As the temperature outside rises, all levels of swimmers will make their way into pools, lakes, bays and oceans. From first time age group swimmers to aspiring triatheletes, there is a steady increase of both recreational and competitive swimmers during the summer months. Swimming is seen as an excellent form of cardiovascular exercise that results in minimal wear and tear on the joints. While the low impact nature of swimming make it seem like a relatively “injury free” sport, the repetitive nature of strokes make shoulder injuries all too common. However, with proper preparation and training, shoulder injuries can be reduced, making swimming a safe and healthy sport for both novice and competitive swimmers.
Although referred to as a ball-in socket joint, the shoulder socket is flat and more of a suspended joint where ligaments and muscles account for the stability of the joint. As can be expected, without a deep socket like the hip, the shoulder loses stability in return for mobility. The important structures that give stability to the shoulder include ligaments, which connect bone to bone, and muscles, which are connected to bone by tendons. The ligaments are the innermost support structures and are covered by an intricate layering of muscles. The rotator cuff muscles (subscapularis, supraspinatus, infraspinatus, and teres minor) are the muscles that are the most intimately attached muscles of the shoulder and are surrounded and covered by larger more powerful muscles like the deltoids and the pectoralis major.
Because the shoulder is the primary motion generator in swimming, it is the site of most swimming injuries. Dubbed “Swimmer's Shoulder”, the injury to most swimmers shoulders' involves overuse or repetitive microtrauma resulting in inflammation of the surrounding tendons. The shoulder relies on a delicate balance of muscle coordination and strength to perform without excessive wear on the bone or overuse of one or more tendons. When a particular motion is repeated thousands of times in one practice, biomechanical flaws are magnified.
A frequent pitfall in early swimming technique is to overuse the groups of muscles that bring the arm closer to the body during the pull phase of the freestyle stroke. The muscles that bring the hand under the body include the pectoralis major, one of the strongest muscles around the shoulder, making it a great power generator. The pitfall is that this muscle may be relied on over other muscles if shoulder strength is not balanced (1). Ideally, in the freestyle stroke the hand reaches and enters the water finger tips first and then begins pulling water towards the chest along an imaginary line that splits the right and left side of the body. The concern is when the hand crosses this line to the opposite side of the body, putting the shoulder, albeit momentarily, in a bad position (1). In this position there are increasing demands on the smaller rotator cuff muscles that intimately surround the shoulder (2). Under these greater demands, rotator cuff muscles like the supraspinatus may become fatigued and inflamed and the muscles may rub against the ridges of the shoulder causing further inflammation and pain.
Prevention
1. Ample stroke technique at young ages. Coaching by someone experienced in swimming mechanics is essential for early stroke development and technique . Biomechanical flaws are often subtle and more easily recognized by a viewer and not the swimmer. Videotaping practice sessions is a useful tool, where stroke mechanics are reviewed with the swimmer.
2. Reinforcement of drills for all swimmers that focus on good technique. Drills that focus on proper stroke mechanics has a place in training regimens at all levels. While the amount of time dedicated to proper form will change as stroke mechanics are mastered reinforcement is important.
3. Core training with a focus on scapula stabilizing exercises provides a link in the kinetic chain between the legs, trunk and shoulder (3). Four effective exercises include scapular elevation, push-ups with a plus, rowing, and press-ups (4). Directions for these exercises can be found at: www.physsportsmed.com/issues/2003/0103/johnson_pa.htm
4. Strengthen external rotators because external rotators like the teres major of the rotator cuff are weaker muscles than the opposing pectoralis major and latissimus dorsi. Strengthening these muscles can limit overuse of other rotator cuff muscles like the supraspinatus (2). Along the same thinking, stretching of the frequently tight pectoralis major and latissimus dorsi are effective in keeping the shoulder balanced (1).
Conclusion
The shoulder relies on a delicate balance of muscle strength and flexibility for optimized performance in sports like swimming. Proper conditioning and stroke technique are necessary for long-term participation in the sport.
Brian Bast, D.O.
Dept. of Physical Medicine and Rehabilitation
Mount Sinai Medical Center
References:
1. Johnson J, Gauvin J, and Fredericscon M. Swimming Biomechanics and Injury Prevention. The Physician and Sportsmedicine. 2003;31(1).
2. Nadler S, Sherman A, and Malanga G. Sport-specific shoulder injuries. Phys Med Rehabil Clin N Am. 2004;(15):607-626.
3. Kibler W. The role of the scapula in athletic shoulder function. Am J Sports Med. 1998;26(2):325-337.
4. Johnson J, Gauvin J, and Fredericson, M. Stronger Shoulders for Swimmers. Physician and Sportsmedicine. 2003;31(1).
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