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Original research
Comparison of electromyographic activity of the lower trapezius and serratus
anterior muscle in different arm-lifting scapular posterior tilt exercises
Sung-min Ha
a
, Oh-yun Kwon
b
,
*
, Heon-seock Cynn
c
, Won-hwee Lee
a
, Kyue-nam Park
a
, Si-hyun Kim
a
,
Do-young Jung
d
a
Department of Rehabilitation Therapy, Graduate School of Yonsei University, Wonju, Republic of Korea
b
Department of Physical Therapy, College of Health Science, Laboratory of Kinetic Ergocise Based on Movement Analysis, Yonsei University, 234 Maeji-ri, Heungeop-myeon, Wonju,
Kangwon-do 220-710, Republic of Korea
c
Department of Physical Therapy, College of Health Science, Yonsei University, Wonju, Republic of Korea
d
Department of Physical Therapy, College of Tourism & Health, Joongbu University, 101 Daehak-ro, Chubu-myeon, Geumsan-gun, Chungnam, Republic of Korea
article info
Article history:
Received 22 February 2011
Received in revised form
21 September 2011
Accepted 9 November 2011
Keywords:
Arm lift
Lower trapezius
Scapular posterior tilting
Serratus anterior
abstract
Objective: To determine the most effective exercise to specifically activate the scapular posterior tilting
muscles by comparing muscle activity generated by different exercises (wall facing arm lift, prone arm
lift, backward rocking arm lift, backward rocking diagonal arm lift).
Design: Repeated-measure within-subject intervention.
Participants: The subjects were 20 healthy young men and women.
Main outcome measures: Lower trapezius (LT) and serratus anterior (SA) muscle activity was measured
when subjects performed the four exercises.
Results: Muscle activity was significantly different among the four exercise positions (p<0.05). The
backward rocking diagonal arm lift elicited significantly greater activity in the LT muscle than did the
other exercises (p<0.05). The backward rocking arm lift showed significantly more activity in the SA
muscle than did the other exercises (p<0.05).
Conclusions: Clinicians can use these results to develop scapular posterior tilting exercises that specifi-
cally activate the target muscle.
Ó2011 Elsevier Ltd. All rights reserved.
1. Introduction
When elevating the arm overhead, the normal scapula
undergoes a pattern of upward rotation (45e60
), external rotation
(15e35
), and posterior tilting (20e40
)(Escamilla, Yamashiro,
Paulos, & Andrews, 2009; Ludewig, Cook, & Nawoczenski, 1996).
To complete, 180
of humeral elevation, the scapula should depress,
slightly adduct, and tilt posteriorly at the end-range of scapular
upward rotation (Sahrmann, 2002). Scapular posterior tilt (SPT) is
the movement of the coracoid process in a posterior and cranial
direction while the inferior angle of the scapula moves in an
anterior and caudal direction (Clarkson, 2005). During arm eleva-
tion, SPT occurs about a medial-lateral axis of the scapula, with the
inferior angle moving anteriorly (Michener, McClure, & Karduna,
2003), which occurs primarily after 90
and increases sharply at
the end-range (Hammer, 2006). SPT may be important in allowing
the humeral head and rotator cuff tendons to clear the anterior
aspect of the acromion during arm elevation (Escamilla et al.,
2009).
In particular, athletes or workers involved in overhead activity
with abnormal scapular movement at the extremes of humeral
elevation are likely to develop shoulder conditions such as sub-
acromial impingement (SI) and glenohumeral instability (Ludewig
et al., 1996; McQuade, Dawson, & Smidt, 1998; Warner, Micheli,
Arslanian, Kennedy, & Kennedy, 1992). Subjects with SI have
approximately 10
less posterior tilt than asymptomatic subjects
(Lukasiewicz, McClure, & Michener, 1999). Coordination of SPT
muscles is important to prevent abnormal scapular movement and
pain during elevation of the arm overhead (Solem-Bertoft,
Thuomas, & Westerberg, 1993).
The main muscles thought to facilitate SPT are the LT (lower
trapezius) and SA (Serratus anterior) (Ebaugh, McClure, & Karduna,
*Corresponding author. Tel.: þ82 33 760 2721; fax: þ82 33 760 2496.
E-mail addresses: chirore61@hotmail.com (S.-m. Ha), kwonoy@yonsei.ac.kr
(O.-y. Kwon), cynn@yonsei.ac.kr (H.-s. Cynn), kema97@yonsei.ac.kr (W.-h. Lee),
parkkyue@nate.com (K.-n. Park), sihyun0411@naver.com (S.-h. Kim), ptsports@
hotmail.com (D.-y. Jung).
Contents lists available at SciVerse ScienceDirect
Physical Therapy in Sport
journal homepage: www.elsevier.com/ptsp
1466-853X/$ esee front matter Ó2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.ptsp.2011.11.002
Physical Therapy in Sport 13 (2012) 227e232
2005). These muscles are paired to form an important force couple
that controls SPT, which is important for widening the subacromial
space during overhead activities to prevent impingement of the
subacromial tissues (Michener & Leggin, 2001; Solem-Bertoft et al.,
1993). A change in the LT and SA muscle function influences SPT and
is associated with poor shoulder function and chronic SI (Cools,
Witvrouw, Declercq, Danneels, & Cambier, 2003; Kibler &
McMullen, 2003). Furthermore, reduction in the force generation
of the SPT muscles increases the potential for developing SI
syndrome (Ludewig & Cook, 2000; Wuelker, Wirth, Plitz, &
Roetman, 1995).
Many studies have addressed strengthening exercises of the LT
and SA muscle to treat shoulder dysfunction (Arlotta, LoVasco, &
McLean, 2011; Ekstrom, Donatelli, & Soderberg, 2003; Hardwick,
Beebe, McDonnell, & Lang, 2006; Pontillo, Orishimo, Kremenic,
McHugh, Mullaney, & Tyler, 2007). SA muscle activity increases
in a linear fashion with arm elevation (Kibler, Sciascia, Uhl,
Tambay, & Cunningham, 2008; Ludewig et al., 1996). Conversely,
LT muscle activity tends to be low at less than 90
of scaption,
abduction, and flexion, and then increases exponentially from 90
to 180
(Hardwick et al., 2006; Smith et al., 2006). Ekstrom et al.
(2003) reported that prone overhead arm raise in line with the
LT muscle produced maximum activity in the LT muscle.
Selective strengthening of the muscles that facilitate SPT is
important for rehabilitation of scapular movement impairment;
there are plenty of studies available to help clinicians develop
effective programs to exercise these muscles (Decker,
Hintermeister, Faber, & Hawkins, 1999; Ekstrom et al., 2003;
Ekstrom, Soderberg, & Donatelli, 2005; Hardwick et al., 2006;
Kibler, 1998; Oyama, Myers, Wassinger, & Lephart, 2010). Effective
exercise positions are based on what is known of the functional
anatomy and biomechanics of the shoulder complex, previous
electromyography (EMG) studies, and clinical experience
(Ballantyne et al., 1993). Recently, clinicians and researchers have
focused on activation of the LT and SA muscles for normal scapular
upward rotation at arm elevation angles above 90
(Decker et al.,
1999; Ekstrom et al., 2003, 2005; Hardwick et al., 2006; Kibler,
1998). Representative exercises include the wall facing arm lift,
scapular plane shoulder elevation, and overhead arm raise (Decker
et al., 1999; Ekstrom et al., 2003; Hardwick et al., 2006; Townsend,
Jobe, Pink, & Perry, 1991). Hardwick et al. (2006) reported that SA
activity significantly increased with increasing humeral elevation
angle (90
,120
, and 140
), with no significant differences between
the wall slide (37.1e75.4% MVIC) and scapular plane shoulder
elevation exercises (41.1e82.4% MVIC). Ekstrom et al. (2003) found
the SA muscle activity was significantly higher in the scapular plane
shoulder elevation exercises (96% MVIC) above 120
than below
80
, and the overhead arm raise in line with LT muscle fibers was
the highest level of LT muscle activity (97% MVIC). Oyama et al.
(2010) reported that LT activity (72% MVIC) was highest in 120
shoulder abduction with external rotation (thumb pointing toward
ceiling) among 6 scapular retraction exercises.
The stabilization of spine, posture of the thorax and shoulder
abduction angle may affect SPT and upper extremity movement
(Kebaetse, McClure, & Pratt 1999; Lewis, Wright, & Green, 2005;
Sahrmann, 2010). To our knowledge, no reported study has quan-
tified activity in the LT and SA muscles at the final stage of scapular
upward rotation (i.e., during SPT) during different arm-lifting SPT
exercises. The present study compared the muscle activity during
the wall facing arm lift (WAL), prone arm lift (PAL), backward
rocking arm lift (BRAL), and backward rocking diagonal arm lift
(BRDAL) exercises to determine the most effective exercise for
activating the LT and SA muscles. We hypothesized that activity of
the LT and SA muscles would differ among the four arm-lifting SPT
exercises.
2. Methods
2.1. Subjects
Twenty healthy young subjects (10 men, 10 women) participated
in this study (Table 1). The inclusion criteria were 1) the subject was
able to comfortably perform full flexion in the sagittal plane, full
abduction in the frontal plane, and full scaption in the scapular
plane; 2) the pectoralis minor, levator scapulae, and rhomboid
muscles were within the normal length using muscle length tests
(Phil, Clare, & Robert, 2010; Sahrmann, 2002). The exclusion criteria
were current shoulder pain or shoulder surgery and history of
neurological, musculoskeletal, or cardiopulmonary disease that
could interfere with shoulder motion in the testing positions.
The principal investigator explained the procedure to the
subjects in detail prior to the experiment and all subjects signed an
informed consent form. This study was approved by the Yonsei
University Wonju Campus Human Studies Committee.
2.2. Instrumentation
EMG data were collected using a Noraxon TeleMyo 2400T and
analyzed using MyoResearch Master Edition 1.06 XP software
(Noraxon, Scottsdale, AZ, USA). The electrode sites was shaved and
cleaned with rubbing alcohol. Surface electrode pairs were posi-
tioned at an interelectrode distance of 2 cm. The reference elec-
trode was placed on the ipsilateral clavicle. EMG data were
collected for the LT muscle (placed at an oblique vertical angle with
one electrode superior and one inferior to a point 5 cm infer-
omedial from the root of the spine of the scapula) and the SA
muscle (placed vertically along the mid-axillary line at rib levels
6e8) (Cram, Kasman, & Holtz, 1998). The sampling rate was
1000 Hz. A bandpass filter between 20 and 300 Hz was used. EMG
data were processed into the root-mean-square (RMS) value, which
was calculated from 50-ms data points of windows.
2.3. Procedures
The dominant arm (the preferred arm when performing eating
and writing tasks) was used in all tests (Yoshizaki, Hamada, Tamai,
Sahara, Fujiwara, & Fujimoto, 2009). All subjects reported the right
arm as their dominant arm. EMG activity in the LT and SA muscles
was tested during four different exercises. A target bar was used to
control the angle of shoulder flexion in each exercise. The target bar
distance was determined by a vertical line from the wall to the
subject’s earlobe in the WAL exercise position. The target bar was
placed at this same distance from the surface of the therapeutic
table in the PAL, BRAL, and BRDAL exercises. These exercises
distinguished by exercise position (standing, prone, and backward
rocking), and shoulder abduction angle (180
, and 145
).
2.4. Wall facing arm lift (WAL)
Hardwick et al. (2006) and Sahrmann (2002) described the wall
slide exercise. The subject was required to stand facing the wall and
contact it from nose to knees with feet shoulder-width apart. In the
starting position, the ulnar border of the forearms and medial side
Table 1
Descriptive data for participants in this study (n¼20).
Variable ALL Male (n¼10) Female (n¼10)
Age (y) 23.1 1.8 23.6 2.2 22.6 1.3
Height (cm) 168.5 6.3 173.7 4.2 163.2 2.5
Mass (kg) 58.4 6.8 64.0 4.5 52.8 2.6
Values are expressed as mean (SD).
S.-m. Ha et al. / Physical Therapy in Sport 13 (2012) 227e232228
of the humerus were in contact with the wall, and shoulder
abducted 90
with elbow flexed 90
. The subjects were instructed
to slide their arms up the wall. The sliding movement was ended
when the shoulder reached 145
of abduction. The subject was then
instructed to lift both hands with elbows extended until the radial
border of the wrist slightly touched without pushing the target bar
and maintained the arm position (Fig. 1A).
2.5. Prone arm lift (PAL)
The subject was placed in the prone position. Using a goniom-
eter, the humerus was aligned diagonally overhead with shoulder
abduction of 145
and the forearm was in the neutral position. The
subjects were asked to place the non-dominant hand under the
forehead and push slightly on the forehead with the dorsum of
their hand to stabilize the neck and thoracic spine. The subject was
then instructed to lift the dominant arm with elbow extended until
the radial border of the wrist slightly touched without pushing the
target bar and maintained the arm position, which was placed at
the same distance used in the WAL exercise (Ekstrom et al., 2003)
(Fig. 1B).
2.6. Backward rocking arm lift (BRAL)
We invented the backward rocking arm lift exercise. Initially, the
subjects were placed in the quadruped position and instructed to
rock backward slowly until the buttocks touched both heels. The
subjects were asked to place the non-dominant hand under the
forehead and push slightly on the forehead with the dorsum of the
hand to stabilize the neck and thoracic spine. The principal inves-
tigator abducted the subject’s dominant shoulder to 180
using
a goniometer. The subject was then instructed to lift the dominant
arm until the radial border of the wrist slightly touched without
pushing the target bar and maintained the arm position, which was
located in a predetermined position (Fig. 1C).
2.7. Backward rocking diagonal arm lift (BRDAL)
The subjects were placed in the quadruped position and
instructed to rock backward slowly, and the head was positioned as
in the BRAL exercise. The shoulder was abducted to 145
by the
principal investigator and the subject was instructed to lift the
dominant arm with the elbow extended until the radial border of
the wrist slightly touched without pushing the target bar and
maintained the arm position, which was located in the pre-
determined position (Fig. 1D).
Subjects were familiarized with the four arm-lifting SPT exer-
cises during a 30 min period prior to testing. During the familiar-
ization period, the principal investigator instructed the subjects to
move their dominant arm until the radial border of the wrist
touched the target bar, which was located in a predetermined
position for each exercise. The familiarization period was
completed when the subject was able to maintain the four exercise
positions for 5 s. All of the subjects were comfortable after the
familiarization period, and none reported fatigue. A 15 min rest
period was allowed after the familiarization period before data
collection began.
2.8. Data collection and processing
The order of testing was randomized using the random number
generator in Microsoft Excel (Microsoft Corp., Redmond, WA, USA).
The EMG data were normalized by calculatingthe mean RMS of three
trials of maximal voluntary isometric contraction (MVIC) for each
muscle. Weused the manual muscle testing positions recommended
by Kendall and McCreary (2005) for measuring MVIC. LT muscle
activitywas tested in the prone position; the subject’sarmwasplaced
diagonally overhead, in line with the lower fibers of the trapezius
muscle during external rotation, while resistance was applied distal
to the elbow. The SA muscle was tested while the subject was seated
on a treatment table with no back support. The shoulder was inter-
nally rotated and abducted to 125
in the scapular plane, while
resistance was applied proximal to the subject’s elbow by the prin-
cipal investigator. Each contraction was held for 6 s with maximal
effort against manual resistance. The first and last second of the EMG
data from each MVIC trial were discarded, and the remaining 4 s of
data were used (De Oliveira, De Morais Carvalho, & De Brum, 2008;
Vezina & Hubley-Kozey, 2000). Three repetitions of each test were
performed, with a 2 min rest interval between repetitions to mini-
mize muscle fatigue (Vera-Garcia, Moreside, & McGill, 2010). The
mean MVIC value of the three trials was calculated.
Fig. 1. Type of exercise (A: Wall facing arm lift, B: Prone arm lift, C: Backward rocking arm lift, D: Backward rocking diagonal arm lift).
S.-m. Ha et al. / Physical Therapy in Sport 13 (2012) 227e232 229
Each isometric arm-lifting exercise was performed for 6 s; the
first and last second of each exercise trial were discarded, and the
remaining 4 s of EMG data were used (De Oliveira et al., 2008;
Vezina, & Hubley-Kozey, 2000). The mean of three trials for each
arm-lifting exercise was analyzed. The participants were allowed to
rest for 2 min between trials, and 3 min between the different
exercises positions (De Mey, Cagnie, Danneels, Cools, & Van de
Velde, 2009; Lehman, MacMillan, MacIntyre, Chivers, & Fluter,
2006). The data for each trial were expressed as a percentage of
the calculated mean RMS of the MVIC (% MVIC), and the mean %
MVIC of the three trials was used in the analysis.
2.9. Data analysis and statistics
A one-way repeated-measure analysis of variance (ANOVA) was
used to test for differences in LTand SA muscle activities among the
four arm-lifting SPT exercises. Significant main effects were fol-
lowed up using the Bonferroni post-hoc test. The Statistical Package
for the Social Sciences version 12 (SPSS Inc., Chicago, IL, USA) was
used to conduct the statistical tests, and p-values <0.05 were
deemed statistically significant.
3. Results
The normalized EMG data and the results of the statistical
analyses are shown in Table 2. LT muscle activity was significantly
higher when performing the BRDAL compared to the other exer-
cises (Fig. 2). The LT muscle activity is shown inTable 2. It increased
in the order of WAL <BRAL <PAL <BRDAL (p<0.05) (Fig. 2). LT
muscle activity was significantly lower during the WAL exercise
than during the other exercises (p<0.05). LT muscle activity did
not differ significantly different between the PAL and BRAL
exercises.
SA muscle activity was significantly greater when performing
the BRAL exercise than during the other exercises (p<0.05) (Fig. 3).
SA muscle activity did not differ significantly among the WAL, PAL,
and BRDAL exercises.
4. Discussion
We investigated muscle activity in the LT and SA muscles during
four different arm-lifting SPT exercises. Sufficient upward rotation
and posterior tilting of the scapula are essential components for
throwing and overhead activities (Borsa, Timmons, & Sauers, 2003;
Hammer, 2006; McClure, Bialker, Neff, Williams, & Karduna, 2004).
We believe that our study is the first to investigate activity of the LT
and SA muscles at the end-range of scapular upward rotation
during different arm-lifting SPT exercises.
For the LT, our results showed that the LT muscle activity was
significantly greater during the BRDAL exercise than during the PAL,
BRAL, or WAL exercises (p<0.05). Previous studies using Kendall’s
instructions (Kendall, & McCreary, 2005) for positioning the LT
during muscle testing found that the “diagonal overhead”arm
raised in line with the lower part of the trapezius in the prone
position produced the maximum mean EMG activity (97% MVIC) in
this muscle (Ekstrom et al., 2003). Oyama et al. (2010) reported that
LT activity (72% MVIC) was highest in 120
shoulder abduction with
external rotation (thumb pointing toward ceiling) among 6 scap-
ular retraction exercises. The results of our study are similar to
those of previous studies showing that LT muscle activity is highest
when the shoulder is abducted to 145
.Moseley, Jobe, Pink, Perry,
and Tibone (1992) reported that, of the 16 exercises tested, the
prone rowing exercise with shoulder abduction below 90
was the
most effective in activating the LT muscle. Prone external rotation
at 90
abduction has been reported to increase LT muscle activity
significantly more than the empty can exercise (Ballantyne et al.,
1993). It is difficult to compare the results of our study directly
with those of previous studies because of the different exercise
positions and protocols. We found that BRDAL elicited a higher
level of LT muscle activity (63.49 %MVIC) than did the other exer-
cises (PAL: 53.71 18.43% MVIC, BRAL: 47.99 20.87% MVIC, WAL:
25.88 21.23% MVIC), whereas the WAL position elicited the
lowest level of LT muscle activity. The BRDAL, PAL, and BRAL
exercises were performed in antigravity positions, which may
explain why the WAL position elicited the least LT muscle activity of
the four arm-lifting SPT exercises. In the present study, LT muscle
activity elicited by BRAL was less than that elicited by BRDAL and
PAL. McMahon, Jobe, Pink, Brault, and Perry (1996) reported that LT
muscle activity was greater at 145
shoulder abduction than at 180
in the prone position. The BRAL exercise was performed at 180
shoulder abduction in the present study. Unlike the WAL and PAL
exercises, the BRDAL exercise was performed with the neck and
trunk stabilized by the backward rocking position. Position of
Table 2
Mean (SD) EMG activation expressed as a percentage of maximal voluntary isometric contraction for each exercise.
Muscle Exercise FP
a
WAL
b
PAL
c
BRAL
d
BRDAL
Lower trapezius 25.88 21.23 53.71 18.43 47.99 20.87 63.50 23.92 26.46 0.000
Serratus anterior 43.33 25.09 38.21 21.88 60.04 28.04 43.38 22.36 10.39 0.000
Values are expressed as mean (SD).
a
WAL: Wall facing arm lift.
b
PAL: Prone arm lift.
c
BRAL: Backward rocking arm lift.
d
BRDAL: Backward rocking diagonal arm lift.
WAL
PAL
BRAL
BRDAL
0
10
20
30
40
50
60
70
*
*
*
*
*
Exercise T
y
pe
%MVIC
Fig. 2. Comparison of the lower trapezius muscle activity among four different
exercises.
S.-m. Ha et al. / Physical Therapy in Sport 13 (2012) 227e232230
thoracic spine could be a possible explanation why the LT muscle
activity was greater in BRDAL than in PAL. The thoracic spine will
flex more in the BRDAL position compared to PAL. A flexed thoracic
spine may induce scapula anterior tilting. Kebaetse et al. (1999)
reported that a slouched posture decreased scapular posterior
tilting during arm movements. The BRDAL position will be a more
challenging position to tilt the scapular posteriorly. Therefore, it is
likely that LT muscle activity was greater in the BRDAL position,
compared to PAL.
The SA muscle activity elicited by exercise in the BRAL position
was significantly greater than that elicited by the other positions.
For the SA, the BRAL exercise was performed with 180
shoulder
abduction, whereas the other exercises were performed with 145
shoulder abduction. Several exercises have been used to activate SA
muscles. SA muscle exercises using resistance, weights, or body-
weight are forward punch, push-up plus, and closed chain scapular
protraction (Burkhart, Morgan, & Kibler, 2000; Hintermeister,
Lange, Schultheis, Bey, & Hawkins, 1998; Moseley et al., 1992).
Self-exercises with no external weight are the open-chain scapular
protraction exercise, wall slide exercise, and scapular plane eleva-
tion (Burkhart et al., 2000; Hardwick et al., 2006; Ludewig et al.,
1996). Several studies demonstrated that the maximum EMG
activity in the SA muscle was shown during shoulder flexion or
abduction exercise from 120
to 150
(Ekstrom et al., 2003;
Hammer, 2006; Inman, Saunders, & Abbott, 1944; McClure et al.,
2004; McMahon et al., 1996; Moseley et al., 1992). However, our
results were not consistent with previous findings. Hammer (2006)
and Sahrmann (2002) stated that SPT increased sharply at the end
of shoulder abducted position. Bagg and Forrest (1986) reported
that SA muscle activity increased continuously until maximal
abduction. BRAL exercise was performed at the end-range of
shoulder abduction (compared to the other three exercises), which
simulates to maximal SPT (McClure et al., 2004), and facilitates
activation of SA. Additionally, BRAL position has shortened range of
SA muscle, which produced maximal muscle activity, compared to
other exercise positions (Lunnen, Yack, & LeVeau, 1981). Further-
more, the BRAL position elicits less muscle activity in the LT
because of fiber orientation (Ekstrom et al., 2003). Thus, the SA may
require greater activation to produce maximal SPT in the BRAL
position than in the other positions. The EMG activity of the SA was
not significantly different among the WAT, PAL, and BRDAL exercise
positions.
Previous studies have shown that spine stabilization activates
the target limb muscle, but also prevents unwanted motion and
muscle activation (Cynn, Oh, Kwon, & Yi, 2006; Oh, Cynn, Won,
Kwon, & Yi, 2007; Sahrmann, 2010). Some studies have investi-
gated the effects of spine stabilization during lower extremity
movement (Cynn et al., 2006; Oh et al., 2007); however, no study
has assessed the effect of spine stabilization on the upper
extremities. Stabilization of the cervical spine by pushing the
forehead on the dorsum of hand and prevention of thoracic and
lumbar extension using the backward rocking position may
enhance the trunk stability. Isolated contraction of LT in BRDAL and
SA in BRAL by stabilization of the spine could be a possible expla-
nation for increasing muscle activity. We did not directly measure
spine motion during the four arm-lifting SPT exercises; however,
we postulate that stabilization of the spine in backward rocking
position may have contributed to the increase in the muscle activity
observed in the LT and SA muscles.
Our study has several limitations. First, we did not measure the
SPT during each arm lift exercise because it is difficult to collect
kinematic data on SPT at the end-range. Further studies are
necessary to determine correlation between the amount of SPT and
other end-range exercises for the scapular. Second, the general-
ization of the study is limited because we recruited only young
healthy subjects; thus, future studies are necessary to determine
whether the present findings can be generalized to a symptomatic
population. If patients are not able to perform end-range exercises,
therapists can assist holding their shoulder at end-range. Further-
more, longitudinal studies are needed to assess the long-term effect
of the backward-rocking exercises (BRAL and BRDAL) on selective
activation of the LT and SA muscles.
5. Conclusions
The present study measured EMG activity in the LT and SA
muscles during different arm-lifting SPT exercises. LT muscle
activity during BRDAL was significantly greater than that during the
other exercises, whereas SA muscle activity during BRAL was
significantly greater than during the other exercises. Clinicians can
use these results to develop SPT exercises that specifically activate
the LT or SA muscles.
Conflict of Interest
None declared.
Ethical Approval
This study was approved by the Yonsei University Wonju
Campus Human Studies Committee.
Funding
None declared.
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0
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*
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*
Exercise T
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