Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement

BACKGROUND AND PURPOSE: Treatment of patients with impingement symptoms commonly includes exercises intended to restore "normal" movement patterns. Evidence that indicates the existence of abnormal patterns in people with shoulder pain is limited. The purpose of this investigation was to analyze glenohumeral and scapulothoracic kinematics and associated scapulothoracic muscle activity in a group of subjects with symptoms of shoulder impingement relative to a group of subjects without symptoms of shoulder impingement matched for occupational exposure to overhead work. SUBJECTS: Fifty-two subjects were recruited from a population of construction workers with routine exposure to overhead work. METHODS: Surface electromyographic data were collected from the upper and lower parts of the trapezius muscle and from the serratus anterior muscle. Electromagnetic sensors simultaneously tracked 3-dimensional motion of the trunk, scapula, and humerus during humeral elevation in the scapular plane in 3 handheld load conditions: (1) no load, (2) 2. 3-kg load, and (3) 4.6-kg load. An analysis of variance model was used to test for group and load effects for 3 phases of motion (31(-60(, 61(-90(, and 91(-120(). RESULTS: Relative to the group without impingement, the group with impingement showed decreased scapular upward rotation at the end of the first of the 3 phases of interest, increased anterior tipping at the end of the third phase of interest, and increased scapular medial rotation under the load conditions. At the same time, upper and lower trapezius muscle electromyographic activity increased in the group with impingement as compared with the group without impingement in the final 2 phases, although the upper trapezius muscle changes were apparent only during the 4.6-kg load condition. The serratus anterior muscle demonstrated decreased activity in the group with impingement across all loads and phases. CONCLUSION AND DISCUSSION: Scapular tipping (rotation about a medial to lateral axis) and serratus anterior muscle function are important to consider in the rehabilitation of patients with symptoms of shoulder impingement related to occupational exposure to overhead work. [Ludewig PM, Cook TM. Alterations in shoulder kinematics and associated muscle activity in people with symptoms of shoulder impingement.     

Shoulder function and 3-dimensional kinematics in people with shoulder impingement syndrome before and after a 6-week exercise program

BACKGROUND AND PURPOSE: Shoulder impingement syndrome is a common condition and is often managed with an exercise program. The purpose of this study was to examine an exercise program in patients with shoulder impingement syndrome. Specifically, the purpose was to identify changes that might occur in 3-dimensional scapular kinematics, physical impairments, and functional limitations. SUBJECTS: Fifty-nine patients with impingement syndrome were recruited, and 39 patients successfully completed the 6-week rehabilitation program and follow-up testing. Impingement was defined as having at least 3 of 6 predefined clinical signs or symptoms. METHODS: Subjects were assessed before and after a 6-week rehabilitation program and again at 6 months. Pain, satisfaction, and function were measured using the University of Pennsylvania Shoulder Scale. Range of motion, isometric muscle force, and 3-dimensional scapular kinematic data also were collected. Subjects were given a progressive exercise program that included resistive strengthening, stretching, and postural exercises that were done daily at home. Subjects also were given shoulder education related to anatomy, the basic mechanics of impingement, and strategies for reducing load on the shoulder. Each subject attended one physical therapy session per week for a 6-week period, primarily for monitoring and upgrading the exercise program. Pretest and posttest scores were compared using paired t tests and repeated-measures analysis of variance. RESULTS: Passive range of motion increased for both external and internal rotation but not for elevation. Abduction external and internal rotation force all increased. There were no differences in scapular kinematics. Improvements were found for pain, satisfaction, and shoulder function and for Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) scores related to physical function. At 6-month follow-up, improvements made in pain, satisfaction, and function were maintained. DISCUSSION AND CONCLUSION: The use of this exercise protocol in the management of shoulder impingement syndrome may have a positive impact on patients' impairments and functional limitations. Our findings suggest a relatively simple exercise program combined with patient education may be effective and, therefore, merits study in a larger trial using a control group. Changes in scapular kinematics did not appear to be a primary mechanism underlying improvement in symptoms and function.     

Comparison of scapular kinematics between elevation and lowering of the arm in the scapular plane

Objective. To compare scapular orientation during both the concentric (elevation) and eccentric (lowering) phases of scapular plane abduction in subjects with and without shoulder impingement.

Design. Mixed model analysis of variance with one between-subjects factor (group) and within-subjects factors of phase, humeral angle, and trial.

Background. Abnormal scapular kinematics have been identified in shoulder impingement patients during the concentric phase of arm elevation, and under static conditions. Because abnormal scapular motion is observed clinically during the eccentric phase of arm elevation, analysis of this phase of motion is warranted.

Methods. Twenty-six symptomatic and 26 healthy subjects performed five repetitions of humeral scapular plane abduction. An electromagnetic tracking device described three-dimensional scapular kinematics during arm elevation and lowering. Angular values for scapular anterior/posterior tipping in the sagittal plane, upward/downward rotation in the scapular plane, and internal/external rotation in the transverse plane were calculated. Scapular orientation relative to the thorax at humeral angles of 40°, 60°, 80°, 100°, and 120° was statistically tested for effects of phase and trial, or for interactions of phase with group or humeral angle.

Results. Internal rotation was significantly increased in the eccentric phase for both groups at the 100° angle (P<0.05) and for the symptomatic group only at the 120° angle (P<0.05). Scapular anterior tipping was significantly decreased during the eccentric phase in both groups at the 80° (P<0.001), 100° (P<0.0001), and 120° (P<0.0001) angles.

Conclusions. Small but statistically significant differences in scapular tipping and internal rotation during the eccentric phase of arm elevation were identified at higher humeral angles in both subject groups, while no significant phase differences for scapular upward rotation or for scapular variables at lower humeral angles were found. Averaged across phases, the symptomatic group demonstrated significant reductions in upward rotation at lower humeral elevation angles, and significant increases in anterior tipping at higher elevation angles as compared to the healthy group.

Relevance Normal and abnormal scapular kinematics during varying types of motion need to be understood in order to optimally design rehabilitation programs for individuals with impingement syndrome.     

Effects of muscle fatigue on 3-dimensional scapular kinematics

OBJECTIVE: To determine the effects of fatigue during an external rotation task on 3-dimensional scapular kinematics. DESIGN: A single-group, pretest-posttest measurement design. SETTING: Research laboratory. PARTICIPANTS: Thirty healthy subjects. INTERVENTIONS: Not applicable.Main Outcome Measures: Three-dimensional scapular kinematics were recorded with a Polhemus magnetic tracking device during arm elevation in the scapular plane. RESULTS: There was a significant fatigue effect for all scapular rotations in the early to middle phases of humeral elevation. Significantly less posterior tilting (up to 90 degrees of elevation), external rotation (up to 120 degrees of elevation), and upward rotation (up to 60 degrees of elevation) were observed. Additionally, there were fair to good correlations (r range,.39-.60) between the changes in scapular posterior tilting and the amount of muscle fatigue. CONCLUSIONS: Fatigue in shoulder external rotation altered the scapular resting position and the movement of posterior tilting in the early range during arm elevation in the scapular plane. Observed changes in scapular kinematics may affect the amount of area in the subacromial space and facilitate impingement. Data regarding changes produced by fatigue of the external rotators may also help with the development of a model of diminished rotator cuff function.     

Thoracic position effect on shoulder range of motion, strength, and three-dimensional scapular kinematics.

OBJECTIVES: To determine the effect of thoracic posture on scapular movement patterns, active range of motion (ROM) in scapular plane abduction, and isometric scapular plane abduction muscle force. STUDY DESIGN AND METHOD: Repeated measures design. There were 34 healthy subjects (mean age, 30.2 yrs). Each subject was positioned and stabilized while sitting in both erect and slouched trunk postures. In each sitting posture a three-dimensional electromechanical digitizer was used to measure thoracic flexion and scapular position and orientation in three planes. Measurements were taken with the arm (1) at the side, (2) abducted to horizontal in the scapular plane, and (3) at maximum scapular plane abduction. In each posture, isometric abduction muscle force was measured with the arm at the side and abducted to horizontal in the scapular plane. RESULTS: In the slouched posture, the scapula was significantly more elevated in the interval between 0 to 90 degrees abduction. In the interval between 90 degrees and maximum abduction, the slouched posture resulted in significantly less scapular posterior tilting. There was significantly less active shoulder abduction ROM in the slouched posture (mean difference = 23.6 degrees +/- 10.7 degrees). Muscle force was not different between slouched and erect postures with the arm at the side, but with the arm horizontal muscle force was decreased 16.2% in the slouched position. CONCLUSION: Thoracic spine position significantly affects scapular kinematics during scapular plane abduction, and the slouched posture is associated with decreased muscle force.     

Kinematic evaluation of patients with total and reverse shoulder arthroplasty during rehabilitation exercises with different loads

Background

Following shoulder arthroplasty, any well-planned rehabilitation program should include muscle strengthening. However, it is not always clear how different external loads influence shoulder kinematics in patients with shoulder prostheses. The objective of this study was to describe shoulder kinematics and determine the contribution of the scapulothoracic joint to total shoulder motion of patients with total and reverse shoulder arthroplasties and of healthy individuals during rehabilitation exercises (anteflexion and elevation in the scapular plane) using different loading conditions (without external load, 1 kg and elastic resistance).

Methods

Shoulder motions were measured using an electromagnetic tracking device. A force transducer was used to record force signals during loaded conditions using elastic resistance. Statistical comparisons were made using a three-way repeated-measures analysis of variance with a Bonferroni post hoc testing.

Findings

The scapula contributed more to movement of the arm in subjects with prostheses compared to healthy subjects. The same applies for loaded conditions (1 kg and elastic resistance) relative to unloaded tasks. For scapular internal rotation, upward rotation and posterior tilt no significant differences among groups were found during both exercises. Glenohumeral elevation angles during anteflexion were significantly higher in the total shoulder arthroplasty group compared to the reverse shoulder arthroplasty group.

Interpretation

Differences in contribution of the scapula to total shoulder motion between patients with different types of arthroplasties were not significant. However, compared to healthy subjects, they were. Furthermore, scapular kinematics of patients with shoulder arthroplasty was influenced by implementation of external loads, but not by the type of load.     

Effect of sitting posture on 3-dimensional scapular kinematics measured by skin-mounted electromagnetic tracking sensors

OBJECTIVE: To determine the effect of trunk sitting posture on scapular kinematics during humeral elevation by using skin-mounted electromagnetic tracking sensors. DESIGN: Repeated-measures design contrasting scapular kinematics in 2 different sitting postures. SETTING: A biomechanics laboratory in Hong Kong with a real-time, 3-dimensional electromagnetic tracking device for measuring movements of the scapula. PARTICIPANTS: A sample of 16 healthy adults (12 women, 4 men; age, 21.6+/-3.92y) with full, pain-free shoulder range of motion and no history of shoulder pathology. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Movements of the scapula were measured while each subject performed humeral elevation in an upright seated position and a slouched seated position. RESULTS: In both postures, posterior tip, lateral and upward rotation of the scapula, and lateral rotation of the humerus were observed during humeral elevation. When the slouched posture was adopted, there were significant decreases in the posterior tip and lateral rotation of the scapula, but there was no significant change in the magnitude of the upward rotation of the scapula. CONCLUSION: Increased thoracic kyphosis significantly alters the kinematics of the scapula during humeral elevation.     

Scapular kinematics and impairment features for classifying patients with subacromial impingement syndrome

Subacromial impingement syndrome (SAIS), which is associated with pain and a loss of function, has a high occurrence in the physically active population. Not all patients respond positively to treatment. Classifying patients can improve decision-making. The scapular kinematic and clinical impairments can aid in classifying the patients who are more likely to respond to physical therapy treatment. Thirty-three subjects (males, 20–33 years) presenting SAIS were studied to determine altered scapular kinematics and clinical impairments. Three measurements were collected: (1) three-dimensional scapular kinematics during performing functional tasks; (2) impairment outcomes of range of motion and muscle force; and (3) self-reported measurements of pain, satisfaction, and function. All patients received 6-week (2 times per week) physical therapy treatment. Improvement with treatment was determined using the Global Rating of Change Scale. Scapular kinematics and clinical impairments were first identified by t-test in predicting improvement and then combined into a multivariate prediction method. A prediction method with three variables (Flexilevel Scale of Shoulder Function score < 41, muscle power of serratus anterior < 27.4% body weight, degree of scapular internal rotation at 30° shoulder elevation during descending arm phase in unloaded condition < 0.7°) were identified. It appears that scapular kinematics and impairment features can be used to classify subjects with SAIS in addition to self-report. Prospective validation of the proposed prediction method requires further investigation.     

Influence of age on scapulo-thoracic orientation

Background. Scapular activity during shoulder motion is critical for normal shoulder function. With aging, muscle function deteriorates in almost all people, which may lead to shoulder impingement syndrome.

Methods. Forty-four normal subjects, 23 men and 21 women aged from 16 to 73 years with a mean age 48, were enrolled in the study. Static antero-posterior radiography at both 0° and 90° of abduction were undertaken and correlation between age and scapular orientations were evaluated by Pearson’s correlation coefficient test. The purpose of this study is to investigate the relationship between aging and scapulo-thoracic orientation.

Findings. Significant correlation coefficients were observed between aging and scapular orientations. With the shoulder at 0° abduction, posterior tilt showed significant negative correlation with aging. At 90° abduction, both posterior tilt and upward rotation angle correlated negatively with aging. The correlation was apparent at 90° abduction.

Interpretation. The results indicate that shoulder aging closely relates to changes of scapular orientation, which consist of decreases of the posterior tilt at 0° and 90° abduction and the upward rotation angle at 90°. The current study indicated that one of the effects of aging on the shoulder is a decrease of posterior tilt and upward rotation angle as seen in an abducted position; and that these alterations are similar to the scapular kinematics of shoulder impingement syndrome. By taking this concept into consideration, the effects of aging on shoulder kinematics can be appropriately evaluated.     

Stretching and strengthening exercises: their effect on three-dimensional scapular kinematics.

OBJECTIVE: To quantitatively evaluate the effects of commonly used shoulder exercises on shoulder kinematics and resting posture. STUDY DESIGN: A repeated-measures design was used with measurements performed before and after a 6-week exercise program. METHOD: Twenty asymptomatic subjects with forward shoulder posture were recruited. Stretching exercises for the pectoral muscles and resisted strengthening exercises for the scapular retractors and elevators and the glenohumeral abductors and external rotators were performed three times per week for 6 weeks. A three-dimensional electromechanical digitizer was used to measure thoracic inclination and scapular orientation and position. These measurements were taken with the arm (1) at the side, (2) abducted to 90 degrees, and (3) at maximal abduction. The isometric force of glenohumeral external and internal rotation and horizontal abduction and adduction were measured with a hand-held dynamometer. All subjects were tested before and after the 6-week exercise program. Hotelling's T2 and paired t tests were used for data analysis. RESULTS: The strength of horizontal abduction and internal and external rotation increased after exercise (p < .01). The anterior inclination of the thoracic spine decreased, and the glenohumeral contribution to arm elevation increased (p < .01). Resting scapular posture did not change. As the arm was abducted to 90 degrees, the scapula showed less upward rotation and less superior translation after the exercise program (p < .01). CONCLUSION: The exercise program improved muscle strength, produced a more erect upper trunk posture, increased scapular stability, and altered scapulohumeral rhythm.     

Shoulder dysfunction assessment: self-report and impaired scapular movements

BACKGROUND AND PURPOSE: Shoulder dysfunction is common in various patient populations. This investigation was performed to assess shoulder dysfunction with self-report and performance-based functional measures. SUBJECTS: Fifty men (25 with shoulder dysfunction and 25 without shoulder dysfunction) participated in this study. METHODS: Self-report functional disabilities were assessed with the Flexilevel Scale of Shoulder Function (FLEX-SF), and electromagnetic tracking sensors were used to monitor 3-dimensional scapular movements during 4 functional tasks. RESULTS: Relative to the control group, the group with shoulder dysfunction showed significant alterations in scapular movements (averages of 6.9 degrees less posterior tipping, 5.7 degrees less upward rotation, and 2.3 cm more elevation). Scapular kinematics correlated significantly (r) with the Self-report FLEX-SF measure during functional tasks (posterior tipping = .454 to .712, upward rotation = .296 and .317, and elevation = -.310). DISCUSSION AND CONCLUSION: Functional disabilities were identified with self-report and performance-based functional measures. The inadequate scapular posterior tipping and scapular upward rotation as well as the excessive elevation may have implications in planning intervention strategies for people with shoulder dysfunction.     

Effect of motor control and strengthening exercises on shoulder function in persons with impingement syndrome: a single-subject study design

The aim of the study was to evaluate the effect of an intervention including shoulder control and strengthening exercises on function in persons with shoulder impingement. Eight subjects with shoulder impingement were evaluated weekly during the nine weeks of this single-subject design study. The study was divided into three phases (A(1)-B-A(2)) and involved repeated measures of shoulder pain and function (Shoulder Pain And Disability Index (SPADI) questionnaire), painful arc of motion, peak torque and 3-dimensional scapular attitudes. During the intervention phase, each subject participated in 12 exercise sessions supervised by a physiotherapist. Measures taken during the intervention and post-intervention phases were compared to pre-intervention values. All subjects showed significant improvement in the SPADI at the end of the study. A disappearance of a painful arc of motion in flexion and abduction (n=6), an increase in isometric peak torque in lateral rotation (n=3) and abduction (n=2), and changes in the scapular kinematics, mainly in the sagittal plane, were also observed. The present results provide preliminary evidence to support the use of shoulder control exercises to reduce pain and improve function of persons with shoulder impingement.     

Comparison of scapular kinematics and muscle strength between those with a positive and a negative Scapular Assistance Test

BackgroundThe Scapular Assistance Test was suggested to directly assess the influence of scapular motion on pain and indirectly measure the function of the scapular rotators. However, it is still not clear if individuals with a positive Scapular Assistance Test actually present changes in scapular motion and muscle strength. This study compared scapular kinematics and muscle strength between those with a positive Scapular Assistance Test and those with a negative Scapular Assistance Test.MethodsFifty individuals with shoulder pain were randomly allocated to: positive (n = 25) or negative Scapular Assistance Test (n = 25) group. Scapular kinematics was measured during elevation and lowering of the arm. Strength of the serratus anterior and lower trapezius was also measured. Two-way analysis of variance was used to compare kinematics between groups. Unpaired Student's t-test and Mann-Whitney test were used to compare strength of serratus anterior and lower trapezius, respectively.FindingsThere were no differences (P > 0.05) in scapular internal rotation and upward rotation between both groups. For scapular tilt, there was group main effect (P < 0.05) during elevation and lowering of the arm, whereas the positive Scapular Assistance Test group presented greater scapular anterior tilt. There was no difference (P > 0.05) in strength between groups.InterpretationIndividuals with a positive Scapular Assistance Test are more likely to present decreased scapular posterior tilt in those with shoulder pain. Strength of the scapular muscles seems to be same in those with a positive and a negative Scapular Assistance Test.     

Kinematics of the contralateral and ipsilateral shoulder: a possible relationship with post-stroke shoulder pain.

OBJECTIVE: Post-stroke shoulder pain is a common phenomenon in hemiplegia and impedes rehabilitation. The aim of this study was to identify a possible relationship between post-stroke shoulder pain, scapula resting position and shoulder motion. METHODS: Shoulder kinematics of 27 patients after stroke (17 men) were compared with 10 healthy age-matched control subjects. Using an electromagnetic tracking device, the kinematics of both the contralateral and ipsilateral (i.e. paretic and non-paretic) arm during active and passive abduction and forward flexion were measured and expressed in Euler angles. RESULTS: Scapular lateral rotation relative to the thorax was increased in patients with post-stroke shoulder pain compared with both patients without post-stroke shoulder pain and control subjects at rest as well as during arm abduction and forward flexion. Additionally, glenohumeral elevation was decreased in patients with post-stroke shoulder pain during passive abduction. No differences were found regarding scapula position (displacement relative to the thorax). CONCLUSION: In patients with post-stroke shoulder pain a particular kinematical shoulder pattern was established, characterized by enhanced scapular lateral rotation and diminished glenohumeral mobility.     

Scapular asymmetry in participants with and without shoulder impingement syndrome; a three-dimensional motion analysis

BackgroundThis study analyzed the dynamic three-dimensional scapular kinematics and scapular asymmetry in participants with and without shoulder impingement syndrome.MethodsTwenty-nine participants with shoulder impingement syndrome, have been suffering from unilateral shoulder pain at the dominant arm lasting more than six weeks and thirty-seven healthy controls participated in the study. Scapular kinematics was measured with an electromagnetic tracking device during shoulder elevation in the sagittal plane. Data for bilateral scapular orientation were analyzed at 30°, 60°, 90°, and 120° of humerothoracic elevation and lowering. The symmetry angle was calculated to quantify scapular asymmetry throughout shoulder elevation.FindingsStatistical comparisons indicated that the scapula was more downwardly rotated (p < 0.001) and anteriorly tilted (p = 0.005) in participants with shoulder impingement syndrome compared to healthy controls. Side-to-side comparisons revealed that the scapula was more anteriorly tilted on the involved side of participants with shoulder impingement syndrome (p = 0.01), and the scapula was rotated more internally (p = 0.02) and downwardly (p = 0.01) on the dominant side of healthy controls. Although there were side-to-side differences in both groups, symmetry angle calculation revealed that the scapular movement was more asymmetrical for scapular internal and upward rotation in individuals with shoulder impingement syndrome when compared with healthy controls (p < 0.05).InterpretationThe findings of the study increase our knowledge and understanding of scapular alterations in symptomatic and asymptomatic populations, which creates biomechanical considerations for shoulder assessment and rehabilitation.     

Scapular kinematics and muscle performance in a single case of Parsonage–Turner

This study characterized the impairments of range of motion, three-dimensional scapulo-thoracic kinematics, isokinetic muscle performance and disability in a patient with Parsonage–Turner Syndrome. The patient had a history of 2.5-years of shoulder pain, and electroneurodiagnostic testing indicative of suprascapular neuropathy. The patient-rated Disabilities of the Arm, Shoulder and Hand (DASH) score was 33.3% (0 = no symptoms/disability), and reduced shoulder internal rotation, external rotation, and flexion as compared bilaterally. There were deficits in isokinetic muscle performance at slow and fast speeds during abduction, lateral and medial rotations as compared to the uninvolved side. Alterations in scapular kinematics were decreased posterior tilt, increased internal rotation, and increased upward rotation during arm elevation and lowering. This information can be used to assist clinicians in developing treatment programs to address the alterations caused by this neuralgic amyotrophy.     

Scapular kinematics in professional wheelchair tennis players

BackgroundParticipating in wheelchair tennis increases the demands placed on the shoulder and could increase the risk of developing shoulder pain and injury that might be associated with differences in scapular kinematics. The aim of the study was to examine the presence of shoulder pain and scapular kinematics in professional wheelchair tennis players.MethodScapular kinematics were obtained in 11 professional wheelchair tennis players, 16 people with shoulder impingement and 16 people without shoulder impingement during humeral elevation and lowering. Clinical examination of the wheelchair tennis players was undertaken using the Wheelchair Users Shoulder Disability Index (WUSPI) and clinical signs of shoulder impingement.FindingsThe WUSPI questionnaire (mean = 28 SD 13.8) demonstrated wheelchair tennis participants experienced little shoulder pain and clinical examination revealed negative impingement tests. Wheelchair tennis players had greater scapular posterior tilt during humeral elevation (3.9° SE 1.71; P = 0.048) and lowering (4.3° SE 1.8; P = 0.04) on the dominant compared to non-dominant side. The dominant scapulae of wheelchair tennis players were significantly (P = 0.014) more upwardly rotated (21° SD 6.7) than the scapulae of people with shoulder impingement (14.1° SD 7.0) during scapular plane humeral elevation.InterpretationThis first study of scapular kinematics in professional wheelchair tennis athletes demonstrated bilateral asymmetries and differences to able-bodied participants with shoulder impingement. Understanding the role of sport participation on shoulder function in wheelchair users would assist in the development of preventative and treatment exercise programmes for wheelchair users at risk of shoulder injury and pain.     

Effects of Kinesio Taping on scapular kinematics and electromyographic activity in subjects with shoulder impingement syndrome

ObjectiveTo investigate the effects of Kinesio Taping® (KT) on scapular kinematics and electromyographic (EMG) activity in subjects with shoulder impingement syndrome (SIS).MethodsTwenty subjects with a diagnosis of SIS performed abduction, scaption, and flexion movements in two load conditions: (1) without load and (2) holding a dumbbell. The same movements were evaluated again with the use of KT over the deltoid muscle with a 20% tension. Scapular kinematics data of the shoulder complex were captured with BTS SMART-DX at a frequency rate of 100 Hz. EMG activity was evaluated for the upper trapezius, lower trapezius, middle deltoid, and serratus anterior muscles with BTS FREE EMG 1000 at a frequency rate of 1000 Hz. The root mean square values normalized by the maximal voluntary contraction and the peak values of upward rotation, internal rotation, and posterior tilt were compared with the KT conditions through repeated-measures ANOVA (α = 0.05) using SPSS software.ResultsNo significant differences between KT conditions were found for scapular kinematics (p > 0.05). For EMG activity, a reduction in the lower trapezius was found (p < 0.05) during abduction with load (p < 0.05) and elevation without load (p < 0.05).ConclusionsAccording to the results of this study, it was not possible to verify changes in scapular kinematics in subjects with SIS. However, a reduction in EMG activity was observed for the lower trapezius muscle. Therefore, caution should be taken in prescribing KT for SIS subjects, who already have a reduction in EMG activity in this muscle, as KT may have an adverse effect.     

Gender effect on the scapular 3D posture and kinematic in healthy subjects

Populations considered for shoulder analysis are often composed of various ratios of men and women. It is consequently hypothesized that gender has no significant effect on the joint kinematic. However, the literature reports, for the shoulder, differences in the range of motion between genders. The specific influence of gender on the scapulo‐thoracic kinematics has not been studied yet. The dominant shoulder of two populations of men and women composed of 11 subjects each were evaluated in three dimensions for three distinct motions: flexion in the sagittal plane, abduction in the frontal plane and gleno‐humeral internal/external rotation with the arm abducted at 90°. Posture, kinematics and range of motion were studied separately. For flexion and abduction and with regard to the scapular kinematic, external rotation was significantly larger for women than men. The differences were of at least 5° at 120° of humeral elevation. Upward rotations were identical. Women also showed larger average active humero‐thoracic range of motion. The mean differences were of 13°, 7°, 12° and 5° for abduction, flexion, internal rotation and external rotation, respectively. No difference was observed between the scapular resting positions of both populations. The observed differences concerning both the scapular and humeral patterns would indicate that the shoulder behaviour of men and women should not be expected to be similar.