Methods: Nine healthy competitive college tennis players from a Division III college participated in this study. High-speed
motion capture allowed for 3-dimensional analysis of shoulder kinematics during a tennis serve. Two conditions were
evaluated while the athletes performed a high-velocity tennis serve: a standard tennis shirt and a posture-cuing shirt.
Results: Shoulder internal rotation velocity increased when wearing the posture-cuing shirt. Peak internal rotation velocity
increased from 960.61°/s ± 93.24°/s to 1217.96°/s ± 155.01°/s (t = –1.76, P = .058). Internal rotation velocity at the time of
impact increased from 765.18°/s ± 95.48°/s to 900.54°/s ± 105.33°/s (t = –1.50, P = .086). Shoulder maximum external
rotation did not differ between the 2 conditions, at 172.00° ± 2.92° and 170.89° ± 3.70° (t = 0.325, P = .754).
Conclusions: Wearing a posture-cuing shirt may possibly alter shoulder kinematics during an overhead sport activity
such as tennis. Internal rotation velocity seemed to improve while wearing this shirt, although shoulder external rotation
position did not change. It is not known if these improvements can influence injury risk. (J Chiropr Med 2017;16:49-53)
Key Indexing Terms: Shoulder; Posture; Kinesiology, Applied; Biomechanical Phenomena
INTRODUCTION
The anatomy of the shoulder joint presents unique problems
for overhead athletes, such as tennis players, baseball pitchers,
and volleyball players. The effective and efficient function of
the shoulder complex requires the coordinated movements of
the scapula, clavicle, and glenohumeral joint.1 Instability of the
glenohumeral joint, altered kinematics of scapular motion, and
muscle imbalances of the shoulder complex place overhead
athletes at increased risk for shoulder injury.2-5 These functions
have been associated with injury risk and dysfunction specific
to the glenohumeral joint, which is dependent on proper
scapular motion during upper extremity activities.5-7
With tennis in particular, the tennis serve is considered the
most important stroke in this sport and is also considered the
most influential on injury occurrence to the shoulder in tennis
players.8,9 The tennis serve involves the coordinated effort of
the lower extremities and trunk and also the integrated motions
of the scapula with the humerus.9 Not surprisingly, shoulder
internal and external rotation motions, which are dependent on
scapular positioning, are associated with shoulder injury in
athletes, including tennis players.9,10 For instance, glenohumeral
internal rotation deficit, which is defined as the imbalance
of shoulder arc of rotation, creating excessive external rotation
and a lack of internal rotation range of motion (ROM), is
associated with scapular dyskinesia and subsequent injury to
the shoulder of overhead athletes.3,10-12 As noted in prior
studies, shoulder internal rotation is directly associated with
racquet speed and ball velocity after impact, and shoulder
external rotation is associated with shoulder internal rotation
function.8-10 Hence, effective movement of the glenohumeral
joint, during the tennis serve, is a critical element to the
mechanics of the serve but also critical to minimizing the risk of
injury to the shoulder.
a South West Health Spine and Sport, Costa Mesa, CA.
b The Institute for Spine and Sports Care, Santa Monica, CA. c Chapman University, Orange, CA.
d Department of Physical Therapy, West Coast University, Irvine, CA.
Corresponding author: Daniel J. Cipriani, PhD, West Coast
University, Center for Graduate Studies, 590 North Vermont Ave,
Los Angeles, CA 90004. Tel.: +1 3234545048; fax: +1
3236610935. (e-mail:
Paper submitted November 10, 2014; in revised form April 22,
2016; accepted May 26, 2016.
1556-3707
© 2016 National University of Health Sciences.
http://dx.doi.org/10.1016/j.jcm.2016.05.003
A recent adjunct to shoulder prevention and rehabilitation
programs is the addition of kinesiotape (KT).
Kinesiotaping has been reported to increase both muscle
activation and ROM when used in conjunction with
training programs. 13 It has also been reported to improve
the resting position of the scapula.14 Along with improving
the starting position of the scapula, Shaheen et al15
reported that taping increased ROM of scapular retraction,
upward rotation, and posterior tilting in asymptomatic
patients. Finally, taping has also been reported to increase
serratus activation during entire range of scaption (shoulder
abduction in the plane of the scapula), as well as facilitate the
activation of the lower trapezius.16 Because normal scapular
positioning and ROM have been proven to be important in
injury prevention, taping may be a great supplemental
treatment for athletes.13,14,17
A unique garment recently introduced to the athletic
community is a posture-cuing (PC) shirt that attempts to
replicate the influence of KT on upper body posture,
including scapular positioning. This shirt is designed to
reproduce the KT influence of the shoulder girdle,
particularly the scapula. The shirt is also compressive,
which is linked to overall improved recovery.18,19 Limited
research exists as to the effectiveness of these PC shirts on
shoulder function. Cole et al 20 reported that these types of
shirts with tension have improved the postural alignment of
the shoulder, decreased forward shoulder posture, and
increased activation of the lower trapezius during scaption
and flexion in overhead athletes with forward-head,
rounded-shoulder posture. Russell et al 21 also reported
that the PC shirt improved function for pitchers. These
studies support the need for more research on such
technology, specifically in populations at risk for upper
extremity injuries.
The purpose of this study was to determine any influence of
a compressive PC shirt on the kinematics of the glenohumeral
joint during a tennis serve. This preliminary study attempted to
determine whether a PC shirt has any impact on joint
kinematics (ie, joint positioning and joint motion) during an
overhead tennis serve, given that prior research on KT and PC
shirts indicated influence on scapular positioning. It was
hypothesized that the PC shirt, reported to influence the scapula
and upper torso, would provide a change in joint kinematics of
the glenohumeral joint during an overhead tennis serve. We
focused on internal rotation velocity, which is associated with
ball velocity of a serve, and shoulder external rotation position,
which is associated with glenohumeral internal rotation deficit
and shoulder function.10
METHODS
Participants
Participants were recruited from a Division III university
tennis program. Participants included 4 men (Xage = 19.5 ±
1.3 years; Xht = 1.78 ± 0.05 m) and 5 women (Xage = 20.0 ±
0.71 years; Xht = 1.66 ± 0.04 m), and all had a minimum of
3 years of competitive tennis experience. Participants were
healthy with no recent history of upper extremity injuries in
the past 6 months. This study was granted exemption status
by the university’s Institutional Review Board.
Procedures
All participants completed a standard warmup as prescribed
by the tennis program. The participants then
completed 2 full serves at game speed effort. One serve
(control) was performed while wearing the standard athletic
clothing for the participant. A second serve was performed
while wearing the PC shirt. Order of the conditions was not
randomized; all participants performed the control condition
first and the PC shirt condition second. Participants were not
blinded to the 2 conditions.
Data were collected using a 3-dimensional (3-D) motion
analysis system. This system included 2 high-speed
cameras at a rate of 240 Hz (EXZR200 cameras, Casio
Computers Ltd), positioned approximately orthogonal to
the athlete, with 1 camera parallel to the serve line and the
second camera positioned at approximately 90°, from an
anterior view of the participant. Before collecting movement
data, the capture field was calibrated using an 8-point
direct linear transformation object placed in the serve area.
The optical data were then digitized using Motus software
(Vicon Motus, Version 10.0; Vicon, Englewood, NY),
identifying joint centers for the shoulder, elbow, wrist,
hand, and torso, as well as identifying markers in the center
of the tennis handgrip and the head of the racquet. The 2-D
data were first smoothed with fast Fourier transformation
using a 28-ms window. In addition, the elbow (6 Hz) and
wrist (14 Hz) were filtered using a Butterworth low-pass
filter. The filtered 2-D data were then incorporated into a
vector system to produce 3-D coordinates, using a Butterworth
filter at 13 Hz. Anatomic references were then created
using these 3-D filtered coordinates to produce a linkage
system to calculate the kinematic data. All kinematic data
were calculated using the Zenolink software program
(ZenoLink, Endicott, NY). The variables of interest focused
on joint angular positions and angular velocities of the
glenohumeral joint. Specifically, peak internal rotation
velocity, peak external rotation position, and internal rotation
velocity at the time of impact with the tennis ball were
all estimated.
Data Analysis
Kinematic data of shoulder positions (peak shoulder
external rotation, peak internal rotation velocity, internal
rotation velocity at impact) were averaged across the
participants. Paired t tests were used to determine if
differences existed between the control condition and the
50 Zappala et al Journal of Chiropractic Medicine
Posture-Cuing Shirt and Tennis Serve March 2017
PC shirt condition. Because this was an exploratory study, a
P value of .10 was established a priori to identify potentially
clinically relevant trends.
RESULTS
Shoulder internal rotation velocity increased when
wearing the PC shirt. Peak internal rotation velocity
increased from 960.61°/s (standard error [SE] = 93.24) to
1217.96°/s (SE = 155.01; t = –1.76, P = .058). Internal
rotation velocity at the time of impact increased from
765.18°/s (SE = 95.48) to 900.54°/s (SE = 105.33; t = –1.50,
P = .086). Shoulder maximum external rotation did not differ
between the 2 conditions at 172.00° (SE = 2.92) and 170.89°
(SE = 3.70; t = 0.325, P = .754).
DISCUSSION
The results indicated there was a significant increase in
both peak internal rotation velocity and internal rotation
velocity at the time of impact while wearing the PC shirts.
There were no significant changes in maximum shoulder
external rotation. In terms of improved performance, we can
only speculate that the improved shoulder internal rotation
velocity might result in improved ball velocity after contact
with the racquet; we did not measure ball velocity in this
study. However, prior research by Sprigings et al 10 reported
that racquet-head speed was most dependent on shoulder
internal rotation velocity. The present results are fairly
consistent with prior research in terms of peak internal
rotation velocity, with values ranging from 620°/s in trained
tennis players to 1370°/s in professional female tennis
players. 22,23 However, the magnitude of external rotation
position in our study exceeds that of other researchers
(115-140°).22
The changes in internal rotation speed may be attributed
to changes in scapular positioning while wearing the PC
shirts given the reported influence of a PC shirt on scapular
and torso posture, as well as the influence of kinesiotaping
on scapular motion.1,14,16,20 However, this is only conjecture
because we did not study the scapular motion and base
this assumption on prior research. Ujino et al 14 hypothesized
that “KT (kinesiotape) may have placed the scapula
more posterior which may increase activation of shoulder
musculature.”14,16 Posture-cuing shirts were reported to
provide similar influence, as noted by Cole et al.20 They
observed that “tension straps on PC shirts decrease forward
shoulder angle and alters some muscle activity,” resulting in a
decrease in upper trapezius and an increase in lower trapezius
muscle activity during shoulder flexion while wearing a PC
shirt. These improvements in scapular motion, either with KT
or PC, are attributed to improved function of the glenohumeral
joint during overhead motions.14,16,20 We observed improved
speed of the glenohumeral joint while the athletes wore the PC
shirt, yet we did not observe any changes in glenohumeral
external rotation. If the PC shirt did in fact influence scapular
positioning, we suspect this would improve internal rotation
speed, but we also would suspect a change in shoulder external
rotation, which we did not observe. Because we did not
evaluate scapular position in our particular study, any
explanation for the improvement in glenohumeral internal
rotation speed is speculative.
The PC shirts may also increase the tactile input, influencing
the time to activate the muscles of the scapula stabilizers to
maintain a stable base for the humeral internal rotators to
function. Kinesiotape has been reported to “provide additional
sensory feedback...pressure and stretching effect of KT
stimulates cutaneous mechanoreceptors which conveys information
about joint position and movement therefore enhancing
proprioception.”13 Cole et al20 also hypothesized that PC shirts
would have the same effect as KT, “slight EMG changes in both
conditions (compression shirts with or without tension straps)
might suggest an effect on joint alignment due to enhanced
proprioception and proprioceptive feedback.”20 We can only
postulate that the PC shirt might have influenced muscle
activation, which may have contributed to the changes in
internal rotation velocity of the shoulder. However, just as with
scapular positioning, we did not assess muscle activity in this
current study and thus this relationship is speculative.
Limitations
Some limitations to this study are the small number of
participants because of the specific inclusion criteria.
Participants only completed 1 serve in each condition,
leading to possible error; more trials would decrease the
amount of error and increase the validity and reliability of
the results. The motion capture system employed in this
study has proven reliability in previous dynamic studies;
however, we did not directly measure the error in this study.23
The participants were also not randomized as to which
condition they performed first; all participants performed first
with normal clothing, then with the PC shirt. The lack of
randomization could have led to an order effect or even a
placebo effect as a result of the athletes’ expectations of the PC
shirts. Also, starting scapular position was not measured, so the
cause for the change in velocity can only be theorized. Future
research should address long-term effects of PC shirts. A
longitudinal study should address strength, starting alignment,
and ROM. Long-term changes in any of these categories can
give us a better insight into functional changes like velocity
while wearing PC shirts. In addition, it will be important to
study the influence of PC shirts on scapular kinematics in order
to better appreciate any possible relationship between
glenohumeral motion and scapular motion while wearing a
PC shirt. Finally, given the demonstrated influences of KT on
scapular and shoulder kinematics, a comparison study between
PC and KT on overhead kinematic activities such as the tennis
serve is highly warranted.
Journal of Chiropractic Medicine Zappala et al 51
Volume 16, Number 1 Posture-Cuing Shirt and Tennis Serve
CONCLUSIONS
This study provides preliminary findings that suggest a
PC shirt might provide influence on glenohumeral joint
motion during overhead activities such as a tennis serve.
Specifically, a change in relative internal rotation velocity
of the shoulder was observed when athletes wore a PC shirt.
Whether this is a result of a change in glenohumeral joint
positioning, scapular motion, or muscle activation is a
subject for future research.
FUNDING SOURCES AND CONFLICTS OF INTEREST
No funding sources or conflicts of interest were reported
for this study.
CONTRIBUTORSHIP INFORMATION
Concept development (provided idea for the research):
D.J.C., J.Z., C.O., E.B., H.F., D.S.
Design (planned the methods to generate the results):
D.J.C., J.Z., C.O., E.B., H.F., D.S.
Supervision (provided oversight, responsible for organization
and implementation, writing of the manuscript):
D.J.C., J.Z., C.O., E.B., H.F., D.S.
Data collection/processing (responsible for experiments,
patient management, organization, or reporting data):
D.J.C., J.Z., C.O., E.B., H.F., D.S.
Analysis/interpretation (responsible for statistical analysis,
evaluation, and presentation of the results): D.J.C.,
J.Z., C.O., E.B., H.F., D.S.
Literature search (performed the literature search):
D.J.C., J.Z., C.O., E.B., H.F., D.S.
Writing (responsible for writing a substantive part of the
manuscript): D.J.C., J.Z., C.O., E.B., H.F., D.S.
Critical review (revised manuscript for intellectual
content, this does not relate to spelling and grammar
checking): D.J.C., J.Z., C.O., E.B., H.F., D.S.
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Practical Applications
• Compression shirts and PC shirts may
possibly improve athlete performance.
• A PC shirt may improve athlete upper body
function, particularly for overhead activities.
• Coaches might consider recommending PC
shirts as part of training for athletes, however
more research is necessary.
52 Zappala et al Journal of Chiropractic Medicine
Posture-Cuing Shirt and Tennis Serve March 2017
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muscle activity in overhead athletes with poor posture. J Athl
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Compression shirts decrease pain and improve performance
in youth pitchers. Med Sci Sports Exerc. 2013;
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