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Packing on Trapezius and Deltoid Mass With Smith Machine Shoulder Presses |
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Written by Stephen E. Alway, PhD, FACSM
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Monday, 23 April 2007 |
The shoulder is a complex structure, but its complexity should not be a hindrance in developing a set of massive and symmetrical deltoid and trapezius muscles. When it comes to bodybuilding, poor shoulder muscles are almost impossible to hide, because the shoulders are visible from all angles. On the other hand, mammoth trapezius muscles and massive striated deltoids produce an illusion of upper body width unlike development in any other body part.
The shoulder joint is vulnerable to injury and it is therefore not uncommon to find that many gym-related injuries are shoulder-related. Injury can be avoided and muscle symmetry will only be achieved if all three regions of the deltoid are stressed and proper exercise technique is employed.
Activated Muscles
Smith machine presses primarily activate the flexion/extension and abduction components of the shoulder. The deltoid muscle is involved in all these functions. Although they are not truly separate heads, the deltoid muscle does originate from three regions on the bony portions of the shoulder. The anterior fibers of the deltoid take their origin from the lateral part of the clavicle. The posterior fibers take their origin from along the spine of the scapula, which is located on the upper and posterior side of the scapula. The medial fibers originate from regions between the previous two origins from the acromion of the scapula. The fibers from this muscle converge to attach to the anterior and upper portion of the humerus bone. The anterior fibers of the deltoid produce strong flexion of the humerus at the shoulder (bringing the humerus bone of the upper arm forward). They also produce medial (internal) rotation of the humerus at the shoulder. The medial fibers primarily produce abduction of the humerus (raising the humerus away from the side of the body). The posterior fibers produce strong extension (bringing the humerus bone posteriorly) and lateral rotation of the humerus. In medial rotation, the anterior aspects of the arm and palm of the hand are rotated toward the body. The reverse is true for lateral rotation.
Another important part of the press overhead requires that the scapula (shoulder blade) be rotated upward; this engages the trapezius and the serratus anterior muscles. The superior (upper) part of the trapezius muscle (the top of the diamond) runs from the base of the skull and the seventh cervical (neck) vertebrae to the lateral part of the clavicle (collarbone) and along the scapula. The superior fibers lift the scapula and shoulder structures toward the ears (shrugging). The middle one-third of the trapezius extends from the upper thoracic spine, laterally to the posterior side of the scapula and clavicle. The most inferior (lowest) parts of the muscle travel from an inferior medial position at the lower thoracic vertebrae and attach to the scapula from below. The primary independent function of the inferior fibers of the trapezius is to forcefully depress (lower) the scapula after it has been elevated by the upper fibers of this muscle. Working together with the serratus anterior, the fibers of the trapezius muscle cause an upward rotation of the scapula so you can bring your arm over your head.
The fibers of the serratus anterior attach to the superior eight ribs, but they do become visible where they interlock with the external oblique muscle. The fibers insert along the medial border of the scapula. The serratus anterior stabilizes the scapula and helps rotate the shoulder joint that's part of the scapula upward during the press upward on the Smith machine.
Seated Smith Shoulder Press (behind the neck)
There have always been controversies about what constitutes the best shoulder exercise. The most fundamental type of shoulder exercise involves forms of pressing movements. Some people have argued that the shoulder press involves too many other muscles, and it's often limited by the fatigue status of the triceps. Nevertheless, most bodybuilders swear by this exercise. The Smith machine version provides greater stability and safety, as well as good isolation of the shoulders and trapezius muscles. Nevertheless, those with particularly weak triceps might wish to employ other types of shoulder exercises.
1. Place a bench that has a back support between the upright stands of a Smith machine. When you're seated on the bench, the bar should be above your head, but the trajectory of the bar should go behind your head.
2. Place your hands on the bar with a pronated grip that's about two inches wider than shoulder width, so the forearm will travel in a vertical line during the movement.
3. Flex your wrists to move the safety latch so the weight is free to travel up and down on the vertical poles.
4. Push the weight upward and begin to straighten your elbows (elbow extension). Ensure that your forearms are as vertical as possible throughout this upward movement. Continue to push the weight upward to an overhead position, but terminate the extension just short of locking out your elbows. By keeping your elbows slightly bent at the top, the anterior and medial deltoids will be maintained under constant tension and they will not get a chance to rest at any point during the repetition. This will result in your feeling an incredible burn after a few of these non-lockout repetitions (particularly if you do them more slowly and under control both in the upward lift and in the descent of the weights).
5. Flex your neck slightly forward and slowly lower the bar to a position behind your neck. While the bar is dropping behind your neck, pull your elbow slightly posteriorly (backward), rather than pulling your head and neck excessively forward.
6. When the bar is about to make contact with the trapezius muscles at the base of the neck, reverse the movement and begin the pressing portion again. If the bar contacts your neck, stop and move your seat further forward.
7. At the end of the set, flex your wrists to roll the bar so it locks into the safety-latched position.
Important Tips
There are at least two advantages of using the Smith machine. First, you don't have to worry about losing your balance during the lifting, so you can concentrate on the exercise and the muscles that are being activated. Second, when you're fatigued, you can simply flex your wrists and roll the bar so the safety hooks on the bar lock onto the uprights. This provides a nice safety feature to prevent injury, without having to rely on an alert partner to get the weight.
The up-phase of this movement involves both flexion and abduction of the humerus at the shoulder. This means both the anterior and medial fibers of the deltoid will be worked. However, the version behind the head also forces some small amounts of shoulder extension in the down phase, thereby obtaining some work for the posterior fibers of the deltoid. The trapezius and serratus anterior muscles are active for most of the press upward. The trapezius and other upper back muscles and the triceps will do most of the work during the last quarter of this lift as your arms are straightened. Most of the work for the deltoids is performed in the lower region of this lift. Thus, it's not essential to lock out your elbows at the top of this movement.
It's also worth noting that the descent of the Smith bar behind the neck should be slow and controlled (i.e., do not bounce the weight off of your upper back to begin the upward movement). I have known a few lifters who carelessly let the bar drop and bounce off the base of their necks, with the result of cracking their cervical (neck) vertebrae. There is no excuse for this type of sloppy training that only leads to costly injuries.
Since the shoulder is a very unstable joint and is literally being held together by its muscle attachments, it's important to isolate the muscle regions with relatively strict movements; the Smith machine helps keep the movements strict. The press behind the neck should not be done by someone who has suffered a rotator cuff injury (unless approved by a physician) because the extension phase of the lift places a lot of stress on the supraspinatus muscle of the rotator cuff and this can destabilize the shoulder joint. It is probably a better (and safer) choice to use medium weights and aim for at least eight to 10 repetitions when you're completing presses behind the neck on the Smith machine, as opposed to using super human weights for fewer than five repetitions. Although you can never guarantee an injury-free career, there is no point trying to invite injuries. It's important to train strictly and carefully when you are working the shoulders. After all, your goal is to produce massive shoulders and trapezius, not to end up on a surgeon's table.
References
Bull, M. L., Vitti, M., Freitas, V., & Rosa, G. J. (2001a). Electromyographic validation of the trapezius and serratus anterior muscles in military press exercises with middle grip. Electromyogr Clin Neurophysiol, 41, 263-268.
Bull, M. L., Vitti, M., Freitas, V., & Rosa, G. J. (2001b). Electromyographic validation of the trapezius and serratus anterior muscles in military press exercises with open grip. Electromyogr Clin Neurophysiol, 41, 179-184.
Ekstrom, R. A., Donatelli, R. A., & Soderberg, G. L. (2003). Surface electromyographic analysis of exercises for the trapezius and serratus anterior muscles. J Orthop Sports Phys Ther, 33, 247-258.
Fees, M., Decker, T., Snyder-Mackler, L., & Axe, M. J. (1998). Upper extremity weight-training modifications for the injured athlete. A clinical perspective. Am J Sports Med, 26, 732-742.
K.L. Moore, A.F. Dalley. (1999) Clinically Orientated Anatomy. 4th ed. London, Baltimore: Lippincott Williams & Wilkins ISBN: 0-683-06141-0
Raske, A. & Norlin, R. (2002). Injury incidence and prevalence among elite weight and power lifters. Am J Sports Med, 30, 248-256.
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