• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1229-1237
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• 2012

This study aimed to investigate the effect of hand grip force on the activity of shoulder muscles in 2 arm postures. The muscle activity of the upper trapezius, lower trapezius, infraspinatus, anterior deltoid, and posterior deltoid muscles in 22 healthy subjects (11 men and 11 women) were measured using surface electrodes during 4 hand gripping tasks (0%, 30%, 50%, and 70% of maximum voluntary contraction) in 2 shoulder positions (neutral position and $90^{\circ}$ elevation position). Among changing grip force significantly differenced infraspinatus, anterior deltoid, and posterior deltoid muscles' activity in the shoulder neutral position(p<0.05). In the shoulder $90^{\circ}$ elevation position, anterior deltoid, posterior deltoid muscles' activity was significantly differenced(p<0.05). Hand gripping was found to alter muscle activation. The hand grip task activated the infraspinatus muscle in the neutral position and inhibited the deltoid muscle in the $90^{\circ}$ elevation position. This finding may prove useful for the development preventative measures and rehabilitation strategies for shoulder injuries.

• Clinics in Shoulder and Elbow
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• v.24 no.3
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• pp.178-182
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• 2021

A 50-year-old woman who had been previously diagnosed with systemic lupus erythematosus consulted our clinic for pain and weakness in her right shoulder. On examination, she had an atrophied deltoid muscle, a painful right shoulder on movement, and a tender mass in the deltoid area. The patient was diagnosed with corticosteroid-induced deltoid myopathy, shoulder pain, and loss of range of motion that did not resolve with conservative treatment. We decided to perform reverse shoulder arthroplasty. No complications were observed at the last follow-up visit at 3 years postoperative. Unlike deltoid insufficiency that results from axillary nerve injury, deltoid myopathy due to corticosteroid use contains intact fibers,. Therefore, we increased the effectivity of the remaining deltoid fibers by extending the moment arm of the anterior fibers using reverse shoulder arthroplasty and achieved reliable improvements in clinical symptoms and function without increasing the risk of dislocation.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.61-68
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• 2007

The purpose of this study was to analyze the shoulder joint torque and muscle pattern performing as Tennis serve by Isokinetic motions on Isomed 2000. The subject, who was 5 males Korean national high school tennis players. By analyzing the flexion/extension of the shoulder, the peak torque of the internal/external rotation motion(at 60,180 and 300 degree/sec) at peak torque degree, the weight, peak torque, and power. combined with the timing of the electrode of the attached trapezius and posterior deltoid at the three part. From the data analysis & discussion the following conclusions were drawn. When doing a shoulder extension, the peak torque can be widely seen at 60degree per second. However the degree may be different depending on angular velocity. When doing an internal rotation at 90degree abduction, peak torque per weight was seen at 60degree per second. The degree of peak torque was at 31.6-44.2 and peak power was faster when angular velocity was increased. The aspect of muscle pattern was seen more at the internal rotation in the 90degree abduction rather than the shoulder extension. However the angular velocity was not influenced by muscle mobilization(in order of anterior deltoid, posterior deltoid and trapezius. To properly apply the above conclusion, when tennis players serve it is better the elbow be impacted by the extension. when doing isokinetic motion it is better to increase angular velocity and improve muscle power. also the anterior deltoid amongst the shoulder muscle should be improved to develop serve speed.

• Journal of Korean Medicine Rehabilitation
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• v.21 no.3
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• pp.57-69
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• 2011

Objectives : The purpose of this study is to know the effects of the bee venom pharmacopuncture on muscle activity and pain reception of trapezius and deltoid the upper limbs muscles. Methods : We allocated healthy volunteers into two groups. After having exercise with barbell for load to trapezius and deltoid, we measured sEMG(surface electromyography) and VAS(visual analogue scale). In a moment, inject bee venom pharmacopuncture and saline each group. After 30 minutes, we measured sEMG and VAS again. We compared before and after sEMG and VAS data. Results : On sEMG data, bee venom pharmacopuncture had effects on muscle fatigue on left trapezius, muscle fatigue and fatigue and recovery on right trapezius and both deltoid. On VAS data, values of bee venom pharmacopuncture decreased more than that of saline. Conclusions : These results show that bee venom pharmacopuncture have effects on muscle activity aid pain reception of trapezius and deltoid the upper limbs muscle. But further studies should be carried out to verify the exact effects of bee venom.

• Journal of International Academy of Physical Therapy Research
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• v.10 no.3
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• pp.1856-1861
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• 2019

Background: Although there are interventions available for the improvement of arm functions of patients with stroke, measuring changes in global synkinesis (GS) according to changes in the muscle activity of paretic and nonparetic side muscles is an important factor and studies to investigate such potential factors are evaluated necessary. Objective: To examine the correlation between the affected arm muscle activity and GS changes in patients with stroke. Design: Randomized controlled trial Methods: In order to measure muscle activities of 30 stroke patients, anterior deltoid, posterior deltoid, biceps brachii and triceps brachii of the affected arms were measured using surface electromyography (EMG) and for analyzing GS, biceps brachii and triceps brachi of the affected arms were measured using the same instrument. Results: When the correlations between the muscle activity and GS of the affected arm were analyzed, the results showed significant correlations between the posterior deltoid and the triceps brachii(p < .01) and between the triceps brachii and GS(p < .05). Conclusion: : The results of this study suggest that the efficient movements of the affected arms of stroke patients, it is possible to increase extensor activity by improving smooth antagonism of the arm.

• Physical Therapy Korea
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• v.30 no.3
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• pp.237-244
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• 2023

Background: The external rotation (ER) exercise in performed at a 90° abduction of the shoulder joint is an effective to strengthen the infraspinatus. However, failure of the humeral head to control axial rotation during exercise can be increased the posterior deltoid over activity. Biofeedback training is an effective method of promoting motor learning and control it could look forward to activate the infraspinatus selectively by controlling the humeral head during exercise. Objects: The aim of this study was investigated that whether biofeedback for axial rotation was effective to activate selectively the infraspinatus during ER exercise. Methods: The 15 healthy males participated, and all subjects performed both ER exercise in a sitting position with shoulder abducted 90° under conditions with and without axial rotation biofeedback. Exercise was performed in a range of 90° ER, divided into three phases: concentric, isometric, and eccentric. The infraspinatus and posterior deltoid muscle activity were observed using surface electromyography. Results: Both infraspinatus activity (p < 0.01) and infraspinatus to posterior deltoid activity ratio (p = 0.01) were significantly higher with biofeedback however, posterior deltoid activity was significantly lower with biofeedback (p = 0.01). The infraspinatus muscle activity and muscle activity ratio were the highest in the isometric contraction type, and there were significant differences for all contraction types (p < 0.05). Whereas, the posterior deltoid activity was the lowest in the isometric contraction type, and showed a significant difference between isometric and other two contraction types (p < 0.05), but no significant different between concentric and eccentric contraction. Conclusion: Our results indicate that the axial rotation biofeedback during sitting ER exercise might be effective method to activating selective infraspinatus muscle and recommended to enhance the dynamic stability of the shoulder joint.

• Physical Therapy Korea
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• v.15 no.2
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• pp.73-80
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• 2008

With the introduction of the video display terminal (VDT), the efficiency and productivity of work has improved. However, VDT syndrome is threatening the health of workers as a side effect of prolonged use of a VDT. Among various VDT syndromes, the musculoskeletal disorder, especially, the cumulative trauma disorder (CTD) is the common research topic related with upper extremities function. The aim of this study was to investigate the effect of the wrist-hand orthosis (WHO) on fatigue in middle deltoid, anterior deltoid, serratus anterior, and upper trapezius during one-hour computer keyboard typing. Twelve healthy subjects participated in this study. Surface electromyography was used to assess the localized muscle fatigue (LMF), and the LMF was calculated at 10 minutes, 20 minutes, 40 minutes, and 60 minutes in each muscle, with and without the WHO. Data were analyzed by paired t-test with a level of significance of .05. The results of this study are as follows: 1) At 10 minutes, the LMF decreased significantly with applied WHO in the middle deltoid, anterior deltoid, and upper trapezius (p=.001, p=.026, p=.019, respectively). 2) As the computer keyboard typing period increased, there were no significant LMF differences, except for the upper trapezius. Therefore, it can be concluded that the WHO can be applied to decrease the LMF for the initial 10 minute period in the middle deltoid, anterior deltoid, and upper trapezius' but that the long term effect of WHO in reducing the LMF was proven only in upper trapezius during continued computer keyboard typing.

• Korean Journal of Applied Biomechanics
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• v.18 no.4
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• pp.143-149
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• 2008

The purpose of this study was to investigate the muscle activities of pectoralis major, upper serratus, lat dorsi, anterior deltoid, rhomboids, infraspinatus, and posterior deltoid using Noraxon 8 channels EMG system during T-ball swing in children with Down syndrome. Five Down syndrome, one healthy children, and one baseball adult player were participated in the study. Down syndrome's children showed higher muscle activity than one healthy children and one baseball adult player during address to backswing and backswing to impact swing phase. While Down syndrome's children showed lower muscle activity than one healthy children and one baseball adult player during impact to follow swing phase. The strength of the pectoralis major and upper serratus muscle may help to improve T-ball swing movement during impact to follow swing phase.

• The Journal of Korean Physical Therapy
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• v.30 no.4
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• pp.117-122
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• 2018

Purpose: The objective of this study was to examine the effect of vibration exercises generated from an $XCO^{(R)}$ trainer on supraspinatus, infraspinatus, teres minor, and deltoid muscle thickness. Methods: Thirty subjects were evenly divided into two groups. Muscle thickness was measured by a sonogram prior to the study, and at three and six weeks after the intervention. Changes in muscle thickness were analyzed using a repeated measure analysis of variance (ANOVA). The significance level for the statistical test was set at ${\alpha}=0.05$. Results: A statistically significant differences in timing, interactions between timing and the groups, and between-group changes were demonstrated for supraspinatus muscle thickness (p<0.05). A similar finding was reported for infraspinatus, teres minor, and deltoid muscles with regard to the interactions between timing and the groups (p<0.05), although the between-group change did not reach statistical significance (p>0.05). Conclusion: Significant changes were observed in the thickness of the supraspinatus, infraspinatus, teres minor, and deltoid muscles, owing to the use of vibration exercises generated from an $XCO^{(R)}$ trainer. These findings can be used as a foundation for future studies on rehabilitation training.

• Korean Journal of Applied Biomechanics
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• v.28 no.3
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• pp.187-191
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• 2018

Objective: The purpose of the present study is to investigate the effect of a muscle activity by applying the complex exercise method of sling in accordance with the provision of various vibration intensities for paraplegia-spinal cord injury. Method: The subjects of the study were 15 men in their 40s and 50s with lower limb disabilities and low potential risk, who were randomly divided into a sling exercise group (SG n=4), a sling with low frequency vibration group (SLVG n=4), a sling with mid-frequency vibration group (SMVG n=4), and a sling with high frequency group (SHVG n=4) in accordance with the provision of slings and vibration stimuli. The vibratory intensity provided was divided into low frequency (30 Hz), mid-frequency (50 Hz), and high frequency (70 Hz). The anterior deltoid (AD), the posterior deltoid (PD), the pectoralis major (PM), the upper trapezius (UT), the latissimus dorsi (LD), and the multifidus (MF) were measured to compare and analyze muscle activity. Results: The closed kinetic chain (CKC) exercise to the shoulder joint showed higher muscle activity in most muscles for the SMVG, and statistically significant differences in the anterior deltoid (AD), the pectoralis major (PM), and the multifidus (MF) in particular. Conclusion: The intermediate frequency (50 Hz) string vibration was the effective vibration stimuli for Closed kinetic chain (CKC) exercises.