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THE AMERICAN JOURNAL OF SPORTS MEDICINE, Vol. 26, No. 1
© 1998 American Orthopaedic Society for Sports Medicine
A Correlation Between Shoulder Laxity and
Interfering Pain in Competitive Swimmers*
William C. McMaster,† MD, Andrew Roberts, and Terry Stoddard
From the Department of Orthopaedic Surgery, University of California, Irvine,
Orange, California
competitive swimmers without specific reference to cause.
This has resulted in confusion and misinterpretation.
We previously demonstrated significant shifts in rotator
cuff muscle strength ratios in swimmers and water polo
players that parallel the changes noted in athletes in
other overhead sports.1, 5, 9, 10, 22 A remedial exercise protocol designed to reestablish the rotator cuff muscle
strength ratios in swimmers was tested and showed promise.6 A common denominator in the aquatic athlete with
shoulder complaints may be excessive joint laxity.8 Glenohumeral stability is a necessity for proper joint mechanics,
and its absence is associated with significant disability.
Condensations of the glenohumeral capsule, defined as
ligaments, provide joint stability.18, 20 Their incompetence
and the resulting joint laxity are associated with a variety
of complaints.
There is a spectrum of normal shoulder joint mobility as
a result of intrinsic joint capsule and ligamentous laxity.
Physiologic laxity may occur only as increased range of
motion without other recognizable signs. As laxity increases, joint translation may cross the threshold of stability into the realm of instability. At this point, the laxity
has become pathologic. This increase in laxity may be
recognized by the athlete and may result in apprehension
and in a voluntary avoidance of certain joint attitudes.
Pathologic shoulder joint laxity is implicated in subluxation and dislocation, labrum tears, and rotator cuff impingement.2, 7, 14 –16 Fowler3 previously suggested this association in swimmers. Zemek and Magee23 compared
glenohumeral laxity in recreational and competitive
swimmers and found an increase in glenohumeral and
general joint laxity in competitive swimmers, suggesting a
genetic component. A question is whether repetitive activity results in joint laxity or whether genetic factors, influencing joint laxity, incline certain people to a given sport.
The flexibility needed to be mechanically efficient in
swimming may be genetic and, therefore, may preselect
the group of athletes who will be successful, remain in the
sport, and rise to the elite ranks.
This study was designed to look for a correlation between significant interfering shoulder pain in senior na-
ABSTRACT
Shoulder pain in the swimming athlete that interferes
with effective training is serious and may result in
decreased performance. Based on the hypothesis that
shoulder laxity is an important factor in shoulder pain,
this study of 40 senior national and elite swimmers was
undertaken. A questionnaire identified those athletes
currently suffering from such pain. Shoulder laxity was
assessed using standard clinical tests, from which a
laxity score was derived. A statistically significant correlation was identified between the shoulder laxity
score and the presence of interfering shoulder pain,
confirming the hypothesis of the study. These results
have direct implications for training the symptomatic
athlete.
Shoulder pain in competitive swimmers is demonstrated
to be present at all levels of participation.11 This is especially problematic when it interferes with training
progress and affects performance. In the ranks of the elite
and Olympic athlete, shoulder pain may affect world
standing, achievement of medals, and national and world
record achievement. The effect of shoulder pain on a U.S.
athlete’s accomplishments has economic consequences for
the United States Swimming National Governing Body,
which derives development funds based on world championship and Olympic results. The athletes themselves receive support based on their performance in competition
and their world standings.
The term “swimmer’s shoulder” has been applied to a
variety of complaints involving pain in the shoulders of
* Presented at the annual meeting of the AOA, Boca Raton, Florida, June
1997.
† Address correspondence and reprint requests to William C. McMaster,
MD, Department of Orthopaedic Surgery, University of California, Irvine, 1310
Stewart Drive #508, Orange, CA 92868
No author or related institution has received any financial benefit from
research in this study.
83
84
McMaster et al.
American Journal of Sports Medicine
tional and elite swimmers and a shoulder laxity score that
was weighted for clinical signs of instability. The hypothesis of the study was that excessive shoulder laxity is a
common denominator that causes significant interfering
shoulder pain in the swimming athlete.
MATERIALS AND METHODS
The study group consisted of the senior national and elite
group of an internationally prominent U.S. competitive
swimming training program. There were 40 swimmers, 13
women and 27 men, all of whom met U.S. Swimming
Senior National time standards and some of whom were
Olympians. All subjects were informed of the nature of the
study and assured of the confidentiality of the individual
data. All subjects completed questionnaires that provided
individual demographics including handedness. Each was
asked to identify whether he or she currently had interfering pain in either shoulder. The subjects were given a
definition of interfering pain as that which prevents effective training or progress in training, as opposed to the
normal soreness that vigorous training produces and that
does not interfere with continued quality training. Frequent timed efforts and competitions provided the athletes with specific objective feedback on their progress
based on performance.
Clinical examinations were performed by the senior author (WCM) on both shoulders of all subjects using five
standard clinical testing maneuvers. The sulcus sign and
anterior and posterior manual provocation tests in the
sitting and recumbent positions were used. The sulcus
sign was measured in centimeters of inferior displacement
from the acromion. The manual provocation tests were
judged based on the displacement of the humeral head
relative to the glenoid. Four positions of humeral head
displacement were recorded: none, shift, joint edge perch,
and frank dislocation. Each test was additionally
weighted if the subject exhibited apprehension during the
test. An additive score for each shoulder was recorded
(Table 1). The resultant scores for all shoulders were analyzed against the results of the pain questionnaire using
a one-factor analysis of variance statistical procedure. A
positive correlation was sought and a statistically significant threshold was accepted at P ⬍ 0.05.
TABLE 1
Clinical Shoulder Examination Scoring Protocol (Points)a
Displacement (cm)
Test
0
1
2
⬎2
Sulcus
1
2
4
8
0
Shift
Perch
Dislocation
1
1
1
1
2
2
2
2
4
4
4
4
8
8
8
8
Provocation test
Sitting anteriorly
Sitting posteriorly
Lying anteriorly
Lying posteriorly
a
For apprehension on any test, add 4.
RESULTS
The average age of the group was 17.5 ⫾ 2.4 years (range,
14 to 24). The total study group of swimmers represented
80 shoulders at risk for possible pain. Fourteen swimmers
(35%) noted significant interfering shoulder pain to be
present at the time of the assessment. Within the 14
swimmers with current significant shoulder pain, 28
shoulders were at risk. Nine swimmers reported the pain
as being bilateral; five swimmers reported unilateral pain,
two had pain in the right shoulder and three had pain in
the left. In swimmers with unilateral pain, there was no
correlation to handedness. Eleven right and 12 left shoulders were symptomatic. The results of the clinical examination scores compared with the presence of interfering
shoulder pain are presented in Table 2. Athletes with
current interfering pain had higher point totals on clinical
examination than those who had no shoulder pain. The
statistical analysis revealed a positive correlation at the
95% confidence level between the clinical examination
score and the presence of interfering shoulder pain.
DISCUSSION
Thirty-five percent of this group of senior national and
elite swimmers reported the current presence of interfering shoulder pain. This correlates to our prior findings
based on a large survey of competitive swimmers and
reaffirms the concern about the effect this might have on
the ability of our swimmers to effectively compete in the
international arena.11 It is our belief that a common denominator in the aquatic athlete with interfering shoulder
pain is the degree of inherent shoulder laxity.
Overhead athletes from a variety of sports show
changes in the rotator cuff muscles on strength testing.1, 5, 9, 10, 22 These changes are thought to be a normal
adaptation to the training effect of a repetitive activity.
Not only do individual components of the rotator cuff show
these changes, but the strength ratios between paired
groups, such as adductors and abductors and internal and
external rotators, are also affected. In swimmers and water polo players, there is a relative increase in the strength
of the internal rotators and adductors.9, 10 In the pathologically lax shoulder, these changes may potentiate the
problem by reinforcing abnormal joint mechanics. The
laxity condition may be enhanced as a consequence of
fatigue of certain muscle groups such as the external
TABLE 2
Clinical Examination Scores by Pain Group
Group
N
Examination score
SD
Pain now
R shoulder
L shoulder
11
12
15a
16a
8.3
8.9
No pain now
R shoulder
L shoulder
29
28
9.8
10.7
3.2
3.8
a
Significant correlation with the presence of interfering shoulder pain at the 95% confidence level.
Vol. 26, No. 1, 1998
rotators that, for example, resist anterior joint translation. While pathologic shoulder laxity may be unidirectional, it is often multidirectional in swimmers. This may
lead to secondary definable causes of shoulder pain such
as impingement syndrome due to superior migration of
the humeral head.
The glenohumeral capsule ligaments are the prime stabilizers of the shoulder, especially the anteroinferior glenohumeral ligament.18, 20 A spectrum of joint mobility and
laxity is present in the population. Varying degrees of
glenohumeral laxity are consistent with normal function.
Laxity that allows excessive joint translations resulting in
instability may be a key factor in causing shoulder pain.
Indeed, if glenohumeral instability is the important variable, this would account for the fact that only certain
athletes subjected to the same training program and work
load suffer interfering shoulder pain. That is, only those
athletes who have crossed the threshold from physiologic
laxity to instability would be prone to developing symptoms. This would also reconcile the documented influence
that heavy-resistance overhead weight training has on
causing shoulder pain in swimmers.4 This is presumably
due to forced subluxation of the lax joint during the
activity.
To excel at the sport of competitive swimming, mechanical efficiency is an important factor. The swimming technique that produces the greatest distance per stroke at the
most efficient energy use will produce the best result. A
significant mechanical factor the swimmer has to overcome in the water is drag.13, 19, 21 Drag is both passive and
active. While passive drag may be influenced by genetic
factors such as body shape or body segment ratios, active
drag may be influenced by body position and movement of
the propeller hand through the water.17 Poor body mechanics may result in increased active drag and decreased
swimming efficiency. It is commonly understood that poor
flexibility and general joint tightness negatively affect the
ability to swim efficiently. Bulky, tight people usually are
relatively inefficient swimmers. Some variance from this
is seen in male sprinters in particular, in events such as
short-duration, largely anaerobic sprints where high
power production may overcome some of the negative effects of bulk and tightness. It is possible that there is a
preselection process operating whereby athletes who have
genetic factors more conducive to swimming, such as joint
flexibility, long body profiles, and increased aerobic capacity, tend to be the more efficient swimmers, succeed at the
sport, and remain to compete at the higher levels. The
less-efficient swimmers tend to gravitate to other sports.
We tested a remedial exercise protocol to ameliorate the
rotator cuff strength ratio shifts that occur in swimmers
and found that this can be helpful for symptomatic athletes but may not be universally effective.6 Clinically, for
swimmers with demonstrated pathologic shoulder laxity
and pain, the exercise protocol, which emphasizes
strengthening of the abductors, external rotators, and
lower trapezius muscle, seems to be helpful. The efficacy
of such a program may be multifactorial, including reducing fatigue in the external rotators and scapula stabilizers, and better centering the humeral head in the lax joint,
Shoulder Laxity and Interfering Pain in Competitive Swimmers
85
thereby reducing subluxation potential. The joint-laxity
limits consistent with normal shoulder mechanics have
not been determined; however, there is a threshold beyond
which the physiologically lax shoulder becomes pathologic
and pain may appear. This threshold may be different for
each individual athlete.
This study has demonstrated a statistically significant
correlation between a clinical score of glenohumeral joint
laxity and the presence of interfering shoulder pain in
senior national and elite swimmers. This supports the
hypothesis of the study that shoulder laxity may be a
common denominator in the causation of significant interfering shoulder pain in the swimming athlete. We believe
that the group of athletes who are asymptomatic yet demonstrate significant shoulder range of motion capacity are
situated at a point along the spectrum of joint laxity that,
while excessive compared with the population norm, has
not crossed the threshold between excessive laxity and
instability.
These findings have implications for the swimmer and
his or her coach. Given the shoulder joint laxity of this
population, caution should be exercised when prescribing
certain training activities that may have a laxity-potentiating effect. Activities that need to be critically examined
include passive stretching of the shoulder, especially when
forced or causing discomfort, the use of hand paddles, and
heavy-resistance overhead weight training. Any activity
that promotes increased joint laxity and has the potential
to move the situation from physiologic to pathologic laxity
must be examined. For the swimmer with painful shoulders, certain technical adaptations may be helpful. These
include increasing body roll, maintaining a high elbow,
and avoiding excessive elbow extension before beginning
the hand insweep. In any swimmer with significant pain,
an accurate physical examination and diagnosis is important. If pathologic joint laxity is identified, all potentially
contributing factors should be identified and altered if
possible. The most important goal for the medical managers of the swimming athlete should be maintaining training capacity. Even short absences from effective training
have been shown to result in significant detraining, which
is anathema to the endurance athlete.12
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