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Posted: May 14, 2006
Multisport: Swimmer’s Shoulder
By Jenn Turner, BPHE (hon), DC, ART®, CPTN- CPT, CCSS(C) (resident)
Introduction
If you are a swimmer or triathlete that has ever put some serious time in the pool or lake, chances are you have had some sort of shoulder injury. Statistics reveal that 80 % of competitive swimmers have had a shoulder injury at some point in their career (1). Shoulder injuries are more common in swimmers than any other overhand athletes as swimmers shoulder muscles aren’t given any rest before they are required to perform the next repetition. Some swimmers and triathletes may complete up to 2500 shoulder revolutions a day (4). When 90% of the propulsive force of swimming comes from the upper body, it is easily understood why the shoulder is very susceptible to overuse or cumulative trauma disorders (1).
Cumulative Trauma Disorder Cycle
Continuous motion on the shoulder can lead to a cycle of muscle fatigue, inefficient and faulty stroke mechanics, injury to soft tissues due to microtrauma and muscle imbalance due to compensation. This cycle is very difficult for the athlete to break. This is especially challenging for a competitive swimmer or triathlete who can’t afford to take time off of their sport to allow the shoulder to heal. It is these athletes who have the most problem recovering and continuing on in their sport(1).
Shoulder Anatomy
The shoulder is the most complex joint in the entire body and has the largest range of motion. The three bones that comprise the shoulder joint (or gleno-humeral joint) are the scapula, the clavicle and the humerus. The most significant muscles of the shoulder are the rotator cuff muscles- involving the subscapularis, supraspinatus, infraspinatus and teres minor muscles. These muscles function to stabilize the humeral head in the shoulder socket or glenoid cavity. Additional stabilization is provided by the serratus anterior, latissimus dorsi, rhomboids, lower trapezius and levator scapulae muscles. These muscles are essential for providing stability to the free-floating scapula which has tremendous influence on the shoulder joint mobility. All of these muscles are important to evaluate in a swimmer with a shoulder injury (7).
Swimmer’s Shoulder
The most common type of shoulder injury is “impingement syndrome” or “Swimmer’s shoulder”. This expression is generally used as an umbrella term to describe numerous pathologies of the shoulder joint. Looking at the picture above of the bony anatomy of the shoulder joint, you can see a small gap between the humeral head and the acromion. This is called the sub acromial space and it is a very small distance measuring only 5-10 mm (7). Most impingement injuries involve this space and usually implicate the supraspinatus tendon, biceps tendon or subacromial bursa, all structures located within this opening. These structures can become “pinched” between the humeral head and the acromion, particularly during the action of shoulder flexion – or raising the arm above the head.
Recent research has coined the term PRIMARY impingement for mechanical problems in the joint such as excess bone in the subacromial space (2). Generally this is an uncommon occurrence in swimmers and more widespread in older patients. Osteophytes or bone spurs can grow on the acromion impeding the small space where the supraspinatus tendon sits (7).
SECONDARY impingement is the usual cause of shoulder pain in swimmers (1,2,4). This kind of impingement in related to “instability” of the shoulder joint. For reasons discussed below, the humeral head is able to move forwards or upwards more than normal and the soft tissues between the humeral head and the acromion can become easily compressed.
This injury indicates a problem or a change within the neuromuscular system that allows this instability to occur. Changes such as modifications in the amount of muscular activation or an increase in muscle tightness of certain muscles can contribute to the cycle of cumulative trauma discussed previously.
Causes Of Swimmers Shoulder
There are various factors that can contribute to the development of swimmer’s shoulder.
The muscles mentioned earlier that stabilize the scapula can fatigue or be affected by the changes in neuromuscular functioning. This causes abnormal movement between the scapula and the humerus. As a result, imbalanced stress and strain on anterior structures of the shoulder cause increased laxity at the posterior shoulder creating excessive forward movement of the humeral head. This in turn results in secondary impingement on the structures passing through the acromial space (ie. the supraspinatous tendon, biceps tendon and subacromial bursa) causing pain (4).
All of the below can be contributing factors in the development of swimmer’s shoulder (1,2,3,4,6):
• faulty stroke mechanics
• sudden increases in training loads or intensity
• repetitive micro traumas related to overuse
• training errors (such as unbalanced strength development)
• use of training devices like hand paddles
• higher levels of swimming experience
• practices that uses a higher percentage of one stroke, particularly freestyle
• weaknesses in the scapular stabilizer muscles
• weakness or tightness of the posterior cuff muscles or the posterior shoulder capsule
• shoulder joint with excessive mobility
• previous, unrehabilitated or poorly rehabilitated shoulder injuries (ie. Dislocations, tendinosis)
Signs & Symptoms
The signs and symptoms of swimmer’s shoulder are usually very typical. They include slow onset of pain over time, a decrease in range of motion, and pain at the front of the shoulder. Coaches may find that swimmers change their stroke mechanics to avoid pain provoking positions in the water. In particular, the swimmer may find that pain in the first half of the pull is exceptionally uncomfortable.
STAY tuned as the next health feature will focus on treatment and rehabilitation strategies for swimmer’s shoulder, something that is not always done properly, leaving the shoulder susceptible to further damage!
References
1. Su, KPE, Johnson, MP, Gracely, EJ & Karduna AR. (2004). Scapular rotation in swimmers with and without impingement syndrome: practice effects. Medicine & Science in Sports & Exercise. 36(7):1117-1123.
2. Blanch, P. (2004). Masterclass: Conservative management of shoulder pain in swimming. Physical Therapy in Sport. 5:109-124.
3. Johnson, JN, Gauvin, J & Fredericson, M. (2003). Swimming injury biomechanics and prevention. The Physician and Sportsmedicine. 31(1).
4. Scuderi, GR & McCann, PD. Sports Medicine A comprehensive Approach, 2nd Ed. Mosby (2005) Chapter 41- Swimming Injuries.
5. Sterling, M, Jull, G & Wright A. (2001). Cervical mobilization: concurrent effects on pain, sympathetic nervous system activity and motor activity. Manual Therapy, 6:72-81.
6. Pink, MM & Tibone, JE (2000). The painful shoulder in the swimming athlete. Orthopaedic Clinics of North America. 31:247-261.
7. Andrews, JR, Harrelson, GL & Wilk, KE. Physical Rehabilitation of the Injured Athlete. 3rd Ed. Saunders (2004). Chapter 19- Shoulder Rehabilitation.
Dr. Jenn Turner is a chiropractor and a certified ART® provider. She is a Team Canada Triathlon team member and is familiar with injuries caused by swimming, biking and running. She is completing a residency in Chiropractic Sports Sciences in order to further her training specializing in treating athletic injuries. Dr. Turner practices Chiropractic in North Vancouver at a multi-disciplinary sports medicine clinic called Fluid Movement Inc. (110-889 Harbourside Drive, North Vancouver BC, V7P 3S1 www.fluidmovement.ca ) and can be reached at jturner@fluidmovement.ca.
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