• Physical Therapy Korea
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• v.11 no.1
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• pp.45-52
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• 2004

Altered scapular kinematics in the scapular joint is commonly believed to be a factor contributing to trunk posture. The purpose of this study was to analyze the muscle activity with several changes of the shoulder angle. Tests were performed on 10 male subjects by repeated measures. Each subject was measured while sitting in both erect and slouched trunk positions. In each sitting posture, a three-dimensional motion analysis measurement was used to measure thoracic angle and shoulder abduction angle. Measurements were taken with the shoulder abdcution angle at $0^{\circ}$, $30^{\circ}$, $60^{\circ}$, $90^{\circ}$, $120^{\circ}$, and $150^{\circ}$. By using surface Electromyography (EMG) electrodes, we recorded the activity of the upper trapezius, middle trapezius, lower trapezius, middle deltoid, and serratus anterior muscle while the subject held a 4 kg weight at each angle. The mean of root mean square (RMS) of EMG activity was calculated. The middle trapezius, lower trapezius, and middle deltoid muscle activity showed significantly higher results but serratus anterior muscle activity showed significantly lower results (p<.05). With the shoulder angle increased, the muscle activity was also significantly increased (p<.05). In conclusion, the thoracic spine posture significantly affects the scapular muscle during scapular plane abduction, and the slouched posture is associated with increased trapezius muscle activity and with decreased serratus anterior muscle activity.

• The Journal of Korean Physical Therapy
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• v.12 no.2
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• pp.95-105
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• 2000

Glenohumeral internal and external rotation with shoulder abducted in the frontal plane often causes impingement of the supraspinatus tendon. whereas similar activity in scapular plane does not cause impingement. The Purpose of this study was to determine if assessment among the three positions as 30 degrees, 60 degrees, 90 degrees abduction in the sitting position of the scapular plane could be affected the comparison between intemal and external peak torque, total work, average power. In this study, Isokinetic shoulder rotational strength was evaluated in twenty healthy male university students, using the Cybex NORMTM System (CYBEX Division of LUMEX, Inc., Ronkonkoma, New York). Test data was gathered in the plane of the scapular, 30 degrees of horizontal flexion anterior to coronal plane, and the subjects performed the test with the arm 30, 60, and 90degrees abducted in the sitting position. also, test speed was set at deg/sec. Statistical analysis was performed using SPSS 7.5 for Windows software and mean and standard deviations were calculated. ANOVA was used to analyze the difference of the values in the three test positions. A paired t-test was used of examining the difference in the means peak torque between external and internal rotation. Not any significant difference was found among three abduction positions in scapular plane, even though there was a consistent pattern of greater strength in the abducted position of 60 degrees. Internal relation strength peak torque and total work were greater than those of external rotation in every test positions.

• Physical Therapy Korea
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• v.23 no.4
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• pp.38-46
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• 2016

Background: Shoulder stabilization commonly involves two components: the glenohumeral stabilization exercise (GSE) and scapular stabilization exercise (SSE). Despite the fact that the shoulder stabilization has advantageous merit, to our knowledge, only a few studies have compared the superior of the GSE and the SSE. Objects: The purpose of this study was to assess the effects of GSE in patients with nonspecific shoulder pain. Methods: Thirty subjects with nonspecific shoulder pain were randomly divided into an experimental group and control group, each with 15 patients. The experimental group used an GSE, whereas the control group did SSE. All subjects were measured in shoulder stability, scapular symmetric alignment, pain, muscle power, and range of motion before and after the intervention. Results: GSE resulted in significantly better shoulder stability (p=.046, from $8.67{\pm}7.54$ score to $13.93{\pm}9.40$) in the experimental group compared with SSE in the control group. However, no significant effects were observed for scapular symmetric alignment including the angles of inferior scapular distance (p=.829) and inferior scapular height difference (p=.735), pain (p=.113), muscle power including shoulder flexion (p=.723) and abduction (p=.897) and range of motion including shoulder flexion (p=.853) and abduction (p=.472). Conclusion: These findings suggest that GSE may be more effective in increasing the shoulder stability than the SSE in patients with nonspecific shoulder pain, probably through a centralization effect on the shoulder mechanism.

• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.155-161
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• 2021

Objective: There is a lack of studies using the 3D-2D image registration techniques on the mechanism of a shoulder injury for ice hockey players. This study aimed to analyze in vivo 3D glenohumeral joint arthrokinematics in collegiate ice hockey athletes and compare shoulder scaption with or without a hockey stick using the 3D-2D image registration technique. Method: We recruited 12 male elite ice hockey players (age, 19.88 ± 0.65 years). For arthrokinematic analysis of the common shoulder abduction movements of the injury pathogenesis of ice hockey players, participants abducted their dominant arm along the scapular plane and then grabbed a stick using the same motion under C-arm fluoroscopy with 16 frames per second. Computed tomography (CT) scans of the shoulder complex were obtained with a 0.6-mm slice pitch. Data from the humerus translation distances, scapula upward rotation, anterior-posterior tilt, internal to external rotation angles, and scapulohumeral rhythm (SHR) ratio on glenohumeral (GH) joint kinematics were outputted using a MATLAB customized code. Results: The humeral translation in the stick hand compared to the bare hand moved more anterior and more superior until the abduction angle reached 40°. When the GH joint in the stick hand was at the maximal abduction of the scapula, the scapula was externally rotated 2~5° relative to 0°. The SHR ratio relative to the abduction along the scapular plane at 40° indicated a statistically significant difference between the two groups (p < 0.05). Conclusion: With arm loading with the stick, the humeral and scapular kinematics showed a significant correlation in the initial section of the SHR. Although these correlations might be difficult in clinical settings, ice hockey athletes can lead to the movement difference of the scapulohumeral joints with inherent instability.

• Korean Journal of Applied Biomechanics
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• v.21 no.2
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• pp.243-252
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• 2011

The purpose of this study was to determine the effect of trunk posture on muscle activity and motion of scapular and scapulohumeral rhythm. Thirty-one healthy subjects performed right-arm abduction and adduction along the frontal plane while standing in both upright and flexed posture of trunk. Scapular upward rotation, anterior tilting and internal rotation ware recorded using a motion analysis system and muscle activity of upper trapezius, lower trapezius and serratus anterior ware recorded using surface electromyography during abduction and adduction in both trunk postures. then, scapulohumeral rhythm was calculated. Scapulohumeral rhythm and scapular posterior tilting in flexed posture was significantly decreased than in upright posture. Also, muscle activity of lower trapezius in flexed posture was significantly increased and serratus anterior was significantly decreased than in general posture. The result of this study revealed that flexed posture of trunk altered the muscle activity and kinematic of scapular. Measurement of trunk posture should be included the evaluation of dysfunction and disorder of shoulder girdle since rehabilitation of trunk posture is important to restore of upper limbs function.

• Physical Therapy Korea
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• v.26 no.3
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• pp.1-10
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• 2019

Background: Winged scapular (WS) causes muscle imbalance with abnormal patterns when moving the arm. In particular, the over-activation of the upper trapezius (UT) and decrease in activity of the lower trapezius (LT) and serratus anterior (SA) produce abnormal scapulohumeral rhythm. Therefore, the SA requires special attention in all shoulder rehabilitation programs. In fact, many previous studies have been devoted to the SA muscle strength training needed for WS correction. Objects: The purpose of this study was to investigate the effect of shoulder girdle muscle and ratio according to the angle of shoulder abduction and external weight in supine position. Methods: Twenty three WS patients participated in this experiment. They performed scapular protraction exercise in supine position with the weights of 0 kg, 1 kg, 1.5 kg, and 2 kg at shoulder abduction angles of $0^{\circ}$, $30^{\circ}$, $60^{\circ}$, and $90^{\circ}$. The angle and weight applications were randomized. Surface electromyography (EMG) was used to collect the EMG data of the SA, pectoralis major (PM), and UT during the exercise. The ratio of PM/SA and UT/SA was confirmed. Two-way repeated analyses of variance were used to determine the statistical significance of SA, PM, and UT and the ratios of PM/SA and UT/SA. Results: There was a significant difference in SA according to angle (p<.05). Significant differences were also identified depending on the angle and weight (p<.05). The angle of abduction at $0^{\circ}$, $30^{\circ}$ and weight of 2 kg showed the highest SA activity. However, there was no significant difference between PM and UT (p>.05). There was a significant difference between PM/SA and UT/SA in ratio of muscle activity according to angle (p<.05). Significant differences were found at PM/SA angles of $30^{\circ}$, $60^{\circ}$ and $90^{\circ}$ (p<.05). For UT/SA, significant difference was only observed at $90^{\circ}$ (p<.05). Conclusion: Based on the results of this study, in order to strengthen the SA, it was found to be most effective to use 1 and 1.5 kg weights with abduction angles of $0^{\circ}$ and $30^{\circ}$ at shoulder protraction in supine position.

• The Journal of Korean Physical Therapy
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• v.35 no.3
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• pp.71-76
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• 2023

Purpose: This study investigated effect of the scapular retraction exercise on the subacromial and costoclavicular space using different thera-band intensities. Methods: Thirty-six healthy adults participated in this study, and the subjects were randomly divided into three groups (low, moderate, and high-intensity groups). The exercise was conducted twice a week for three weeks. The subacromial and costoclavicular space were measured before and after the intervention via ultrasonography. Data analysis was performed using the two-way Analysis of Variance with repeated measures and the paired t-test. Results: The effect of the scapular retraction exercise on the subacromial and costoclavicular space using a thera-band after a 60° shoulder abduction has significant difference in all groups (p<0.05). However, there was no significant difference between the groups, and the values in the groups before the exercise did not differ significantly from those after the exercise (p>0.05). Conclusion: Our results indicate that the scapular retraction exercise after a 60° shoulder abduction can be used to widen the subacromial and costoclavicular spaces.

• Physical Therapy Korea
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• v.30 no.2
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• pp.160-168
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• 2023

Background: Individuals with scapular winging have a weak serratus anterior (SA) muscle, and to compensate, the pectoralis major (PM) and upper trapezius (UT) muscles excessively activate, which can cause upper extremity dysfunction. This study aimed to compare the effects of isometric horizontal abduction (IHA) on SA, PM, and UT muscle activity, as well as the SA/PM and SA/UT muscle activity ratios during knee push-up plus (KPP) at 90° and 120° of shoulder flexion. Objects: This study aimed to compare the effects of IHA on SA, PM, and UT muscle activity, as well as the SA/PM and SA/UT muscle activity ratios during KPP at 90° and 120° of shoulder flexion. Methods: This study, conducted at a university research laboratory, included 20 individuals with scapular winging. Participants performed KPP with and without IHA at 90° (KPP90) and 120° (KPP120) of shoulder flexion. SA, PM, and UT muscle activity were measured using surface electromyography. Results: PM activity in KPP90 with IHA was significantly lower than KPP90 and in KPP120 was significantly lower than KPP90. UT activity was significantly greater with IHA than without IHA and at 120° than 90° of shoulder flexion. SA/PM muscle activity ratio was significantly higher in KPP90 with IHA than without IHA and in KPP120 than in KPP90. SA/UT muscle activity ratio was significantly lower with IHA than without IHA. Conclusion: KPP90 with IHA and KPP120 are effective exercises to reduce PM activity and increase SA/PM muscle activity ratio. However, applying IHA in KPP90 also reduces SA/UT muscle activity ratio, implying that it would be preferable to apply KPP120 in individuals overusing their UT muscles.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.2
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• pp.9-16
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• 2015

PURPOSE: The objective of this study was to identify the effects of shoulder abduction strength and EMG activities of the selected scapular and shoulder muscles during isometric shoulder abduction. METHODS: Thirty-four healthy young females were recruited for this study. Surface EMG equipment with inline force sensor was used to determine the shoulder abductor strength and the activity of the serratus anterior (SA), upper trapezius (UT), lower trapezius (LT), and middle deltoid (MD) during three shoe heel height conditions: (1) barefoot, (2) 3-cm shoe heel height, and (3) 7-cm shoe heel height. RESULTS: Isometric shoulder strength showed statistically significant difference among the conditions (p<0.05), and post-hoc test showed lower strength during the 7-cm condition ($49.98{\pm}17.56kg$) than during the barefoot ($44.97{\pm}20.15kg$) and 3-cm conditions ($36.59{\pm}17.07kg$). Furthermore, EMG activities of the SA, UT, and MD appeared to be statistically significantly different among the conditions, with lower values in the 7-cm condition compared to the barefoot condition (p<0.05). EMG ratios (MD/UT and SA/UT) were lower during the 7-cm condition than during the barefoot condition (p<0.05). CONCLUSION: These findings suggest that isometric shoulder abduction strength and EMG activities of scapular and shoulder muscles may be adversely changed with increasing shoe heel height.

• Physical Therapy Korea
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• v.30 no.1
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• pp.41-49
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• 2023

Background: Scapular dyskinesis may cause not only rotator cuff (RC) tear but also weakness of the upper extremity, studies on scapular dyskinesis that may occur after RC repair is still lacking. Objects: To determine whether scapular dsykinesis was present in patients after arthroscopic RC repair and to investigate the influence of passive scapular stabilization on upper extremity strength. Methods: A total of 30 patients after RC repair participated in this study. To compare the scapula of the arthroscopic RC repair shoulder and the contralateral shoulder, the winged scapula (WS) was measured using a scapulometer and scapular dyskinesis was also classified by type. Fixed instruments for muscle strength measurements were used to measure upper extremity muscle strength differences depending on passive scapular stabilization position or natural scapular position. A chi-square test, an independent t-test and a 2-way mixed measures analysis of variance (ANOVA) was used as statistical analysis. In analyses, p < 0.05 was deemed to be statistically significant. Results: Postoperative shoulder had a significant association with scapular dyskinesis and the WS compared to the contralateral shoulder (F = 0.052, p < 0.01). Postoperative shoulder, muscle strength in the shoulder abduction (p < 0.01), elbow flexion (p < 0.01) and forearm supination (p < 0.05) were significantly greater in the scapular stabilization position than in the scapular natural position. Conclusion: Patients underwent arthroscopic RC repair had a significant association with scapular dyskinesis and muscle strength was improved by a passive scapular stabilization position, therefore scapular stabilization is important in rehabilitation program.