Journal of Electromyography and Kinesiology xxx (2014) xxx–xxx

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The effect of scapular posterior tilt exercise, pectoralis minor stretching, and shoulder brace on scapular alignment and muscles activity in subjects with round-shoulder posture Ji-hyun Lee a,1, Heon-seock Cynn a,⇑, Tae-lim Yoon a,b,1, Chang-hee Ko a,1, Woo-jeong Choi a,1, Sil-ah Choi a,1, Bong-sam Choi b,2 a Applied Kinesiology and Ergonomic Technology Laboratory, Department of Physical Therapy, The Graduate School, Yonsei University, Baekwoon-kwan, 1 Yonseidae-gil, Wonju, Kangwon-do, Republic of Korea b Department of Physical Therapy, College of Health and Welfare, Woosong University, #17-2, Jayang-dong, Dong-gu, Daejeon, Republic of Korea

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Article history: Received 7 June 2014 Received in revised form 18 October 2014 Accepted 20 October 2014 Available online xxxx Keywords: Pectoralis minor stretching Scapular posterior tilting exercise Shoulder brace Round-shoulder posture

a b s t r a c t Background: There are various methods for rehabilitating round-shoulder posture (RSP), including strengthening exercises, stretching, and using a shoulder brace or taping to correct the altered posture. However, no study has determined which intervention is the most effective of the three methods to decrease RSP (intervention #1: scapular posterior tilting exercise alone [hereafter, SPT], intervention #2: the scapular posterior tilting exercise after PM stretching [PM stretch + SPT], and intervention #3: the scapular posterior tilting exercise with use of a shoulder brace [SPT + brace]). Objectives: The purpose of this study was to compare the SPT, PM stretch + SPT, and SPT + brace on RSP, PM index (PMI), and lower trapezius (LT) and serratus anterior (SA) activity in subjects with RSP. Methods: In total, fifteen young men with RSP, participated in the study (21.46 ± 2.30 years old). RSP was confirmed using a caliper measure. Surface electromyography (SEMG) data for LT and SA activity were collected during the three interventions, and the SEMG data are expressed as a percentage of the maximal voluntary isometric contraction (%MVIC). Results: RSP was significantly less in the PM stretch + SPT and SPT + brace than in the SPT (P < 0.05). PMI was significantly greater in the PM stretch + SPT and SPT + brace than in the SPT (P < 0.05). LT activity was significantly greater in the PM stretch + SPT than in the SPT or SPT + brace in subjects with RSP (P < 0.05). Conclusions: The PM stretching exercise and application of a shoulder brace may help correct RSP and restore the length of the PM. The posterior tilting exercise after PM stretching was the most effective method for eliciting greater LT muscle activation among the interventions tested. Ó 2014 Elsevier Ltd. All rights reserved.

1. Introduction Round-shoulder posture (RSP) is characterized by a protracted, downwardly rotated, and anteriorly tipped scapula position with increased cervical lordosis and upper thoracic kyphosis (Chansirinukor et al., 2001; Magee, 2002; Wong et al., 2010). Several factors may cause RSP, such as loss of lower trapezius (LT) and serratus anterior (SA) activity, tightness in the pectoralis minor (PM), greater thoracic kyphosis, and the scapular anatomical structure itself (Borstad and Ludewig, 2005; Ekstrom et al., 2003; Finley ⇑ Corresponding author. Tel.: +82 33 760 2427; fax: +82 33 760 2496. E-mail addresses: [email protected] (J.-h. Lee), [email protected] (H.-s. Cynn), [email protected] (T.-l. Yoon), [email protected] (C.-h. Ko), [email protected] (W.-j. Choi), [email protected] (S.-a. Choi), [email protected] (B.-s. Choi). 1 Tel.: +82 33 760 2497; fax: +82 33 760 2496. 2 Tel.: +82 42 630 4622.

and Lee, 2003; Hall, 2005; Kebaetse et al. 1999; Ludewig et al., 2004; Lukasiewicz et al., 1999; Sahrmann, 2002; Smith et al., 2002; Wang et al., 1999). Accordingly, altered scapular kinematics and associated muscle imbalance in RSP place the anterior acromion in close proximity to the supraspinatus and infraspinatus tendons and increase the potential for subacromial impingement (Holmgren et al., 2012; Ludewig and Cook, 2000; McClure et al., 2004; Peterson et al., 1997; Thigpen et al., 2010). Many previous studies have investigated various methods for rehabilitating RSP, including LT and SA strengthening exercises, PM stretching, and using a shoulder brace or taping to correct the altered posture (Hrysomallis, 2010; Hrysomallis and Goodman, 2001; Thigpen et al., 2010). Of theses methods, strengthening of the LT and SA have routinely been included in rehabilitation to actively counteract the strength and movement loss associated with RSP (Ekstrom et al., 2003; Hall, 2005; Ludewig et al., 2004; Smith et al., 2002). Lynch et al. (2010) also

http://dx.doi.org/10.1016/j.jelekin.2014.10.010 1050-6411/Ó 2014 Elsevier Ltd. All rights reserved.

Please cite this article in press as: Lee J-h et al. The effect of scapular posterior tilt exercise, pectoralis minor stretching, and shoulder brace on scapular alignment and muscles activity in subjects with round-shoulder posture. J Electromyogr Kinesiol (2014), http://dx.doi.org/10.1016/j.jelekin.2014.10.010

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J.-h. Lee et al. / Journal of Electromyography and Kinesiology xxx (2014) xxx–xxx

reported that muscle strengthening exercises successfully decreased RSP in elite swimmers. In particular, a scapular posterior tilting exercise in the prone position was the most effective method for strengthening the LT and SA, and stabilizing the scapula to the thoracic wall (Ekstrom et al., 2003; Ha et al., 2012). PM stretching exercises have also been used (Kisner and Colby, 2002; Sahrmann, 2002), and have been reported to reduce RSP significantly versus the pre-treatment baseline (Wong et al., 2010). Previous studies have demonstrated that strengthening the posterior scapular stabilizers, combined with stretching of the PM, can result in improved muscle strength in the scapular adductors, anterior inclination of the thoracic spine, and altered scapulohumeral rhythm in healthy subjects (Wang et al., 1999). Another method for restoring normal shoulder posture and scapular muscular activity involves bracing around the shoulder girdle. A shoulder brace is believed to affect the resting position of the scapula and to help maintain the proximal shoulder girdle stability necessary to perform elevation of the arm (Uhl et al., 2005, 2006). A previous study found that application of a shoulder brace decreased the forward shoulder angle (Cole et al., 2013). Another found that a functional shoulder brace demonstrated the same improvements in shoulder pain and function as traditional rehabilitation in subjects with subacromial impingement syndrome (Walther et al., 2004). Based on these previous researches, we included a scapular posterior tilting exercise, PM stretching, and shoulder brace use in this study. To determine which intervention is the most effective of the three interventions to decrease RSP and increase LT and SA muscle activity in subjects with RSP, the scapular posterior tilting exercise alone (hereafter, SPT), the scapular posterior tilting exercise after PM stretching (PM stretch + SPT), and the scapular posterior tilting exercise with use of a shoulder brace (SPT + brace) were compared in terms of effects on scapular alignment (degree of RSP and scapular upward rotation angle), PM index (PMI), and LT and SA activity in subjects with RSP. We hypothesized that scapular alignment, PMI, and LT and SA activity would differ among the interventions.

2. Methods 2.1. Subjects The G-power software was used for power analyses (G-power software 3.1.2; Franz Faul, University of Kiel, Kiel, Germany). The necessary sample size of seven subjects was calculated from data obtained from a pilot study of eight subjects to achieve a power of 0.80 and an effect size of 0.52 (calculated from the partial g2 of 0.21 from the pilot study), with an a level of 0.05. Thus, fifteen young men with RSP participated (age = 21.46 ± 2.30 years, height = 174.85 ± 3.41 cm, weight = 66.00 ± 4.24 kg, and BMI = 21.59 ± 1.27). The dominant side (preferred arm when eating and writing) was used in all tests (Yoshizaki et al., 2009). All of the subjects reported the right arm as their dominant side. RSP was confirmed via measurement using a caliper by the principal investigator (JHL), who had 10 years of clinical experience. The distance between the posterior border of the acromion and the table in the supine position was measured, as a simple measurement for RSP (Magee, 2002; Sahrmann, 2002; Wong et al., 2010). A supine position for measuring RSP could avoid measurement variations due to humeral rotation and unwanted scapular movement. The interclass correlation coefficient (ICC) of this measurement was 0.88–0.94 (Nijs et al., 2005). A score P 2.5 cm was defined as RSP (Sahrmann, 2002). Exclusion criteria were a history or clinical exam revealing pain or dysfunction that substantially limited shoulder motion or resulted in gross instability of the shoulder during daily activities,

signs and symptoms of cervical pain, adhesive capsulitis, thoracic outlet syndrome, or a current complaint of numbness or tingling in the upper extremity. The examination included the impingement tests of Hawkins, Neer, and Jobe, the apprehension test for anterior instability, the scapular winging test using a scapulometer (>2 cm), and the short head tendon of the biceps brachii and coracobrachialis muscle length test (Magee, 2002; Weon et al., 2011). Prior to participation, the subjects provided written informed consent. The investigation was approved by Yonsei University Wonju Institutional Review Board. 2.2. Electromyography (EMG) recording and data processing Surface EMG data were collected using a Noraxon TeleMyo-DTS with a wireless telemetry system (Noraxon, Inc., Scottsdale, AZ, USA) and analyzed using the Noraxon MyoResearch 1.06 XP software. EMG signals were amplified, band pass-filtered (10 and 450 Hz), and notch-filtered (60 Hz, 120 Hz) before being recorded digitally at 1000 Hz and processed into root-mean-square data. Data were collected from the LT and SA on the dominant side. After shaving and rubbing the skin with alcohol, disposable Ag/AgCl surface electrodes were placed on each muscle at standardized sites (Criswell, 2010). To minimize cross-talk from proximal deep or superficial muscles, this study selected the best electrode size (1 cm in diameter). Two electrodes were placed approximately 2 cm apart, in the direction of the muscle fibers. The LT electrodes were placed at an oblique vertical angle, with one electrode superior and one inferior to a point 5 cm inferomedial from the root of the spine of the scapula. The SA (lower part) electrodes were attached just below the axillary area at the level of the inferior tip of the scapula and medial to the latissimus dorsi. Correct electrode placement was confirmed by visual inspection of the EMG signals on a computer screen during specific muscle testing. Maximal voluntary isometric contractions (MVIC) were collected to normalize the EMG data from the LT and SA using the manual muscle testing positions recommended by previous studies (Ekstrom et al., 2005; Kendall et al., 2005). To determine the MVIC value for LT, each subject was tested in the prone position. The subject’s arm was placed diagonally overhead, in line with the lower fibers of the trapezius muscle during external rotation while resistance was applied just above the elbow joints (Ekstrom et al., 2003; Kendall et al., 2005). To obtain the MVIC value for SA, the subject was seated on a treatment table with no back support. The subject’s shoulder was rotated internally and abducted to 125° in the scapular plane, while resistance was applied above the elbow by the investigator (Ekstrom et al., 2005). Each contraction was held for 5 s, with maximal effort against manual resistance, and a 2-min rest was given between trials to minimize muscle fatigue (Vera-Garcia et al., 2010). The first and last second of the EMG data from each MVIC trial were discarded, and the remaining 3 s of data were used (De Oliveira et al., 2008; Vezina et al., 2000). We took the mean value of 3 s in three trials. And then, the mean of the three trials was calculated for data analysis. Intra-class correlation coefficient (ICC) for MVICs of LT and SA were 0.96 (95% Confidence Interval [CI]: 0.87–0.99) and 0.94 (95% CI: 0.83–0.98), respectively. The gathered EMG amplitudes for LT and SA during the exercises were expressed as a percentage of the mean MVIC (%MVIC). 2.3. Procedures Degree of RSP, scapular upward rotation angle, and PMI were obtained after each intervention (SPT, PM stretch + SPT, and SPT + brace). The results were not recorded by any investigator. A student read the values of the results so that the investigator remained blind. The EMG activities of the LT and SA muscles were collected during 5 s in each intervention, and a 2-min rest was

Please cite this article in press as: Lee J-h et al. The effect of scapular posterior tilt exercise, pectoralis minor stretching, and shoulder brace on scapular alignment and muscles activity in subjects with round-shoulder posture. J Electromyogr Kinesiol (2014), http://dx.doi.org/10.1016/j.jelekin.2014.10.010

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given between 2 trials. The mean value was used for data analysis (De Luca, 1997). Subjects performed the three interventions in randomized order; subjects drew lots to avoid learning effects or fatigue. Subjects had a wash-out period of 12 min among the interventions to avoid the effects of stretching, based on previous studies that demonstrated that a single session of static or PNF hold-relax stretching results in increased flexibility that lasts approximately 3 min (4 repetitions stretching  3 min lasting = 12 min rest) (DePino et al., 2000; Spemoga et al., 2001). If measuring RSP (with a caliper) was performed more than 12 min after the stretching procedure, the stretching effect would be disappeared. Thus, we measured RSP, scapular upward rotation angle, and PMI immediately after each intervention. To ensure that each subject performed the exercises at a standard speed, a metronome was set at one beat per second (Nyland et al., 2004). Subjects were familiarized with the SPT prior to testing. The familiarization period was ended when the subject was able to maintain the exercise positions for 5 s. All of the subjects were comfortable after the familiarization period, and none reported fatigue. A 5-min rest period was allowed after the familiarization period before data collection began.

2.3.1. Scapular upward rotation angle measurement The subject was in a standing position. Scapular upward rotation was measured with two inclinometers; one was used to measure the 135° humeral abduction position, and the second was used to measure the upward rotation of the scapula, manually aligned along the scapular spine. Yano et al. (2010) demonstrated that the mean maximum arm elevation angles of healthy subjects were 135.4° (range, 125.0–150.0°) for dominant arms. Thus, we measured upward rotation in a 135° humeral abduction position. The ICC was 0.88 (Watson et al., 2005).

2.3.2. PMI measurement PMI was used to measure the length of the PM. The subjects were standing erect with their test arm resting at their side. Forearm position was neutral and hand was resting position. The resting muscle length was determined between the medial-inferior angle of the coracoid process and just lateral to the sternocostal junction of the inferior aspect of the fourth rib with a caliper measure. The PMI was calculated by dividing the resting muscle length by the subject’s height and multiplying by 100 (Borstad and Ludewig, 2005). Increased PMI indicates increased PM length. Borstad (2008) demonstrated the concurrent validity between the caliper and the electromagnetic system with two anatomical landmarks for measuring resting PM length; the ICCs for were 0.83–0.87 (Fig. 1). The test–retest reliability for PMI measurement was 0.94 in the current study (95% CI = 0.81–0.98, standard error of measurement [SEM] = 0.32, minimal detectable changes 95% confidence interval [MDC95] = 0.89, and coefficient of variation [CV] = 10.60%).

2.3.3. Scapular posterior tilting exercise The subject began in quadruped and then shift the body backward into a deep kneel position during 3 s. The subject’s shoulder was abducted to 145° by the investigator, and the subject was instructed to lift the dominant arm, with extended elbow, neutral forearm, extended hand. The radial border of the wrist slightly touched but did not push a wooden target bar, and then to maintain this arm position (Fig. 2). This bar, positioned at the subject’s earlobe line in the backwards rocking exercise position, was used to control the angle of shoulder flexion in each exercise (Ha et al., 2012).

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Fig. 1. Measurement of pectoralis minor muscle length by a caliper. The resting muscle length was determined between the medial-inferior angle of the coracoid process (A) and just lateral to the sternocostal junction of the inferior aspect of the fourth rib (B) with a caliper measure. The pectoralis minor index was calculated by dividing the resting muscle length by the subject’s height and multiplying by 100.

2.3.4. Scapular posterior tilting exercise after PM stretching (PM stretch + SPT) The subjects were positioned in a supine position, with their hips and knees bent (90° flexion) and their feet on the floor. The test arm was abducted and rotated externally to 90°, and the subject’s elbow was flexed to 90°. Subjects were instructed to contract their abdominals by sucking their belly in towards their spine to avoid rib cage elevation during PM stretching. The investigator stabilized each subject’s body by placing one hand on the contralateral coracoid. Then the investigator passively horizontally abducted the subject’s shoulder. The stretching was performed for four sequential repetitions, holding the stretches for 30 s, with a 30 s break between each stretch. The investigator applied all of the stretches at the end range of motion (Williams et al., 2013). Williams et al. (2013) introduced the gross stretching technique for PM stretching. However, they did not clearly describe how to control rib cage elevation. A modified version of their stretching technique was used in this study (Fig. 3). The PM stretching exercise was overseen by a licensed physical therapist with 10 years of clinical experiences. Following the PM stretching exercise, the subjects performed the scapular posterior tilting exercise.

2.3.5. Scapular posterior tilting exercise with use of a shoulder brace (SPT + brace) The brace was applied by the principal investigator (JHL) according to the manufacturer’s specifications using a 1-strap method for controlling strap tension (Fig. 4). The subject was in the standing position as the shoulder brace was put on. Subjects raised both arms. The investigator wrapped the strap at the subjects’ coracoid process on the lower shoulder side first. Then the investigator pulled it towards the cranial and lateral side (the strap ran from the midthorax, crossed at the coracoid process and axillary area, and terminated at the midthorax again). This method was repeated on the opposite side. Then the subject assumed a quadruped position, as in the scapular posterior tilting exercise. The principal investigator confirmed correct application of the shoulder brace before the subject performed the tilting exercise. And then, the subjects performed the scapular posterior tilting exercise. The principal investigator also monitored electrode sites during the tilting exercise to prevent a source of noise from the brace.

Please cite this article in press as: Lee J-h et al. The effect of scapular posterior tilt exercise, pectoralis minor stretching, and shoulder brace on scapular alignment and muscles activity in subjects with round-shoulder posture. J Electromyogr Kinesiol (2014), http://dx.doi.org/10.1016/j.jelekin.2014.10.010

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J.-h. Lee et al. / Journal of Electromyography and Kinesiology xxx (2014) xxx–xxx

Fig. 2. Scapular posterior tilting exercise. The subject began in quadruped and then shift the body backward into a deep kneel position. The subject was instructed to lift the dominant arm, with the elbow extended until the radial border of the wrist slightly touched but did not push a wooden target bar, and then to maintain this arm position.

p [MDC95 = SEM ⁄ 1.96 2] was calculated (Ries et al., 2009). Effect size (ES) is generally considered more appropriate to determine if meaningful change has occurred, because it does take group variability into account. The ES is calculated to determine meaningful changes between interventions [differences of mean between interventions/standard deviation of SPT or differences of mean between PM stretch + SPT and SPT + brace/standard deviation of SPT + brace] (Portney and Watkins, 2009). A one-way, repeatedmeasures ANOVA was used to assess the statistical significance of degree of RSP, scapular upward rotation angle, PMI, and LT and SA activity among the three interventions. The level of significance was set at 0.05. 3. Results 3.1. Degree of RSP, scapular upward rotation angle, and PMI Fig. 3. Pectoralis minor stretching exercise.

2.4. Statistical analysis PASW Statistics 18 software (SPSS, Chicago, IL, USA) was used to perform all statistical analyses. Test–retest reliability of EMG measurements in three interventions (SPT, PM stretch + SPT, and SPT + brace) was assessed by ICC, 95% CI, the SEM, and MDC95. The SEM was calculated for each measurement to assess absolute p consistency [SEM = SD (1-ICC)]. Additionally, the CV is another measure of variability which is a measure of relative variation [CV = SD/mean ⁄ 100] (Portney and Watkins, 2009). MDC95

There were significant differences in degree of RSP among the interventions (F2, 13 = 36.59, P < 0.05), with the values being significantly less in the PM stretch + SPT (P < 0.05, ES = 2.21) and SPT + brace (P < 0.05, ES = 2.26) than in the SPT. There were also significant differences in PMI (F2, 13 = 6.971, P = 0.011) among the three interventions. PMI was significantly greater in the PM stretch + SPT (P = 0.017, ES = 0.43) and SPT + brace (P = 0.004, ES = 0.70) than in the SPT. However, there were no significant differences in scapular upward rotation angle among the three interventions (F2, 13 = 1.498, P = 0.266; ES between the SPT and the PM stretch + SPT was 0.68 and ES between the SPT and the SPT + brace was 0.52, Fig. 5, Table 1).

Fig. 4. Shoulder braces application. (A) The subjects raised both arms in the standing position. (B) The investigator wrapped the strap at the subjects’ coracoid process on the lower shoulder side first. Then the investigator pulled it towards the cranial and lateral side (the strap ran from the midthorax, crossed at the coracoid process and axillary area, and terminated at the midthorax again). (C) This method was repeated on the opposite side. (D) The subjects lowered their arms to the side from elevated position.

Please cite this article in press as: Lee J-h et al. The effect of scapular posterior tilt exercise, pectoralis minor stretching, and shoulder brace on scapular alignment and muscles activity in subjects with round-shoulder posture. J Electromyogr Kinesiol (2014), http://dx.doi.org/10.1016/j.jelekin.2014.10.010

J.-h. Lee et al. / Journal of Electromyography and Kinesiology xxx (2014) xxx–xxx

3.2. LT and SA muscle activity The test–retest reliabilities for EMG measurement of LT and SA muscle were substantial in three interventions (SPT: ICC = 0.86, 95% CI = 0.61–0.96, SEM = 7.22, MDC95 = 20.00, and CV = 45.00% for LT (49.02 ± 22.06%MVIC), and ICC = 0.95, 95% CI = 0.84–0.98, SEM = 2.81, MDC95 = 7.79, and CV = 46.86% for SA (25.82 ± 12.10%MVIC); PM stretch + SPT: ICC = 0.87, 95% CI = 0.63–0.96, SEM = 10.22, MDC95 = 28.33, and CV = 46.29% for LT (61.01 ± 28.24%MVIC), and ICC = 0.99, 95% CI = 0.98–0.99, SEM = 2.09, MDC95 = 5.79, and CV = 74.75% for SA (32.31 ± 24.15%MVIC); SPT + brace: ICC = 0.95, 95% CI = 0.84–0.98, SEM = 4.05, MDC95 = 11.23, and CV = 35.55% for LT (48.98 ± 17.41%MVIC), and ICC = 0.89, 95% CI = 0.65–0.97, SEM = 6.31, MDC95 = 17.49, and CV = 57.41% for SA (33.60 ± 19.29%MVIC). There were significant differences in LT muscle activity (F2, 13 = 7.405, P = 0.009) among three interventions, with the PM stretch + SPT showing significantly greater LT muscle activity than the SPT or SPT + brace (P = 0.002, ES between the SPT and the PM stretch + SPT was 0.55; P = 0.002, ES between the PM stretch + SPT and the SPT + brace was 0.69, Fig. 6). There were no statistically significant differences in SA muscle activity among the three interventions (F2, 13 = 2.331, P = 0.143; ES between the SPT and the PM stretch + SPT was 0.54, ES between the SPT and the SPT + brace was 0.64, and ES between the PM stretch + SPT and the SPT + brace was 0.07, Fig. 6).

4. Discussion We compared the effects of three different interventions, namely, SPT, PM stretch + SPT, and SPT + brace, on scapular alignment, PMI, and LT and SA activity in subjects with RSP. To the best of our knowledge, this is the first study to make this comparison. Degree of RSP was significantly less in the PM stretch + SPT than in the SPT, decreasing by 2.94 cm (30.72%). Decreased RSP indicates less anterior tilting in the sagittal plane and internal rotation

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in the transverse plane of the scapula confirming stretching effect of the tight PM in subjects with RSP. These findings support the research hypothesis and are consistent with previous studies (Lynch et al., 2010; Kluemper et al., 2006; Roddey et al., 2002). Roddey et al. (2002) found that a 2-week self PM stretching program decreased RSP in asymptomatic forward-head-posture with RSP subjects. Two previous studies also reported that stretching of the anterior shoulder muscles (the levator scapulae, sternocleidomastoid, and PM) and strengthening of the posterior shoulder muscles (middle trapezius, LT, and SA) decreased RSP following 6- or 8-week treatments in swimmers (Kluemper et al., 2006; Lynch et al., 2010). The mechanism behind this change is believed to be a viscoelastic response of the muscle–tendon unit due to static stretching (Klinge et al., 1997). A viscoelastic response results in passive tension reduction for any given length of the tissue, allowing increased flexibility to be achieved (Klinge et al., 1997; Taylor et al., 1997). Thus, our results indicate that the PM stretching method with SPT may be more effective for improving RSP versus SPT alone. We also found that degree of RSP was significantly less in the SPT + brace compared to the SPT, decreasing by 3.01 cm (31.45%). Especially, decreased RSP indicates less internal rotation of the scapula in the transverse plane suggesting beneficial effect of applying brace in subjects with RSP. These results are consistent with previous reports, although the application methods and materials of the shoulder braces differed slightly among studies (Cole et al., 2013; Dewan et al., 2014). Cole et al. (2013) reported that application of a shoulder brace decreased RSP (or the forward shoulder angle) in a compression shirt with fully tightened straps. Other researchers have also demonstrated that scapular taping decreases RSP (Dewan et al., 2014; Lewis et al., 2005). However, the application of adhesive tape might cause skin irritation in some patients and might not be a feasible treatment for daily or prolonged use. Thus, we chose the shoulder brace instead of straps or tape. The mechanisms of shoulder brace action may include a mechanical change in shoulder girdle alignment and proprioception input augmentation (Cole et al., 2013). Use of the shoulder

Fig. 5. Comparison of degree of round-shoulder posture, pectoralis minor index, and scapular upward rotation angle among the scapular posterior tilting exercise alone, the scapular posterior tilting exercise after PM stretching, and the scapular posterior tilting exercise with use of a shoulder brace. ⁄ indicates a significant difference (p < 0.05). The pectoralis minor index was calculated by dividing the resting muscle length by the subject’s height and multiplying by 100. An increased pectoralis minor index indicated increased pectoralis minor muscle length.

Please cite this article in press as: Lee J-h et al. The effect of scapular posterior tilt exercise, pectoralis minor stretching, and shoulder brace on scapular alignment and muscles activity in subjects with round-shoulder posture. J Electromyogr Kinesiol (2014), http://dx.doi.org/10.1016/j.jelekin.2014.10.010

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Table 1 Data of amounts of round shoulder posture, pectoralis minor index, and scapular upward rotation angle after scapular posterior tilting exercises alone, scapular posterior tilting exercises after pectoralis minor stretching, and scapular posterior tilting exercises with applying shoulder brace. Variables

Amounts of round shoulder posture (cm) Pectoralis minor index (%) Scapular upward rotation angle (°)

Interventions After SPT

After PM stretch + SPT

After SPT + Brace

9.57 ± 1.33a 16.51 ± 1.75 35.62 ± 6.40

6.63 ± 1.33 17.26 ± 2.18 39.99 ± 11.55

6.56 ± 1.34 17.47 ± 2.55 38.95 ± 7.28

SPT: Scapular posterior tilting exercise alone. PM stretch + SPT: scapular posterior tilting exercises after pectoralis minor stretching. SPT + Brace: posterior tilting exercises with applying shoulder brace. a Mean ± standard deviation.

Fig. 6. Comparison of muscle activity in the lower trapezius and serratus anterior among the scapular posterior tilting exercise alone, the scapular posterior tilting exercise after PM stretching, and scapular posterior tilting exercise with use of a shoulder brace. ⁄ indicates a significant difference (p < 0.05).

brace involves having the subject retract and depress the scapula, then applying the brace over the coracoid process, thorax, and scapular spine. Thus, use of the shoulder brace is more effective for restoring shoulder position than the SPT in subjects with RSP. Because there was no significant difference in the degree of RSP between the PM stretch + SPT and SPT + brace groups, our results suggest that both methods may be incorporated into the treatment protocol to improve RSP. Our results revealed greater PMI in the PM stretch + SPT and SPT + brace than in the SPT group, increasing by 0.75 (4.54%) and 0.96 (5.82%) in the former intervention, respectively. Increased PMI indicated the lengthening of the PM. These findings support the research hypothesis. However, no previous study has examined PMI in relation to the three interventions used in the present study. Therefore, it is not possible to compare these results directly with those of any other previous study. When the PM is shortened, excessive anterior tilt, protraction, and scapular downward rotation would limit normal scapulothoracic motions and cause even impingement syndrome. Thus, lengthen PMI might be expected to correct the RSP by posterior tilt, retraction, and scapular upward rotation. In addition to this lengthening effect of the PM, our results suggest that the PM stretch + SPT and SPT + brace are effective for lengthening the PM muscle compared to SPT alone in subjects with RSP. However, there were no significant differences in scapular upward rotation angle among the three interventions, although it did increase by 4.37° (12.27%) and 3.33° (9.35%) in the PM stretch + SPT and SPT + brace compared to the SPT. The hypothesis was based on the theory that 30° or greater shoulder elevation angles would require the scapular upward rotation and further posterior tilt through lengthening of the shortened muscle (Muraki et al., 2009). However, these findings did not support

the research hypothesis. These findings are similar to those reported by McClure et al. (2004) and Williams et al. (2013), both of which reported that there was no difference in scapular upward rotation angle after PM stretching exercises. According to McClure et al. (2004), this may have been due to the protocol they used not being challenging enough. No previous study has examined changes in scapular upward rotation angle while using a shoulder brace; thus, it is not possible to compare our results with previous work. Considering our results, none of the interventions applied in the present study may be sufficient to alter the scapular upward rotation angle immediately. We also found that LT activity increased significantly in the PM stretch + SPT group compared to the SPT (by 24.02%) and SPT + brace (by 24.56%). The result supports the research hypothesis. However, again, no previous study has considered these aspects and thus we cannot directly compare our results to any other studies. There are several possible explanations for the increased activity of the LT following PM stretch + SPT. First, after PM stretching, the scapular posterior tilting increased due to the lengthened PM. This was confirmed by the RSP and PMI measurements. Due to this increased range, the LT was able to continue to contract during the SPT exercise. Second, after PM stretching, the viscoelastic properties of the PM may have changed. Reduced passive tension allowed increased activation of LT as a main scapular posterior tilting muscle. Third, PM stretching might reduce the muscle imbalance between PM and LT; thus, the inhibited LT could be activated more after PM stretching. These results also suggest that simply providing afferent feedback from cutaneous receptors under the shoulder brace is not enough to increase LT activity immediately. Additionally, the subscapularis, pectoralis major, coracobrachialis, biceps long head, teres major and latissimus dorsi to an extent, were well stretched during the PM stretching. Thus, all of these muscles may have had an effect on the ability to perform the LT exercise. These mechanisms may explain why LT activity increased after PM stretching whereas no change occurred after SPT + brace. However, there were no significant differences in SA activity among the three interventions, although it did increase by 16.59% and 12.11% in the PM stretch + SPT and SPT + brace compared to the SPT. The results for the SPT + brace are consistent with Cole et al. (2013), who reported no significant difference in SA activity with and without a shoulder brace. A lack of tactile feedback on the SA muscle may partially explain these results because the brace is applied to the midthorax, coracoid process, and axillary area. Thus, the brace may be insufficient to elicit SA activity. Consequently, the usage of a brace should not be encouraged to increase LT and SA activity in subjects with RSP. This study has several limitations. First, its generalizability is limited because healthy, young male subjects with no symptoms of subacromial impingement participated. The results may have been different if we had used female subjects or subjects with such symptoms. Second, this study used a wash-out period based on

Please cite this article in press as: Lee J-h et al. The effect of scapular posterior tilt exercise, pectoralis minor stretching, and shoulder brace on scapular alignment and muscles activity in subjects with round-shoulder posture. J Electromyogr Kinesiol (2014), http://dx.doi.org/10.1016/j.jelekin.2014.10.010

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previous studies (Depino et al., 2000; Spemoga et al., 2001) although the applying muscles and stretching technique differed from our study. Thus, future research should examine the washout period after stretching techniques. Third, it was a cross-sectional study. Therefore, long-term effects of PM stretching and brace use cannot be determined. Further studies should compare the long-term effects of these different treatments on scapular upward rotation angle, PMI, and LT and SA activity in subjects with RSP. 5. Conclusions Degree of RSP decreased and PMI increased after the PM stretch + SPT and SPT + brace treatments compared to SPT alone. Thus, PM stretching exercises and use of a shoulder brace may reduce RSP and restore the length of the PM. LT activity increased after PM stretch + SPT compared to the SPT and SPT + brace. The PM stretch + SPT elicited the greatest LT muscle activation among the interventions compared. Conflict of interest We certify that no party having a direct interest in the results of the research supporting this article has or will confer a benefit on us or on any organization with which we are associated. References Borstad JD. Measurement of pectoralis minor muscle length: validation and clinical application. J Orthop Sports Phys Ther 2008;38(4):169–74. Borstad JD, Ludewig PM. The effect of long versus short pectoralis minor resting length on scapular kinematics in healthy individuals. J Orthop Sports Phys Ther 2005;35(4):227–38. Chansirinukor W, Wilson D, Grimmer K, Dansie B. Effects of backpacks on students: measurement of cervical and shoulder posture. Aust J Physiother 2001;47:110–6. Cole AK, McGrath ML, Harrington SE, Padua DA, Rucinski TJ, Prentice WE. Scapular bracing and alteration of posture and muscle activity in overhead athletes with poor posture. J Athl Train 2013;48(1):12–24. Criswell E. Cram’s introduction to surface electromyography. 2nd ed. Massachusetts: Jones and Bartlett Publishers; 2010. De Luca C. The use of surface electromyography in biomechanics. J Appl Biomech 1997;13:135–63. De Oliveira AS, De Morais Carvalho M, De Brum DP. Activation of the shoulder and arm muscles during axial load exercises on a stable base of support and on a medicine ball. J Electromyogr Kinesiol 2008;18:472–9. DePino GM, Webright WG, Arnold BL. Duration of maintained hamstring flexibility after cessation of an acute static stretching protocol. J Athl Train 2000;35(l):56–9. Dewan N, Raja K, Miyaru GB, Macdermid JC. Effect of box taping as an adjunct to stretching–strengthening exercise program in correction of scapular alignment in people with forward shoulder posture: a randomised trial. ISRN Rehabil 2014:1–12. Ekstrom RA, Donatelli RA, Soderberg GL. Surface electromyographic analysis of exercises for the trapezius and serratus anterior muscles. J Orthop Sports Phys Ther 2003;33:247–58. Ekstrom RA, Soderberg GL, Donatelli RA. Normalization procedures using maximum voluntary isometric contractions for the serratus anterior and trapezius muscles during surface EMG analysis. J Electromyogr Kinesiol 2005;15(4):418–28. Finley MA, Lee RY. Effect of sitting posture on 3-dimensional scapular kinematics measured by skin-mounted electromagnetic tracking sensors. Arch Phys Med Rehabil 2003;84(4):563–8. Ha SM, Kwon OY, Cynn HS, Lee WH, Park KN, Kim SH, et al. Comparison of electromyographic activity of the lower trapezius and serratus anterior muscle in different arm-lifting scapular posterior tilt exercises. Phys Ther Sport 2012;13(4):227–32. Hall CM. The shoulder girdle. In: Hall CM, Brody LT, editors. Therapeutic exercised moving towards function. second ed. Philadelphia: Lippincott Williams and Wilkins; 2005. p. 643–97. Holmgren T, Hallgren HB, Oberg B, Adolfsson L, Johansson K. Effect of specific exercise strategy on need for surgery in patients with subacromial impingement syndrome: randomised controlled study. BMJ 2012;344(787):1–9. Hrysomallis C. Effectiveness of strengthening and stretching exercises for the postural correction of abducted scapulae: a review. J Strength Cond Res 2010;24(2):567–74.

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Ji-Hyun Lee is a Ph.D. Student in the Department of Physical Therapy at the Graduate School of Yonsei University. She received B.S. degree in Physical Therapy from Hanseo University, M.S. degree in Physical Therapy from Yonsei University. She is a member of applied kinesiology and ergonomic technology laboratory, and she is a part time lecturer of Yonsei University. Her main research interests are shoulder and hip assessment and treatment strategy. Her papers have been published in several international journals in these fields.

Heon-Seock Cynn is a professor in the Department of Physical Therapy at the College of Health Science of Yonsei University. He received B.S. degree in Physical Therapy from Yonsei University, M.A. degree in Physical Therapy from New York University, and Ph.D. degree in Physical Therapy from Yonsei University. He was a full time lecturer of Seoul Health College and an associate professor of Hanseo University. He is a director of applied kinesiology and ergonomic technology laboratory, and his research interests are identification of etiologic factors, classification, and intervention approaches for movement disorders and musculoskeletal diseases.

Tae-Lim Yoon is a professor in the Department of Physical Therapy at the College of Health and Welfare of Woosong University and Ph.D. Candidate in the Department of Physical Therapy at the Graduate School of Yonsei University. He received B.S. degree in Physical Therapy from Yonsei University, M.A. degree in Physical Therapy from New York University. He is a member of applied kinesiology and ergonomic technology laboratory, and his research interests are movement analysis, human factors and ergonomics, and prevention and management of musculoskeletal problems.

Chang-Hee Ko is a M.S Student in the Department of Physical Therapy at the Graduate School of Yonsei University. He received B.S degree in Physical Therapy from Hanseo University. He is a member of applied kinesiology and ergonomic technology laboratory and his current research interests include the forward shoulder posture and muscle performance after applying figure of 8 brace. He currently works as a physical therapist in Seoul National University Bundang Hospital.

Woo-Jeong Choi is a M.S. Student in the Department of Physical Therapy at the Graduate School of Yonsei University. She received B.S. degree in Physical Therapy from Yonsei University. She is a member of applied kinesiology and ergonomic technology laboratory. Her research interests are musculoskeletal problems including the scapular winging.

Sil-Ah Choi received her B.S. degree in Physical Therapy from Yonsei University, and M.S. degree in Physical Therapy from Yonsei University. She is a member of applied kinesiology and ergonomic technology laboratory. Her research interests are the clinical biomechanics associated with musculoskeletal problems.

Bong-sam Choi is an associate professor and chair in the Department of Physical Therapy at the College of Health and Welfare, Woosong University. He earned a B.S. degree in Department of Health Science from Yonsei University, a Master’s degree in Public Health in the Graduate School, Yonsei University, and a Ph.D degree in the Department of Rehabilitation Science, University of Florida, Gainesville, Florida. He has an extensive clinical experience in the care of patients with Parkinson’s, musculoskeletal, and geriatricrelated diseases at acute care hospitals, sub-acute rehabilitation/long-term care, and out-patient settings for 20 years in the United States. His research interests involve the development of patient-reported instruments as well as rehabilitation outcome measures.

Please cite this article in press as: Lee J-h et al. The effect of scapular posterior tilt exercise, pectoralis minor stretching, and shoulder brace on scapular alignment and muscles activity in subjects with round-shoulder posture. J Electromyogr Kinesiol (2014), http://dx.doi.org/10.1016/j.jelekin.2014.10.010