• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.337-342
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• 2013

Purpose: This study was conducted in order to determine the effect of visual and tactile feedback on muscle activity of the gluteus maximus (Gmax) and abdominal muscles and the motion of pelvic rotation during performance of clam exercise (CE). Methods: Thirteen subjects without low back pain were recruited for this study. Each subject was instructed to perform the CE without and with feedback. The subjects were instructed to keep pelvic from rotating backwards by palpating the ASIS and monitoring the pelvic movement by themselves during performance of CE with feedback. The electromyographic (EMG) activities of Gmax and abdominal muscles were collected using surface EMG. Angles of pelvic rotation were measured using a 3-dimensional motion-analysis system. Paired t-tests were used for comparison of EMG activities in each muscle and the angle of pelvic rotation. Results: The EMG activities of all abdominal muscles were not significant between CM without and CM with feedback (p>0.05). The EMG activity of Gmax was significantly greater in CM with feedback compared with CM without feedback (without vs. with feedback; 14.2% vs. 20.7%MVIC) (p<0.05). The angle of pelvic rotation was significantly less in CM with feedback compared with CM without feedback (without vs. with feedback; $15.3^{\circ}$ vs. $10.8^{\circ}$ ) (p<0.05). Conclusion: Therefore, these findings suggest that CM with the visual and tactile feedback is effective in activation of the Gmax and correcting of the uncontrolled lumbopelvic rotation during CE.

• Physical Therapy Korea
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• v.22 no.1
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• pp.49-57
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• 2015

The purpose of this study was to investigate the dynamic balance and activity of internal oblique muscle, multifidus muscle, gluteus maximus muscle, biceps femoris muscle during the Y balance test following the wearing of pelvic compression belt. Forty healthy adults were recruited for this test. The dynamic balance score was estimated as the following: (anterior+posteromdial+posterolateral)/($3{\times}leg$ length)${\times}100$. The electromyography signals were measured through %reference voluntary contraction, which was normalized by reference voluntary contraction of Y balance test without wearing the pelvic compression belt. The paired t-test was carried out to compare the dynamic balance score and the activity of the trunk and hip extensor with and without the wearing of pelvic compression belt. The dynamic balance score of the Y balance test when wearing pelvic compression belt was significantly than when measured without wearing the pelvic compression belt (p<.05). The muscle activity of the internal oblique and the multifidus was significantly decreased when wearing pelvic compression belt (p<.05). The muscle activity of the gluteus maximus was significantly increased when wearing pelvic compression belt (p<.05). However, there was no significant difference in hamstring muscle activity, with or without wearing the belt (p>.05). In conclusion, this study shows that the wearing of pelvic compression belt affects trunk muscle and hip extensor muscle activity related to the pelvic mobility and stability and increases dynamic balance and also contributes to the stabilization of the external pelvic stabilization.

• Physical Therapy Korea
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• v.14 no.4
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• pp.21-27
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• 2007

The purposes of this study were to compare core muscle activities with and without the use of Pilates resistive equipment during bridging exercises and to investigate the efficacy of a Pilates device. Fourteen healthy individuals (6 males, 8 females) between 20 to 26 years of age were examined. They were engaged in a bridging exercise with and without a magic circle. Three consecutive repetitions of each exercise were performed. Surface electromyography (sEMG) was used to measure the electrical activities of the right side internal oblique, the adductor longus, the multifidus, and the gluteus maximus muscles. Normalized EMG activities were compared using a paired t-test and the level of significance was set at =.05. The results showed that the EMG activities of the internal oblique (p=.0078), the adductor longus (p=.0007), and the gluteus maximus (p=.0001) muscles were significantly higher when using the magic circle during the Pilates bridging exercise. Also, statistically significant change existed in the multifidus muscle (p=.0106). The bridging exercise, combined with hip adduction using the magic circle, may enhance core stabilization. Therefore, using a magic circle during hip adduction combined with bridging exercise may be recommended usefully for individuals wanting to strength the core muscles. Further research is needed to access the nature of motor control of the Pilates mat exercises and to deliver exercise intervention for lower back pain patients.

• The Journal of Korean Physical Therapy
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• v.24 no.2
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• pp.66-72
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• 2012

Purpose: The purpose of this study is to explore the importance of the image distortion correction in the cross sectional area measurement for the iliopsas muscle, tensor fasciae latae muscle, gluteus maximus muscle and the knee extensor muscles, by using (magnetic resonance imaging) MRI. Methods: This study was performed using an open 0.32T MRI system. To estimate the image distortion, T1 images for an AAPM homogeneity/linearity phantom were acquired, and the region in which the maximum geometric distortion was less than or equal to the pixel size (1.6 mm) of the images, it was defined as the distortion correction-free region. The T2 images for a human subject's pelvis and thigh in normal positions were obtained. Then, after the regions of interest in the pelvis and thigh were moved into the distortion correction-free region, T2 images for the pelvis and thigh were scanned with the same imaging parameters used in the previous T2 imaging. The cross-sectional areas were measured in the two T2 images that were obtained in the normal position, and the distortion correction-free region, as well as the area error caused by geometric image distortion was calculated. Results: The geometrical distortion is gradually increased, from the magnet center to the outer region, in axial and coronal plane. The cross-sectional area error of gluteus maximus muscle and the knee extensors was as high as 9.27% and 3.16% in before and after distortion correction, respectively. Conclusion: The cross-sectional area of the muscles that suffered from the geometrical distortion is necessary to correct for the estimation of the intervention.

• The Journal of Korean Physical Therapy
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• v.11 no.3
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• pp.1-12
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• 1999

The aim of this study is to examine the sensitivity and characteristics of electromyography abnormalities detected by using various paramenters in patients with lumbosacral radiculopathies. EMG is widely used for disgnosing and localizing the level of radiculopathy. The results of the study were as follow : 1. In electromyography, L5 radiculopathy usa 95 cases(51.690). S1 radiculopathy was $45m(24.5\%)$ L4 radiculopathy was 18cases $(9.8\%)$, and L2, 3 radiculopathy was 8cases$(4.3\%)$. Remains 18cases$(9.8\%)$ had no definite radiculopathy. 2. Peroneal and tibial motor nerve conduction velocity studies were not significant as compared to the side to side. 3. Latency of H-reflex in L5 radiculopathy was $30.55\pm2.47$ in affected side, $29.47\pm2.29$ in unaffected side, in S1 radiculopathy was $33.00\pm2.03$ in affected side, R30.18\pm2.21$ in unaffected side. It was statistically significant(p<0.01). H-reflex mean difference of S1 radiculopathy group was significantly prolonged as compared to the L5 and S1 radiculopathies(p<0.001). 4. In L2, 3 radiculopathy, abnormal spontaneous activities and motor unit action potentials were showed high sensitivity in upper lumber paraspinal, hip adductors, quadriceps and iliopsoas muscles. 5. In L4 radiculopathy, lower lumbar paraspinal, tibialis anterior, quadriceps muscles were showed high sensitivity. 6. In L5 radiculopathy, lower lumbar paraspinal, extensor hallucis longus, extensor digitorum longus, peroneus longus, extensor digitorum brevis, gluteus maximus, tensor fasciae latae muscles were showed high sensitivity. 7. In S1 radiculopathy, lower lumbar paraspinal, gluteus maximus, peroneus longus, soleus, abductor hallucis, hamstrings, extensor digitorum brevis, extensor hallucis lognus, gastrocnemius muscles were showed high sensitivity.

• Korean Journal of Applied Biomechanics
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• v.28 no.1
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• pp.37-43
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• 2018

Objective: The aim of this study was to analyze muscle activation of the lower extremities as a function of changes of the center of pressure (CoP) of the foot during squats in order to provide quantitative information to trainers who would like to teach correct movements for developing muscles. Method: Ten men with over three years of weight training experience participated in this study (age: $26.1{\pm}0.8yrs$, height: $171.2{\pm}3.9cm$, body mass: $71.1{\pm}5.7kg$, 60%RM: $84{\pm}9kg$, career: $4.0{\pm}0.7yrs$). The participants were instructed to perform a squat in each of 3 conditions, with different CoP's (the front, middle, and rear of the foot). Results: The position of the CoP showed significant differences according to instructions in both the eccentric and concentric contraction phases (p < .05). The range of movement of the hip and ankle joints showed significant differences corresponding to changes of the CoP position (p < .05). The rectus femoris and gluteus maximus muscle showed significant differences for different CoP positions only in the concentric contraction phase, while the gastrocnemius and anterior tibialis were significantly different in both the concentric and eccentric contraction phase (p < .05). Conclusion: When the target muscle of squat training is the gastrocnemius, the CoP should be located in the front of the foot for effective muscle training. When the target muscles of squat training are the gluteus maximus and quadriceps femoris, the CoP should be located on the rear of the foot.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.3
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• pp.339-348
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• 2012

Purpose : The purpose of this study is to compare muscle activations of neck, trunk and leg in cerebral palsy of spastic diplegia with genu recurvatum and knee flexion contracture, when using anterior and posterior walkers. Methods : We selected 21 cerebral palsy and received the written consent to participate in this study. The inclusion criteria for participation required patients to have spastic diplegic CP; to be between 3~6 years of age, to have a GMFCS III grade, to have no botulinum toxin injection and orthopedics surgery within before six months starting the study. Measurements of muscle activities (sternocleidomastoid, splenius capitis, rectus abdominis, erector spinea, gluteus maximus, rectus femoris, medial hamstring and calf muscles) were evaluated anterior and posterior walker ambulations. Statistical evaluation of these data were accomplished by utilizing the paired t-test and independent t-test by SPSS 20.0 program. Significance level was set at p<.05. Results : The following results were obtained. There was significant difference on muscle activation of neck, trunk and legs(soleus except) in anterior and posterior walkers. There was no significant difference in muscle activation of neck but significant difference in muscle activation of trunk, legs between genu recurvatum and knee flexion contracture(rectus abdominis, medial hamstring when using anterior walker, rectus abdominis, erector spinea, gluteus maximus, medial hamstring when using posterior walker). Conclusion : The conclusion of this study is the different knee joint forms would have different effect on muscle activation of trunk and legs while cerebral palsy of spastic diplegic ambulated with anterior walker and posterior walker.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.3
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• pp.39-45
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• 2019

PURPOSE: We investigated the most effective way to activate the posterior oblique sling muscles by performing prone hip extension exercises. METHODS: An electromyography system was used to measure the activation of the posterior oblique sling muscles (latissimus dorsi, gluteus maximus, multifidus, and biceps femoris) in three different prone hip extension exercises of in 12 healthy individuals (6 men and 6 women): 1) prone hip extension, 2) prone hip extension with internal rotation and extension of the arm, and 3) prone hip extension with internal rotation and extension of the arm with a 1-Ib dumbbell. RESULTS: The overall muscular activation of the posterior oblique sling muscles was more increased when performing 1) prone hip extension with internal rotation and 2) prone hip extension with internal rotation and extension of the arm with a 1-Ib dumbbell as compared with that during prone hip extension except for the biceps femoris activation. There was a statistically significant difference in the activities of the contralateral multifidi among all three exercises; of the ipsilateral multifidi in PHE1) prone hip extension alone, PHE2) prone hip extension with internal rotation and extension of the arm and PHE3) prone hip extension with internal rotation and extension of the arm with 1-Ib dumbbell; and of the ipsilateral gluteus maximus among all the prone hip extension exercises. There was no significant difference in the activity of the biceps femoris among the three exercises. CONCLUSION: Prone hip extension with internal rotation and with internal rotation and extension of the arm with 1-Ib dumbbell can activate the posterior oblique sling muscles and so prevent back pain in healthy people.

• Korean Journal of Applied Biomechanics
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• v.32 no.1
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• pp.31-36
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• 2022

Objective: The purpose of this study was to investigate muscle activation according to the four strap lengths in the TRX plank exercise to provide scientific and accurate data on effective training methods. Method: Twenty healthy men who had at least 6 months of weight training experience and could fully adjusted plank exercise, were participate in this study (age: 25.2 ± 3.7 yrs., height: 174.2 ± 3.9 cm., weight: 71.2 ± 9 kg). To pursue the study purpose, surface electrodes were attached to trunk muscles (pectoralis major, rectus abdominis, external oblique, internal oblique, erector spinae, latissimus dorsi) and lower extramity muscles (gluteus maximus, rectus femoris, gastrocnemius), and the muscle activity was measured using 11-channel electromyography equipment. In order to verify the muscle activation according to the four strap lengths during TRX plank exercise, an one-way ANOVA with repeated measure was used with statistical significance level set at as α=.05. Results: First, there were statistically significant differences in pectoralis major, rectus abdominis, external oblique, internal oblique, and erector spinae among TRX strap lengths. Second, there were statistically significant differences in gluteus maximus, rectus femoris, and gastrocnemius among TRX strap lengths. Third, even though no statistically significant difference found in latissimus dorsi, but increased muscle activation tendency was showed as the length of the strap increased. Conclusion: From the results of this study, it may be possible that TRX exercise prevent injuries and improve lower extremity muscle as well as trunk muscles by setting appropriate length of strap.

• PNF and Movement
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• v.20 no.1
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• pp.67-72
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• 2022

Purpose: The aim of this study was to compare trunk and lower extremity muscle activity during deadlift on stable - and unstable surfaces. Methods: Twenty healthy men participated in this study. The participants performed deadlift exercise on both a stable surface and an unstable surface. During the deadlift, the activities of the trunk and lower extremity muscle were collected by using electromyography. Results: The results showed that the electromyographic activity of the gluteus maximus significantly increased during deadlift on an unstable surface compared to on a stable surface (p <0.05). However, in the electromyographic activities of the rectus femoris, biceps femoris, and erector spinae, there were no significant differences (p >0.05). Conclusion: The finding that the electromyographic activity of the gluteus maximus increases significantly during deadlift on an unstable surface compared to stable one could be used to develop an efficient exercise program.