Shoulder pain caused by impingement of subacromial tissues is a common
overuse injury on swimming, especially among adolescents who may have rigorous
training schedules and be skeletally immature. A case of a 14 year old girl
with swimmer's shoulder demonstrates the diagnostic work up, which involves
pertinent history, inspection, palpation, and assessment of strength,
impingement, and instability. Treatment focuses on icing, relative rest,
physical therapy, and modifying the swimming workout to reduce overuse and
impingement.
Shoulder pain, the hallmark of swimmer's shoulder, is the most common
musculoskeletal complaint among competitive swimmers. Interfering shoulder
pain is reported to be present in 9% to 35% of competitive swimmers, while
38% to 75% of competitive swimmers have a history of shoulder pain.
Swimmer's shoulder was first described in 1974 as a common, painful
syndrome or repeated shoulder impingement in swimmers. The term 'swimmer's
shoulder' generally refers to subacromial impingement syndrome and related
dysfunction in swimmers. It is most common with the freestyle and butterfly
strokes, but can occur with the backstroke.
Case Report
A 14 year old female swimmer presented with left shoulder pain. She
said the pain occurred during swimming and was most bothersome during freestyle
and butterfly strokes; it worsened during difficult workouts and occasionally
persisted afterward. The pain was not alleviated with icing after practice
or with 2 to 3 days rest.
The patient reported she swam 8,000 to 10,000 yards a day, five days or
more each week, and weight trained three times a week using her own program.
She also complained that her times had not improved as expected over the summer
swim season. There was no history of shoulder injury or dislocation. The
patient sat with her shoulders slightly slouched forward during the examination.
The patient's posterior shoulder musculature was underdeveloped bilaterally
on inspection and on palpation of the rotator cuff and scapular stabilizers.
She had mild winging of the left scapula. Palpation of the acromioclavicular
joint and the coracoid process produced no pain, although there was tenderness
to palpation of the impingement interval. There was also tenderness to
palpation of the left biceps and supraspinatus tendons. The patient had
full range motion on flexion, abduction, and internal and external rotation.
Strength testing revealed slightly decreased strength of the supraspinatus and
infraspinatus muscles bilaterally. She had full strength of the internal
rotators, arm extensors, and arm flexors. The patient had moderate anterior
and posterior laxity of both shoulders and bilateral positive sulcus signs.
Impingement and adduction-compression tests of her left shoulder were positive,
but the apprehension test was negative. Neck and elbow exams revealed no
abnormalities.
Anteroposterior, outlet, and axillary radiographs of the shoulder were
obtained. They revealed no soft tissue or bony abnormalities, specifically
no subacromial narrowing or spurring of the acromion.
The diagnosis was left-sided impingement syndrome consistent with swimmer's
shoulder, including multi-directional instability and weakness of the rotator
cuff and scapular stabilizers.
Treatment included episodic icing, anti-inflammatory medications, physical
theraphy, and relative rest. Physical therapy included strengthening exercises
for the rotator cuff and scapular stabilizers. Relative rest consisted of three weeks
of easy swimming below the pain threshold, with kick boards pool workouts
and biking to maintain aerobic fitness.
We also referred her to a collegiate swimming coach who evaluated her
technique and helped modify her workout plan. He instructed her to carefully
warm up and stretch before each workout. She progressed back into regular
workouts slowly and was instructed to maintain her training with less overall
yardage using interval training and regular rest periods (see table below at end of article).
The coach taughter her how to modify her stroke to lessen impingment by keeping
the elbow lower during the recovery phase and by not crossing the midline
with her hand during the pull through phase of her stroke. After the above
period of relative rest and three more weeks of gradually increasing workouts, the
patient raced the last two months of the season, recording personal best times
despite training with less overall yardage.
Understanding Swim Stresses
Swimming repeatedly stresses the complex shoulder joint. The shoulder's
range of motion in multiple directions requires a degree of instability
and little bony support. For stabilty, the shoulder relies on the capsule,
the rotator cuff muscles, and the larger surrounding muscles such as the
pectoralis major, the deltoids, the serratus anterior, and long head of the
biceps. The scapula, though mobile, is the base of the glenohumeral joint
and must be controlled for proper shoulder function. The rhomboids, serratur
anterior, and trapezium muscles are the main scapular stabilizers in
swimming. Impingement occurs when the soft tissues of
the subacromial space are compressed between the head of the humerus and the
coracoacromial arch and anterior acromion subacromial tissues include the
supraspinatus tendon, the tendon of the long head of the biceps, and the
subacromial bursa. As these tissues become maimed, the
narrow space becomes even tighter, worsening the impingement.
Swimming brings the shoulder through at least one impingement position
with each stroke. A 10,000 yard training session may include 4000 or more
strokes with each arm, probably the most overhead arm strokes used in any
sport. The freestyle stroke consists of a pull-through phase while the
arm is in the water, which provides propulsion, and a recovery phase in
which the arm is above the water. In this stroke, which
mmost swimmers use for the majority of training, the shoulder is subject
to impingement when the shoulder is in the early to a 'pull-through phase,'
which involves estreme adduction and internal rotation. The extrememly
abducted arc of the recovery phase also produces impingement, as the humeral
head is brought the lateral acromion.
Rotator cuff fatigue, scapular dysfunction, and shoulder laxity, can
contribute to impingement syndrome. The rotator cuff holds the humeral head
in position and depressed against the forces of the other muscles, preventing
its anterior and superior translation. Fatigue of the rotator cuff, then,
allows impingement to worsen. Swimmers who have multi-directional laxity
may also have more translation, compounding the impingement. When the muscles
that anchor the scapula are overused, especially the serratus anterior,
impingement can worsen because of a downward tilt of the scapula. In
addition, the impinged area of the supraspinatus tendon is poorly vascularized,
and the adduction and internal rotation at the end of the pull-through
phase may contribute to tensonitis by compressing the tensons vascular
supply.
Inflexibility in the shoulder and anterior chest wall could indicate a strength imbalance
as was seen in the patient in the case report; the slouched posture observed during her
examination suggested a tight anterior chest wall and a strength imbalance.
Weight training has classically focused on the anterior chest wall and internal
rotators, while the external rotators and supportive muscles may be underdeveloped
and unable to stabilize the shoulder. Greipp found that impingement pain
increases in swimmers who increase the intensity and duration of weight
training and in those who has less flexibility in the shoulder musculature.
Are Young People's Injuries Different?
Children naturally avoid activities that cause soreness and discomfort,
but they are pushed beyond discomfort in competitive athletics when they have
the motivation to succeed and the pressure to please coaches and parents.
Though swimmer's shoulder is seen in both adults and young people, the
incidence is increasing in young swimmers as the intensity, length of practices,
and the duration of the season increase. In addition, the syndrome may
become worse because of adolescents relatively underdeveloped shoulder
musculature, increased laxity about the shoulder joint, articular softness,
and bone immaturity. The sites of growth cartilage (the joint surface, the
epiphyseal plate, and the apophysis) are susceptible to injury and may be
involved in symptomatic young athletes. Often the physician will not become
aware of the problem until the patient's symptoms interfere with practice
and performance, and a complete assessment is vital.
Making the Diagnosis
The diagnosis of swimmer's shoulder is usually not difficult. Classically,
the patient complains of pain in the anterior shoulder during or after
swimming. It may interfere with the stroke or be associated with a
certain phase of the stroke, although early in the course the discomfort
may be present only after swimming. It is helpful to determine the strokes
used, the usually distance swum, and the intensity of the training. History
of other injury or dislocation may help determine any contributing factors.
The shoulder exam should include inspection, palpation, and testing of
passive and active range of motion, strength, instability, and impingement.
It is vital to completely examine both shoulders as well as the neck and
elbows. Inspection of posture, muscle groups, and bones for asymmetry will
help evaluate atrophy, muscle imbalance, and evidence of traumatic injury.
Palpation of the supraspinatus tendon and the tendon of the long head of the
biceps will help pinpoint tendonitis. Instability testing should include
the apprehension test. Impingement can be elicited by the classic arc from
60 degrees to 120 degrees of abduction, especially with the arm internally
rotated, plus other impingement tests.
Radiographs should include the anteroposterior view with the arm in external
rotation, outlet view with 10 degree caudal angulation and the axillary view.
The swimmer's form should be closely assessed for abnormal mechanics. It is
useful to consult an experienced coach to assess and correct form. The
differential diagnosis for swimmer's shoulder includes labral damage,
subluxation, rotator cuff tear, and, in young athletes, stress fractures
of the proximal humeral physis (Little League shoulder) and a apophyseal
injury. These injuries may coexist with impingement and should be looked
for in the evaluation of a swimmer with shoulder pain.
Target the Source of the Problem
The mainstay of treatment for overuse injuries is relative rest and
activity modification, and swimmer's shoulder is no exception. Frequent
icing and use of anti-inflammatory may speed healing. A period of relative
rest or activity below the pain threshold should be recommended to allow
healing and decrease inflammation. When prescribing relative rest, alternative
activities should be suggested to prevent deconditioning. Fitness can be
maintained with activities that do not stress the injured area. It is also
appropriate to prescribe physical therapy and rehabilitation to guide
strengthening and sretching programs.
Allegrucci et. al. nicely outline specific modalities and phases of the
physical therapy useful in the rehabilitation of patients who have swimmer's
shoulder. Treatment focuses on correcting any imbalances in muscle strength
and flexibility. In the patient described above, strengthening the rotator
cuff and scapular stabilizers helped restore glenohumeral stability and
allowed a more rapid return to activity. Subacromial-injections have been
used in the treatment of swimmer's shoulder, but they should be reserved for
severe cases that do not respond to conservative treatment.
Discourage Overtraining
Swimmer's shoulder is a common problem that can restrict a swimmer's season.
Prevention of this overuse syndrome is much easier than treating it mid-season.
Stretching and controlled warm-ups should be stressed in swimming programs
at all levels. Strength training should emphasize external rotator development
in the preseason.
As physicians, it is important that we encourage knowledge of overuse
injuries and work with other professionals to develop alternative training
techniques and to discourage overtraining.
Table 1. Modified Training Routine for Prevention or Treatment of
Swimmer's Shoulder
Less than 6000 yds each day with controlled warm-up; quality days should
alternate with recovery days (drills, technique, etc.)
Warm-up:
1,600 yd with rest between sets
- 400 yd easy swim with floppy, very relaxed stroke
- 400 yd easy swim with stroke of choice
- 300 yd kick only
- 400 yd easy swim with focus on strict, proper technique
- 100 yd easy swim with floppy or relaxed stroke
Body:
Swims with rest periods to maximize effort and ensure proper form using
one of the following:
- 5-8 of 500 yd each
- 3 or 4 of 800-1,000 yd each
- 2 of 1,500 yd each
Cool Down:
- 200-500 yd easy swim
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