• Physical Therapy Korea
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• v.2 no.1
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• pp.36-43
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• 1995

The purpose of this study was to determine whether the vastus medialis oblique muscle(VMO) had greater electrical activity than the vastus lateralis muscle(VL) when hip adduction and knee extension exercise were performed. Electrical activity of the VMO and VL was measured on 42 healthy subjects (28 men, 14 women) during maximal voluntary isometric contractions of hip adduction and knee extension by an EMG-BIOFEEDBACK. The results showed that the electromyographic activity of the VMO was significantly greater than that of the VL during the hip adduction exercise. Differences noted with knee extension by performing hip adduction exercises. Isometric hip adduction exercises, therefore, may be advisable in the treatment of patients with patellofemoral pain.

• PNF and Movement
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• v.15 no.2
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• pp.177-183
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• 2017

Purpose: This study compared and analyzed the effect of the proprioceptive neuromuscular facilitation (PNF) arm extension pattern and leg flexion pattern on the contralateral lower extremity muscles when the patterns were applied to the same subject. Methods: In the study, 35 healthy men and women who understood the PNF patterns were selected as participants. The participants completed the PNF arm extension-abduction-internal rotation pattern and leg flexion-adduction-external rotation with knee flexion pattern in the supine position. While the patients' completed each pattern, the contralateral leg muscle activity was measured to examine the irradiation effect. The maximum isometric contraction time of the muscles to be measured was kept for 5 seconds, and the mean value was obtained by repeating the pattern three times. Results: When the leg flexion-adduction-external rotation with knee flexion pattern was completed, the muscle activity in the vastus lateralis, vastus medialis, biceps femoris, tibialis anterior, and gastrocnemius of the contralateral lower extremity was significantly greater than that found in the PNF arm extension-abduction-internal rotation pattern. Conclusion: The PNF leg flexion pattern showed greater muscle activity on the contralateral lower extremity than the arm extension pattern. Thus, the PNF leg extension pattern is more effective in the activation of the muscles associated with weight-bearing activity.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.3
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• pp.249-253
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• 2014

PURPOSE: This study intends to examine the effects of change of anatomical position of the ankle joint in open kinematic chain, an appropriate position for selective muscle training, on vastus lateralis obliques, rectus femoris, vastus medilais obliques, and rectus abdominalis muscle activation and to present an effective method of muscle training for patients and normal people. METHODS: The participants of this study were Korean healthy adult in their 20s. The 8 channel surface electromyography was used to measure muscle activation while the subjects raised their legs under each condition. Under each condition, while the subjects raised the leg to hip joint flexion at $60^{\circ}$ along the arch. RESULTS: The analysis result of muscle activation by each section and position during leg rising. There were significant differences. CONCLUSION: For independent strengthening of each muscle, muscle activation was measured according to leg raising angles and the result differed according to each section and position. If this study result is applied to muscle training for patients who need selective muscle training, more effective muscle strengthening will be made possible.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1492-1495
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• 2008

As a prerequisite of developing muscle biofeedback system which can simulate analogous isokinetic exercise, the purpose of this study was to study the effects of frequency and amplitude of whole-body vibration on the difference in sEMG on lower extremities during leg press exercise with/without vibration. The amplitude of vibration was set to 20, 50, 80 and the frequency of vibration was set to 10, 20, 30, and 50 Hz. EMG were measured at Vastus lateralis muscle and Vastus medialis muscle. MP100 EMG module(BIOPAC system Inc., USA) was used for EMG measurement. The result showed that the combination of frequency of 30Hz and amplitude of 50 had more activated EMG than other combination with relatively small work load (30kg). It is necessary to experiment the frequency between 20 and 40Hz in detail, and to normalize sEMG using maximal voluntary contraction (MVC).

• The Journal of Korean Physical Therapy
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• v.27 no.4
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• pp.190-195
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• 2015

Purpose: The aim of this study was to determine the effects of isokinetic eccentric training (IET) on lower extremity muscle activation and walking velocity according to slow velocity and fast velocity of isokinetic eccentric training in stroke patients. Methods: Thirty subjects were randomly divided into three groups: experimental group I (n=10), group II (n=10), and control group III (n=10). Each group was provided intervention under three conditions, as follows: isokinetic eccentric training + slow velocity (group I), isokinetic eccentric training + fast velocity (group II), and sit to stand training (group III). The training program was conducted for eight weeks (five times per week; 30 minutes per day). Subjects were measured on lower extremity muscle (vastus lateralis, vastus medialis, gastrocnemius) activation and walking velocity. Analysis of covariance (ANCOVA) were performed for comparison of lower extremity muscle activation and walking velocity between different intervention methods. Results: Significant difference in lower extremity muscle activation and walking velocity was observed in experimental group I and group II compared with the control group III (p<0.01). Results of post-hoc analysis showed a significant in lower extremity muscle activation and walking velocity in group I compared with group II and group III. Conclusion: Findings of this study suggest that slow velocity and fast velocity using isokinetic eccentric training may have a beneficial effect on improvement of lower extremity muscle activation and walking velocity in stroke patients.

• PNF and Movement
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• v.16 no.1
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• pp.125-132
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• 2018

Purpose: The aim of this study was to investigate the isolated activation ratio of the quadriceps femoris muscle on different support surfaces during squat exercise. Methods: Twenty participants (10 males and 10 females) voluntarily agreed to participate in the research after receiving an explanation about the purpose and process of the study. Each participant performed squat exercises on three different support surfaces (a flat surface, a form roller, and an unstable surface). Muscle activities of the rectus femoris (RF), vastus medialis (VM), and vastus lateralis (VL) were measured by electromyography. The isolated activation ratio of the quadriceps femoris muscle was calculated using the %isolation formula. Results: For the squat exercise, the %isolation value of the VM was significantly higher on the unstable surface than on the flat surface and form roller. In contrast, the %isolation values for the RF for the squat exercise were significantly higher on the flat surface and form roller than on the unstable surface. There was no significant differences in the %isolation values of the VL on the three different surfaces. Conclusion: The findings indicate that squat exercise on different surfaces results in differential activation of the quadriceps femoris muscle, which suggests that squat exercise on a multi-directional unstable surface could increase the isolated activation ratio of the VM.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.11 no.1
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• pp.7-12
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• 2013

Purpose : The purpose of this study was to identify effects of virtual reality-based closed kinetic chain (CKC) exercise on lower extremity muscle activity in chronic stroke patients Methods : Subjects were assigned randomly either to VR+CKC exercise group (n=15) or the CKC exercise group (n=15). When the study began, both groups received conventional physical therapy five times per week. The VR+CKC exercise group received virtual reality programs and the CKC exercise group received close kinetic chain exercises. Each exercise program was performed for six weeks (5 times per weeks; 20 minutes per time). Participants were measured on lower extremity muscle activity using EMG. Results : There was a significant increase of muscle activity (%RVC) in vastus lateralis and vastus medialis. Conclusion : In this study, the virtual reality-based closed kinetic chain exercise program was an effective exercise for improving lower extremity muscle activity in chronic stroke patients.

• The Journal of Korean Physical Therapy
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• v.28 no.3
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• pp.212-216
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• 2016

Purpose: The current study seeks to identify the relationship between torque values of the quadriceps and muscle activity during isometric and isokinetic exercises. Methods: The subjects of the study included 29 healthy individuals 17 men and 12 women) who took part in isometric and isokinetic exercises that utilized the quadriceps. The isometric exercises were performed three times each at 4 different angles (0, 30, 60, and 90 degrees). For the isokinetic exercises, concentric contraction and eccentric contraction were undertaken three times each at two angular velocities (30 and 60 degrees). Results: The muscle activity of the quadriceps during the isometric exercises showed significant differences at the 30, 60, and 90 degree angles. During the concentric contractions and eccentric contractions, muscle activity at the peak torque of the quadriceps indicated significant differences in vastus medialis, vastus lateralis, and rectus femoris at angular velocities of 30 and 60 degrees. Conclusion: When applied clinically based on the biomechanical analysis of the current study, it is possible to anticipate and selectively strengthen muscles with isometric and isokinetic exercises for not only healthy adults and professional athletes, but also for those who experience limited knee movement for long periods following knee surgeries.

• Biomedical Engineering Letters
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• v.8 no.4
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• pp.345-353
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• 2018

This study suggested a new EMG-signal-based evaluation method for knee rehabilitation that provides not only fragmentary information like muscle power but also in-depth information like muscle fatigue in the field of rehabilitation which it has not been applied to. In our experiment, nine healthy subjects performed straight leg raise exercises which are widely performed for knee rehabilitation. During the exercises, we recorded the joint angle of the leg and EMG signals from four prime movers of the leg: rectus femoris (RFM), vastus lateralis, vastus medialis, and biceps femoris (BFLH). We extracted two parameters to estimate muscle fatigue from the EMG signals, the zero-crossing rate (ZCR) and amplitude of muscle tension (AMT) that can quantitatively assess muscle fatigue from EMG signals. We found a decrease in the ZCR for the RFM and the BFLH in the muscle fatigue condition for most of the subjects. Also, we found increases in the AMT for the RFM and the BFLH. Based on the results, we quantitatively confirmed that in the state of muscle fatigue, the ZCR shows a decreasing trend whereas the AMT shows an increasing trend. Our results show that both the ZCR and AMT are useful parameters for characterizing the EMG signals in the muscle fatigue condition. In addition, our proposed methods are expected to be useful for developing a navigation system for knee rehabilitation exercises by evaluating the two parameters in two-dimensional parameter space.

• The Journal of Korean Physical Therapy
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• v.33 no.1
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• pp.40-46
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• 2021

Purpose: This study compared the muscle activity of the lower limb according to the three types of fixed angles of the ankle joint during a lunge exercise. Methods: Twenty healthy subjects performed the lunge motion in a trial including the three types of fixed angle. The lunge motion with a neutral, 20° dorsiflexion, and 20° plantarflexion of the ankle joint were randomized and measured repeatedly. The muscle activity of the rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), and semitendinosus (ST) was measured by surface electromyography. Results: In the change in ankle joint angle, the RF, VL, BF, and ST muscle activity showed significant differences (p<0.05). In the 20° dorsiflexion position, the muscle activity of VL, BF, and ST showed a significant decrease compared to that in the neutral position (p<0.017). The muscle activity of RF and VL in the neutral position was greater than that in the 20° plantarflexion position (p<0.017). Only the muscle activity of the BF in the 20° plantarflexion position was significantly greater than the 20° dorsiflexion position (p<0.017). Conclusion: These results revealed a difference in the muscle activity of lower extremities in the proximal region according to the angle of the ankle joint during the lunge.