• PNF and Movement
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• v.22 no.1
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• pp.151-158
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• 2024

Purpose: The present study investigated how variations in diagonal exercises affect shoulder muscle activity, examining changes in neuromuscular activation during scapular and shoulder diagonal patterns of exercises. Furthermore, we explored whether the exercise phase affects muscle activation. Methods: Sixteen asymptomatic male participants were recruited. Four diagonal pattern exercises (scapular anterior elevation, posterior elevation, flexion-adduction-external rotation, flexion, abduction-external rotation), and two exercise phases (concentric and eccentric) were administered. Surface electromyography data were collected. Results: Upper trapezius activity was significantly higher during the concentric phase of scapular posterior elevation exercises compared with the others (p<0.05). The serratus anterior, anterior deltoid, and infraspinatus activities were significantly higher during shoulder diagonal pattern exercises compared with the scapular diagonal pattern exercises (p<0.05). Except for the lower trapezius, muscular activities during the concentric phase were significantly greater compared with the eccentric phase (p<0.05). Conclusion: The current study suggests that the diagonal pattern of exercise may contribute to selective strengthening of the shoulder complex muscles and that the form of exercise should be tailored to the subject. It also suggests that diagonal exercises with concentric contractions tend to be more beneficial than eccentric contractions for overall muscle recruitment, but the effects vary for specific diagonal patterns.

• Journal of Korean Physical Therapy Science
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• v.26 no.3
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• pp.57-69
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• 2019

Background: The purpose of this study was to compare and analyze the effects of neck and trunk combined exercise program and single exercise on neck angle and neck and shoulder muscle activity. Design: Randomized controlled trial. Methods: In the single exercise group, the basic stretching, head bending and neck bending exercises were performed. The neck and trunk combined exercise group performed torso strength and trunk stability exercises to stabilize the trunk, and then performed the same neck exercise as the single exercise group. The exercise program was conducted 5 days per week for 2 weeks. One-way repeated ANOVA was used to investigate the statistical analysis of neck angle, neck and upper and middle trapezius muscle activity. Results: 1) There was no significant difference in neck angle degree after exercise in neck single exercise group. 2) In the neck and trunk combined exercise, the neck angle degree decreased continuously with the increase of the experimental period and showed a significant difference. 3) In the single exercise group, the muscles which showed significant difference compared to the post-exercise were the right upper, left and right middle trapezius. 4) In the neck and trunk combined exercise group, the right neck muscles showed significant difference after the exercise before the experiment. Conclusion: It was found that the neck and trunk combined exercise was more effective in reducing neck angle and the muscle activity of the subjects with forward head posture was decreased and increased. However, both exercises showed positive effects.

• Physical Therapy Rehabilitation Science
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• v.4 no.2
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• pp.108-114
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• 2015

Objective: The purpose of this study was to examine the effect on vital capacity (VC) and inspiratory muscle activation according to the anterior and posterior pelvic tilt positions. Design: One group pretest-posttest design. Methods: Twenty-six healthy adult men and women, age 19 to 27 years, volunteered to participate in this study. Forced vital capacity (FVC), and forced expiratory volume in 1 second ($FEV_1$) were measured by desktop spirometer in the pelvic positions during respiration, and muscle activation was recorded from sternocleidomastoid, upper trapezius, external intercostal, rectus abdominis, and external oblique muscles by surface electromyography (EMG) at the same time. EMG values were normalized by maximum muscle contractions (% maximum voluntary isometric contraction). Subjects were to breathe in as much air as possible and then exhale as quickly as possible in both anterior and posterior pelvic tilt positions. To measure lung capacity, inspiration was measured for 5 seconds and expiration was measured for 7 seconds with data collection taken place during the middle three seconds. Lung capacities were measured in each position three times. Results: For the results of this study, there was a significant increase in both FVC and $FEV_1$ values during the anterior pelvic tilting compared to the posterior pelvic tilting posture (p<0.05). The sternocleidomastoid, upper trapezius muscle, rectus abdominus and external oblique muscle activation was significantly increased during anterior pelvic tilt compared to the posterior pelvic tilt position (p<0.05). Conclusions: These findings suggest that pelvic anterior tilt position could be more effective for vital capacity and respiratory muscles activation during respiration.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.22 no.1
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• pp.51-58
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• 2016

Background: Evidence for effective management of scapular downward rotation syndrome is limited. The present study was performed to compare the scapular muscle activation through 4weeks wall slide exercise and sling slide exercise in subjects with scapular downward rotation syndrome. Methods: Twenty-two subjects with scapular downward rotation syndrome participated in the study. Surface electromyography data were collected from the upper and lower trapezius, serratus anterior and pectoralis major during shoulder flexion of $60^{\circ}$, $90^{\circ}$ and $120^{\circ}$ in the sagittal plane. The alignment of the scapula was measured using radiographic analysis. Subjects were assessed pre and post a 4 weeks exercise (wall slide, sling slide). The significance of the difference in pre- and post-exercise within each groups was assessed using a paired t-test. The significant difference between wall- and sling-exercise was used a independent t-test. Results: In the wall slide group, the muscle activity of upper trapezius decreased significantly during shoulder flexion at $60^{\circ}$, $90^{\circ}$ and $120^{\circ}$ after 4 weeks, and the muscle activity of serratus anterior increased significantly at all angles. Also, the muscle activity of pectoralis major decreased significantly at $90^{\circ}$ and $120^{\circ}$. Conclusions: Based on such results, it can be said that wall slide exercise is effective than sling slide exercise for the subjects with scapular downward rotation syndrome.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.435-441
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• 2012

This study is intended to provide a basic clinical data useful for preventing shoulder injuries related to occupation and curing them, by measuring the shoulder muscle activity of normal adults in an arm posture type of a wide shoulder joint angle, according to several differences of hand grip force. In order to examine the shoulder muscle activity during hand grips at a variety of intensity, according to the arm posture type, MVCs of all subjects were measured, and %MVCs of anterior deltoid, supraspinatus, the upper trapezius and infraspinatus at 0 degree, 90 degrees and 160 degrees of shoulder angle were yielded according to the grip force in an arm posture type, changing the maximum grip force into 30%, 50% and 90%, randomly. When measuring the hand grip at 30%, 50% and 70% of the maximum grip force to compare %MVC of each group depending on the arm posture type, there were no significant differences of muscle activity at 0 degree of shoulder angle among anterior deltoid, supraspinatus, the upper trapezius and infraspinatus, but there were significant differences of it among them at 90 degrees and 160 degrees of should angle(p<.001). According to the results of post-hoc test, also, anterior deltoid had the highest muscle activity, whereas the upper trapezius had the lowest muscle activity.

• Physical Therapy Korea
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• v.30 no.1
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• pp.23-31
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• 2023

Background: Several factors contribute to shoulder pain, including abnormal neck posture, repeated use of the upper limbs, work involving raising the upper limbs above the head, and the effects of vibration. However, previous study has reported that constant vibration exposure could impact improvement of the stability on joints related with muscle recruitment and activation. For this difference reason, we need to verify for the complex study of relationship with repetitive upper limb movements, poor head posture, and constant vibration exposure. Objects: Our study was made to investigate the influence of vibration exposure on the shoulder muscle activity during forward-head and over-head tasks with isometric shoulder flexion. Methods: In a total of 22 healthy subjects, surface electromyography (EMG) data were collected from shoulder muscles (upper/lower trapezius, serratus anterior, and lumbar erector spinae) on tasks (neutral-head task [NHT], forward-head task [FHT], and over-head task [OHT]) with and without vibration exposure. Results: In all tasks, the EMG data of the upper trapezius and serratus anterior significantly increased with vibration exposure (p < 0.05). Furthermore, the EMG data of the lumbar erector spinae significantly increased with vibration exposure in the NHT and FHT (p < 0.05). Conclusion: We suggest that continuous vibration exposure during the use of hand-held tools in the tasks could be associated with harmful effects in the workplace. Lastly, we clinically need to examine the guidelines regarding the optimal posture and vibration exposure.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.4
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• pp.113-121
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• 2015

PURPOSE: The purpose of this study was to determine the effect of shoulder external rotation on muscle activities of the scapular upward rotators during arm elevation. METHODS: Nineteen healthy subjects with no medical history of shoulder pain or upper extremity disorders were recruited for this study. Electromyography (EMG) was used to measure the muscle activities of the serratus anterior (SA), upper trapezius (UP), lower trapezius (LT) and infraspinatus (IS) muscles during arm elevation. The EMG activities were recorded while the subjects performed $90^{\circ}$ arm elevation with three different arm positions; palm down (PD), neutral position (NP), and palm up (PU). While seated in a chair, the subject was asked to raise the upper extremity in the sagittal plane in random order. Subjects performed $90^{\circ}$ arm elevations in three trials at each arm position. The mean EMG activity normalized by the maximal voluntary isometric contraction was analyzed across three arm positions. Repeated measures one-way ANOVA and the post hoc Bonferroni tests were used to determine the differences in muscle activities among the three arm positions. RESULTS: The EMG activities of the SA and IS were significantly greater in the PU condition than in the other conditions during arm elevation. No significant difference was noted between the NP and PD conditions during arm elevation. CONCLUSION: These results suggest that shoulder external rotation (palm up position) can be used to activate the SA. Therefore, we recommend a scapular protraction exercise in the palm up position for strengthening the SA.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.356-362
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• 2012

This study examined the effects of vocalization on upper extremity muscle activity during reaching task in patients with hemiplegia. Thirteen persons with right brain stroke performed reaching to a cup under four concurrent speech conditions of vocalizing the word "Ah" with hemiplegic side. These four conditions are self-vocalization, external vocalization, imaginary vocalization, and no vocalization. The muscle activity(Biceps brachii, Triceps brachii, Middle deltoid, and Upper trapezius) were measured using MP150. Muscle activity was significantly higher under self-vocalization and external vocalization conditions compared to the muscle activity under imaginary vocalization and no vocalization conditions on triceps brachii muscle.(p<0.05). Triceps brachii muscle was highly correlated with biceps brachii muscle(r=0.777, p<0.05). The results suggest that self-vocalization and external vocalization can be used in facilitating upper extremity movements in patients with stroke. When working with patients with right hemispheric stroke, therapists might explore possibilities of using patient's self-speech to enhance the quality of upper extremity movement performance.

• The Journal of Korean Physical Therapy
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• v.34 no.5
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• pp.278-281
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• 2022

Purpose: This study sought to compare the muscle activity of the deltoid muscle according to the range of motion during the proprioceptive neuromuscular facilitation (PNF) upper extremity D2 pattern exercise performed with an isokinetic exercise device. The aim was to provide basic data for selecting an exercise for the relevant segment of the range of motion to enhance function in clinical practice. Methods: In this study, the relevant measurements of the anterior and middle trapezius of 25 healthy adults were taken using a surface electromyography system. The upper extremity pattern exercise was performed in three ranges (0% to 50%, 50% to 100%, and 25% to 75%) using the upper extremity isokinetic device. Results: There was a statistically significant difference in the muscle activity ratios of the anterior and middle deltoid muscles according to the measurement conditions (p<0.05). There was a statistically significant difference in the activity ratio of the middle deltoid muscle according to the measurement conditions in the ratio from the start range to the end range (p<0.05). There was no significant difference in the muscle onset time difference according to the measurement conditions (p>0.05). Conclusion: The muscle activity of the anterior and middle deltoid muscles was analyzed according to the range of motion during the PNF upper extremity pattern exercise performed with an isokinetic device. The results could be used as a basis for selecting exercises for the relevant segment of the range of motion according to the function to be emphasized.

• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.197-204
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• 2016

Objective: The purpose of this study was to analyze the kinematic factors of motion during air pistol shooting. Method: This study aimed to investigate changes in forces during movement and determine the factors that affect changes in force during the first, middle, and last periods of shooting an air pistol. Two ground reaction force systems (force platform), SCATT (a shooting training system), and EMG (electromyogram) to measure the action potentials in the muscles of the upper body were used in this study. Four university air pistol players (age: 19.75 years, height: 175.50 cm, body mass: $69.55{\pm}11.50kg$, career length: $6.25{\pm}6years$) who are training to progress to a higher rank were enrolled. Results: In terms of the actual shooting results, the mean score in the middle section was $42.48{\pm}1.74$ points, higher than those in the first and the last periods when using SCATT. The gunpoint moved 13.48 mm more vertically than horizontally in the target trajectory. With respect to action potentials of muscles measured using EMG, the highest action potentials during the aiming-shooting segments, in order higher to lower, were seen in the trapezius (intermediate region), trapezius (superior region), deltoid (lateral), and triceps brachii (long head). The action potentials of biceps brachii and brachioradialis turned out to be high during grasping motion, which is a preparatory stage. During the final segment, muscle fatigue appeared in the deltoid (lateral), biceps brachii (long head), brachioradialis, and trapezius (intermediate region). In terms of the ground reaction force, during the first period of shooting, there was a major change in the overall direction (left-right $F_x$, forward-backward $F_y$, vertical $F_z$) of the center of the mass. Conclusion: The development and application of a training program focusing on muscle groups with higher muscle fatigue is required for players to progress to a higher rank. Furthermore, players can improve their records in the first period if they take part in a game after warming up sufficiently before shooting in order to heighten muscle action potentials, and are expected to maintain a consistent shooting motion continuously by restoring psychological stability.