Kinesiotaping for scapular dyskinesis: The influence on scapular kinematics and on the activity of scapular stabilizing muscles

Journal Pre-proofs Kinesiotaping for scapular dyskinesis : the influence on scapular kinematics and on the activity of scapular stabilizing muscles Camille Tooth, Cédric Schwartz, David Colman, Jean-Louis Croisier, Stephen Bornheim, Olivier Brüls, Vincent Denoël, Bénédicte Forthomme PII: DOI: Reference:

S1050-6411(20)30015-8 https://doi.org/10.1016/j.jelekin.2020.102400 JJEK 102400

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Journal of Electromyography and Kinesiology

Received Date: Revised Date: Accepted Date:

3 May 2019 12 December 2019 31 January 2020

Please cite this article as: C. Tooth, C. Schwartz, D. Colman, J-L. Croisier, S. Bornheim, O. Brüls, V. Denoël, B. Forthomme, Kinesiotaping for scapular dyskinesis : the influence on scapular kinematics and on the activity of scapular stabilizing muscles, Journal of Electromyography and Kinesiology (2020), doi: https://doi.org/10.1016/ j.jelekin.2020.102400

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Kinesiotaping for scapular dyskinesis : the influence on scapular kinematics and on the activity of scapular stabilizing muscles Camille Tooth (PT) a,b, Cédric Schwartz (PhD)a , David Colman (PT)b, Jean-Louis Croisier (PT, PhD) a,b, Stephen Bornheim b, Olivier Brüls a,c(PhD) , Vincent Denoël (PhD)a,d, Bénédicte Forthomme a,b(PT,PhD)i a Laboratory of Human Motion Analysis, University of Liège, Liège, Belgium b Department of Physical Medicine and Rehabilitation, University of Liège, Liège, Belgium c Department of Aerospace and Mechanical Engineering, University of Liège, Liège, Belgium d Department of Architecture, Geology, Environment and Constructions, University of Liège, Liège, Belgium File number Ethics Committee: B707201732302 Email address of the corresponding author: [email protected]

Key words: Electromyographic, scapular dyskinesis, kinesiotaping, scapular kinematics, rehabilitation

Kinesiotaping for normalizing scapular dyskinesis : the influence on scapular kinematics and on the activity of scapular stabilizing muscles Conflict of interest The authors, their immediate families, and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article.

Acknowledgements The authors wish to thank the Wallonia-Brussels Federation (Belgium) for its support. The Wallonia-Brussels Federation was not involved in data collection, data analysis or the preparation of or editing of the manuscript. The authors also thank all the volunteers who agreed to participate to this study.

Abstract (199 words) Scapular dyskinesis is observed in 61% of overhead athletes [3]. For most of them, it remains asymptomatic. However, scapular dyskinesis is considered a risk factor for shoulder injury by some authors [4]. The aim of this study is to explore the effectiveness of kinesiotaping in modifying scapular kinematics and peri-scapular muscle activity in dyskinetic athletes. The 3-dimensional position and orientation of the scapula as well as the activation of upper trapezius, lower trapezius and serratus anterior were recorded in twenty asymptomatic athletes during shoulder movements (flexion and abduction), in loaded and unloaded conditions and in three circumstances (standard, kinesiotaping 1, kinesiotaping 2). A significant decrease between 9 and 12% in upper trapezius activity was observed with kinesiotaping 1 and 2. Lower trapezius activity was slightly increased with kinesiotaping 1 while it was significantly decreased about 15-20% with kinesiotaping 2. No change was observed in serratus anterior activity, for either kinesiotaping 1 or 2. Considering scapular kinematics, both kinesiotaping 1 and 2 significantly increased posterior tilt and upward rotation. External rotation was decreased with kinesiotaping 2, in comparison to standard condition. Kinesiotaping, and especially taping 1, seems to be an effective method for changing periscapular muscle activity and scapular kinematics.

Introduction Overhead sports like volleyball, handball, baseball, javelin throwing, swimming may induce glenohumeral modifications and scapulo-thoracic alterations like scapular dyskinesis. These alterations may occur after an active season or after a few years of practice but can also be present just after a training session [3][54]. Indeed, Madsen et al. observed 37% scapular dyskinesis in swimmers before and 82% after a one-hour training session [32]. In a 12-weeks follow-up period, Hibberd et al. [13] found an increase in forward shoulder posture, measured during overhead squats, in regular swimmers. Postseason, in baseball players, Thomas et al. [54] noted an increase at 0° as well as a decrease at 90° and 120° of upward rotation during arm abduction in comparison to preseason tests. The relationship between scapular dyskinesis and shoulder injuries has been studied at great lengths and has been discussed for many years but there is still no consensus about this issue [6][22][30] . Considering shoulder girdle biomechanics [25] and the roles of scapula described by Kibler et al. [23], there are reasons to believe that abnormal scapular motion can lead to a decrease of subacromial space and to impingement syndrome. Data from litterature still tends to show an association between scapular dysfunction and shoulder pain [4][14][50]. McKenna et al. [36], in a prospective study, found an association between scapular position at rest and the occurrence of shoulder injuries in swimmers. Indeed, these authors observed that swimmers with a shorter distance between the inferior border of the scapula and the spine and between the anterior part of the glenohumeral head and the acromion were more likely to sustain a injury. Struyf et al. [50] remarked a decrease of upward rotation at 45° and 90° at the beginning of the season in injured overhead athletes. Clarsen et al. [4] demonstrated that obvious dyskinesis was considered as a risk factor of shoulder pain in handball players. Respectively in rugby and in volleyball, Kawasaki et al. [21] and Merolla et al. [37] found a decrease in rotator cuff muscles strength, specifically of the infraspinatus, and a shoulder discomfort in athletes with scapular dyskinesis. Likewie, Su et al. [51] found a decrease in external and in upward rotation at 45°, 90° and 135° in swimmers suffering from a subacromial impingement. Johansson et al. [19] observed that a large proportion of kayakers with shoulder pain presented scapular dyskinesis. In a recent systematic review, Hickey et al. [14] proclaimed that scapular dyskinesis increased the risk of shoulder pain by 43% yet. Möller et al. [38] went a little bit further, saying that scapular dyskinesis would be a risk factor of shoulder pain if there were an increase between 20% and 60% of the training load. This shows the multifactorial nature, including both intrinsic (muscle stiffness, muscle weakness etc….) and extrinsic factors (training load for example), of musculoskeletal injuries. However, other researchers like Myers et al.[40], Forthomme et al. [10] or Hjelm et al. [15] found no significant relationship between scapular dyskinesis and shoulder injuries in overhead athletes during the subsequent season. 4

Electromyographic alterations have been associated with scapular dyskinesis too, essentially in symptomatic people [7][31][49][57]. In fact, Smith et al. [49] found an increase in the activation of upper trapezius and a decrease in the activation of lower trapezius in dyskinetic symptomatic subjects. Thigpen et al. [53] observed a decrease in the activation of serratus anterior in subjects with a forward head posture, which is accompanied by an increase in scapular anterior tilt. As for Wadsworth et al. [57], these authors noticed differences in the timing of scapular muscles activations in subjects with soulder pain in comparison to healthy subjects. They found an increased variability of timing of activation among the symptomatic population with a delayed activity of serratus anterior during shoulder elevations in scapular plane. Kinesiotaping, an original method developed by Kenso Kase in the 1970’s, has been suggested by different authors as a potential solution to normalize scapular dysfunction [17] without limiting range of motion. Differents functions were given to theses elastic tape bands: improving recruitment motor pattern by stimulating mecanoreceptors [16][52][58], improving blood and lymphatic flow [42], decreasing pain by using the gate control principle [26][28][42], mechanical effects [16][56]. But the exact mechanism associated with kinesiotaping effects remains unclear. In the treatment of scapular dysfunction, Mc Connel taping (inhibitory upper trapezius tape) [34][35], which consist in a rigid taping applied from the coracoïd process until the inferior border of the scapula, is often used to correct scapulothoracic motion. This technique was based on Morrissey’s principle [39], which sustained the hypothesis that a tape placed perpendicular to a muscle tends to increase its activity and a tape placed parallele to a muscle tended to decrease its activity. Moreover, Van Herzeele et al. [56] found a positive mechanical effect of Mc Connel taping in asymptomatic handball players with a moderate increase of upward rotation and posterior tilt after placement of the tape. Scapular dyskinesis often consists of a lack of posterior tilt, upward and external rotation of the scapula, as well as a decrease of sub-acromial space that can lead to shoulder impingement if the shoulder is frequently solicited. Therefore, correction of scapular dysfunction could help decrease sub-acromial compression and prevent shoulder disorders. In view of the multidirectional pattern of the dysfunction, a single taping seems to be insufficient to correct dysfunction in the three planes. The first aim of this study was assess the effectiveness of kinesiotaping in the normalization of scapular kinematics and peri-scapular muscle activity in dyskinetic asymptomatic athletes. The second aim was to compare the two different techniques and to define which is most efficient.

Methods 1) Participants

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Twenty volunteer athletes were enrolled in this study. They were aged 21.9 ± 1.8 years, measuring 179.2 ± 4.8 centimeters and weighing 73.4 ± 8.2 kg. They practiced various sports including overhead sports (tennis, volleyball, crossfit, football, swimming, basketball, boxing) with an average time of 6.5 ± 2.5 hours/week for at least four years.. The recruitment consisted in a visual evaluation and clinical measures. Volunteers had to present unilateral or bilateral scapular dyskinesis [55] visible at rest and during ten repeated shoulder elevations (“yes/no” method) [55], in frontal and in sagittal planes. The characteristics of scapular dyskinesis were assessed by two different experienced physiotherapists in blind condition. The reproducibility between the two assessors, assessed with kappa correlation, was good (0.83). Scapular dysfunction was also evaluated with the “Lateral Scapular Slide Test”[8][27][41], described by Kibler et al.[23] and widely used in clinical practice. A minimum difference of 1.5 centimeters between the dominant and the non-dominant sides had to be found in at least two of the three positions of the test. Then scapular upward/downward rotation was measured at rest, with an inclinometer (with the same method as the one used by Johnson et al.)[20]. A good reproductibility has been demonstrated on 20 non-overhead sportspeople (mean age 22.1±2.8) by the experimenter for this method (ICC= 0.653 (0.053-0.871)) (nonpublished data). A downward rotation had to be observed in volunteers because kinesiotaping aimed to act on its. Exclusion criteria were asymmetry of length of lower limbs, scoliosis or dorsal hyperkyphosis, shoulder surgical history, shoulder pain, shoulder injury (muscular, osseous, ligamentary, tendinous) or positive tendinous and impingement tests (Jobe, Patte 0°, Patte 90°, Lift off Test, Palm-up Test). Moreover, it has been checked, by a visual evaluation, that all the subjects were able to attain full range of motion (without pain) in flexion and in abduction, to confirm that they were “healthy”. The protocol has been validated by the Medical Ethics Committee of the University of Liege. All the participants were informed about the nature of the tests and the progress of the experimentations before the beginning of the tests. 2) EMG acquisitions The electromyographic (EMG) signals were collected with Trigno Standard and Trigno Mini wireless sensors (Delsys, Boston, MA, USA) using silver-contact bipolar bar electrodes with fixed 10 mm inter-electrode spacing [45]. Three of the main scapular stabilizing muscles of the shoulder were investigated: upper trapezius, lower trapezius and serratus anterior. Electrodes were placed following Barbero et al. [1] recommandations. They were placed on the dyskinetic side. In case of bilateral scapular dyskinesis, electrodes were placed on the side where the most important dysfunction was observed, following Mc Clure et al. criteria (normal motion, subtle abnormality and obvious abdnormality) [33]. Data was acquired at a sample frequency of 1000 Hz. As a warm up, the volunteers were asked to perform two series of 10 shoulder internal rotations and two series of 10 shoulder external rotations at 0° of abduction with a resistive elastic band. Volunteers then performed maximum voluntary isometric contractions (MVIC) in order to determine the peak electromyographic signal for each muscle. These contractions were 6

performed in 6 differents positions (illustrated in Figure 1) as recommended by Schwartz et al.[45]. To limit a possible influence of the investigator, the MVIC positions were maintained using a steel structure rather than manual pressure. This structure could adapt to both the test positions and the specific size of the volunteers. Prior to each test position, the volunteers were asked to perform 3 increasing sub-maximal trials of 6 seconds to get used to the exercice and the effort. Subsenquently, they performed 3 trials of 6 seconds in each test position. During the trials, the volunteers were given verbal encouragement. To avoid fatigue, a minimum of 30 seconds rest intervals was provided between each trial and each MVIC test position respectively. This timing was chosen based on the article by Schwartz et al. [45]. The order of the position’s tests has been randomized with the function “random sort” in Excel 2016 (Microsoft, USA). All these tests were carried out bilaterally because Fischer et al. [9] observed a 14% increase of the force of the upper trapezius in the bilateral « empty can position » compared to unilaterally testing. Another reason justifying this decision was the limitation of thoracic compensations. 3) Three-dimensionnal assessment Scapular kinematics was assessed using a three-dimensional motion analysis system, an optoelectronic system based on active markers (Codamotion, Charnwood Dynamic, UK) [43]. For that purpose, four Codamotion CX1 units were used, at a sampling of 100 Hz. The validity, the precision and the reproducibility of the laboratory and the system has been proved in previous study [43][44] (peak-to-peak values = 0.4 mm in the x-axis, 2.5 mm in the y-axis and 3mm in the y-axis). Fifteen active markers were placed on the skin of the subject on the same side as the EMG electrodes: 4 on the thorax, 6 on the scapula, 4 on the arm and 1 on the acromio-clavicular joint. Reference position of the body and of the scapula was defined with the volunteer standing upright, arms by their sides and looking forward. The center of the gleno-humeral head was estimated using abductions, flexions and circumductions, with the same method as suggested by Gamage et al.[11]. 4) Movements

After MVIC and three-dimensional marker placement, participants were asked to perform 10 active shoulder flexions (sagittal plane) and 10 active shoulder abductions (frontal plane) both with and without loading. The forearm was placed in a neutral pro-supination position for flexion movement and in shoulder external rotation position for abduction movement (the thumb in the direction of the movement). The movements were guided by a wood apparatus. In order to standardize the speed of movement, a metronome at 30 beats per minute was used. At each beat, the arm had to be alternately at maximal elevation and by their side.

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The load used in flexion and abduction corresponded to 25% of the strength (maximal value out of the three repetitions) developped in Seated U 90° position (Figure 1), measured by means of a manual dynamometer (MicroFet 2, Hoggan Scientific LLC, USA). During flexion and abduction, electromyographic activity of scapular stabilizing muscles (upper trapezius, lower trapezius and serratus anterior) and scapular kinematics was recorded in three different conditions : without kinesiotaping (standard condition), with Taping 1 (KT1) and with Taping 2 (KT2). The order of the different conditions was randomized. 5) Kinesiotaping method Kinesiotaping was applied in two different ways. KT1 was inspired by McConnell taping and KT2 was imagined by our research team. For applying KT1, the volunteer sat on a stool, shoulder placed at 60° of flexion in sagittal plane and supported. Taping was applied from the coracoid process, then firmly on the upper trapezius and finally on the inferior angle of the scapula. The strip was full stretched between the spine and the inferior border of the scapula. Applying KT2 began with the same method as for KT1. The first strip was exactly the same as McConnell taping. The second strip was applied from the thoracic spine and to the inferior border of scapula. Full tension was applied from the inferior border of the scapula to the lateral side in order to enhance scapular upward rotation (Figure 2). To standardize the placement and to be as reproducible as possible, all the strips were applied by the same investigator. For the same reasons, the placement of the strips was not individualised according to the characteristics of the dysfunction observed in each subject.

6) Data reduction

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The EMG signals were first band pass filtered (20–500 Hz, zero-phase 4th order Butterworth filter) and then processed using a root-mean-square filter (100 ms moving window). The EMG signals were then normalized with respect to the values obtained during the MVIC tests in order to obtain a percentage of the maximal voluntary activity (MVA) for each of the muscles considered. The level of activation of each muscle (upper trapezius, lower trapezius and serratus anterior) was then defined as the average value of the processed signal among the five last repetitions [45]. The last five movements out of the ten repetitions were considered for scapular kinematics to better appreciate scapular dysfunction. Scapular kinematics results were expressed only up to 120° because the accuracy of the measurements of scapular motion is hugely disrupted by skin movements and soft tissue artefacts after this range of motion. Scapular orientation was expressed relative to the thorax by use of YXZ Cardan decomposition [59]. The orientation of the humerus, for flexion and abduction, was expressed relative to the thorax by use of YXZ Cardan decomposition [47] to avoid Gimbal lock. The scapular orientation was then expressed relative to the humeral elevation. The two phases of movement (upward and downward) were processed independently as Borstad et al. measured significant differences between concentric and eccentric phases of arm elevations. [2][43]. Values measured in the reference position (straight, arms to the sides and looking ahead) were subtracted from the values measured during movements in order to only consider changes during movements and to limit interindividual adaptations. Upward rotation, external rotation and posterior tilt are expressed with negative values while downward rotation, internal rotation and anterior tilt are represented with positive values. Both for EMG and scapular kinematics, 4 angles of movement were retained for the analysis (30°, 60°, 90°, 120°). Activity and kinematics at 30° were estimated based on the average of the values measured between 25° and 35°. The same method was used for the other angles in order to limit biais. 7) Statistical analysis Statistical analysis was performed using the MiniTab software (MiniTab Inc., State College, Pennsylvania, USA). Descriptive statistics were calculated at 30°, 60°, 90 and 120° of elevation in sagittal and frontal planes. A Shapiro-Wilk test was done to assess the normality of the variables. Since all the variables were normally distributed, comparisons between the three different conditions were made using repeated measures ANOVA, both for EMG and kinematics analysis. The level of significance was set at p < 0.05 for all the tests done.

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Results All participants completed the study. No complaints or shoulder pain were reported either during or after the assessment. Four subjects were excluded from the three-dimensional analysis because of technical problems but data from the 16 others were retained for analysis. As for EMG analysis, the data from the 20 volunteers was used and analysed. 1) EMG activity of scapular stabilizing muscles In the standard condition, during shoulder movements (flexion and abduction), muscular activity of the 3 muscles considered tended to increase from 30° till 120°, except for the upper trapezius during loaded flexion (sagittal plane) where the activity only increases until 90° (Table 1). During the concentric phase of shoulder flexion in the loaded condition, in comparison with the standard condition, the activity of the upper trapezius decreased between 9 and 12%, at 90° and 120° (p=0.001) after kinesiotaping placement, without significant difference between KT1 and KT2. In the eccentric phase of this movement, if we compare kinesiotaping to standard condition, a decrease about 10-11% is observed at 120° (KT1 and KT2) and 60° (KT1) (p=0.022-0.044) in the unloaded condition and at 120° with KT2 (p=0.030) in the loaded condition. In the concentric phase of abduction (frontal plane), a decrease between 9 and 11% of the activity of upper trapezius is still observed after kinesiotaping placement, in comparison to standard condition. This was measured at 90° (KT2) and 120° (KT2) (p=0.0001-0.027) in the loaded condition. In the eccentric phase of abduction, no difference is found between standard and kinesiotaping conditions (Table 1). During flexion (sagittal plane) and abduction (frontal plane), essentially in the concentric phase, when compared to standard condition, the activity of lower trapezius tends to increase with KT1 while the opposite effect is observed with KT2, where the activity is decreased by about 15-20% in comparison to the standard condtion and to the KT1 condition. This decrease reaches significance at 60° and 120° (p=0.031-0.032) of the upward phase of flexion, in the unloaded condition. No significant difference is noted in the other conditions (Table 1). Considering the serratus anterior, no change is observed, either for KT1 or KT2, in comparison to standard condition. 2) Scapular kinematics Scapular kinematics was characterised in three different planes of scapular rotation: upward/downward rotation, internal/external rotation and anterior/posterior tilt.

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In standard condition, external rotation reaches lower values in the unloaded compared to the loaded condition, both in the sagittal plane (8.11-8.25° loaded vs 4.54-6.57° unloaded) and in the frontal plane (17.32-18.22° loaded vs 14.90-15.45° unloaded), but this difference is not statistically significant (p>0.05). No differences in upward rotation and posterior tilt are found between loaded and unloaded elevations (sagittal and frontal plane). The upward rotation range is between 33.70° and 34.25° when doing elevations in the sagittal plane and between 32.59° and 32.36° when the frontal plane is considered. As for posterior tilt range of motion, it reaches values between 11.91° and 12.09° in the sagittal plane and between 11.75° and 12.76° in the frontal plane (Table 2). Regarding the effects of kinesiotaping, some statistical differences can be highlighted when compared to standard condition. These differences appear mainly in the first degrees of the movements (30°, 60°), i.e. approximately at the range of motion where the kinesiotape was placed on the skin of the subjects. Considering upward rotation, kinesiotaping tends to significantly increase the range of motion. Even if KT2 seems to further increase upward rotation, no significant differences is found when compared with KT1. In the concentric phase of flexion (sagittal plane), significant effects of kinesiotape are found at 30°, 60° and 90° in the unloaded condition (p=0.0001-0.016) and in 30° and 60° in the loaded condition (p=0.0001-0.027), in comparison with the standard condition. In the eccentric phase, differences reach significance at 90°, 60° and 30° in the unloaded condition (p=0.0001-0.002) and at 90° and 30° in the loaded condition (p=0.014-0.015). In the concentric phase of abduction (frontal plane), significant differences are found at 30° and 60° both in the loaded (p=0.005-009) and unloaded (p=0.0001-0.003) conditions when compared to the standard condition. In the eccentric phase of abduction, significant effects of kinesiotaping are observed at 30° and 60° in the unloaded condition (p= 0.0001-0.039) and at all amplitudes (30°,60°,90°,120°) in the loaded condition (p=0.0001-0.011) (Table 2). Concerning external/internal rotation, during flexion (sagittal plane), in the concentric phase of the movement, kinesiotaping tends to increase internal rotation in the first degrees of the movement (30°,60°) in the loaded (p=0.0001-0.038) and unloaded (p=0.0001-0.032) conditions. Considering the eccentric phase of flexion, internal rotation was significantly increased at 90° and at 30° without distinction between loaded (p=0.0001-0.013) and unloaded (p=0.001-0.011) conditions. Considering abduction (frontal plane), in the concentric phase of the movement, kinesiotaping decreases external rotation at 30° and 60° in the unloaded condition (p=0.0001-0.001) and at 30° in the loaded condition (p=0.009). In the eccentric phase of the abduction movement, external rotation is decreased at 60° in the unloaded condition (p=0.007) while it is decreased at 60° and 30° in the loaded condition (p= 0.009). In all of these conditions, no significant differences are observed between KT1 and KT2, except for the upward phase of abduction, in the unloaded condition, where the effect of KT2 in decreasing internal rotation are more pronounced than the ones observed with KT1 (p=0.0001) (Table 2). Posterior tilt is also highly influenced by kinesiotaping. In the concentric phase of flexion (sagittal plane), posterior tilt is increased after the placement of the strips. It reaches significance at 60° and 90° in the unloaded condition (0.002-0.011) and at 30°,60° and 90° in the loaded condition (p=0.004-0.031). In the eccentric phase of

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flexion, significant differences are observed at 30°, 60° and 90° in the unloaded condition (p=0.001-0.013) and at 30° and 60° in the loaded condition (p=0.001-0.037) in comparison to the standard condition. In abduction (frontal plane), the analysis failed to find significant effects in the upward phase of the movement but in the eccentric phase, kinesiotaping significantly increases posterior tilt at 30° in the unloaded condition (p=0.015). Once more, no significant differences are found between KT1 and KT2, even if KT2 tends to further increase posterior tilt (Table 2).

Discussion Scapular dyskinesis is observed in 61% of overhead athletes [3] and for most of them, it remains asymptomatic. Kibler et al. [23] described the different roles of the scapula: the stable point of the glenohumeral articulation, retraction-protraction on the thoracic wall, elevation of the acromion, to be the base for muscle attachment and to be a link of an important kinetic chain. All of these roles lead us to believe that scapular dysfunction may lead to an increased risk of shoulder injuries by limiting acromion elevation and inducing instability [6][24]. Different authors confirmed this link [4][14][50], some of them affirming that scapular dyskinesis increase the risk of future shoulder injuries by 46% [14]. According to the roles described by Kibler et al. [23], scapular dysfunction is suggested to also decrease shoulder performance, by disrupting the kinetic chain and thus the energy transfer. All of this suggests that normalizing scapular dyskinesis is interesting in asymptomatic subjects, with two main objectives: preventing shoulder injuries and optimizing performance. That’s why the purpose of this study was to assess the effectiveness of 2 different kinesiotaping techniques on changing scapular kinematics and the activity of scapular stabilizing muscles. Considering EMG activity, the results showed a decrease of 8-13% of the activity of the upper trapezius after kinesiotaping placement, both in flexion and abduction, in comparison to the standard condition, without significant difference between KT1 and KT2. This decrease was mostly present at 120° but sometimes at 90° and 60° too. As for the lower trapezius activity, a significant decrease about 15-20% was observed with KT2, at 60° and 120°, both in flexion and abduction while serratus anterior activity was not influenced by kinesiotaping. All of these results, with the exception of those observed in 12

the serratus anterior, are clinically interesting, as Smith et al. [49] demonstrated an increase in upper trapezius activity and a decrease in lower trapezius activity in dyskinetic symptomatic subjects. If we compare our results to the literature, with the same kinesiotaping method as used for KT1 in this study, Lin et al. [29] found a decrease in upper trapezius activity too but also observed an increase in serratus anterior activity, which was not demonstrated in our study. Using another kinesiotaping technique, Hsu et al. [16] confirmed the hypothesis that strips placed parallel to muscle length tend to increase activity. When compared to the results observed with McConnell rigid taping, Selkowitz et al.[46] found an increase in lower trapezius activity combined with a decrease in upper trapezius activity in shelf task elevations while Cools et al. [5] and Intelangelo et al. [18] found no interaction between kinesiotaping and muscular activity. One hypothesis explaining the effects observed may be that cutaneous mechanoreceptors are stimulated following strips stretching, which influence the information’s sent the central nervous system and to the muscles (by myotatic reflex) and have an impact on muscle activity [16][58]. Moreover, kinesiotaping may, by its mechanical effects modify muscle length at some part and modify muscle activity in consequence. Concerning scapular kinematics, the most important effects were observed at 30° and 60°, which corresponds to approximately the range of motion where the kinesiotaping was placed on the skin of the subjects. An increase in upward rotation was observed in flexion and abduction with kinesiotaping and was most important in the unloaded condition and with KT2. Considering external/internal rotation, an increase in internal rotation was observed in flexion while a decrease in external rotation was found in abduction. This effect was more pronounced with KT2 than with KT1, which had a rather negative impact. Finally, posterior tilt was also increased after kinesiotaping placement, without significant differences between KT1 and KT2. Our results confirm those of Van Herzeele et al. [56], who analyzed scapular kinematics with the same technique as used for KT1 in the current study. This reiterated the mechanical effects of kinesiotaping previously described by other authors [16][17][48][58]. If we consider posterior tilt improvement, we can consider that kinesiotaping helps correcting forward shoulder posture. The same mechanical effects on posture were demonstrated by Hajibashi et al.[12]. From a clinical point of view, different points should be retained. Kinesiotaping seems to be effective in modifying scapular-stabilizing muscles’ activity and scapular kinematics. Considering that the effects are mostly observed at the range of motion where the strips were placed, we recommend that the importance of the dysfunction and the amplitude at which it predominates should be considered during strip placement. The effects depending on the amplitude show that kinesiotaping is not a “miracle technique” but may be helpful for its mechanical (passive correction), proprioceptive (neuromotor stimulation and conscious correction) and reassuring effects for patients (feeling of being supported). When comparing the two different kinesiotaping techniques, the results seems to show that the second one (KT2) should not be used in case of decreased upper trapezius/lower trapezius ratio because this technique tends to decrease lower trapezius activity (which increase scapular dysfunction) and tends to have negative effects on scapular external rotation. Knowing that the lower trapezius plays a role in scapular external rotation and in posterior tilt, a decrease in lower trapezius activity may have a negative impact on scapular kinematics in those kind of people. However, cocking position requires the

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scapula to be in posterior tilt, upward rotation and external rotation. So, KT1 seems to favor this cocking position and strength transfer from the lower limbs and the trunk to the upper limb. The positive effects of KT1 on upward rotation would also reduce rotator cuff compression while increasing sub-acromial space in subjects with downward rotation at rest and therefore limiting the occurrence of injuries. These hypotheses should be further explored by assessing performance with and without kinesiotape or by making ultrasonographic measurements of sub-acromial space. Moreover, it would also be interesting to assess the effects of KT1 on shoulder injury prevention through a prospective study. In any cases, given the controversial effects reported in literature, kinesiotaping must be considered as an additional/complementary technique and must not replace muscular and articular rehabilitation. However, kinesiotaping could perhaps be useful, simultaneous to rehabilitation, to increase the effects of a specific scapular stabilizing muscles strengthening and to help people with poor motor control to activate specific muscles (proprioceptive effect). Nevertheless, dyskinetic pattern can change from one patient to another, some patients having a lack of serratus anterior activity for example. In this case, another technique will have to be found. This study has some limitations. The first limitation is the large variability of the scapular dyskinesis observed (type 1 vs type 2, obvious vs subtle). Scapular dyskinesis may be better normalized in some subjects rather than others depending on the characteristics of the dysfunction observed. The second limitation is the important variability of the sports practiced by the volunteers which may influence the dysfunction observed (football, volleyball, tennis, swimming, boxing, etc.) as some sports frequently solicit the upperlimb while others do not. The dysfunction observed may also have been highly influenced by an incorrect posture in some of the subjects included. The last limitation was the lack of a control group, which does not allow us to know if a real normalization is observed following kinesiotaping placement.

Conclusion KT1 and KT2 induce modifications of both scapular kinematics and the EMG activity of two of the muscles concerned (upper and lower trapezius). However, beside these positive effects, KT2 induces a decrease in lower trapezius activity and highly limits external rotation of the scapula. So, KT1 can be considered as the most effective technique in the case of scapular dyskinesis characterized by upper trapezius/lower trapezius imbalance. The mechanical and proprioceptive effects of KT1 could be useful in limiting shoulder injuries in overhead athletes with downward rotation at rest or forward shoulder posture by increasing subacromial space. Further studies will be necessary to assess the

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effectiveness of this prevention technique, potentially combined with scapular muscle rehabilitation.

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Figures and tables

Figure 1: Illustration of the Maximum Voluntary Isometric Contraction tests: (1) empty can, (2) seated U 90°, (3) prone-v-thumbs up, (4) rotation 90°, (5) seated U 125°, (6) seated T.

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Figure 2: Illustration of the two kinesiotaping techniques (KT1 and KT2)

Table 1: Muscle activity (in %Maximal Voluntary Activation) of upper trapezius (UT), lower trapezius (LT) and serratus anterior (SA) during shoulder flexion (Flex) and shoulder abduction (Abd) (30°, 60°, 90° and 120°) with load (W) and without load (UW) [median-value ± standard deviation] UP=upward phase; DN= downward phase; T0= standard condition ; T1= KT1 ; T2= KT2 *= significant differences for the muscle in the movement considered A,B,C = groups made by Tukey comparison if p reached significance (<0.05)

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Table 2: Scapular kinematics (expressed in degrees) during shoulder flexion (Flex) and shoulder abduction (Abd) (30°, 60°, 90° and 120°) with load (W) and without load (UW) [median-value ± standard deviation] UP=upward phase; DN= downward phase ; U/D= upward/downward rotation; I/ER= internal/external rotation; A/P= anterior/posterior tilt; T0= standard condition ; T1= KT1 ; T2= KT2 *= significant differences for the movement considered A,B,C = groups made by Tukey comparison if p reached significance (<0.05)

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Camille Tooth, PT, is a sports physiotherapist at Sports Medical Centre of the University Hospital in Liege (Belgium), specialized in shoulder rehabilitation. Whether at preventive or curative levels, she manages many athletes in her practice, including many overhead athletes. She is also an Assistant Professor at the University of Liege where she teaches basic techniques of physiotherapy and courses about upperlimb rehabilitation. Currently, she works on a PhD at the University of Liege on the topic of scapular dyskinesis and scapular rehabilitation.

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