• Physical Therapy Korea
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• v.31 no.1
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• pp.72-78
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• 2024

Background: Limitations of shoulder range of motion (ROM), particularly shoulder internal rotation (SIR), are commonly associated with musculoskeletal disorders in both the general population and athletes. The limitation can result in connective tissue lesions such as superior labrum tears and symptoms such as rotator cuff tears and shoulder impingement syndrome. Maintaining the center of rotation of the glenohumeral joint during SIR can be challenging due to the compensatory scapulothoracic movement and anterior displacement of the humeral head. Therefore, observing the path of the instantaneous center of rotation (PICR) using the olecranon as a marker during SIR may provide valuable insights into understanding the dynamics of the shoulder joint. Objects: The aim of the study was to compare the displacement of the olecranon to measure the rotation control of the humeral head during SIR in individuals with and without restricted SIR ROM. Methods: Twenty-four participants with and without restricted SIR ROM participated in this study. The displacement of olecranon was measured during the shoulder internal rotation control test (SIRCT) using a Kinovea (ver. 0.8.15, Kinovea), the 2-dimensional marker tracking analysis system. An independent t-test was used to compare the horizontal and vertical displacement of the olecranon marker between individuals with and without restricted SIR ROM. The statistical significance was set at p < 0.05. Results: Vertical displacement of the olecranon was significantly greater in the restricted SIR group than in the control group (p < 0.05). However, no significant difference was observed in the horizontal displacement of the olecranon (p > 0.05). Conclusion: The findings of this study indicated that individuals with restricted SIR ROM had significantly greater vertical displacement of the olecranon. The results suggest that the limitation of SIR ROM may lead to difficulty in rotation control of the humeral head.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.8
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• pp.67-73
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• 2021

In this study, we installed forward and reverse rotation rotavators on a tractor to measure the load in the field and analyze the power consumed. The rotavator is attached to the rear of the tractor and transmits the power applied from the power take off (PTO) of the tractor to the rotating shaft of the rotavator, and it plows or reverses the soil according to the rotational direction of the rotating shaft. Depending on the rotational direction of the rotavator, the power consumed in the tractor engine and the power transmitted to the tractor axle and rotavator also vary, thus, research of load and power is an essential factor in designing the system. As a field test results, 84.1-93.5% power was consumed by the forward rotation rotavator, and 37.8-57.5% power was consumed by the reverse rotation rotavator. In addition, depending on the rotation direction of the rotavator, the power consumed by the tractor was in the order of PTO and axle. Based on the research results, development of reliable rotavator systems would be possible in the future research.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.28 no.3
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• pp.33-40
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• 2022

Background: The cross-body and the sleeper stretches have been used to improve posterior shoulder tightness (PST). However, such stretching techniques may not always help achieve scapular stability and may even aggravate patient's symptoms. Therefore, a new stretching technique (passive glenohumeral internal rotation with bridging) was developed as a more effective method that may allow for greater scapular stability without aggravating the symptoms. Thus, this study aimed to examine and compare this novel stretching technique to determine its effect on the range of motion (ROM) and acromio-humeral distance (AHD) in patients with glenohumeral internal rotation deficits (GIRD) with posterior shoulder tightness. Methods: A total of 30 symptomatic patients with asymmetrical GIRD were randomly assigned to two groups: the novel stretching group (n=15) and the joint mobilization group (n=15). The intervention was conducted twice a week for a total of four weeks. The ROM of shoulder internal rotation was measured by a goniometer and the AHD was evaluated by an X-ray before and after the intervention. Results: Both the treatments improved ROM and AHD in patients with GIRD (p<.05). However, the improvements in internal rotation ROM and AHD in the novel stretching group were significantly greater than that of the subjects in the mobilization group. There was a significant difference between the two groups (p<.05). Conclusion: These results show that both novel stretching and joint mobilization improved ROM and AHD in patients with GIRD with PST. However, novel stretching was more effective than joint mobilization.

• Korean Journal of Applied Biomechanics
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• v.24 no.1
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• pp.1-9
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• 2014

The purpose of this study was to investigate the muscle mechanical properties of the pelvic axial pre-rotational movement for the Jireugi in the Taekwondo Juchumseogi stance. Eleven elite Taekwondo Poomsae athletes participated. Each participant performed 5 right hand Jireugi in Juchumseogi stance as fast and strong as possible while their motion was recorded by a 3D motion analysis system and the ground reaction forces by two force plates. The power and work of the muscular group surrounding the waist were analyzed to verify the effect of the stretch-shortening cycle (SSC) theory. The cause of the greater power seems to be the application of the SSC by the muscles surrounding the waist during the preparation phase of the pre-rotation group. For the none pre-rotation group, they only used the concentric contraction of the muscles surrounding the waist. Because the pre-rotation group used the SSC theory, they had the effect of shortening of the range of movement, creating a fast and more powerful rotation, thus anticipating the increase the magnitude of impact.

• The Journal of Korean Physical Therapy
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• v.31 no.2
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• pp.76-81
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• 2019

Purpose: This study examined the effects of squatting with different foot positions on the muscle activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles in subjects with genu varum. Methods: Thirty four subjects participated in this study. Surface electromyography was used to measure the muscle activation of the VMO and VL muscles at the knee angles ($15^{\circ}$, $60^{\circ}$) at three foot positions (internal rotation, neutral position, external rotation) during squatting. Results: Muscle activation differences at different knee angles and foot positions differed significantly between the VMO and VL muscles in both the varus and normal groups. In addition, there was a significant difference according to the knee angles with the foot in external rotation in the VMO and VL ratio. In the varus group, however, the VMO and VL ratio were significantly different only with the feet in internal rotation. In the muscle activation changes of the knee angle differences in the foot position, there was no significant difference in the varus group, but both the VMO and VL muscles were significant different in the normal group. Conclusion: In both groups, regardless of the foot position, muscle activation of the VMO and VL muscles increased with increasing knee flexion angle. In the normal group, when squatting with the feet in external rotation, the VMO and VL muscles activations increased with increasing knee angle. In the varus group, however, the foot position did not affect the VMO or VL muscle activation. This study shows that subjects with genu varum and normal subjects have different VMO and VL muscle activation patterns during squat exercises.

• Physical Therapy Korea
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• v.22 no.3
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• pp.50-60
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• 2015

The purpose of this study was to apply the joint mobilization technique to the level of segments with pain and to the level of segments with hypomobility respectively and compare the immediate effects of the joint mobilization technique on the pain, the active cervical range of motion (ROM), and treatment satisfaction of patients with acute mechanical neck pain. After the baseline assessment, forty-two patients were randomized into two groups: a painful group ($n_1=21$) that received joint mobilization at the most painful cervical spine level and a hypomobile group ($n_2=21$) that received joint mobilization at the most hypomobile cervical level. The patients received an intervention that applied unilateral posterior-anterior gliding for 5 minutes and two repetitions of 10 times of active extension motion with distraction. In the Wilcoxon signed-rank test, the painful group and the hypomobile group were improved significantly in all pain variables (p<.001), while the painful group was improved significantly in the active cervical flexion (p<.001), extension (p<.001), left side-bending (p<.01), right side-bending (p=.001), left rotation (p<.001), and right rotation (p<.001). The hypomobile group was significantly improved in active cervical flexion (p=.001), extension (p<.001), left side-bending (p<.05), right side-bending (p=.001), left rotation (p=.001), and right rotation (p<.01) after intervention. In the Mann-Whitney U test, there was no significant difference in any of the dependent variables after the intervention between the two groups, but the painful group was slightly superior to the hypomobile group in all variables except for the right lateral flexion ROM and treatment satisfaction. These outcomes suggest that the cervical joint mobilization may be applied to either the level of painful segments or the hypomobile segments for the treatment of patients with acute mechanical neck pain.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.20 no.2
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• pp.15-20
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• 2014

Objective: The purpose of this study was to investigate the effects of sling exercise on the cervical lordotic angle, craniovertebral angle, and head rotation angle among adolescents in the forward head posture. Methods: The subjects include 22 adolescents that recorded a mild level or higher on the posture evaluation index by New York State. They were randomly divided to the hand exercise group (n=11) and the control group (n=11). The former group participated in the sling exercise program three times a week over four weeks in total with each session lasting 60 minutes, whereas the latter group was not included in the program. The cervical lordotic angle, craniovertebral angle, and head rotation angle were measured before and after the intervention. Results: The study compared the cervical lordotic angle between the two groups before and after sling exercise and found that the sling exercise group made an increase of $7.36^{\circ}$ from $21.91^{\circ}$ to $29.27^{\circ}$ after the intervention(p<.05). As for the comparison results of the craniovertebral angle, the sling exercise group made an increase of $5.64^{\circ}$ from $48.91^{\circ}$ to $54.55^{\circ}$ after the intervention (p<.05). As for the comparison results of the cranial-rotation angle, the sling exercise group made an decrease of $-7.73^{\circ}$ from $148.82^{\circ}$ to $141.09^{\circ}$ after the intervention (p<.05). The control group showed no differences before and after the intervention (p>.05). Conclusion: Those findings indicate that the application of sling exercise in the forward head posture can be a good program to maintain the right posture and improve or prevent an abnormal posture and raise a need for more clinical applications and ongoing researches.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.45-55
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• 2007

We investigated the biomechanics and characteristics of shoulder rotator muscles for professional woman volleyball players. The purpose of this study was to analyze the isokinetic peak torque and range of motion for shoulder joint rotation. We measured the strength and ROM of the internal rotation(IR) and external rotation(ER) of shoulders joint for nine professional woman Volleyball players and nine University students with Biodex and Simi-motion. 1. We measured peak torques for the shoulder joint rotator at angular velocities of 60/s and 180/s. It was found that the peak torques were significantly different between the two groups and also between the hands used. 2. At angular velocity of 60/s, IR/ER ratio of the shoulder joint was significantly different depending on the groups and the hands in use. There was a significant difference for 'Dominant side' at angular velocity of 180/s, but no significant difference for 'Non-dominant side' and the controls group. 3. Regarding the ROM of rotation of the shoulder joint group, IR was significantly different between the groups and the hands in use. 4. IR/ER ratio of the shoulder joint for Dominant side was quite different between the groups.

• PNF and Movement
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• v.18 no.2
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• pp.223-231
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• 2020

Purpose: The purpose of the study was to compare the effects of different methods of pelvic control on abdominal muscle activity and lumbopelvic rotation angle during active straight leg raising (ASLR) in patients with chronic back pain. Methods: The study participants were patients with low back pain (n = 30). They were instructed to perform ASLR with pelvic control, ASLR with pelvic belt, and ASLR only. Surface electromyography data were collected from the ipsilateral rectus femoris (IRF), ipsilateral internal oblique (IIO), contralateral external oblique (CEO), and ipsilateral rectus abdominal (IRA) muscles, and lumbopelvic rotation angle was measured using a motion analysis device. Results: Activation of all abdominal muscles was greater in the ASLR with pelvic control group than in the ASLR with pelvic belt and ASLR groups. The lumbopelvic rotation angle was lower in the ASLR with pelvic control group than in the other two groups (p < 0.05). Conclusion: These results suggest that ALSR with pelvic control is an effective means of increasing abdominal muscle activity and reducing unwanted lumbopelvic rotation in patients with chronic low back pain. Controlling the pelvis using the opposite leg is an effective form of ASLR exercise for patients with chronic low back pain.

• Korean Journal of Acupuncture
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• v.30 no.2
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• pp.88-96
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• 2013

Objectives : In the acupuncture treatment of Korean Medicine, the Tonifying or Purging depending on how many times the needle is rotated has been used widely. However, there is little evidence about the optimal number of rotation. This study, therefore, was aimed to investigate the optimal number of rotation. Methods : Heart rate variation was measured before and after exercise in 20 healthy adults. Acupuncture was performed at PC6 immediately after exercise according to the protocol of each group without remaining. Pre-exercise and post-exercise measurements were compared and the rotation number that produced statistically significant difference was investigated. Results : Significant differences were found in the heart rate variation and R-R interval Average, between non-rotation group (control) and both of 15 times rotation group of tonifying and 6 times rotation group of purging. Conclusions : Significantly effective number of rotation in the effect of PC6 on the HR and RRAv was 15 times in the tonifying and 6 in the purging respectively.