Normal muscular control of the scapula is important for

Transcription

1 DAVID M. SELKOWITZ, PT, PhD, OCS, DAAPM 1 CASEY CHANEY, PT, PhD, OCS, CSCS 2 SANDRA J. STUCKEY, PT, PhD 2 GEORGEANNE VLAD, PT, MA 2 The Effects of Scapular Taping on the Surface Electromyographic Signal Amplitude of Shoulder Girdle Muscles During Upper Extremity Elevation in Individuals With Suspected Shoulder Impingement Syndrome Normal muscular control of the scapula is important for activities involving upper extremity (UE) elevation. The upper and lower trapezius and the serratus anterior muscles have important and specific roles in upward rotation of the scapula during UE elevation. 2,3,18,28 Muscular dysfunction, including weakness of scapulothoracic muscles, 9 has been implicated in disorders such as shoulder (subacromial) impingement and rotator cuff strain. Shoulder pain due to these disorders has been associated with significantly reduced health. 30 STUDY DESIGN: Multifactorial, repeated-measures, within-subjects design. OBJECTIVES: To investigate the immediate effects of scapular taping on surface electromyographic (EMG) signal amplitude of shoulder girdle muscles during upper extremity elevation in individuals with suspected shoulder impingement syndrome. BACKGROUND: Individuals with shoulder impingement syndrome may present with increased activity of the upper trapezius and inhibition of other shoulder muscles active during upper extremity elevation. Scapular taping is theorized to normalize shoulder girdle function during scapular upward rotation by decreasing upper trapezius activity and increasing the activity of the lower trapezius and other muscles. METHODS AND MEASURES: Twenty-one volunteers with suspected shoulder impingement syndrome performed shoulder abduction in the scapular plane and a functional overhead-reaching ( shelf ) task, both with and without tape. Surface electrodes were applied over the upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscles. Mean root-mean-square of the EMG signal, normalized to maximum contraction, was assessed for each muscle. RESULTS: Upper trapezius activity was significantly lower with tape during shelf task elevation (P =.002), especially above 90 (P.002). Lower trapezius activity was significantly higher with tape (P =.043). No significant differences were found between the tape and no tape for other muscles for the shelf task. During shoulder abduction in the scapular plane, the main effect for upper trapezius showed a significant decrease of EMG signal amplitude (P =.047) for tape versus no tape, but no significant interactions were found among components of this activity, or for other muscles. CONCLUSION: Scapular taping decreased upper trapezius and increased lower trapezius activity in people with suspected shoulder impingement during a functional overhead-reaching task, and decreased upper trapezius activity during shoulder abduction in the scapular plane. Taping did not affect the other muscles under the loads tested, but it is possible that the activity of these muscles was not deficient at the time of testing. J Orthop Sports Phys Ther 2007;37(11): doi: /jospt KEY WORDS: biomechanics/upper extremity, electromyographic activity, EMG, pain, scapula Ludewig and Cook 23 found that EMG signal amplitude of the upper trapezius is increased, while that of the lower trapezius is decreased, in patients with shoulder impingement. This has been suggested to result in an imbalance between the upper trapezius and serratus anterior in producing upward scapular rotation, resulting in a shoulder shrug when attempting UE elevation. 22,24 Ludewig and Cook 23 also found that there is decreased scapular upward rotation during UE elevation in patients with shoulder impingement. Decreased serratus anterior activity has also been found in patients with shoulder impingement. 34 Several authors agree that anterior tipping of the scapula during UE elevation was present in subjects with shoulder impingement. 4,23,25 These findings also suggest diminished lower trapezius action during upward rotation of the scapula. Cools et al 8 found significant delays in lower and middle trapezius activation in overhead (ie, overhead-throwing/- functioning) athletes with impingement syndrome compared to overhead athletes who were uninjured. They also found significant delays in lower trapezius activation on the injured side compared to the uninjured side in the injured subjects. 8 In addition, Cools et al 9 found decreased lower trapezius surface EMG signal amplitude during isokinetic shoulder retraction in overhead athletes with shoulder 1 Professor, Western University of Health Sciences, Pomona, CA. 2 Associate Professor, Western University of Health Sciences, Pomona, CA. Partial funding for this study was provided through a grant from the California Physical Therapy Fund, Inc. This study was approved by the Institutional Review Board of Western University of Health Sciences. Address correspondence to David M. Selkowitz, 365 Lincoln Ave, Pomona, CA dselkowitz@westernu.edu 694 november 2007 volume 37 number 11 journal of orthopaedic & sports physical therapy

2 impingement compared to those without impingement. People with shoulder impingement have been found, using fine-wire EMG, to demonstrate decreased rotator cuff activity, particularly of the infraspinatus muscle, during isotonic shoulder abduction in the scapular plane. 32 This may result in insufficient humeral head depression during UE elevation leading to shoulder impingement. 32 Infraspinatus is considered to have an important role in depression of the humeral head and in providing glenohumeral joint stability during UE elevation. 14 McConnell (unpublished course notes, 1994) has proposed a method of scapular taping for treatment of shoulder impingement and other pathologies thought to occur due to imbalances of the shoulder musculature. McConnell s method of scapular taping and her theories regarding scapulothoracic region pathomechanics and rehabilitation have not been adequately tested. In a study involving uninjured subjects, Cools et al 7 found that, both with and without lifting a load, there were no significant differences in surface EMG of the upper and lower trapezius and serratus anterior muscles between scapular taping and no-taping conditions, during UE elevation and lowering. Alexander et al 1 found that a scapular taping technique used on healthy individuals decreased the amplitude of the lower trapezius H-reflex until the tape was removed, indicating an inhibitory influence of taping. In contrast, Morin et al 27 found a significant decrease in upper trapezius EMG signal amplitude and a concomitant significant increase in middle/lower trapezius EMG signal amplitude with scapular taping compared to no taping, in uninjured subjects. A case report by Host 17 investigated the use of scapular taping on a patient with a diagnosis of shoulder impingement. The patient required 8 treatment sessions that included the application of scapular tape combined with therapeutic exercise before being able to perform full shoulder flexion and abduction without pain. At the 3-week follow-up after the end of therapy, the patient reported that he no longer had pain and that he had resumed all his leisure time activities, including playing tennis several times a week. However, muscle activity was not examined in that patient. Further research, such as experimental studies and clinical trials, is necessary to elucidate the effects and effectiveness of scapular taping. The purpose of this study was to determine if scapular taping has an influence on surface EMG signal amplitude of the upper trapezius, lower trapezius, serratus anterior, and infraspinatus muscles during UE elevation in subjects with signs and symptoms suggestive of shoulder impingement. Based on the previously described impairments associated with shoulder impingement, a beneficial effect of scapular taping would be a decrease in activity of the upper trapezius and an increase in the activity of the lower trapezius, serratus anterior, and infraspinatus muscles. The effects on the upper trapezius could be as a result of the location of the tape, while the effects on the other muscles could be considered indirect and related to changes in activation of the upper trapezius. Based on prior research and a pilot study on the immediate effects of scapular taping, we hypothesized that, in subjects with signs and symptoms of shoulder impingement syndrome, scapular taping would significantly decrease upper trapezius surface EMG signal amplitude compared to no taping. Additionally, we hypothesized that in these subjects there would be no significant difference in surface EMG signal amplitude between scapular taping and no-taping conditions for the lower trapezius, serratus anterior, and infraspinatus muscles. METHOD This study was approved by the Institutional Review Board of Western University of Health Sciences. Informed consent was obtained, and data were collected on 21 volunteers (11 males and 10 females) from the University community and selected affiliated physical therapy clinics. Subjects were offered a $5 stipend for participation in the study to defray transportation costs. The subjects were at least 18 years of age (mean, 42.8 years), with a mean body mass of 72.1 kg and a mean height of cm. They reported having shoulder pain for varying duration, ranging from 1 week to several years. Inclusion criteria were a positive Neer 29 and/or Hawkins-Kennedy 16 test, history of pain in the proximal portion of the C5-6 dermatome with UE elevation, 25 and no prior scapular taping, no history of shoulder or cervical spine surgery, no cervical spine pathology, and no neurological conditions. The subjects also needed to be able to elevate their involved UE to at least 100 of shoulder flexion and 100 of abduction in the scapular plane. Instrumentation Strips of 2-in (5.08-cm) CoverRoll tape and Leukotape were used for the scapular taping procedure, which is based on the McConnell method. The EMG data acquisition and processing were performed with Noraxon (Noraxon USA, Inc, Scottsdale, AZ) equipment. This included the Myosystem channel surface EMG unit, and MyoResearch software to process the EMG signal. Characteristics of the Noraxon signal detection and processing system were eighth-order Butterworth low-pass filter of 500 Hz ( 1%), first-order high-pass filter of 10 Hz ( 10%), a sampling frequency of 1000 Hz, a baseline noise of less than 1-μV root-meansquare (RMS), an input impedance of greater than 100 M, a common-mode rejection ratio of greater than 100 db, and a gain of The software was programmed to perform rectification and smoothing of the signal by calculating the RMS using a 50-ms moving window. The mean RMS of each muscle was normalized to a maximum voluntary isometric contraction (MVIC). Normalization was performed using a 1-second moving win- journal of orthopaedic & sports physical therapy volume 37 number 11 november

3 Figure 1. Posterior and oblique views of scapular taping (A) and electrode placements for the upper trapezius (B), infraspinatus (C), lower trapezius (D), and serratus anterior (E). Figure 2. SCAPTION movement experimental setup. dow for the peak (highest average) of the MVIC. A Noraxon single electrode placed over the proximal sternum was used as the reference electrode. Noraxon blue sensor dual (bipolar, single differential) electrodes, 1 cm in diameter, with an interelectrode distance of 2 cm, were used to collect the EMG signal from the target muscles on the side of impairment. Electrode placement (FIGURE 1) was based on the work of Cram and Kasman 10 and Jensen et al. 19 The electrodes for the upper trapezius muscle were placed approximately 2 cm lateral to the midpoint of an imaginary line connecting the spinous process of the seventh cervical vertebra and the acromion (just lateral to where the scapular tape was placed). Electrode placement for the lower trapezius muscle was approximately 10.5 cm inferomedial to the medial border of the spine of the scapula, at a 55 oblique angle to the horizontal plane, but not below T12. The serratus anterior muscle was monitored along its lower fibers, with electrodes placed inferior to the axillary region (following the midaxillary line) at the level of the inferior angle of the scapula, just anterior to the border of the latissimus dorsi muscle and the midaxillary line. The electrodes for the infraspinatus muscle were placed approximately 4 cm inferior to the spine of the scapula over the infraspinatus fossa on the lateral aspect of the muscle. All electrodes were oriented parallel to the direction of the respective muscle fibers. Two large wooden boards were placed at a 120 angle to each other for the subjects to use as a guide for performing elevation and return from elevation in the scapular plane ( SCAPTION ; 30 anterior to the coronal plane). Subjects were instructed to elevate as high as tolerable, at least to 100. For the other activity ( SHELF ), a shelf was mounted on a wall for a functional task in which subjects raised and lowered their involved UE to place and remove a 0.5-kg bottle of water. The shelf height was adjusted according to each individual s capability and tolerance, so that the angle of shoulder flexion when reaching the shelf was at least 100, as measured with a plastic goniometer. A metronome, set at 40 beats per minute, was used to pace the subjects UE movements in both activities. A Sony video camera was used to film the subjects while they performed shoulder elevation and lowering activities. The location of the camera relative to the subject was the same for all subjects within each of the 2 activities. Myovideo software was used to process the video signal. The video signal was used to identify the beginning and end of the elevation and lowering phases of both SCAPTION and SHELF, to assist in defining the time period used to derive the RMS. Procedure After informed consent, a brief history of injury, demographic data, and anthropometric data were obtained. Electrodes were applied on the involved UE as previously described after cleaning and abrading the skin at the points of contact. Each subject then performed a MVIC for each muscle, with manual resistance applied by 1 of the examiners. The upper trapezius was resisted, first using a shrug of the shoulders, followed by the lower trapezius, with force applied to extend the UE when it was held at 90 of shoulder flexion (elbow fully extended). Then the infraspinatus was resisted with a force applied toward shoulder internal rotation, with the upper extremities held at 0 of shoulder flexion and abduction and 90 of elbow flexion. The serratus anterior was resisted last in a push-up-plus position against the wall. 24 Following the normalization phase, each subject performed the SCAPTION and SHELF activities, both with and without scapular tape. Both the order of application of tape and the order of activity performance were randomized for 8 possible combinations using a balanced Latin-square design. The same scapular taping procedure was applied to each subject. First, the CoverRoll tape was applied to the skin over the upper trapezius on the involved side, starting from the clavicle anteriorly and extending posteriorly, caudally, and medially to the paraspinal area proximal to the lower trapezius electrode, so that the tape was approximately perpendicular to the course of this portion of the upper trapezius. The Leukotape was applied next on top of the CoverRoll tape, with compression over the upper trapezius (FIGURE 1). SCAPTION was performed with the subjects standing at, and facing, the area where the 2 wooden boards intersected (FIGURE 2). The subjects were instructed to use the wooden boards to guide them as they elevated both UEs simultaneously in the scapular plane, but to not touch the boards. The subjects practiced this activity for a few repetitions using 696 november 2007 volume 37 number 11 journal of orthopaedic & sports physical therapy

4 the metronome (40 beats per minute) to pace the movements. Each elevation was completed in 1 beat and each lowering was completed in 1 beat, successively. After the subjects appeared to be familiarized with the movement, they performed 5 repetitions of elevation and lowering the UEs in the scapular plane while data were collected. Although EMG data were collected only from the involved UE, both UEs were elevated and lowered simultaneously, to better control for unwanted compensatory movements and because this method is commonly used in clinical practice for evaluation. The SHELF task (FIGURE 3) was performed beginning with the bottle on the shelf. The activity was performed with only the involved UE moving, in the sagittal plane, paced by the metronome. A practice period was conducted as with SCAPTION. Subjects began the activity with the involved UE down at the side of the trunk without the bottle, and raised their involved UE to reach for and grasp the bottle on the shelf. Then they lowered the UE to the starting position while holding the bottle. The activity continued with the subjects raising the UE to the shelf again, this time holding the bottle and placing it on the shelf, and they completed the activity by lowering the UE to the starting position without the bottle. This completed cycle was considered 1 repetition, and 5 repetitions were performed in total. As with SCAPTION, each elevation in the SHELF task was 1 beat and each lowering was 1 beat (with or without the bottle). Reported pain was assessed as a secondary variable, immediately prior to, and after, both SCAPTION and SHELF tasks, using a 10-cm visual analog scale (VAS), with anchors of no pain and worst pain imaginable. Data Analysis Noraxon MyoResearch software computed the mean RMS of the EMG signal for each of the 4 muscles, for each repetition. The MyoResearch software normalized the mean RMS of each muscle s signal, for each repetition, to its respec- Figure 3. SHELF task experimental setup. tive MVIC RMS. The 5-repetition mean of the normalized mean RMS values was used as the EMG signal amplitude dependent variable. The 2 activities, SCAPTION and SHELF, were analyzed separately. For both activities, taping (TAPE) was compared to no taping (NO TAPE) for EMG signal amplitude of the same 4 muscles. It was considered possible that muscle function and activity might be affected differently in impingement conditions, depending on the direction in which the UE was moving and where in the range of motion (ROM) the shoulder movement was occurring. Therefore, these were factored into the analysis such that the direction of movement was dichotomized into elevation (UP) and lowering (DOWN), and the ROM into greater than 90 ( 90 ) and less than 90 ( 90 ), for both SHELF and SCAPTION. In addition, since the SHELF activity included periods in which the subject was raising and lowering the UE while holding a bottle, the analysis dichotomized this factor into bottle (B) and no bottle (NB). Statistical analysis was performed using SPSS software (SPSS Inc, Chicago, IL) to compare the TAPE and NO TAPE conditions for the SCAPTION movements (UP, DOWN) and the SHELF movements (UP-NB, DOWN-B, UP-B, DOWN-NB) in order of performance, for the 2 parts of the ROM, for each of the 4 muscles. A 3-factor (2-by-2-by-2) repeated-measures analysis of variance (ANOVA) was performed for SCAPTION, for each of the 4 muscles. The factors (and their corresponding levels) were taping condition (TAPE, NO TAPE), direction of movement (UP, DOWN), and ROM ( 90, 90 ). For SHELF, a 4-factor (2-by-2- by-2-by-2) repeated-measures ANOVA was performed with the same factors (and levels) as for SCAPTION, except for the addition of the load factor and levels (B, NB). If there were significant interaction effects involving the tape condition, these were explored further with paired comparison tests, comparing TAPE versus NO TAPE for the multifactor variables. The alpha level for all tests was.05, except for the paired comparisons, in which this alpha was divided by the number of paired comparisons (Bonferroni correction). In addition, paired comparisons of interest (determined a priori) were assessed for the multicomponent factors of the SCAPTION and SHELF activities for each muscle using dependent t tests, with the alpha level of.05 divided by the number of paired comparisons (4 for SCAP- TION and 8 for SHELF). Subjects reported no pain immediately prior to beginning each task. The immediate posttask pain VAS for each of the tasks (SCAPTION, SHELF) was compared for TAPE and NO TAPE, using dependent t tests, with an alpha level of.05. RESULTS During the SCAPTION activity, subjects elevated their UE to a mean ( SD) of when taped and to when not taped. This difference was not statistically significant (P =.136; dependent t test). During the SHELF task, subjects elevated their UE to a mean of flexion in both conditions, as shelf height was kept constant between taping conditions. journal of orthopaedic & sports physical therapy volume 37 number 11 november

5 TABLE 1 EMG* Comparisons Between TAPE and NO TAPE for SCAPTION Component Movements (Multifactor Variables), for the Upper Trapezius and Lower Trapezius Muscles Upper Trapezius Lower Trapezius Movement TAPE NO TAPE P TAPE NO TAPE P UP (47.2) 90.8 (48.3) (24.7) 29.7 (21.5).842 UP (56.8) (81.9) (64.6) 70.7 (58.7).152 DOWN (29.6) 68.5 (33.8) (46.7) 48.9 (47.9).197 DOWN (21.4) 43.3 (25.9) (21.3) 21.6 (22.4).357 Abbreviations: <90, shoulder movement below 90 elevation in the sagittal plane; >90, shoulder movement above 90 in the sagittal plane; DOWN, lowering direction of movement; NO TAPE, condition with no scapular taping; SCAPTION, task of elevation and return from elevation in the scapular plane; TAPE, condition with scapular taping; UP, elevation direction of movement. * Values expressed in mean (SD) normalized to percent maximum voluntary isometric contraction (%MVIC). No statistically significant differences using paired t tests with Bonferroni correction (alpha =.05/4 =.0125). TABLE 2 EMG* Comparisons Between TAPE and NO TAPE for SCAPTION Component Movements (Multifactor Variables), for the Serratus Anterior and Infraspinatus Muscles Serratus Anterior Infraspinatus Movement TAPE NO TAPE P TAPE NO TAPE P UP (34.3) 50.6 (35.9) (30.3) 27.4 (21.1).487 UP (51.8) (57.0) (34.1) 35.8 (30.3).624 DOWN (38.5) 63.2 (36.6) (29.3) 24.7 (17.0).363 DOWN (27.7) 33.7 (29.0) (28.3) 20.7 (18.9).527 Abbreviations: <90, shoulder movement below 90 elevation in the sagittal plane; >90, shoulder movement above 90 in the sagittal plane; DOWN, lowering direction of movement; NO TAPE, condition with no scapular taping; SCAPTION, task of elevation and return from elevation in the scapular plane; TAPE, condition with scapular taping; UP, elevation direction of movement. * Values expressed in mean (SD) normalized to percent maximum voluntary isometric contraction (%MVIC). No statistically significant differences using paired t tests with Bonferroni correction (alpha = 0.05/4 = ). The 3-factor repeated-measures ANOVA for EMG signal amplitude of the upper trapezius during SCAPTION showed that there were no significant 2- way or 3-way interactions among taping condition and the other factors (P.05). However, there was a significant main effect (P =.047) for the taping condition. Upper trapezius EMG signal amplitude was significantly less with TAPE than with NO TAPE. There were no significant differences between TAPE and NO TAPE (main or interaction effects) for any of the other muscles (P.05). The 4-factor repeated-measures ANOVA for the upper trapezius during the SHELF task showed a significant interaction between the factors of tape condition and direction of movement (df = 1, F = 5.214, P =.033). Paired comparison testing (paired t tests with Bonferroni correction: alpha 2 = for the 2 paired comparisons) showed that the upper trapezius had significantly less EMG signal amplitude during the elevation phase of movement with TAPE compared to NO TAPE (df = 20, t = 3.222, P =.004). The magnitude of the mean decrease was 9.6% (97.7%-88.3% MVIC: [ ] 100]. The other relevant paired comparison for this interaction comparing TAPE to NO TAPE during the lowering phase of movement was not statistically significant (P =.224). There were no significant interactions among taping condition and the other 2 factors (P.05). The 4-factor repeated-measures ANOVA for the lower trapezius during the SHELF task showed that there were no significant 2-, 3-, or 4-way interactions among taping condition and the other factors (P.05). However, there was a significant main effect (P =.047) for the taping condition. The lower trapezius had significantly greater EMG signal amplitude with TAPE compared to NO TAPE (df = 1, F = 4.649, P =.043). The magnitude of the mean increase was 13.5% (61.3%-69.6% MVIC). There were no significant differences between TAPE and NO TAPE (main or interaction effects) during the SHELF task for the serratus anterior and infraspinatus muscles (P.05). TABLES 1 through 4 display descriptive statistics for all components of the SCAPTION and SHELF activities, respectively, for each muscle. The paired comparisons of interest (determined a 698 november 2007 volume 37 number 11 journal of orthopaedic & sports physical therapy

6 TABLE 3 EMG* Comparisons Between TAPE and NO TAPE for SHELF Component Movements (Multifactor Variables), for Upper Trapezius and Lower Trapezius Upper Trapezius Lower Trapezius Movement TAPE NO TAPE P TAPE NO TAPE P UP NB (40.7) 80.2 (47.5) (32.0) 27.6 (33.0).647 UP NB (45.4) (46.4) (37.2) 35.4 (33.0).077 DOWN B (28.0) 70.1 (31.2) (36.9) 42.3 (35.1).031 DOWN B (19.2) 35.9 (19.6) (24.8) 20.8 (25.0).240 UP B (45.0) 84.2 (42.8) (32.4) 31.3 (30.0).407 UP B (56.8) (81.9) (53.8) 43.0 (38.7).173 DOWN NB (23.8) 54.2 (22.2) (28.3) 29.3 (26.2).011 DOWN NB (20.8) 32.3 (20.0) (25.3) 15.4 (25.4).185 Abbreviations: <90, shoulder movement below 90 elevation in the sagittal plane; >90, shoulder movement above 90 in the sagittal plane; B, holding bottle; DOWN, lowering direction of movement; NB, without holding bottle; NO TAPE, condition with no scapular taping; SHELF, functional task in which subjects raised and lowered their involved upper extremity; TAPE, condition with scapular taping; UP, elevation direction of movement. * Values expressed in mean (SD) normalized to percent maximum voluntary isometric contraction (%MVIC). Statistically significant difference using paired t tests with Bonferroni correction (alpha =.050/8 =.00625). TABLE 4 EMG* Comparisons Between TAPE and NO TAPE for SHELF Component Movements (Multifactor Variables), for Serratus Anterior and Infraspinatus Serratus Anterior Infraspinatus Movement TAPE NO TAPE P TAPE NO TAPE P UP NB (38.2) 47.0 (34.1) (18.6) 25.1 (18.6).271 UP NB (57.1) 98.5 (57.9) (21.7) 32.0 (19.7).924 DOWN B (46.4) 79.1 (47.0) (17.0) 30.2 (18.2).257 DOWN B (35.8) 35.6 (46.2) (18.8) 20.5 (16.6).210 UP B (36.4) 49.2 (40.3) (19.5) 27.2 (19.7).300 UP B (72.7) (67.2) (24.1) 39.2 (26.4).194 DOWN NB (42.8) 58.1 (38.7) (13.3) 23.6 (11.4).843 DOWN NB (36.5) 36.4 (47.6) (17.0) 17.8 (14.1).171 Abbreviations: <90, shoulder movement below 90 elevation in the sagittal plane; >90, shoulder movement above 90 in the sagittal plane; B, holding bottle; DOWN, lowering direction of movement; NB, without holding bottle; NO TAPE, condition with no scapular taping; SHELF, functional task in which subjects raised and lowered their involved upper extremity; TAPE, condition with scapular taping; UP, elevation direction of movement. * Values expressed in mean (SD) normalized percent maximum voluntary isometric contraction (%MVIC). No statistically significant differences using paired t tests with Bonferroni correction (alpha =.050/8 =.00625). priori) were analyzed for the difference between TAPE and NO TAPE during the SHELF task for each component of the 2 activities using paired t tests. The comparisons between TAPE and NO TAPE during the SHELF task for the upper trapezius, for UP B 90 and for UP NB 90, were statistically significant (P.001 and P.002, respectively), based on the Bonferroni-corrected alpha (.05/8 =.00625). None of the other comparisons of interest between TAPE and NO TAPE for SCAPTION and SHELF for the upper trapezius and the 3 other muscles were significant (P.00625). There were no significant differences in mean pain scores between TAPE and NO TAPE during SHELF (TAPE, 1.1 cm; NO TAPE, 1.6 cm; P =.057) or SCAP- TION (TAPE, 1.4 cm; NO TAPE, 1.6 cm; P =.267) on the VAS. Considering the low mean pain scores, and based on studies of other musculoskeletal conditions, 6,11,35 these VAS differences between taping conditions for SHELF and SCAPTION (0.5 cm and 0.2 cm, respectively) were also too small to be clinically relevant. DISCUSSION This study investigated the immediate effects of a particular scapular taping method on activation of the shoulder musculature in individuals who had signs and symptoms of shoulder impingement. The scapular taping method journal of orthopaedic & sports physical therapy volume 37 number 11 november

7 used in this study resulted in a small but significant decrease in EMG signal amplitude of the upper trapezius compared to no taping, during a functional task requiring shoulder elevation. Scapular taping also produced a significant overall decrease in upper trapezius activity during shoulder abduction in the scapular plane. There was also a significant overall increase in lower trapezius EMG signal amplitude during the functional task when scapular taping was used. The upper trapezius was more affected during elevation than lowering. Because this subject sample did not have high pain levels, it is possible that the effect was greater above 90 because that is where there is greater impingement and, therefore, it was more provocative. In addition, if the upper trapezius is more biomechanically and physiologically (length-tension) challenged above 90, this could also have been a factor. The serratus anterior and infraspinatus were not significantly affected by scapular taping. It is possible that this method of taping provides an insufficient indirect influence (via alteration of upper trapezius activation), and these muscles require exercise training to increase their activity in the presence of impingement. It is also possible that there were no deficits in activation of these muscles. Comparison to the Literature The results for the upper and lower trapezius muscles are in agreement with the findings of Morin et al, 27 who found significant decreases in upper trapezius and increases in lower trapezius activity with scapular taping compared to no taping in uninjured subjects. Morin et al 27 differed in their experimental method from the current study and those previously mentioned. They placed the lower trapezius electrode between the medial scapular border and the thoracic spine, halfway between the superior and inferior angles of the scapula. This may have been more representative of the middle trapezius or a combination of lower and middle trapezius. In addition, the activity measured by Morin et al 27 was a type of isometric, seated, inclined row (approaching a shrug). Alexander et al 1 found that a scapular taping technique inhibited the lower trapezius. However, they applied the tape onto the skin overlying the lower trapezius and parallel to the direction of its fibers, rather than over and perpendicular to the upper trapezius as was done in the current study. Cools et al 7 found no significant differences in uninjured subjects between scapular taping and no taping for the upper, middle, and lower trapezius, and serratus anterior. The results of the current study were similar to those of Cools et al 7 for serratus anterior, but differed in its finding of a decrease in upper trapezius activation and an increase in lower trapezius activation. Cools et al 7 divided the movement directions and ROM into 0 to 90, 90 to 180, 180 to 90, and 90 to 0, as in the current study. However, Cools et al 7 investigated shoulder flexion and abduction, which were slightly different than the movement tasks in the current study. In addition, the location of the upper trapezius electrode was midway between the C7 spinous process and the acromion in the Cools et al 7 study, which has been reported to depress the signal amplitude of the upper trapezius. 19 They applied the tape lateral to the electrodes and laterally over the upper trapezius. Perhaps the most important difference between the 2 studies involves the subject populations: the current study used injured individuals rather than noninjured subjects. Possible Study Limitations The small significant differences for the upper and lower trapezius, as well as the lack of significant differences between taping and no taping for EMG signal amplitude of the serratus anterior and infraspinatus might represent the true phenomenon, or might be due to characteristics of this study s subject population. The duration of shoulder problems varied among these subjects. However, such variation is consistent with other reports in the literature investigating people with shoulder impingement problems, including greater than 1 week, 20 up to 12 weeks, 36 and some studies having indicated no time period at all. 8,9,31 The subjects in the current study were not in acute pain, which is also consistent with this literature, but might explain the low magnitudes or lack of differences seen with taping. It is also important to note that there is no evidence that any of the muscles studied were deficient at the time this study was conducted. However, Cools et al 9 also found that there were no deficits in surface EMG signal amplitude of the serratus anterior in injured compared to uninjured overhead throwers, despite finding deficits in shoulder protraction torque at high speeds. While the subjects in this study had subjective and objective findings consistent with shoulder impingement, this was not verified with diagnostic imaging tests. This is also similar to other studies. 8,9,25 In addition, this study did not require that the subjects be symptomatic in other clinical physical examination tests besides the Neer or Hawkins-Kennedy tests. 21,31 Although there is much variation in the literature, the physical and subjective examination tests used in this study have been used in combination as sufficient criteria for labeling subjects with shoulder impingement syndrome in the literature. 8,25,26 Several diagnoses and pathologies have been included in the literature as being indicative of shoulder impingement syndrome (eg, partial rotator cuff tear, full-thickness rotator cuff tear, subacromial bursitis, supraspinatus, infraspinatus, subscapularis, and biceps tendinitis), and various methods of making a diagnosis have been used, which add to the confusion in clinical definition. Therefore, the diagnostic label of impingement syndrome may vary depending on the specific tissue pathology involved, as well as the severity, which may result in variations in diagnostic usefulness of the various impingement syndrome tests. This is also an issue among studies that have investigated the diagnostic usefulness of commonly used clinical tests. While some tests not used in this study have been 700 november 2007 volume 37 number 11 journal of orthopaedic & sports physical therapy

8 shown to have high diagnostic value and positive predictive value, both the Neer and Hawkins-Kennedy tests have been shown to have adequately high diagnostic accuracy and positive predictive value and, under certain conditions, even higher than other tests with higher levels of specificity. 5,31 Only in instances of complete rotator cuff tears have the tests used in the current study been found to have lower levels of specificity compared to other tests. 31 McClure et al, 26 in their study of impingement, excluded people with acute inflammation or complete rotator cuff tears. It is likely that the subjects in the current study did not have complete rotator cuff tears or acute inflammation, based on their subjective and objective findings and their performance during the study. In general, the subjects were activating their muscles at higher percent of MVIC in the UP and 90 phases of the SHELF and SCAPTION tasks (TABLES 1-4). The relative activation levels reached 100% or more of MVIC for upper trapezius and serratus anterior, for certain phases of the tasks. However, it is likely that the manual muscle test MVICs in the current study s procedure underestimated the true maximum EMG signal amplitude capability of these muscles, which would overestimate the relative activation levels during these tasks. The normalization contractions used in the current study did not include certain activities reported to produce higher maximum contractions. 15 The high relative activation levels noted above are also higher than those found by Cools et al 7 ; however, they did not report the activities used for maximum contractions, and their subjects were uninjured, unlike the subjects in the current study. The ability of subjects in the current study to maximally activate their muscles might have been impaired, which could also have resulted in higher relative activation levels measured during the tasks. Obtaining true maximum contractions in an injured population, or comparing them to those obtained in uninjured people, can be problematic. The results of the comparisons found in this study are nonetheless valid because the design was within subjects, and submaximal normalization contractions have been reported to be appropriate for studying surface EMG signal amplitude. 12,38 Cross talk (electrical activity from a nearby contracting muscle) is a phenomenon present in surface EMG studies that can contaminate the signal detected from a target muscle. However, surface EMG is an appropriate method for detecting muscle electrical activity and cross talk is limited when the target muscles are relatively large and superficial, 3,15,33 as in the current study. The distance between the electrode pairs of any 2 muscles in the current study was more than 3 cm. This distance has been shown to adequately limit cross talk. 37 The small interelectrode distance (2 cm) within each electrode pair, used in the current study, is also considered to limit cross talk. 13,15 In addition, the singledifferential (bipolar) electrode technique is thought to limit cross talk and the addition of common mode noise from the environment to the signal. 3 The lack of significant change in pain VAS scores and UE elevation ROM in the scapular plane, between taping and no taping, might also have been due to the current stage of the problem in these subjects. Another study investigating the effects of taping on posture in subjects with shoulder impingement syndrome showed that posture and overhead ROM were significantly improved while subjects were taped, but there was no difference in pain complaint. 21 Further study of the effectiveness of the method of scapular taping used in this study would be beneficial in patients who are more symptomatic and for comparison of this taping method to other interventions during rehabilitation for long-term effects. In addition, the effect of load requires further study. CONCLUSION Aparticular method of scapular taping used in individuals with signs and symptoms of shoulder impingement resulted in significantly decreased upper trapezius surface EMG signal amplitude, and significantly increased lower trapezius amplitude, compared to no taping during a functional reaching task involving UE elevation and lowering. The predominant effects on the upper trapezius occurred during UE elevation above 90 of shoulder elevation. There was also a significant decrease in upper trapezius activity with taping compared to no taping during shoulder abduction in the scapular plane. No significant differences in EMG signal amplitude between taping and no taping were found for any of the UE elevation and lowering movements for the serratus anterior and infraspinatus muscles, and no differences in pain complaint were found between taping and no taping for the SCAPTION and SHELF tasks. Further study is necessary to determine if the EMG changes found in the current study are associated with functional improvement in patients with these problems. ACKNOWLEDGMENTS The authors thank the following people for their consultation on data analysis and statistics: Dale Berger, PhD; Gary Gugelchuk, PhD; Stephen Allison, PT, PhD; Carolyn Ervin, PhD; Robert Wiswell, PhD; and Paula Ludewig, PT, PhD. 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