectively known as the rotator cuff) should also be addressed. The internal rotator (the subscapularis) is usually not deficient and, because major players like the pecs, lats and anterior delts assist it, doesn't require much special attention. The external rotators (the teres minor and infraspinatus), on the other hand, are often lacking and imbalance or weakness in these stabilizers is a precursor for injury.
Every time the arm is raised, they are responsible for preventing the humeral head from being pulled up in the socket and impinging the supraspinatus tendon. The fourth rotator cuff muscle (the supraspinatus) shares a similar line of pull as the medial head of the deltoids, so it is difficult to isolate. It's most active when the humerus is internally rotated and movement is restricted to the initial phase of abduction.
In addition, raising the arms in an oblique plane at a 45-degree angle in front of the body is the best alternative. While it's important to train the muscles that cross the shoulder, attention must also be given to those that stabilize the scapulae. Muscles that pull the scapulae upward (the upper trapezius and levator scapulae) are normally worked frequently (shrugs, upright rows and overhead presses target these) and shouldn't be a major concern. Far more essential are those that hold the shoulder blades back (the rhomboids and middle trapezius) and down (the lower trapezius). In addition, muscles that connect the scapulae to the rib cage in front (the serratus anterior and pectoralis minor) are also critical for stability.
Fred DiMenna, a Certified Strength and Conditioning Specialist and Lifestyle and Weight Management Consultant, is a two-time Natural Mr. United States and a WNBF drug-free professional bodybuilder. Visit him on the web at www.freddimenna.com or email him at: firstname.lastname@example.org.