Muscle Form and Function April 05
Muscle Form + Function
By Stephen E. Alway, Ph.D., FACSM
Illustrations by William P. Hamilton, CMI
Mammoth Deltoid Mass with Standing Barbell Presses
When most bodybuilders begin their quest toward building a great physique, they possess a shoulder structure that more closely resembles a hanger on a coat rack than a championship shoulder girdle. Even if you've been blessed with wide shoulders, to be great, you will still have to work very hard to capture the round dense huge boulders needed to cap your shoulder joints. This is not such an easy task because 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. Still, poor shoulder muscles are almost impossible to hide because they're visible from almost every angle. On the other hand, mammoth striated deltoids produce the appearance of an expansively wide upper body even if your genes did not come with a wide bone structure.
Standing barbell presses (also called standing military 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 has three primary origins on the bony portions of the shoulder. The anterior fibers of the deltoid take their origin from the lateral part of the clavicle (collarbone). The posterior fibers take their origin from along the spine of the scapula (shoulder blade), which is on the upper and posterior side of the scapula. The medial fibers of the deltoid originate from regions between the previous two origins along the acromion of the scapula (the point of the shoulder). The fibers from this muscle converge on 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) and 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.
Four scapular muscles (subscapularis, supraspinatus, infraspinatus, and teres minor) form the rotator cuff muscles. All except the supraspinatus are rotators of the humerus bone at the shoulder joint. The infraspinatus muscle fills most of the infraspinatus fossa and it attaches between this fossa and the greater tubercle of the humerus bone. The teres minor muscle attaches between the superior (upper) part of the lateral border of the scapula and the greater tubercle of the humerus. Both the infraspinatus and teres minor muscles rotate the humerus laterally at the shoulder joint and help stabilize the shoulder joint by keeping the head of the humerus in the glenoid fossa. The supraspinatus muscle is a rounded muscle that lies in the supraspinatus fossa (a hollowed out area on the superior, or top, part of the posterior side of the scapula). It begins near the medial side of the scapula (close to the vertebrae and the center of the body) and runs over to the superior part of the head of the humerus. It lies deep to the trapezius muscle and part of it is deep to the coracromial arch and the acromion. The deltoid muscle covers the tendon of the supraspinatus. The supraspinatus muscle is particularly stretched during the overhead part of the press.
Another important part of the standing barbell press requires that the scapula (shoulder blade) be rotated upward and this engages the trapezius and the serratus anterior muscles. The superior (upper) part of the trapezius muscle 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 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 to rotate the shoulder joint that is part of the scapula upward during the upward part of the standing barbell press.
Standing Barbell Presses
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 standing barbell press involves too many other muscles, and it is often limited by fatigue in the triceps. Nevertheless, most bodybuilders will swear by this exercise for obtaining shoulder mass. Nevertheless, those with a particularly weak triceps or an injured rotator cuff might wish to employ other types of shoulder exercises.
- 1. Place a loaded Olympic barbell on the floor in front of a mirror. The mirror is not necessary, but it will help you keep your body position correct during the lift.
- 2. Place your feet under the bar about shoulder-width apart. Take a pronated grip on the bar with your hands a little wider than shoulder width.
- 3. Clean the bar to your shoulders and stand upright with the bar at the level of your clavicles, just below your chin.
- 4. Your elbows should be pointed toward the floor with your arms adjacent to the sides of your ribs. Take a breath, then blow it out as you press the barbell upward. The bar should pass in a line in front of your face rather than directly over your head.
- 5. Continue pressing upward and at the top of the movement you should find that your elbows are bent and pointing to the sides at about ear level. Do not fully straighten your elbows. If you monitor your press in a mirror, you should be able to easily maintain your proper pressing form.
- 6. Slowly lower the weight back to your clavicles as you inhale. Pause for a moment, then push the weight upward again.
The up phase of this movement involves flexion of the humerus at the shoulder, so the anterior fibers of the deltoid are worked strongly. It also causes abduction of the shoulder, which results in a good lateral deltoid workout. It's difficult to functionally isolate the muscles that attach to the scapula from other muscles in the shoulder. As a result, the deltoid works closely with the supraspinatus, so when the deltoid contracts, the supraspinatus also contracts. In addition, the upper (superior) fibers of the trapezius muscle help in many of the movements that are shared by the supraspinatus. Other muscles including the triceps, other upper back muscles and even the musculature of the upper chest are also active to some degree in standing barbell presses.
The elbow position ensures that the arm maintains an abducted position at the beginning and end of the exercise. This position favors activation of the medial fibers of the deltoid and simultaneously stretches the anterior fibers of the deltoid to improve its mechanical activation.
When pressing the weight in front of your face, you'll find that it's too easy to lean your head and upper torso backward and slip your hips forward. However, if this occurs, the upper portion of your chest will assume a much greater portion of the work as if you where doing an incline press, and thereby detract from your anterior shoulder development. Even more importantly, this places your lower back at an enormous risk for injury.
Most of the work for the deltoids is performed in the lower parts of this lift, so it's never necessary (or even desirable) to straighten your elbows at the top of the lift. Furthermore, by keeping your elbows bent, the anterior deltoids are under constant tension and they do not get a chance to rest at any point during the repetition. Thus, you'll begin to feel an incredible "burn" after a few repetitions of these, particularly if you do them more slowly and under control both in the upward lift and descent of the weights.
The standing barbell press will pile on more mass on the anterior and lateral parts of your deltoid muscle than most other exercises. However, it's up to you to determine how high and wide you will build the mounds of deltoid mass. If you're serious about building shoulders with standing barbell presses, you should be prepared to lose all remnants of any skinny coat hanger-like shoulder development, because by summer, mammoth rock-like deltoid boulders can cover your shoulder joints.
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