Swimmer's Shoulder: Prevention and Rehabilitation

Competitive swimmers train an average of ten to twenty thousand yards per day. At eight to ten arm cycles per twenty-five yards, this leads to nearly one million shoulder rotations per week. It’s no wonder studies have shown the lifetime incidence of shoulder injury in competitive swimmers is over 70%.

The most common shoulder injury incurred in swimmers is “swimmer’s shoulder.” This syndrome is a combination of any of the following: rotator cuff or bicipital tendonitis, subacromial bursitis, shoulder impingement, and glenohumeral joint instability. It is not simply a condition of overuse; the repetitive use must be combined with some other aggravating factor, such as supraspinatus or biceps avascular tendinosis, impingement syndrome, labral injury, or instability due to ligamentous laxity or muscular dysfunction.

Muscle Imbalances and Scapular Dysfunction
The most common problem leading to swimmer’s shoulder is a weak serratus anterior. This increases the rhomboid activity, which leads to anterior impingement of the biceps and supraspinatus tendons. The serratus anterior also attaches to the scapula, which is the link in the kinetic chain from the legs and trunk to the shoulder. In fact, scapular dysfunction is present in 68% of all rotator cuff problems. For every two degrees the glenohumeral joint moves, the scapula should move one degree.

Impingement
Impingement occurs when the soft tissues of the subacromial space (supraspinatus tendon, tendon of the long head of the biceps, and the subacromial bursa) are compressed between the head of the humerus, the coracoacromial arch, and the anterior acromion. Inflammation of these tissues worsens the impingement. Impingement is common in swimmers, volleyball players, baseball pitchers, and tennis players, due to increased overhead movements. Poor flexibility in the shoulders can lead to increased impingement symptoms. It is also caused by prolonged postural stresses, such as sitting at a computer for work.

Shoulder Laxity
The rotator cuff holds the humeral head, preventing anterior and superior movement. Common causes of instability are shoulder hypermobility, increased internal rotation and adduction strengths, overuse, overuse of hand paddles while swimming, technique flaws, and decreased core strength. Instability leads to subluxation, and, combined with repetition, leads to inflammation and pain, which leads to scarring, which leads to more inflammation, pain, and dysfunction.

Prevention and Rehabilitation: Technique Changes
Swimming technique needs to incorporate body rotation with core strength, early catch, early exit, and straight-through arm pulls. Thumb-first hand entry stresses the biceps attachment to the labrum, leading to impingement. Hand entry that crosses the midline leads to anterior impingement. Asymmetric body roll and unilateral breathing both cause a compensatory crossover, which increase the risks of impingement. Proper, symmetrical body roll decreases most impingement risks. Other technique contributors are improper head position, forward shoulders, and scapular instability (see Strengthening section). Stretching, proper warm-up, and preventive strengthening must also be incorporated into practices.

Prevention and Rehabilitation: Strengthening
Strengthening, both for injury prevention and rehabilitation, must focus on stretching the strong groups of muscles and strengthening the weak ones. Shoulder injury is prevented first by core stabilization and then by scapular stabilization. Strengthening should focus on endurance of the serratus anterior, lower trapezius, and subscapularis, as well as taking into account the strength ratio of the internal and external rotators. Stretching should focus on the pectoralis major and minor, the posterior shoulder capsule, and the latissimus dorsi. Core strengthening should focus on the lower abdominals and increased pelvic control.

Exercises to include in a swimmer’s routine include: scapular elevation with the thumbs up and arms thirty degrees forward; push-up plus; rowing with scapular retraction and palms rotated up; reverse push-ups; unilateral shoulder shrugs; horizontal abduction; and shoulder abduction. Sport-specific exercises include ball throws with a rebounder, punching, and PNF 2 maneuvers. Athletes can also use an ergometer to work these muscles. These exercises should be done with low weights, 1-3 sets with 25-30 repetitions, or to fatigue. When these exercises can be done without pain, gradually increase the weight in one-pound increments. This routine should be done either after swimming, or as an isolated workout session, to decrease injury risk. Core strengthening exercises can be done any time.

For the internal and external shoulder rotators, isolated exercises have been shown to emphasize better muscular recruitment. If the external: internal rotation strength ratio is 70-80%, focus on internal rotation strengthening. If it is less than 70%, focus on the external rotators. When the ratio is 60-65%, replace the isolated movement with dynamic exercises, such as pull-ups, latissimus dorsi pull downs, overhead presses, reverse pull-ups, and push-ups. All of these exercises will enhance glenohumeral stability. They should be done with 3-7 sets of 8-15 repetitions, with 2-4 minutes of rest between sets.

Conclusion
Approaches to prevention and active rehabilitation of swimmer’s shoulder are essentially the same: correct improper technique; stretch the tight musculature of the chest and anterior shoulder; strengthen the core musculature and the scapular stabilizers; and reduce strength imbalances in the shoulder rotators. Coaches and rehabilitation providers need to work together with these athletes in order to prevent future injury and correct problems that may already be present.

References:
Beneka, Anastasia, Ph.D., Nickos Aggleoussis, Ph.D., Konstatinos Gramnakopoulos, Ph.d., and Georgios Godolias, MD. “Identifying and Treating Rotator Cuff Imbalances.” Strength and Conditioning Journal, Apr 2006: 92-95.

Brumitt, Jason, MSPT, SCS, ATC, CSCS*D, and Erik Meira, PT, CSCS. “Scapula Stabilization Rehab Exercise Prescription.” Strength and Conditioning Journal, June 2006: 62-65.

Johnson, James N., MD, Jason Gauvin, PT, ATC, and Michael Fredercison, MD. “Stronger Shoulders for Swimmers.” The Physician and Sports Medicine, Jan 2003. Online at www.physsportsmed.com.

Johnson, James N., MD, Jason Gauvin, PT, ATC, and Michael Fredericson, MD. “Swimming Biomechanics and Injury Prevention.” The Physician and Sports Medicine. Online at www.physsportsmed.com.

King, Mark, DC. “Impingement Syndrome.” Dynamic Chiropractic, Oct 2005: 28.

Koehler, Scott M., MD, and David C. Thorson, MD. “Swimmer’s Shoulder: Targeting Treatment.” The Physician and Sports Medicine, Nov 1996. Online at www.physsportsmed.com.

Kurtz, James T., DC, DACRB, CCSP, CSCS. “A Chiropractic Case Report in the Treatment and Rehabilitation of Swimmer’s Shoulder.” Journal of the American Chiropractic Association, Oct 2004: 32-38.