Jan 29, 2015
Complex Forces: Maintaining proper shoulder function
By B.J. Baker

A comprehensive shoulder training program can address key deficiencies and provide targeted treatment for a wide range of dysfunctions.

baseball pitcherIs it possible to keep an athlete’s shoulder — a joint with great potential for extreme functional ranges of motion — mobile, stable, strong, powerful and healthy? Is that a realistic goal given the complex demands of sports and the detrimental effects over time of gravity, poor posture, imperfect mechanics, and overuse? Like many sports medicine clinicians who work in performance training, I have been challenged by this shoulder conundrum.

In the past 20 years, I’ve worked with many types of shoulder injuries — a MLB pitcher with dead arm syndrome, a college swimmer with an impingement syndrome, a middle-aged client with a torn rotator cuff, and countless others. Regardless of the dysfunction, there are common threads in shoulder training programs that produce a complete, speedy recovery. Comprehensive shoulder assessment and treatment should focus on the thoracic spine, scapula, rotator cuff, and glenohumeral joint, while also addressing posture and energy transfer throughout the entire kinetic chain.

By addressing all these components in a progressive manner, I have found success treating a range of simple and complicated shoulder injuries. In this article, I’ll provide a detailed look at the main anatomical components of successful shoulder training, and offer exercise strategies that not only restore full function, but can also help make the shoulder more powerful and injury resistant.

Keys of anatomy

→ Thoracic spine. If an athlete has limited mobility in the middle 12 vertebrae of the spinal column, collectively known as the thoracic spine, the scapula won’t have a sound foundation from which to operate, increasing risk for a wide variety of shoulder problems. Thoracic extension is critical to athletic movement, but in today’s seated, backpack-toting, computer-dependent society, a head-forward and kyphotic (“hunchback”) posture has become commonplace. Consistently holding the thoracic spine in this forward position decreases its ability to move fully in other directions, and makes the scapulae much more likely to abduct and tilt anteriorly, closing down on the subacromial space.

That space already offers tight quarters for the rotator cuff tendon, biceps tendon, and subacromial bursa to perform their intended functions. Further decreasing it can lead to bone spurs on the underside of the acromion (a portion of the scapula) due to irritation and pressure from the impinged structures over time. In fact, failure to keep this space open results in some of the more common shoulder pathologies, including rotator cuff fraying, subacromial bursitis, and impingement syndrome.

To further complicate matters, there are three distinct types of acromions: flat (type one), smoothly curved (type two), and hooked (type three). Each functions a bit differently, and a type three acromion increases the likelihood of impingement and anterior bone spurs.

The thoracic spine is the most flexible spinal region for rotation — it has roughly eight degrees of rotation available at each segment. But if that mobility is limited, the body compensates by increasing rotation in the lower lumbar region, producing instability in a segment that’s meant to be stable. This is a common reason for low back injuries in golfers with inadequate thoracic turning.

To break the cycle of poor posture, athletes should be encouraged to regularly interrupt any long sedentary periods throughout the day.

Thoracic rotation should be as symmetrical as possible. Asymmetry can be addressed with corrective exercise, though it may be unrealistic to expect perfect symmetry in athletes whose sport requires unilateral rotation, such as pitchers, golfers, and tennis players. Severely asymmetrical thoracic spine rotation and extension compromise scapular stability and can wreak havoc on the kinetic chain, affecting everything from the glenohumeral joint to the subacromial space. Asymmetry also interferes with efficient energy transfer during the throwing motion, and leads to losses in core strength.

Scapula. Ideally, the scapula is positioned on a rib cage that’s mounted on a fully functioning, symmetrical thoracic spine. Any scapular dyskinesis, or alterations of normal position or motion, directly affect the glenohumeral joint and overall shoulder positioning. Dyskinesis can be caused by inflexibility, weakness, or muscle imbalances.

Pathologies associated with a poorly functioning scapula include glenohumeral instability leading to arthritis, impingement, rotator cuff tendonitis or tendinosis, rotator cuff tears, labrum injuries, and medial elbow pain and injury. In fact, studies have shown that poor stability in the scapula is found in 68% of athletes with rotator cuff problems, and 100% of those with glenohumeral instability.

An athlete’s scapulae must be proficient at protraction, retraction, elevation, depression, upward and downward rotation, and anterior and posterior tilting. No less than 17 muscles affect scapular stability and ability to provide a platform for the rotator cuff and glenohumeral joint. In addition, the glenoid portion of the scapula must be positioned and stabilized in three-dimensional space to act as an appropriate receptor for the humeral head as it rotates at the high velocities needed for activities like throwing.

Attempting powerful shoulder movements with an unstable scapula is like trying to shoot a large cannon from a small, untethered boat — the lack of a firm base will result in much wasted energy, unwanted movement, and inefficiency. Transferring powerful forces up the kinetic chain from the lower extremities through the hips, lumbar fascia, and thoracic spine, only to find a leak in the system at the scapula and glenohumeral joint, is an injury waiting to happen.

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Force couples, mobility, and stability all help maintain the instantaneous center of rotation (ICR) of the humerus in the glenoid. Having an ICR helps ensure proper biomechanical function in the joint, which in turn helps avoid labral fraying and tears. Simply put, when joints are centered, they perform optimally and injury risk is reduced.

Some patterns of dyskinesis related to labral tears in the throwing shoulder are linked to inflexibility of the pectoralis major and minor, and weakness of the lower trapezius and serratus anterior. When you examine an athlete, dyskinesis may present as the inferomedial (lower middle) scapular border being abnormally prominent at rest. Other signs include lack of acromial elevation and lack of full retraction in the throwing motion.

Weakness in the upper and lower trapezius and rhomboids can also lead to winging of the entire medial border of the scapula at rest. Both patterns create excessive scapular protraction and decreased scapular retraction and acromial elevation during throwing. Dysfunctions like these highlight the importance of activating and properly training the peri-scapular musculature, especially the lower trapezius and serratus anterior.

→ Glenohumeral joint. Due to the high stresses and forces created by overhead throwing, there are some pathologies and compensations commonly found in throwing populations. The glenohumeral joint, rotator cuff, and capsule are subjected to tremendous acceleration, deceleration, and distraction forces.

Glenohumeral internal rotation deficit (GIRD) is one of the most common adaptations that can affect throwers. GIRD develops due to the great deceleration forces placed on the posterior capsule and rotator cuff, which cause shortening of the muscles, tightness in the posterior-inferior capsule, and a shift of the glenohumeral rotation point. This migration and changing of the posterior capsule contributes to decentration, or loss of the ICR of the glenohumeral joint. For example, research has shown that Major League Baseball pitchers lose internal rotation in their throwing shoulder due to GIRD.

To evaluate the level of GIRD in a throwing athlete, clinicians perform a goniometric measurement of the total range of motion of both shoulders, adding internal and external rotation. Ideally, the values should be the same on both sides, but in most cases, the throwing shoulder lacks internal rotation and has greater external rotation.

The greater external rotation capacity might be partially explained by retroversion, or a bony adaptation of the humerus due to high volumes of throwing during the developmental years. However, GIRD is mostly caused by shortening of the posterior capsule and rotator cuff musculature.

The restriction of internal rotation should be roughly equal to the increase in external rotation in the same shoulder, and the internal rotation deficit should not be greater than 25 degrees when compared to the non-throwing shoulder. A GIRD above the 25-degree differential raises the likelihood of elbow pathology, pain, and labral tears. If the total range of motion of the throwing shoulder is lower than that of the non-throwing shoulder, addressing GIRD through stretching the posterior capsule and strengthening the posterior musculature of the rotator cuff is the best way to resolve the dysfunction.

Postural concerns

We’ve gotten through the tough part — the anatomy lesson. Now, let’s explore some specific factors that athletes can address through training and targeted intervention to improve shoulder performance and reduce injury risk. One of the biggest of these factors is posture.

Ideal upright posture involves equal co-activation of flexors and extensors, abductors and adductors, and internal and external rotators. In my setting, we have had great success correcting poor posture by focusing on the balance between these muscles, which can be dramatically improved through proper education and corrective exercise.

As mentioned earlier, a kyphotic or forward head posture (FHP) has become very common among athletes and the population at large. The literature suggests that postural changes associated with FHP follow specific patterns, including an increase in the thoracic kyphosis angle and downwardly rotated, anteriorly tilted, protracted scapulae, which in turn lead to increased compression in the subacromial space. All these elements of postural dysfunction are linked to an imbalance in the localized musculature. FHP also affects the function of the thoracic spine, decreasing its ability to extend and rotate, which is critical for symmetrical scapular function.

Regular soft tissue work and thoracic mobilizations are highly effective in helping to manage this problem. In particular, we know from electromyographic (EMG) studies that lower trapezius activation increases when performing self-myofascial release work and simple self-mobilizations using a foam roll. Since the lower trapezius and serratus anterior muscles play a critical role in proper scapular positioning and mobility, exercises to strengthen those muscles should be a top priority when addressing FHP.

A variety of protraction/retraction progressions can successfully activate and strengthen the serratus anterior. Exercise choices include straight-arm punching and retractions, including supine on a foam roll and in quadruped and standing positions using gravity, cables, and dumbbells for resistance. Push-ups are also an integral form of serratus work. Whenever you put a hand in contact with the floor in a closed-chain upper-body position, you get optimal activation of the serratus anterior as well as other scapular stabilizers and rotator cuff musculature. Lower trapezius activation and strengthening progressions include such exercises as prone Y, W, and I shoulder raises, scapular wall slides, 90/90 scapular retraction rope pulls (“face pulls”), lat pulldowns, horizontal rowing, and D2 patterns.

In her text Diagnosis and Treatment of Movement Impairment Syndromes, Shirley Sahrmann discusses a phenomenon called scapular downward rotation syndrome. She argues that frequent exposure to low-amplitude postural loads (in particular the force of gravity) during improper sitting, poorly constructed training programs, and other negative postural and behavioral influences causes the scapular downward rotator muscles to become short and weak. Thus, one of the most important scapular force couples for improving posture is the upper trapezius, lower trapezius, and serratus anterior, since they are responsible for upward rotation of the scapula.

To break the cycle of poor posture, athletes should be encouraged to regularly interrupt any long sedentary periods throughout the day — for instance, to break up long study and computer sessions by simply getting up, moving around, and doing things like stretching their pecs and performing arm circles. Some researchers believe that when we are in a sub-optimal postural position, the body begins to make negative soft tissue adaptations in as little as 15 minutes.

Again, the serratus anterior and lower trapezius are the key players here, so in addition to the aforementioned activation and strengthening progressions for these muscles, using a foam roller placed longitudinally along the spine while performing various scapular patterns can correct many postural issues. Positioning the body supine along a 6-inch round foam roll allows gravity to facilitate the stretching of restricted pecs. It also helps re-establish full ranges of motion for the scapular patterns, and aids in the proper activation of all involved musculature. Common patterns used for this type of exercise include straight-armed protraction/retraction, horizontal ab/adduction, D2, alternating shoulder flexion/extension, and dual shoulder flexion/extension.

Sleep positioning

Of course, for roughly one third of an athlete’s life, upright posture and muscle use patterns don’t apply. Learning about nightly sleep positioning can provide valuable information when addressing shoulder issues.

In our clinic, we have cleared up several cases of shoulder pain simply by improving the way a person positions their body at night, particularly with respect to the shoulder girdle and neck. When conducting an initial assessment of an athlete who’s experiencing shoulder problems, you should always ask when the pain is at its worst. If they say there’s frequent discomfort upon rising in the morning, sleep positioning should absolutely be reviewed.

For the health of the shoulders and spine, sleeping on a side is best, followed by sleeping on the back. Sleeping on the stomach is generally the least advantageous, since it increases the lordotic curve of the lower back and usually strains the neck. If an athlete is a side sleeper, they should fall asleep with the unaffected shoulder down, because that shoulder can best support the spine in its natural alignment and let the back muscles fully relax. This position also prevents compression forces from being placed on the problematic shoulder.

A supportive and comfortable mattress is obviously important, and for added alignment support, side sleepers can place a pillow between their knees, back sleepers can place one under their knees, and stomach sleepers (if they can’t be convinced to change their primary sleep position) can put one under the hips. Also, side sleepers will find that a knees-bent position helps keep the spine and hips aligned, which sometimes relieves back pain.

For the upper body, one of the best ways to improve sleep positioning is to provide better support for the upper torso, neck, and head. Instead of just one pillow under the head, athletes should consider sleeping with two to four pillows (depending on thickness) distributed around the body in front of the chest and under the chest, neck, and head, creating a support structure that improves comfort and alignment while helping to keep both shoulders from falling into an internally rotated position. The pillow(s) under the neck should be large enough to fill all the space between the head, shoulders, and mattress.

Generally speaking, the larger an athlete is, the broader their chest is and the more pillows they’ll need for adequate support. For broad-chested side sleepers in particular, placing several pillows in front of the chest at night is one of the most important adjustments that can be made to improve sleep positioning–it will prevent forward rolling and in turn help protect the down shoulder from impingement under the weight of the torso. In addition, the top shoulder will avoid falling across the chest into an uncomfortable, horizontally adducted, internally rotated position.

Ideally, an athlete falls asleep on their side with their chest completely perpendicular to the mattress, and the shoulders in an anatomically neutral position. Of course, position changes unconsciously several times a night to relieve pressure areas and promote equal blood flow, but the use of extra pillows can help ensure improved alignment and positioning throughout the night.

Soft tissue

The goal of soft tissue work is to decrease muscle tension, myofascial adhesions, and trigger points to improve overall tissue quality. Most sports medicine professionals understand at least the basics of manipulating soft tissue to promote these effects, but getting athletes into the treatment facility for regular massage is a major challenge. And of course, the real benefits of soft tissue therapy only come when it is applied regularly over time.

For that reason, I believe all athletes should learn to perform their own self-care to enhance soft tissue function and prevent injuries. Self-myofascial release (SMR) is an easy, inexpensive, and effective way to address common tissue restrictions and trouble spots. Putting pressure on tender areas of muscle tissue triggers the relaxation of the muscle spindles, helping to dissipate adhesions, increase blood flow, and improve overall mobility. Foam rollers, rolling sticks, and tennis balls are commonly used to assist in this type of therapy.

One thing athletes must learn in order to perform effective self-treatment is how much pressure to apply. Appropriate pressure should invigorate the tissue and produce some discomfort, but not intense pain. When they come to an area of increased tension, or an area that creates referred pain (felt in a different place on the body than the one being manipulated), they should learn to stay on that site with direct pressure for 10 to 30 seconds. Back-and-forth rolling movements with the aid of a roller or ball will promote blood flow to the area and break up myofascial restrictions.

Whether you are massaging an athlete or they’re doing it themselves, soft tissue work should always be the first part of a treatment session or workout — completed before stretching, corrective exercise, sprinting, conditioning, or strength work. A muscle will not activate to its potential or stretch properly when trigger points are present. Instead, this part of the muscle will attempt to protect itself by restricting movement and increasing stiffness in the surrounding tissue to offset pathological instability. These effects must be diminished or eliminated before any type of quality work can be performed.

Clinically, I have found SMR to be extremely valuable in reducing the treatment and rehabilitation time for conditions such as shoulder impingement syndrome, rotator cuff strains, labral tears, subacromial bursitis, and bicipital tendinosis — essentially, any condition that would benefit from improved soft tissue quality and function. In fact, I believe therapeutic or corrective exercise aimed at structures riddled with trigger points or compromised soft tissue is ineffective unless the soft tissue quality is first improved through activation and lengthening.

I often instruct my athletes to “bookend” their days with SMR, performing it first thing in the morning and right before bed. I also tell them to find time for one to three more sessions during the day, especially before workouts. Along with SMR, they use this time to activate the serratus anterior and trapezius muscles as discussed earlier, and to do range of motion work using scapular patterning with a foam roll.

There are a few hypersensitive soft tissue problem areas that often need special attention — in particular, the upper trapezius, levator scapulae, rhomboids, infraspinatus, and lateral border of the scapula just behind the axilla (armpit). In fact, inserting a tennis ball into this area while performing a side-lying sleeper stretch (passive internal rotation for the posterior capsule performed in a side-lying 90/90 position), then actively rotating the humerus into external rotation as the ball “rides” the localized area of sensitivity, is a very effective soft tissue mobilization technique.

Sensitivity will decrease over time and it’s not unusual for athletes who follow a daily SMR schedule to be relatively comfortable doing it within just one to two weeks. And it is not a coincidence that the growing ease of activation, strength of involved muscles, and function of those muscles will be accompanied by steady improvement in tissue quality.

The total-body unit

Anytime you watch an athlete perform an intricate task involving the shoulder complex, you can appreciate the diverse interactions and contributions of the lower extremities, core muscles, spine, and upper torso musculature. When treating any type of shoulder dysfunction, corrective exercise shouldn’t isolate the joint and ignore these pivotal relationships. A comprehensive, total-body approach is the only way to address all the relevant components of the kinetic chain.

For example, during the throwing motion, in order for force to be passed efficiently along the kinetic chain to the distal segments, each bone and joint needs to be positioned properly to receive its portion of the force load. In the normal kinetic chain, the ground, legs, and trunk generate the force, the shoulder acts as a force conduit and attenuator, and the arm delivers the outcome.

Thus, we cannot ignore the hips and core when addressing shoulder function. Often, a throwing athlete’s hip on the non-dominant side has mobility, stability, or strength issues, or the knee, ankle, and foot have strength imbalances relative to their counterparts on the other side. While they’re anatomically far from the shoulder, weaknesses in these areas can greatly affect overhead movement mechanics.

To be more specific, research has identified several kinetic chain alterations as being associated with shoulder impingement, rotator cuff injury, and instability. In addition to the aforementioned GIRD and scapular dyskinesis, all these conditions have been directly linked to shoulder injuries:

  • Inflexibility in the lower back.
  • Non-dominant single-leg stance instability.
  • Pelvic instability during step-up movements.
  • Decreased internal rotation of the non-dominant hip (sometimes known as HIRD: hip internal rotation deficit).
  • Decreased dorsiflexion and ankle mobility on the non-dominant side.
  • Loss of knee flexion or hamstring flexibility on the non-dominant side.

Sometimes, the effects of one of these conditions are observable during activity. For instance, in baseball pitchers with HIRD, the decreased internal rotation causes the pitcher to “fly open” earlier in the delivery (the upper body, shoulders, and arms open with the stride leg and front hip). It also interferes with the consistency of his arm slot positioning and release point. Flying open causes the arm to drag, because the stronger and larger muscles of the legs, hips, and trunk have already fired and are not available to create torque. As a result, most of the pitch velocity has to come from the shoulder and arm musculature, which greatly increases the likelihood of an injury to the rotator cuff, labrum, or medial elbow.

But other times, lingering instabilities and mobility limitations can only be identified through movement screens and other testing. Once identified, these problems can be addressed with individualized corrective exercise, and the end result is often an improvement in shoulder performance, even if the shoulder wasn’t the primary focus of the corrective work.

For the same reason, it’s also valuable to incorporate full-body exercises that develop the entire kinetic chain when designing strength programs for throwing athletes. In my setting, I make medicine ball training an integral component of conditioning progressions because it’s an excellent way to build core strength, stabilization, and explosive power along the entire kinetic chain. We use a variety of stances, such as facing a wall, split stance, perpendicular to a wall, parallel, half-kneeling, and tall kneeling.

Overhead throwing for non-throwing athletes serves as anterior core work, and overhead throwing for throwers is deceleration work for the posterior cuff and scapular stabilizers. We incorporate as many compound movements as possible for multi-joint activation.

The ultimate objectives of a sound shoulder training program are to build strength, symmetry, functional movement, and alignment mechanics. Athletes will never tell you, “I want better internal rotation in my glenohumeral joint and increased subacromial space.” They just want to throw harder, be more durable, and experience full functionality without pain. With a comprehensive approach that addresses the key muscles, joints, and structures while developing the entire kinetic chain, you can help them reach those goals.

B.J. Baker, ATC, CSCS, is Head Athletic Trainer at Train Boston and former Strength and Conditioning Coordinator for the Boston Red Sox. 

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