Visual Scapular Dyskinesis: Kinematics and Muscle Activity Alterations in Patients With Subacromial Impingement Syndrome

External handheld loads affect scapular elevation and upward rotation during shoulder elevation tasks

Altered scapular kinematics is associated with shoulder pain. Resistance exercise is a common treatment; however, the effects of lifting an external load on scapular kinematics is limited. Understanding whether an external handheld load affects scapular kinematics in a healthy population can provide normal values utilized for comparison to individuals with shoulder pain. Currently, no studies have examined the effect of incrementally increased handheld loads. We defined the effects of varying external handheld loads on scapular kinematics during a shoulder elevation task. Healthy participants (n = 50) elevated their shoulder in the scapular plane over 4 trials. One trial of no loading (control) and 3 trials with incrementally increased external handheld loads. Scapular kinematic rotations and translations were measured during ascent and descent phases using 3D motion capture. Compared to no load, the highest external load during ascent increased scapular elevation [mean difference = 3.2 degrees (95%CI: 0.9, 5.4), p = 0.006], and during descent increased scapular elevation [mean difference = 3.9 degrees (95%CI: 2.8, 5.1), p < 0.001] and increased scapular upward rotation [mean difference = 4.5 degrees (95%CI: 2.4, 6.6), p < 0.001]. External handheld loads result in small increases in scapular elevation and scapular upward rotation. These results should be utilized as normal values to compare to individuals with shoulder pain.

Health-related outcomes with supervised exercise and myofascial release versus only supervised exercise in subacromial pain syndrome: a randomized controlled single-blind study

BACKGROUND

Myofascial tissue plays a critical role in shoulder joint mobility disorders. Myofascial release therapy (MFR) is frequently utilized to restore the extensibility of fascial tissue and is considered beneficial for various clinical conditions such as low back pain and ankle injuries. However, no studies have yet evaluated the effects of MFR on periscapular muscles activation and shoulder mobility in patients with subacromial pain syndrome(SAPS).

OBJECTIVE

The purpose of this study was to compare the effectiveness of MFR combined with supervised exercise(SE) and SE alone in patients with SAPS.

DESIGN

Assessor-blinded randomized controlled trial.

SETTING

Sir Run Run Shaw Hospital, Zhejiang University School of Medicine.

SUBJECTS

Subacromial pain syndrome patients.

METHODS

Fifty participants were divided into two groups: SE group and MFR + SE group, each group 25 cases. Both treatment methods were performed 5 times a week for 4 weeks.

MAIN MEASURES

Shoulder pain severity was assessed by visual analog scale (VAS); shoulder range of motion (ROM) by a goniometer; functionality by shoulder Pain and Disability Index (SPADI); and periscapular muscles activation by sEMG. All measurements were evaluated both pre- and post-treatment.

RESULTS

An ANOVA analysis indicated no significant group by time interactions for flexion ROM and resting VAS (p > 0.05). However, significant group by time interactions were found for SPADI, abduction and external rotation ROM, and activity VAS (p < 0.05). Post-hoc tests revealed significant improvements in SPADI, abduction and external rotation ROM, and activity VAS in both groups compared to pre-treatment (p < 0.05). Additionally, there were significant group by time interactions for the sEMG values of the upper trapezius and serratus anterior (p < 0.05). Post-hoc tests showed that compared to pre-treatment, the MFR + SE group had decreased upper trapezius sEMG values and increased serratus anterior sEMG values(p < 0.05), while the SE group showed increased serratus anterior sEMG values(p < 0.05). After the 4-week intervention, there were significant between-group differences in SPADI, abduction and external rotation ROM, activity VAS, and sEMG values of the upper trapezius and serratus anterior(p < 0.05).

CONCLUSION

Four weeks of MFR combined with SE can increase shoulder ROM, improve pain, and thus enhancing functional activities in patients with SAPS. Additionally, it can further improve the balance between the upper trapezius and serratus anterior to improve the dynamics of the periscapular muscles.

TRIAL REGISTRY NUMBER

ChiCTR2200061054. Date of registration 15/06/2022.

Differences in Strength and Fatigue Resistance of Scapular Protractors and Retractors Between Symptomatic and Asymptomatic Dyskinesis

CONTEXT

Scapular dyskinesis is a shoulder dysfunction that can be asymptomatic or associated with pain or weakness. Reduced strength and fatigue resistance of the scapular protractor and retractor muscles that stabilize the scapula might contribute to dyskinesis.

OBJECTIVES

To determine the strength and fatigue resistance profiles of participants with symptomatic or asymptomatic scapular dyskinesis and compare them with healthy control (HC) individuals using isokinetic assessment.

DESIGN

Cross-sectional study.

SETTING

University hospital.

PATIENTS OR OTHER PARTICIPANTS

Twenty HC individuals and 21 overhead athletes with symptomatic (n = 10) or asymptomatic (n = 11) scapular dyskinesis.

MAIN OUTCOME MEASURE(S)

Strength (peak torque, maximum work), fatigue resistance (total work), and protraction:retraction ratios measured during a closed chain isokinetic protocol (40 repetitions in concentric mode at 24.4 cm/s).

RESULTS

The scapular protractors' strength and fatigue resistance were higher (P < .01) in HC individuals (peak torque = 5.0 ± 0.9 N/kg, maximum work = 2.4 ± 0.5 J/kg, total work = 72.4 ± 0.6 J/kg) than in asymptomatic (peak torque = 3.4 ± 0.7 N/kg, maximum work = 1.7 ± 0.4 J/kg, total work = 50.0 ± 13.7 J/kg) or symptomatic (peak torque = 3.8 ± 0.6 N/kg, maximum work = 1.8 ± 0.3 J/kg, total work = 58.1 ± 12.9 J/kg) dyskinetic participants. The symptomatic dyskinetic group presented the highest retractor strength and fatigue resistance (P < .01) values (peak torque = 5.2 ± 0.6 N/kg, maximum work = 2.9 ± 0.8 J/kg, total work = 87.7 ± 22.7 J/kg), followed by the HC individuals (peak torque = 4.7 ± 1.0 N/kg, maximum work = 2.1 ± 0.5 J/kg, total work = 65.3 ± 17.9 J/kg) and the asymptomatic dyskinetic participants (peak torque = 3.9 ± 1.0 N/kg, maximum work = 1.9 ± 0.6 J/kg, total work = 58.6 ± 18.5 J/kg). The protraction:retraction ratios showed a gradual decrease (P < .001) from the HC individuals (1.1) to the asymptomatic (0.9) and symptomatic (0.7) dyskinetic participants.

CONCLUSIONS

Scapular dyskinesis is characterized by weaker scapular protractors and reduced agonist:antagonist ratios, especially when patients are symptomatic. Targeting the scapular protractors to achieve a better balance of scapular musculature in rehabilitation and strengthening programs may improve shoulder symptoms and function, but more interventional studies are required.

Challenges and opportunities in testing sensorimotor processing with tendon vibration and transcranial magnetic stimulation in subacromial impingement syndrome: A case series

BACKGROUND

Non-invasive neurostimulation like muscle tendon vibration (VIB) and transcranial magnetic stimulation (TMS) can provide valuable insights on mechanisms underlying sensorimotor dysfunctions. However, their feasibility in the context of painful musculoskeletal disorders like shoulder impingement syndrome (SIS) remain uncertain.

METHODS

The present work used a case series design including 15 participants with SIS, as well as a secondary group-based analysis comparing participants with SIS to 15 healthy counterparts. Proprioceptive processing was tested by VIB-induced kinesthetic illusions of shoulder abduction, and TMS tested corticospinal excitability of the upper trapezius. Detailed individual data were collected, including any technical challenges and feasibility issues encountered.

RESULTS

VIB was in general well-tolerated and elicited a perceptible kinesthetic illusion in 13 participants with SIS and 14 controls. TMS presented with several challenges related to discomfort, fear-related behaviors, technical problems and high motor thresholds, especially in participants with SIS. It was only possible to collect all TMS measures in 5 participants with SIS (for both the painful and non/less-painful sides), in 7 controls on their dominant side and 10 controls on the non-dominant side. The only significant group-based analysis was a lower illusion speed/amplitude on the painful versus non-painful side in persons with SIS (p = 0.035).

CONCLUSION

Our study provides preliminary data on challenges encountered with TMS and VIB of trunk/proximal muscle in persons with SIS and healthy counterparts. It might help future studies to better address those challenges beforehand and improve the overall feasibility and impact of neurostimulation tools in musculoskeletal disorders.

Voluntary Contraction of the Abdominal Muscles During Shoulder Exercises Increases Scapular Muscle Activation: A Critically Appraised Topic

CLINICAL SCENARIO

The fascial relationship between scapular muscles and abdominal muscles has been documented from previous studies. However, it is not yet clear whether voluntary abdominal contraction has a beneficial effect on scapular muscle activity during shoulder exercises.

CLINICAL QUESTION

Do scapulothoracic muscle activation levels increase if shoulder exercises are performed with voluntary abdominal activation? Summary of Key Finding: After the literature review, 4 cross-sectional studies met the inclusion criteria and were included in this critically appraised topic.

CLINICAL BOTTOM LINE

There is moderate evidence to support dynamic shoulder exercises with voluntary abdominal contraction can increase trapezius and serratus anterior muscle activation level in asymptomatic shoulders. Strength and Recommendation: Findings from 4 cross-sectional trials indicate that there is moderate evidence supporting that dynamic shoulder exercises performed with voluntary abdominal contraction can increase scapular muscle activity.

Effects of manual therapy in addition to stretching and strengthening exercises to improve scapular range of motion, functional capacity and pain in patients with shoulder impingement syndrome: a randomized controlled trial

BACKGROUND

The current study aimed to measure the effectiveness of manual therapy in addition to stretching and strengthening exercises in patients with shoulder impingement syndrome to improve functional capacity, pain, and scapular range of motion.

METHODS

This is a single-blinded randomized controlled trial. Thirty-two participants with chronic shoulder impingement syndrome were randomly allocated into two groups. Both groups received stretching and strengthening exercises while the treatment group was given manual therapy additionally. Treatment was started after the patients signed an informed consent form. The data were collected from the University of Lahore Teaching Hospital between March 2022 and December 2022. The study aimed to measure pain using a numeric pain rating scale, functional capacity was assessed by the disability of the arm and shoulder, and goniometry was used for scapular ranges, i.e., scapular protraction and upward rotation. Each treatment session lasted 45 min for the treatment group and 30 min for the control group. The treatment comprised five days a week for four weeks, after which post-intervention measurements were taken.

RESULTS

Thirty-two participants were enrolled in the study, and 16 were divided into each group. The mean age of the participants in the treatment group was 38.19 ± 7.31 while the comparison group was 35.69 ± 7.98. An independent sample t-test was run on the data with a 95% confidence interval, statistically significant results were obtained, i.e., p-value < 0.05, post-intervention in the treatment group. Both groups have significantly improved functional capacity and scapular protraction (p < 0.005), however, pain and scapular upward rotation were not found statistically significant in the control group (p > 0.05).

CONCLUSION

The addition of manual therapy along with exercise therapy showed clinical and statistical significant results for pain, functional capacity, and scapular range of motion. It demonstrated superior effects than exercise therapy alone for the chronic condition of SIS.

TRIAL REGISTRATION

The trial was registered in the Iranian Registry of Clinical Trials ( https://www.irct.ir/ ) with the registration number: IRCT20230526058291N1, (Date: 12/08/2023).

Exercises With Optimal Scapulothoracic Muscle Activation for Individuals With Paraplegia

Background

Individuals with paraplegia and coexisting trunk and postural control deficits rely on their upper extremities for function, which increases the risk of shoulder pain. A multifactorial etiology of shoulder pain includes "impingement" of the supraspinatus, infraspinatus, long head of the biceps tendons, and/or subacromial bursa resulting from anatomic abnormalities, intratendinous degeneration, and altered scapulothoracic kinematics and muscle activation. Targeting serratus anterior (SA) and lower trapezius (LT) activation during exercise, as part of a comprehensive plan, minimizes impingement risk by maintaining optimal shoulder alignment and kinematics during functional activities. To prevent excessive scapular upward translation, minimizing upper trapezius (UT) to SA and LT activation is also important.

Objectives

To determine which exercises (1) maximally activate SA and minimize UT:SA ratio and (2) maximally activate LT and minimize UT:LT ratio.

Methods

Kinematic and muscle activation data were captured from 10 individuals with paraplegia during four exercises: "T," scaption (sitting), dynamic hug, and SA punch (supine). Means and ratios were normalized by percent maximum voluntary isometric contraction (MVIC) for each muscle. One-way repeated measures analysis of variance determined significant differences in muscle activation between exercises.

Results

Exercises were rank ordered: (1) maximum SA activation: SA punch, scaption, dynamic hug, "T"; (2) maximum LT activation: "T," scaption, dynamic hug, SA punch; 3) minimum UT:SA ratio: SA punch, dynamic hug, scaption, "T"; and (4) minimum UT:LT ratio: SA punch, dynamic hug, "T," scaption. Exercise elicited statistically significant changes in percent MVIC and ratios. Post hoc analyses revealed multiple significant differences between exercises (p < .05).

Conclusion

SA punch produced the greatest SA activation and lowest ratios. Dynamic hug also produced optimal ratios, suggesting supine exercises minimize UT activation more effectively. To isolate SA activation, individuals with impaired trunk control may want to initiate strengthening exercises in supine. Participants maximally activated the LT, but they were not able to minimize UT while upright.

The effect of EMG biofeedback training on muscle activation in an impingement population

Subacromial impingement syndrome (SAIS) is one of the most diagnosed causes of pain in the upper extremity. The purpose of this study was to investigate muscle activity between asymptomatic and SAIS shoulders on the same subject while understanding the effectiveness of EMG biofeedback training (EBFB) on bilateral overhead movements. Ten participants (7 male), that tested positive for 2/3 SAIS clinical tests, volunteered for the study. Bilateral muscle activity was measured via electrodes on the upper trapezius (UT), lower trapezius (LT), serratus anterior (SA), and lumbar paraspinals (LP). Participants performed bilateral scapular plane overhead movements before and after EBFB. EBFB consisted of 10 bilateral repetitions of I, W, T, and Y exercises focused on reducing UT and increasing LT and SA activity. Prior to EBFB, no significant difference in muscle activity was present between sides. A significant main effect of time indicated that after EBFB both sides exhibited reduced UT activity at 60° (p = 0.003) and 90° (p = 0.036), LT activity was increased at all measured humeral angles (p < 0.0005), and SA muscle activity was increased at 110° (p = 0.001). EBFB in conjunction with scapular based exercise effectively alters muscle activity of asymptomatic and symptomatic scapular musculature.

Pitching Biomechanics and Shoulder Function in Baseball Pitchers with Scapular Dyskinesis

The primary purpose was to investigate the influence of scapular dyskinesis (SD) on pitching biomechanics and shoulder function in high school baseball pitchers. The secondary purpose was to identify possible factors associated with shoulder function in pitchers with SD. Thirty-eight pitchers were classified into the SD group (n=26) or the non-SD group (n=12). They were evaluated with the Kerlan-Jobe Orthopaedic Clinic shoulder and elbow (KJOC) scale and clinical measurements of shoulder characteristics, and with measurements of scapular kinematics, muscle activation, and ball speed during fastball pitching. Compared to the controls, the pitchers with SD had less scapular external rotation (difference=11.3 degrees, ES=0.92, p=0.012) during overall pitching and less upper trapezius (UT) activation during the late cocking (difference=7.1%, ES=0.79, p=0.019) and acceleration phases (difference=12.5%, ES=0.75, p=0.035). Higher UT activation during the late cocking phase was significantly associated with higher KJOC scores (standardized β=0.415, p=0.039). In conclusion, deficits in scapular external rotation and decreased UT activation during pitching were found in pitchers with SD. Higher UT activation may be important for shoulder function in pitchers with SD.

Physical and well-being effect of scapular kinesio taping combined with conventional physiotherapy in shoulder impingement syndrome: A randomized controlled study

BACKGROUND

Kinesio taping (KT) is one of the treatment methods used on patients with shoulder impingement syndrome (SIS). There are different results regarding its effectiveness in the literature.

OBJECTIVE

To investigate the effects of scapular KT combined with a conventional physiotherapy program on scapular dyskinesia, shoulder pain, upper extremity function, and well-being in patients with SIS.

METHODS

The study was conducted with 60 outpatients diagnosed with SIS, aged 40-65 years. The patients were divided into two groups: KT [conventional physiotherapy program + scapular KT (targets scapular retraction and is applied along the inferior-medial edge of the scapula, starting from the processus coracoids), n= 30] and control [conventional physiotherapy program, n= 30]. In before- and after-treatment evaluations, the Lateral Scapular Slide Test (LSST) for scapular dyskinesia, a Visual Analogue Scale (VAS) for shoulder pain, and the Disabilities of the Arm, Shoulder, and Hand (DASH) for upper extremity function were used. In addition, at the end of treatment, a Kinesio taping Satisfaction Survey, created by the researchers, was filled out by the KT group for the assessment of well-being.

RESULTS

The interaction effect of Group*Time was not statistically significant in all outcome measures (p> 0.05). However, the main effect of both group and time was statistically significant in the DASH-Function/Symptom, VAS-Rest, VAS-Activity, and VAS-Night (p< 0.05). Moreover, only the main effect of time was statistically significant in LSST-1 and LSST-3 (p< 0.05). In the KT group, the satisfaction level was 8.50 ± 1.69 and the recommendation level was 8.72 ± 1.81.

CONCLUSION

Both conventional physiotherapy programs and additional scapular KT improved scapular dyskinesia, reduced pain, and increased the upper extremity function. Adding scapular KT to treatment did not change the results, but it had positive psychological effects and yielded a high satisfaction rate.

The short-term effectiveness of scapular focused taping on scapular movement in tennis players with shoulder pain: A within-subject comparison

This study aimed to investigate the short-term effectiveness of scapular focused taping (SFT) on scapular position and kinematics during the tennis serve among professional players with and without shoulder pain. The cohort included 7 players who had no history of non-shoulder pain (NSP) and 6 players with shoulder pain (SP). All participants performed tennis flat serves while the Qualisys motion capture system recorded three-dimensional scapular kinematic data according to the International Society of Biomechanics recommendations. SFT was applied to the participants' torso aligned with the lower trapezius, and the same movements were repeated. In the SP group, the scapula was tilted more posteriorly after the application of SFT as compared to before at ball release and maximally externally rotated humerothoracic joint during tennis serve (t = -5.081, P = .004 and t = -2.623, P = .047, respectively). In the NSP group, the scapula was tilted more posteriorly with SFT as compared to without at first 75% timing of the cocking phase and maximally externally rotated humerothoracic joint (t = -3.733, P = .010 and t = -2.510, P = .046, respectively). And the SP group exhibited a more rotated scapula externally after the application of SFT as compared to before at Ball impact (t = 5.283, P = .003). SFT had a positive immediate effect on the scapular posterior tilting and external rotation during certain phases of the tennis serve among tennis athletes with and without shoulder pain. These findings may help clinicians and sports practitioners to prevent and rehabilitate shoulder injuries for overhead athletes. Level of evidence: Level III; Case-Control Design; Comparative Study.

Within-Subject Changes in Shoulder Girdle Muscle Activation After Soft Tissue Mobilization of the Upper Trapezius

Objective

The purpose of this study was to investigate the effect of the integrated neuromuscular inhibition technique (INIT) of the upper trapezius (UT) on shoulder muscle activity in chronic shoulder pain.

Methods

Twenty-two patients (mean age 42.5 ± 16.07) with chronic unilateral shoulder pain with UT myofascial trigger points (MTrPs) (n = 27) and scapular dyskinesis received a single session of INIT (∼15 minutes for each MTrP). The pain on the visual analog scale, along with surface electromyographic activity, maximum voluntary contraction in % (in arm raising and lowering in scapular plane), and pressure pain threshold (PPT) of 5 girdle muscles UT, lower trapezius, serratus anterior, middle deltoid, and infraspinatus were measured before and immediately after treatment. Wilcoxon signed-rank test was used for analysis (at α ≤ 0.05).

Results

Muscle activity of all the muscles, especially the lower trapezius, was reduced during arm raising in the scapular plane (76.69%-71.14% [p = 0.003]). UT activity decreased during arm lowering also (56.70%-45.99% [p ˂ 0.001]). The intensity of shoulder pain reduced (50.50 mm to 22 mm, [p ˂ 0.001]), and PPT values of all 5 muscles improved post-treatment.

Conclusion

The findings of this study provide preliminary evidence for the application of a single session of INIT on UT MTrPs in reducing activity in the scapular muscles, improving shoulder pain, and PPT in chronic unilateral shoulder pain.

Association between changes in pain or function scores and changes in scapular rotations in patients with subacromial shoulder pain: a prospective cohort study

Background

Scapular dyskinesis is reported as one of the potential factors contributing to the presentation of pain in subacromial shoulder pain. In clinical practice, the evaluation and control of scapular dyskinesis is considered important for managing the subacromial shoulder pain. The aim is to determine the association between changes in pain or function and changes in scapular rotations in participants with subacromial shoulder pain.

Method

Pain, function and scapular rotations were measured in 25 participants with subacromial shoulder pain at baseline and after 8 weeks. Pain was measured with Numeric Pain Rating Scale (NPRS) and function was measured with Patient Specific Functional Scale (PSFS). Scapular rotations were measured with a scapular locator at 60°, 90° and 120° of scapular arm elevation. Spearman rank correlations (r_s) were used to assess the association between variables.

Findings

No association was observed between changes in pain or function scores with changes in scapular upward/downward rotations (r_s = 0.03 to 0.27 for pain and − 0.13 to 0.23 for function) and scapular anterior/posterior tilt (r_s = − 0.01 to 0.23 for pain and − 0.13 to 0.08 for function) of arm at 60°, 90° and 120° elevation. Data associated with scapular internal/external rotation was not reported due to low reliability.

Conclusion

These findings reject associations between changes in pain or function scores and scapular rotations. Future observational study is warranted using a multifactorial approach to understand potential factors that contribute to the presentation of subacromial shoulder pain.

Publication Trends and Hot Spots in Subacromial Impingement Syndrome Research: A Bibliometric Analysis of the Web of Science Core Collection

Background

In recent years, the research on subacromial impingement syndrome (SIS) has gradually increased. Although the research directions are diverse, the overall research status and trend are not clear.

Objective

The aim of our study was to use bibliometric analysis to identify the trends in SIS-related research and to analyze the most highly cited scientific publications on SIS.

Methods

All data were retrieved from the Web of Science Core Collection database, and the year of publications, countries, journals, institutions and total number of citations were extracted and analyzed. The results related to countries, institutions and keywords were then analyzed using VOSviewer software and bibliometrics online analysis platform. And, we also identified the 100 most cited articles on SIS.

Results

A total of 548 articles related to AIS were identified. The frequency of publication on SIS has increased substantially over time. Among all countries, Turkey has contributed the most publications on SIS (n=118). The institution with the most articles was Istanbul University (n=17). Journal of Shoulder and Elbow Surgery topped the list of journals and has published 19 SIS-related publications. The hotspot of research changed from the former arthroscopic surgery to physical therapy and rehabilitation.

Conclusion

The scientific research on SIS has rapidly expanded in recent years. This study represents the first bibliometric analysis of SIS, gives us a systematic and comprehensive summary into the development of SIS.

Three-dimensional kinematic analysis of upper limb movements between individuals with and without subacromial shoulder pain exploring the statistical parametric mapping

Subacromial shoulder pain (SSP) accounts for 44-65% of all cases of shoulder pain. Kinematic alterations in the upper limbs have been observed in individuals with SSP, although there is no consensus on such alterations in the literature. Therefore, the present study aimed to compare the three-dimensional kinematics of the scapula, trunk, and arm during shoulder flexion-extension and abduction-adduction movements in individuals with SSP and a control group using statistical parametric mapping (SPM). We evaluated 117 participants [61 with SSP and 56 in the control group (CG)]. The three-dimensional kinematic analysis was performed starting from arm extension/adduction (0%), moving to flexion/abduction, and ending returning to extension/adduction, respectively (100%) in both groups. SSP group flexed more their trunk (0-100%, p < 0.001) and rotated scapula internally (0-20%, p < 0.001 and 75-100%, p < 0.001); rotated upwards (17-32%, p < 0.005 and 58-87%, p < 0.003) and posteriorly tilted (28-79%,p < 0.001 and 81-95%,p < 0.006) less than CG group during arm abduction-adduction. Through arm flexion-extension, the SSP group flexed (38-82% p < 0.009) less their trunk, rotated upwards (5-10% p = 0.021) less their scapula, and posteriorly tilted scapula (0-100% p < 0.001) more than CG. Combining conventional variables used to describe motion in individuals with SSP, such as minimum and maximum values, range of motion, and results provided by SPM can furnish a detailed description of the compensations and limitations of the patient, enabling a better understanding of the function of the scapular girdle as well as improvements in the evaluation process and clinical decision making.

Shoulder-Abduction Angle and Trapezius Muscle Activity During Scapular-Retraction Exercise

CONTEXT

Scapular-retraction exercises are often prescribed to enhance scapular stabilization.

OBJECTIVE

To investigate upper trapezius (UT), middle trapezius (MT), and lower trapezius (LT) activities and UT/MT and UT/LT ratios during scapular-retraction exercises with elastic resistance at different shoulder-abduction angles.

DESIGN

Descriptive laboratory study.

SETTING

Biomechanical analysis laboratory.

PATIENTS OR OTHER PARTICIPANTS

Thirty-five asymptomatic individuals.

MAIN OUTCOME MEASURE(S)

Surface electromyography was used to evaluate UT, MT, and LT activities during the scapular-retraction exercise at 0°, 45°, 90°, and 120° of shoulder abduction.

RESULTS

The mean muscle activity ranged from 15.8% to 54.7% maximal voluntary isometric contraction (MVIC) for UT, 30.5% to 51.6% MVIC for MT, and 21.4% to 25.5% MVIC for LT. A significant muscle × angle interaction was found (P < .001). Post hoc analysis revealed that the MT was more activated than the UT and LT during both retraction at 0° (P < .001 and P = .01, respectively) and 120° (P = .03 and P = .002, respectively). During retraction at 45° and 90°, the LT generated less activity than the UT (P = .02 and P = .03, respectively) and MT (P < .001 and P = .002, respectively). Further, UT/MT and UT/LT ratios during retraction at 0° were lower than at 45° (P = .03 and P = .001, respectively) and 90° (P < .001 and P < .001, respectively). Retraction at 90° resulted in a higher UT/LT ratio than at 45° (P = .004) and 120° (P = .004).

CONCLUSIONS

Due to less UT relative to MT activity, retraction at 0°, 45°, and 120° can be preferable in early shoulder training or rehabilitation. Additionally, retraction at 90° was the most effective exercise in activating all parts of the trapezius muscle.

The effects of muscle fatigue on scapulothoracic joint position sense and neuromuscular performance

BACKGROUND

Fatigue of the scapular musculature might affect the sensorimotor system and neuromuscular control and therefore impair the dynamic alignment of the scapula. The purpose of this study was to investigate the effects of scapular muscle fatigue on joint position sense and the neuromuscular performance of the scapulothoracic joint.

METHODS

Thirty healthy subjects were recruited. The joint position sense (measured as reposition errors during the scapular elevation and protraction task) of the scapulothoracic joint and scapular kinematics and muscle activation (% of maximum voluntary isometric contraction) during scaption, shoulder elevation in the scapular plane, before and after the fatigue task (modified push-up) were measured. The repeated measures analysis of variance (ANOVA) was used to assess the effects of fatigue on scapular reposition error and neuromuscular control.

RESULTS

Although joint reposition sense did not change after fatigue, muscle activation of the serratus anterior increased significantly (18.5%-26.3%, p = 0.006, elevation task; 15.2%-27.4%, p = 0.037, protraction task). At 120° scaption, the scapula showed a decreased posterior tilt (13.8°-10.3°, p < 0.001), increased protraction (10.2°-13.3°, p = 0.004) and lateral rotation (52.8°-54.4°, p = 0.005). Muscle activation of the serratus anterior increased (65.9%-84.6%, p = 0.002) during 90°-120°scaption.

CONCLUSION

Scapular muscle fatigue did not alter the scapulothoracic joint position sense, but increased serratus anterior activation and resulted in a more anteriorly tilted, protracted, and laterally rotated scapula during scaption. Whether or not these fatigue-related changes are linked to the development of shoulder problems needs to be investigated further.

The impact of shoulder pathology on individuals with distal radius fracture

BACKGROUND

Shoulder pathology can occur concurrently with a distal radius fracture (DRF) but few studies have examined this population.

PURPOSE

The purpose of this study was to expand the understanding of the impact of shoulder pathology on individuals with DRF.

STUDY DESIGN

Mixed Methods Design.

METHODS

A total of 45 participants with a DRF were categorized into a DRF only (n = 29) and shoulder pathology concurrent with DRF (SPCDRF) (n = 16) groups. Quantitative data gathered included demographics, Quick Disabilities of the Arm, Shoulder, and Hand, Tampa Scale of Kinesiophobia-11, Visual Analog Scale, and Compensatory Mechanism Checklist. Qualitative interviews were performed with 7 participants in the SPCDRF group. Within group correlations were analyzed via the Spearman Rank. The Mann Whitney U test was used to compare the two groups. Qualitative analysis was performed to describe the experience of participants in the SPCDRF group. A mixed methods analysis compared quantitative and qualitative data.

RESULTS

Sixteen participants (35.6%) in the sample presented with shoulder pathology; 6 participants (37.5%) presented at initial evaluation due to the fall; 10 participants (62.5%) developed shoulder pathology due to compensation or disuse. Average number of days to develop shoulder pathology after the DRF was 43 days. SPCDRF participants had significantly greater pain levels (p = .02) and more activity avoidance (p = .03) than the DRF only group. Four qualitative themes emerged: It's difficult to perform occupations and changes had to be made; There is fear and uncertainty; The impact of pain; Tried to be normal but could not Mixed methods analysis found that qualitative data further illuminated quantitative findings.

CONCLUSIONS

Individuals with shoulder pathology concurrent with a DRF may present with higher pain levels and avoid activity more. In addition, they may describe fearfulness in using their injured upper extremity especially if they have high levels of pain.

STUDY DESIGN

Mixed Methods Design.

Bending the Elbow During Shoulder Flexion Facilitates Greater Scapular Upward Rotation and a More Favorable Scapular Muscle Activation Pattern

CONTEXT

Decreased scapular upward rotation (UR) and diminished activation of the serratus anterior (SA) and lower trapezius (LT) are often observed among patients with subacromial impingement syndrome. Maintaining the elbow fully flexed during shoulder flexion may limit glenohumeral motion due to passive insufficiency of the triceps brachii and therefore facilitate greater scapular UR and increased scapular muscle activation.

OBJECTIVES

To compare scapular UR, SA, upper trapezius (UT), middle trapezius, and LT activation levels between shoulder flexion with the elbow extended (Flexion-EE) to shoulder flexion with the elbow fully flexed (Flexion-EF). This study hypothesized that Flexion-EF would result in greater scapular UR, greater SA and LT activation, and a lower UT/SA and UT/LT activation ratio compared with Flexion-EE.

DESIGN

Cross-sectional study.

SETTING

A clinical biomechanics laboratory.

PARTICIPANTS

Twenty-two healthy individuals.

MAIN OUTCOME MEASURES

Scapular UR and electromyography signal of the SA, UT, middle trapezius, and LT, as well as UT/SA and UT/LT activation ratio were measured during Flexion-EE and Flexion-EF.

RESULTS

Flexion-EF resulted in greater scapular UR compared with Flexion-EE (P < .001). Flexion-EF resulted in greater SA activation, lower UT activation, and a lower UT/SA activation ratio compared with Flexion-EE (P < .001).

CONCLUSIONS

Fully flexing the elbow during shoulder flexion leads to increased scapular UR primarily through greater activation of the SA. This exercise may be of value in circumstances involving diminished scapular UR, decreased activation of the SA, and an overly active UT such as among patients with subacromial impingement syndrome.

Electromyographic analysis of select eccentric-focused rotator cuff exercises

Background: Eccentric-focused rotator cuff exercises are clinically useful in rehabilitation; however, to what extent these exercises activate shoulder musculature is unknown.Purpose: Investigate peak electromyographic (EMG) activity of shoulder musculature during eccentric-focused rotator cuff exercises to inform clinical decision-making.Methods: Surface EMG activity was measured in 15 healthy subjects from 5 muscles of the dominant shoulder: supraspinatus, infraspinatus, upper trapezius, lower trapezius, and middle deltoid. Subjects performed 5 exercises: short-to-long scaption, sit-to-stand scaption, standing external rotation (ER), sidelying ER, and sidelying horizontal adduction. The effects of exercise and muscle on peak EMG activity were analyzed using two-way repeated-measures ANOVA and followed with post-hoc pairwise comparisons.Results: Significant exercise-by-muscle interaction effect was found (p < .001). Short-to-long and sit-to-stand scaption elicited higher activity in supraspinatus and middle deltoid compared to other exercises (p < .05); however, no effect of muscle was found for these exercises (p > .05). Infraspinatus and lower trapezius demonstrated higher activity compared to other muscles during standing ER, sidelying ER, and sidelying horizontal adduction (p < .05).Conclusion: Eccentric-focused exercises sufficiently activate the rotator cuff and is effective for use in rehabilitation. Caution must be taken as some exercises do not target specific musculature.

Acute effect of inhibitory kinesio-tape of the upper trapezius on lower trapezius muscle excitation in healthy shoulders

INTRODUCTION

Shoulder pain increases excitation of the upper trapezius (UT) and reduces excitation in the lower trapezius (LT). Despite inconclusive evidence, kinesio-tape (KT) is often used to modify muscular excitation within the UT and/or LT to help correct alterations in scapular position and motion associated with shoulder pain/injury. The objective of the current study was to determine if inhibitory KT to the UT acutely increases LT excitation and if load alters the magnitude of change in the excitation observed.

METHODS

Twenty-two (N = 22, 11 female) individuals with healthy shoulders (24 ± 3 years) completed 10 repetitions of an arm elevation task during 3 taping conditions (no-tape, experimental KT, sham KT) and 2 loading conditions (no load and loaded). Whole-muscle (mean grid) and spatial distribution (grid row) of LT excitation (root mean squared; RMS) was measured using a single high-density surface electromyography 32-electrode grid.

RESULTS

There was a main effect for loading condition on whole-muscle LT RMS, F (1, 19) = 38.038, p < .001, partial η² = 0.667. Whole-muscle LT RMS was significantly higher in the loaded condition (0.055 V ±0 .005) compared to the no-load condition (0.038 V ±0 .004). No effect of tape condition was observed on whole-muscle or spatial distribution of RMS.

CONCLUSION

Our findings suggest that inhibitory KT to the UT does not alter whole-muscle excitation or shift the distribution of excitation within the LT during a repeated arm elevation task in healthy shoulders.

Muscle activation in specific regions of the trapezius during modified Kendall manual muscle tests

CONTEXT

Manual muscle tests (MMTs) are often used when assessing shoulder pathologies. For the trapezius, individual MMTs are used to selectively test the upper (UTR), middle (MTR), and lower (LTR) trapezius regions. It is assumed that MMTs for each region preferentially recruit the corresponding muscle fibres and produce a "maximal" contraction; however, it is unknown if this is true.

OBJECTIVE

To determine if maximum voluntary isometric contractions (MVICs) for the upper (UT-MVIC), middle (MT-MVIC), and lower (LT-MVIC) trapezius, adapted from the Kendall MMTs, recruit the corresponding trapezius regions.

DESIGN

Cross-Over.

SETTING

Laboratory.

PARTICIPANTS

20 young, healthy individuals.

INTERVENTION

Participants performed three repetitions of each MVIC. High density surface electromyography was collected from the UTR, MTR, and LTR.

MAIN OUTCOME MEASURES

Root mean square (excitation) of the UTR, MTR, and LTR.

STATISTICAL ANALYSIS

Three, one-way repeated measures ANOVAs.

RESULTS

UTR excitation: There was a significant increase in UTR excitation during the LT-MVIC compared to the UT-MVIC (p = .016), and MT-MVIC (p < .001). MTR excitation: There was a significant increase in MTR excitation during the MT-MVIC compared to the UT-MVIC (p = .001), and a significant increase in MTR excitation during the LT-MVIC compared to the UT-MVIC (p < .001). There was also a significant increase in MTR excitation during the LT-MVIC compared to the MT-MVIC (p < .001). LTR excitation: There was a significant increase in LTR excitation during the MT-MVIC (p < .001) and LT-MVIC (p < .001) compared to the UT-MVIC.

CONCLUSIONS

The UT-MVIC and MT-MVIC do not necessarily recruit the corresponding trapezius regions more than the other MVICs. Rather, the LT-MVIC appears to produce the greatest excitation in all trapezius regions. Additional research is needed; however, clinicians should be aware that maximal contractions may not always recruit the desired musculature when forming a clinical interpretation.

Scapular motion is accelerated in asymptomatic individuals with dyskinesis: An observational study

INTRODUCTION

Individuals with shoulder and upper extremity pathology often present with altered scapular motion. Few studies have looked at variations in scapular acceleration as a way of quantifying scapular motion. The purpose was to determine the effectiveness of wireless accelerometers for detecting changes in acceleration in individuals with scapular dyskinesis.

MATERIALS/METHODS

Twenty-seven asymptomatic college students (mean age 24 (SD ± 1.54), 65% female, 93% right handed) were visually screened for scapular dyskinesis using previously described criteria. Of the students recruited, fifteen students were determined to have scapular dyskinesis. After securing a wireless accelerometer (MyoResearch 3D DTS) on the dominate scapula, the participants performed five repetitions of standing scaption from 0 to 140°. Linear scapular accelerations along three orthogonal axes (frontal-y, transverse-z, and sagittal-x) were collected. Intraclass correlation coefficients (ICC_{3, k}) were used to determine the between day intra-rater reliability while a one-way analysis of variance was used to determine differences in acceleration between those with and without dyskinesis.

RESULTS

There was good between day intra-rater reliability for the average of all three axes (ICC = 0.79) and for the x and y axes (ICC > 0.78). Reliability was poor (ICC = 0.31) for the z-axis. There was a significant increase in overall acceleration of the scapula in those with dyskinesis (p = .039). There was also a significant increase in acceleration along the y-axis for those with dyskinesis (p = .003) but not for the other axes (p > .16).

CONCLUSION

Wireless accelerometers reliably quantify scapular acceleration in healthy individuals. In a healthy population with dyskinesis, the overall magnitude of scapular acceleration was greater when compared to a healthy group without dyskinesis.

Electromyographic muscle activity and three-dimensional scapular kinematics in patients with multidirectional shoulder instability

OBJECTIVE

To investigate differences in EMG muscle activity and scapular kinematics during elevation in the scapular plane between healthy controls, participants with multidirectional shoulder laxity (MDL), and patients with multidirectional shoulder instability (MDI) who are diagnosed with hypermobile Ehlers-Danlos syndrome (hEDS) or Hypermobility Spectrum Disorder (HSD).

METHODS

Twenty-seven women with hEDS/HSD and MDI, 27 female healthy control subjects, and 28 female subjects with MDL participated in this study. Scapular 3D kinematic data were obtained using 8 Oqus Qualisys cameras. Simultaneously, surface electromyography (EMG) was used to measure muscle activity of the upper, middle, and lower trapezius, infraspinatus, latissimus dorsi, serratus anterior, posterior deltoid, and pectoralis major during arm elevation in the scapular plane. Group differences were assessed using statistical parametric mapping.

RESULTS

Regarding scapular kinematics, significantly less upward rotation was observed in hEDS/HSD patients with MDI compared to both healthy controls and MDL subjects. Significantly less posterior tilt was seen in hEDS/HSD patients compared to MDL subjects. Furthermore, significantly higher EMG activity of the infraspinatus, middle trapezius, and posterior deltoid was found in hEDS/HSD patients with MDI.

CONCLUSION

hEDS/HSD patients with MDI demonstrate altered scapular kinematics and increased EMG muscle activity compared to subjects without MDI. These findings could serve as stepping stone for future research regarding treatment strategies in patients belonging to the hypermobility spectrum.

Comparison between dry needling plus manual therapy with manual therapy alone on pain and function in overhead athletes with scapular dyskinesia: A randomized clinical trial

Muscles' trigger points can induce scapular dyskinesia (SD) which interferes with overhead athletes' professional training. We aimed to evaluate effects of dry needling (DN) alone and plus manual therapy (MT) on pain and function of overhead athletes with SD. 40 overhead athletes (15 male, 25 female) aged 18-45 with at least 3 points Numeric Rating Scale (NRS) pain intensity during training were recruited and randomly allocated to the treatment group: MT followed by DN on trigger points of Subscapularis, Pectoralis minor, Serratus anterior, upper and lower Trapezius muscles; or the control group: MT alone. The effect of shoulder trigger points DN plus MT with MT alone on pain, function, Pain Pressure Threshold (PPT) and SD in athletes with SD were compared. Both the examiner and the therapist were blinded to group assignment. Both groups were analyzed. Pain, disability and SD were improved in treatment group (P < .05). On the other hand, when only MT was applied, despite reduction in pain and disability (P < .001), scapular slide only improved in hands on waist position. Comparing the differences between groups showed a substantial reduction in pain (P < .001) and disability (P = .02) with significant improvement in scapular dyskinesia in treatment group (P = .02). Moreover, PPT significantly increased in the control group (P = .004). No adverse effects reported by the participants during this study. DN is an easy and applicable method that can synergistically reduce pain, disability and dyskinesia when it is combined with manual techniques to treat shoulder dysfunctions.

Reproducibility and discriminant validity of the Posterior Shoulder Endurance Test in healthy and painful populations

OBJECTIVE

This investigation measured the reproducibility and discriminant validity of the Posterior Shoulder Endurance Test (PSET) on painful and non-painful populations.

DESIGN

Reliability and validity study.

SETTING

Laboratory setting.

PARTICIPANTS

Thirty subjects (male = 11; female = 19).

MAIN OUTCOME MEASURES

Time to failure (TTF) was the primary outcome measure to determine reliability of the PSET. Discriminant validity identified with receiver operator characteristic (ROC) curves utilized TTF separately in men and women since they used different loads.

RESULTS

There were 25/30 subjects (painful = 12; non-painful = 13) tested a second time. ICC, SEM, and MDC90 ranged respectively from 0.77, 13.1 s, 30.6 s in the painful group to 0.85, 7.3 s, 17 s in the non-painful group. The male ROC curve AUC was 0.833 with 47 s resulting in the best combination of sensitivity = 0.833, and specificity = 0.80. The female ROC curve AUC was 0.633 with 46 s resulting in the best combination of sensitivity = 0.600 and specificity = 0.889 at 46 s.

CONCLUSION

The PSET is a reliable way to measure shoulder girdle muscular endurance. These data suggest that the PSET discriminates painful and non-painful individuals better in men compared to women.

Does the Activity in Scapular Muscles During Plyometric Exercises Change When the Kinetic Chain Is Challenged?-An EMG Study

Werin, MB, Maenhout, AG, Icket, J, Jacxsens, N, Kempkes, E, and Cools, AM. Does the activity in scapular muscles during plyometric exercises change when the kinetic chain is challenged?-An EMG study. J Strength Cond Res XX(X): 000-000, 2020-Plyometric exercises for the shoulder are used in rehabilitation and in workout regime when the sport demands high speed power training. The aim of this clinical laboratory electromyography (EMG) study was to determine whether scapular muscle performance differs during plyometric shoulder exercises when changing the demand on the kinetic chain. Thirty healthy overhead athletes, with a mean age of 22.7 years (±2.2), performed 6 exercises, with both a low and a high demand on the kinetic chain, in prone, side and standing in positions. The EMG activity of the upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) on the tested side and bilateral of gluteus maximus (GM) and abdominal oblique externus (OE) was registered with wireless surface EMG. Intermuscular muscle ratios UT/SA, UT/MT, and UT/LT were also calculated. The level of significance set for the study was alpha = 0.05. The muscle ratio UT/SA was significantly lower (p < 0.05) when high demand on the kinetic chain compared with low. SA muscle activity showed significantly (<0.001) higher values in the prone position with high demand on the kinetic chain compared with low. All 3 trapezius muscle parts had significantly higher values (p < 0.001) in the prone compared with side and standing positions. The GM and OE showed significantly higher (p ≤ 0.01) activity in positions more demanding for the kinetic chain. When composing a strengthening or a rehabilitation program for athletes, the knowledge of how scapular and trunk muscles interact can be used to amplify the strengthening effect.

Measurement of scapular prominence in symptomatic dyskinesis using a novel scapulometer: reliability and the relationship to shoulder dysfunction

BACKGROUND

No previous studies have investigated whether the extent of scapular dyskinesis is associated with shoulder dysfunction. This study aimed (1) to establish the reliability of a scapulometer in patients with shoulder pain and (2) to investigate the related factors associated with shoulder dysfunction.

METHODS

One hundred participants with symptomatic scapular dyskinesis were recruited. Twenty-one participants were involved in the reliability study to test the intrarater and inter-rater reliabilities of the scapulometer in patients with shoulder pain. After demographic data and self-reported Flexilevel Scale of Shoulder Function (FLEX-SF) scores were recorded, all participants were measured with a scapulometer to determine the posterior displacement of the root of the spine (ROS) and the inferior angle (IFA) of the scapula from the thorax. Next, the participants performed 5 trials of bilateral scapular plane elevation for scapular kinematics and electromyographic (EMG) data collection. Stepwise multiple linear regressions were used to determine the relationships between self-reported FLEX-SF scores and potential factors. In addition to scapular displacement, pain level, scapular kinematics, and EMG data were included as independent variables.

RESULTS

The intrarater and inter-rater reliabilities of the scapulometer were excellent (intraclass correlation coefficient [ICC] = 0.93-0.97) and moderate to good (ICC = 0.74-0.81), respectively. The Bland-Altman plots showed no systematic bias between raters in the ROS and IFA measurements. Final stepwise multiple regression models showed that more ROS distance, higher serratus anterior activity, and lower pain level during arm elevation were associated with higher shoulder function (total R² = 0.253).

CONCLUSION

The reliability of the scapulometer in patients with shoulder pain is moderate to excellent. Scapular dyskinesis may be a compensatory strategy to avoid shoulder pain and improve shoulder function.

Scapular Dyskinesis and the Kinetic Chain: Recognizing Dysfunction and Treating Injury in the Tennis Athlete

PURPOSE OF REVIEW

This article aims to provide a comprehensive understanding of the evaluation, diagnosis, and management of scapular dyskinesis and its impact on the kinetic chain in tennis athletes.

RECENT FINDINGS

Optimal glenohumeral biomechanics are intimately associated with proper scapular motion and function. The tennis serve requires the scapula to act as a force transducer in the kinetic chain to convert potential energy generated in the lower extremities to kinetic energy in the upper extremity. Any aberration within this complex kinetic chain will result in force uncoupling and increases the potential for injury through compensatory mechanisms. Specifically, scapular dyskinesis has been associated with an increased risk of shoulder pain of up to 43% in overhead athletes. These pathologies include rotator cuff disease, subacromial and posterior impingement, labral injuries, and SLAP tears. Although the direct causality of these injuries remains controversial, multiple kinematic studies have demonstrated altered scapular positioning increasing the predilection for soft tissue pathology. The diagnosis of scapular dyskinesis is predicated upon a thorough history, physical examination, and observational analysis of key nodes in the kinetic chain during tennis activity. Conservative management remains the mainstay of treatment and consists of a graduated physical therapy regimen. Although shoulder pain in the overhead athletes is often multifactorial, early recognition and treatment of scapular dyskinesis generally carry a favorable prognosis and result in improved patient outcomes.

Is there an association between changes in pain or function with changes in scapular dyskinesis: A prospective cohort study

OBJECTIVE

To assess the association between changes in pain or function with changes in scapular dyskinesis in participants with subacromial shoulder pain.

METHOD

Forty-four participants with subacromial shoulder pain were assessed at baseline and 8 weeks later. The outcome measures included 'pain at rest' and 'pain during movement' using Numeric Pain Rating Scale (NPRS), shoulder function using Patient Specific Functional Scale (PSFS), and observation of scapular movement pattern using the scapular dyskinesis test. Robust paired t-tests were used to compare scores between baseline and follow-up. Repeated measures correlation coefficient was used to assess the association between changes in pain or function with changes in scapular dyskinesis scores.

RESULTS

A fair association was found between improvement in function and improvement in scapular dyskinesis (correlation coefficient = -0.4, 95% CI: -0.6 to -0.1). No associations were found between changes in 'pain at rest' (correlation coefficient = -0.1, 95% CI: -0.2 to 0.2) or 'pain during movement' (correlation coefficient = 0.28, 95% CI: 0.0 to 0.5) with changes in scapular dyskinesis.

CONCLUSION

Our findings showed improvement in function is associated with improvement in scapular dyskinesis scores. Future studies should explore whether there is causal effect between improvement in scapular dyskinesis and function.

The Effect of Repeated Shoulder Motion on Scapular Dyskinesis in Army ROTC Cadets

INTRODUCTION

Altered or abnormal scapular motion has been associated with increased shoulder pain and dysfunction. Fatigue of the scapular stabilizing muscles resulting from repeated arm motion has been reported to alter scapular kinematics, which could result in the clinical assessment of scapular dyskinesis. The purpose of this study was to characterize the effect of repeated arm motion on the development of scapular dyskinesis. The hypothesis was that repeated arm motion will induce a subtle or obvious scapular dyskinesis.

MATERIALS AND METHODS

About 30 army Reserve Officer Training Corps (ROTC) cadets participated in the research study. The cadets level of shoulder function was determined using the Quick Disabilities of the Arm Shoulder and Hand and Pennsylvania Shoulder Score shoulder scores. Cadets performed an exercise protocol of 30 repetitions of weighted shoulder motion in the frontal plane. Shoulder and scapular musculature strength measurements were recorded prior to and immediately following the exercise protocol using hand-held dynamometry. The scapular dyskinesis test was performed prior to the exercise protocol and during the last five repetitions of the exercise protocol.

RESULTS

Prior to the exercise, protocol 3/30 were categorized with scapular dyskinesis on the left side and 3/30 were categorized with scapular dyskinesis on their right side. Following the exercise, protocol 8/30 were categorized with left-side scapular dyskinesis (χ2 = 9.167, P = 0.002) and 6/30 with right-side dyskinesis (χ2 = 4.537, P = 0.033). Shoulder strength decreased following the exercise protocol for all participants. The participants that developed scapular dyskinesis were weaker than those with normal scapular motion. However, the difference did not reach statistical significance. Participants graded with obvious scapular dyskinesis following the exercise protocol reported higher Quick Disabilities of the Arm Shoulder and Hand scores (P = 0.04) and lower scores on the Pennsylvania Shoulder Score (P = 0.005).

CONCLUSIONS

Repeated shoulder motion increased the frequency of scapular dyskinesis in army ROTC cadets. The cadets that developed scapular dyskinesis also reported greater disability and lower function of the upper extremity. The results provide a link between scapular dyskinesis, upper extremity function, and the strength of the scapular stabilizing muscles. Improving the strength of the scapular stabilizing musculature might reduce the effects of repeated arm motions.

Scapular Dyskinesis: From Basic Science to Ultimate Treatment

Background: This study intends to summarize the causes, clinical examination, and treatments of scapular dyskinesis (SD) and to briefly investigate whether alteration can be managed by a precision rehabilitation protocol planned on the basis of features derived from clinical tests. Methods: We performed a comprehensive search of PubMed, Cochrane, CINAHL and EMBASE databases using various combinations of the keywords “Rotator cuff”, “Scapula”, “Scapular Dyskinesis”, “Shoulder”, “Biomechanics” and “Arthroscopy”. Results: SD incidence is growing in patients with shoulder pathologies, even if it is not a specific injury or directly related to a particular injury. SD can be caused by multiple factors or can be the trigger of shoulder-degenerative pathologies. In both cases, SD results in a protracted scapula with the arm at rest or in motion. Conclusions: A clinical evaluation of altered shoulder kinematics is still complicated. Limitations in observing scapular motion are mainly related to the anatomical position and function of the scapula itself and the absence of a tool for quantitative SD clinical assessment. High-quality clinical trials are needed to establish whether there is a possible correlation between SD patterns and the specific findings of shoulder pathologies with altered scapular kinematics.

Exercise therapy may affect scapular position and motion in individuals with scapular dyskinesis: a systematic review of clinical trials

BACKGROUND

Therapeutic exercise for scapular muscles is suggested to be effective in reducing shoulder pain in patients with rotator cuff disorders, whereas its effectiveness on scapular position and motion has remained unclear. Therefore, the aim of this systematic review was to investigate whether exercise therapy improves scapular position and motion in individuals with scapular dyskinesis.

METHODS

This study is a wide systematic review including any type of clinical trial in which the effect of any type of therapeutic exercise, including scapular muscle strengthening, stretching, and scapular stabilization exercise, is investigated in adult participants.

RESULTS

Twenty studies were included in this systematic review. Studies were categorized on the basis of the techniques they used to measure scapular position and motion and the included participants. Methodologic quality of the studies was assessed by the Cochrane tool of assessing the risk of bias. Eight studies used 3-dimensional techniques for measuring scapular motions. Among them, 5 studies showed significant effects of exercise on scapular motion, of which 3 studies investigated individuals with subacromial impingement syndrome (SIS). The other 12 studies used 2-dimensional measurement techniques, of which 8 studies reported significant effects of exercise on scapular position and motion both in SIS patients and in asymptomatic individuals. However, their methodologic quality was debatable. Therefore, there was conflicting evidence for the effect of exercise on scapular dyskinesis.

CONCLUSION

There is a lack of evidence for beneficial effects of exercise in improving scapular position and motion in individuals with scapular dyskinesis. However, exercise is beneficial in reducing pain and disability in individuals with SIS.

Relationship between scapular initial position and scapular movement during dynamic motions

Optimal scapular position and movement are necessary for normal function of the shoulder joint and it is essential to focus on scapula in the rehabilitation for shoulder disorders. The aim of this study was to discover the relationship between the scapular initial position and scapular movement during dynamic motions in healthy young men. Thirty-four men participated in this study. The scapular angles at initial position and in elevation and lowering during flexion and abduction were measured using an electromagnetic tracking device. The scapular movements from 30° to 120° during flexion and abduction were calculated. Spearman's rank correlation coefficients were used to analyze the relationship between the scapular initial position and scapular movements. For upward rotation and posterior tilt of the scapula, there were significant positive correlations between the scapular initial position and scapular movement during flexion and abduction. For internal rotation, there were significant positive correlations, except 90° in lowering phase and 120° in both phases. While the humeral elevation increased, the correlation coefficients tended to decrease. Except for the internal rotation our results clarified the interactions between the scapular initial position and scapular movement during dynamic motions in healthy young men. The tendency of the decrease in correlation coefficient with elevation angle was shown.

Effect of Balance Taping Using Kinesiology Tape and Cross Taping on Shoulder Impingement Syndrome: A Case Report

Background and objectives: Shoulder impingement syndrome (SIS) is the most common disorder among people with shoulder pain. The purpose of this case report was to investigate the effect of the combined application of balance taping using kinesiology tape and cross taping on a part-time worker with SIS. Case Report: Combined balance taping and cross taping was applied for 3 weeks (average, 16 hours per day) on a part-time worker with severe pain and a limited range of motion (ROM) in the shoulder who had visual analogue scale (VAS) pain scores of 7 and 8 out of 10 for shoulder flexion and abduction, respectively, and pain and disability scores of the Shoulder Pain Disability Index (SPADI) of 37 out of 50 and 29 out of 80, respectively. After the combined application of balance taping and cross taping, the VAS pain scores for shoulder flexion and abduction decreased from 7 to 0 and from 8 to 0, respectively, and the ROM increased to a normal range. The SPADI pain score decreased from 37 to 2, and the disability score decreased from 29 to 1. Shoulder activity level also increased, and the patient was able to return to his part-time job. Conclusions: We suggest combined application of balance taping and cross taping as an effective treatment for part-time workers with SIS.

Comparison of scapular muscle activation during shoulder elevation in older and young adults: A pilot study

BACKGROUND

The prevalence of degenerative shoulder disease is increasing, and most shoulder diseases are accompanied by changed activation of the scapular muscles. However, the characteristics of scapular muscle activation in older adults have not yet been reported.

OBJECTIVE

The aim of this study was to investigate the effect of age and load on scapular muscle activation during shoulder abduction and flexion.

METHODS

Eleven older adults (5 men, 6 women; 71.1 ± 5.3 years) and ten young adults (5 men, 5 women; 25.0 ± 2.7 years) performed shoulder elevation (abduction and flexion) with and without a dumbbell. Electromyography were recorded from the upper, middle and lower trapezius, and serratus anterior muscles in the dominant side. Muscle activation was normalized by reference voluntary contractions.

RESULTS

During shoulder elevation with a dumbbell load, the activation of the middle trapezius (p= 0.036) in older adults was significantly higher than that in young adults during abduction. The activation of the upper trapezius (p= 0.001) in older adults was significantly higher than that in young adults during flexion.

CONCLUSION

The older adults have a higher activation of the upper and middle trapezius during shoulder elevation with a weighted load.

Scapular Dyskinesia, the forgotten culprit of shoulder pain and how to rehabilitate

The improper movement of the scapula during shoulder movement is termed scapular dyskinesis and is an often-forgotten cause of pain and dysfunction. The scapula is a key part of the upper limb kinematic chain and is a vital component of the glenohumeral rhythm; which is a major determinant of the efficiency and efficacy of the upper limb. We provide an overview of the complex regional anatomy of the shoulder girdle and how this allows the scapula to act as a both a dynamic and static stabilizer to the upper limb. We explore the normal biomechanics and the aetiology, epidemiology and pathological occurrences which can disrupt the normal function and lead to scapula dyskinesis. Scapula dyskinesis is a poorly understood condition and provides a challenge for the clinician in both diagnosis and management. We provide a summary of the clinical assessment which is most likely to identify the source of the pathology and guides the treatment which is largely rehabilitation of the musculature with focused and specialized physiotherapy.

Superficial Shoulder Muscle Synergy Analysis in Facioscapulohumeral Dystrophy During Humeral Elevation Tasks

Facioscapulohumeral dystrophy (FSHD) is a progressive muscle-wasting disease which leads to a decline in upper extremity functionality. Although the scapulohumeral joint's stability and functionality are affected, evidence on the synergetic control of the shoulder muscles in FSHD individuals is still lacking. The aim of this paper is to understand the neuromuscular changes in shoulder muscle control in people with FSHD. Upper arm kinematics and electromyograms (EMG) of eight upper extremity muscles were recorded during shoulder abduction-adduction and flexion-extension tasks in eleven participants with FSHD and 11 healthy participants. Normalized muscle activities were extracted from EMG signals. Non-negative matrix factorization was used to compute muscle synergies. Maximum muscle activities were compared using non-parametric analysis of variance. Similarities between synergies were also calculated using correlation. The Biceps Brachii was significantly more active in the FSHD group (25±2%) while Trapezius Ascendens and Serratus Anterior were less active (32±7% and 39±4%, respectively). Muscle synergy weights were altered in FSHD individuals and showed greater diversity while controls mostly used one synergy for both tasks. The decreased activity by selected scapula rotator muscles and muscle synergy weight alterations show that neuromuscular control of the scapulohumeral joint is less consistent in people with FSHD compared to healthy participants. Assessments of muscle coordination strategies can be used to evaluate motor output variability and assist in management of the disease.

Trapezius muscle activation levels and ratios during scapular retraction exercises: A comparative study between patients with subacromial impingement syndrome and healthy controls

BACKGROUND

Little is known about trapezius muscle activities during scapular retraction exercises in patients with subacromial impingement syndrome. The aim of this study was to compare upper trapezius, middle trapezius and lower trapezius muscle activity and upper/middle and upper/lower trapezius ratios between patients with subacromial impingement syndrome and healthy individuals during six scapular retraction exercises.

METHODS

Twenty-two patients with subacromial impingement syndrome and 22 healthy individuals participated. Upper, middle, and lower trapezius activities were measured by surface electromyography, while the participants performed six scapular retraction exercises at different shoulder abduction angles in a standing position. Upper/middle and upper/lower trapezius ratios were also calculated. Repeated-measures analyses of variance were performed to determine whether muscle activation levels and ratios differed between groups during exercises.

FINDINGS

There was no significant exercise × group interactions for upper, middle, and lower trapezius activation levels and upper/middle and upper/lower trapezius ratios (P > .05). A main effect for the exercise was observed for the upper/middle and upper/lower trapezius ratios (P < .05).

INTERPRETATION

Compared to healthy individuals, patients with subacromial impingement syndrome did not exhibit different upper, middle, and lower trapezius activity and had similar upper/middle and upper/lower trapezius ratios during the various scapular retraction exercises. Therefore, scapular retraction exercises with various shoulder abduction could be safely offered for the patients with subacromial impingement syndrome since it does not lead to abnormal compensatory trapezius muscle activity. If the goal is to minimize upper/middle and upper/lower trapezius ratios, the scapular retraction exercises at 0° shoulder abduction may be used in early stage of shoulder rehabilitation.

Clinical assessment methods for scapular position and function. An inter-rater reliability study

Introduction: The aim of this study was to assess the inter-rater reliability of selected static, semi-dynamic, and dynamic test assessment methods for evaluation of scapular positioning and function. Methods: A standardized three-phase (i.e. training, overall agreement, and actual study) protocol for reliability studies was applied on 41 overhead sports participants, aged 18-56 (22 with obvious scapular winging, classified as visibility of the medial or inferior angle border of scapula). Ten scapular test assessment methods (two static, three semi-dynamic, and five dynamic) were evaluated. Results: Bland-Altman plots showed no funnel effects, although systematic bias and significant differences between raters were present in three of the methods. ICC values ranged from 0.71 to 0.80 for the static test assessment methods and from 0.25-0.92 for the semi-dynamic test assessment methods. Three of the five dynamic test assessment methods had ICCs of 0.47-0.68. For the two remaining dynamic test assessment methods, kappa varied between -0.034 and 0.71. Using PABAK, kappa increased to 0.54-0.86. Conclusion: Four scapular test assessment methods (Upper horizontal distance, Lower horizontal distance at max shoulder flexion, Acromial distance, and Winging scapula) showed satisfactory inter-rater reliability. Simple visual observational methods and quantitative distance measurements have better reliability between clinicians than more complex measurements and may be better suited for use in clinical practice.

Isolated Infraspinatus Atrophy Secondary to Suprascapular Nerve Neuropathy Results in Altered Shoulder Muscles Activity

Context: Isolated infraspinatus atrophy (IIA) is a common condition among overhead activity athletes, which affects the hitting shoulder and is caused by suprascapular nerve injury. The loss of infraspinatus function could lead to altered activity of the glenohumeral and scapulothoracic (ST) muscles and compromise the optimal shoulder function. Objective: To assess the surface electromyographic (sEMG) activity patterns, relationships, and response latencies of relevant shoulder girdle muscles in professional volleyball players with IIA and in healthy control players. Design: Cross-sectional study. Setting: Research laboratory. Patients or Other Participants: Twenty-four male professional volleyball players (12 players with diagnosed IIA and 12 healthy players) recruited from local volleyball teams. Intervention(s): sEMG activity of anterior, middle, and posterior deltoid; upper, middle, and lower trapezius; and serratus anterior (SA) was recorded and evaluated during a movement of shoulder abduction in the scapular plane, monitored with an optoelectronic motion capture system. Main Outcome Measure(s): sEMG activity, relationships, and response latencies of the selected muscles were analyzed with analysis of variance models to highlight statistical differences within and between groups. Results: Athletes with IIA demonstrated significant higher deltoid and trapezius muscles activity and lower SA activity compared with the contralateral shoulder and healthy athletes. The shoulder with IIA also showed a higher activity ratio between the upper trapezius and other ST muscles in addition to anticipated activation of the upper trapezius and delayed activation of the SA, with regard to the onset of shoulder movement. Conclusions: This study highlighted altered shoulder muscle activity levels, ST muscles imbalances, and abnormal ST recruitment patterns in the hitting shoulder of professional volleyball players with IIA, secondary to suprascapular nerve neuropathy. Such shoulder girdle muscles’ impairments may compromise the optimal scapulohumeral rhythm and function, increasing the risk of acute and overuse shoulder injuries.