• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.111-119
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• 2007

The purpose of this study was to investigate muscle activity and gait pattern in lower limb depending on the outsole of heel rockers. Fifteen healthy men volunteered for this experiment. Each subject performed totally three trails with two pairs of different heel rocker shoes and a pair of normal running shoes at speed of 1.33m/s for 1 minute during walking on a treadmill. Kinematic data gathered in 100Hz was recorded and analyzed by using the 3D motion capture system to measure the trunk tilt and joint angle of the right lower limb. And the lower extremity muscle activities were simultaneously recorded in 1000Hz and assessed by using EMG. The statistical analysis was the one-way ANOVA with the repeated measures to compare among the three kinds of shoes. The level of statistical significance for all tests was 0.05. Joint angle of lower limb was showed statistically significant different in MST(hip joint), LHS(ankle joint), and RTO(knee and ankle joint). Muscle activity of rectus femoris and biceps femoris was statistically increased in both heel rocker shoes during gait cycle on treadmill. The maximum peak time of tibialis anterior in the negative heel rocker showed the delay of approximately 23.8%time than normal shoes. Gait pattern variability of the negative heel rocker was increased in the first half of the stance phase and the variability of the positive heel rocker was increased in the terminal stance phase. In Conclusion, stability was decreased in between joints of lower limb on positive heel rocker than negative heel rocker. This study found that there were different joint angle, muscle activity, gait pattern and coordinate system of the lower limb in each kind of shoes. These unstability affected the lower extremity and the whole body. A further study has to be continued with study of rehabilitation and exercise for a long-term.

• Physical Therapy Rehabilitation Science
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• v.4 no.1
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• pp.38-43
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• 2015

Objective: To investigate and compare the size of the rectus femoris (RF), tibialis anterior (TA), and medial gastrocnemius (GMM) using ultrasound (US) imaging in young, elderly, and very elderly groups. Design: Cross sectional study. Methods: This study consisted of 25 young (age 20 years), 24 elderly (age 65-74 years), and 25 very elderly (age 75-90 years) people with no physical dysfunctions. The cross sectional area (CSAs) of the RF and muscle thickness of the TA and GMM were measured at rest and during contraction using an US system. Results: The CSA of the RF and thickness of the TA and GMM were significantly smaller in the elderly and very elderly groups than in the young group (p<0.05). There was a significant difference of the CSA of the RF at rest and during contraction between elderly and very elderly group (p<0.05). In the comparison of the TA and GMM thickness between elderly and very elderly groups, there were no significant differences except for the TA thickness during contraction. There was a significant difference in the percentage change in RF CSA among the three groups (p<0.05). Conclusions: Our results revealed loss of muscle mass in the RF, TA, and GMM in elderly and very elderly people (${\geq}65$ years old). In particular, the greatest age-related decline in muscle mass was observed for the RF. Furthermore, the CSA of the RF declined with aging in the very elderly groups (${\geq}75$ years old).

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.225-232
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• 2019

This study aims to compare muscle activities of trunk and lower extremities according to wearing/not-wearing and forms of backpack. Twenti-six healthy adults were participated in the study. In the backpack with 10% body weight, trunk and lower extremities were measured during carrying the no backpack state(NBs), general backpack state(GBs), a decrease moment arm backpack state(DMBs). The muscle activity in a fore muscles(Obilique, Quadriceps, Tibialis anterior, Gastrocnemius) were analyzed with using wireless electromyogram measuring system. DMBs showed significant improvemet in obilique, quadriceps and gastrocnemius muscle RVC.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.3
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• pp.29-37
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• 2019

PURPOSE: Prone hip extension (PHE) has been used for assessment of lumbo-pelvic movement and strengthening exercise for weakness of the hip joint muscles in patients with chronic low back pain (CLBP). On the other hand, few studies have examined which are the best PHE exercises to activate the gluteus maximus (GM) selectively in physical therapy practice. To aim of this study compared the muscle activity of the GM, rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA) during these four different prone hip extensions, PHE, PHE with quadriceps activation (PHEQA), PHE with ankle dorsiflexion (PHEAD), and PHE with ankle plantarflexion (PHEAP), in subjects with CLBP. METHODS: Nineteen subjects with low back pain participated in this study. Subject performed four PHE exercises and surface electromyography (EMG) was used to evaluate the muscle activity. Data were analyzed by one-way repeated-measures analysis of variance (${\alpha}=.05/3=.017$) and a Bonferroni adjustment was performed if a significant difference was found. RESULTS: The muscle activities recorded by EMG showed significant among the four exercises. The muscle activity of the GM increased significantly during PHEQA than during PHEAP (P=.012). CONCLUSION: PHEQA is the most effective exercise for eliciting greater GM muscle activation among the four PHE exercises in subjects with CLBP.

• Korean Journal of Applied Biomechanics
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• v.32 no.2
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• pp.43-48
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• 2022

Objective: The purpose of this study was to verify the effectiveness among simulating ski jumping trainings by comparing with actual ski jump. Method: Three healthy youth national athletes were recruited for this study (age: 13.70 ± 0.9 yrs, height: 169.30 ± 0.9 cm, jumping caree: 5.3 ± 0.9 yrs). Participants were asked to performed ski jumping with 3 simulating and one actual situation. A 3-dimensional motion analysis with 5 channels of EMG was performed in this study. Muscle activations of Rectus Femoris [RF], Tibialis Anterior [TA], Thoracis [TH], Gluteus maximus [GM], and Gastronemius [GL] were achieved with sampling rate of 2,000 Hz during each jump. Results: In the case of S1 in the actual jumping motion, the deviation of the muscle activity peak did not appear each trial, and the jump timing was consistent. For S2, the timing of the muscles peak activation which can maintain the posture of the upper body and ankles appeared at the beginning. In the case of S3, the part maintaining the ankle posture at the beginning appeared, but it could be expected that it would progress in the vertical direction due to the activation of GL at the time of jumping. Conclusion: The muscle activation peak before the take-off point showed a different pattern for each athlete, and individual differences were large. In addition, it was attempted to confirm the actual jump with simulation jump, and it was found that not only the difference in patterns but also the fluctuations in the timing of each muscle activation peak were large.

• Journal of the Korea Society of Computer and Information
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• v.28 no.2
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• pp.143-151
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• 2023

This study examined the changes in lower body muscle activity and foot pressure during progressive squat exercise in male college students. It was conducted to help efficient exercise guidance by identifying and recognizing muscle imbalance using EMG and smart shoes and providing immediate feedback. The subjects of the study were 20 students from D University. As a result of this study, as the squat load increased, the activity of all muscles except for the left semitendinosus muscle and the anterior tibialis muscle significantly increased among. Foot pressure, when the squat load was increased, the pressure of the forefoot(FF) increased significantly and the pressure of the rear foot(RF) decreased significantly. Therefore, providing immediate feedback using a wearable device will prevent muscle imbalance and provide effective exercise guidance.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.4
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• pp.113-121
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• 2022

PURPOSE: This study is examined the effects of vestibular stimulation through eye movement on balance and muscle activity. METHODS: In 42 healthy adults, no eye exercise was applied to both feet and one foot. The speed of smooth pursuit eye movement (.2 Hz, .3 Hz, and .5 Hz) and saccadic eye movement (.5 Hz and 1.1 Hz) were randomized. The measurements were taken three times for 30 seconds while standing on two feet and measured three times for 10 seconds while standing on one foot. The muscle activity measurement equipment was used to measure the electromyogram signals of the tibialis anterior, peroneus longus, gastrocnemius medialis, vastus medialis, vastus lateralis, biceps femoris, abdominal internal oblique, and erector spinae muscle. RESULTS: As a result of this study, when applying smooth pursuit eye movement on one leg, the pressure center movement increased, the muscle activity of the lower extremity increased, in the saccadic eye movement, and the center of pressure decreased. CONCLUSION: Accordingly, the smooth pursuit of eye movement, the intervention of this study, affects balance. Through this, the balance can be improved by applying eye movement to the target who needs to improve the balance ability.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.3
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• pp.59-67
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• 2022

PURPOSE: This study examined the effectiveness of task gait exercise combined with self-observation training to provide basic clinical data by analyzing the factors that task gait exercise combined with self-observation training has on the leg muscle activity and gait improvement in stroke patients. METHODS: The subjects were assigned randomly to experimental Group I, which mediated task gait exercise combined with self-observation training, and experimental Group II, which mediated task-walking movement. They received 30-minute interventions three times a week for four weeks. The leg muscle activity and 10 m walking test (10MWT) were conducted as pre-intervention tests, and they underwent a post-test four weeks later in the same manner as the pre-test. RESULTS: A statistically significant difference was observed in all muscles and 10MWT (p < .01) in experimental group I (p < .05), while there were significant differences only in the rectus femoris, biceps femoris, and 10MWT (p < .05). In a comparison of the changes between groups, there were statistically significant differences only in the tibialis anterior, soleus muscle, and 10MWT (p < .05). CONCLUSION: Self-observation training in experimental group I was effective in increasing the leg muscle activity and improving walking speed by discovering and correcting incorrect movements and following a normal gait pattern using the ankle joint. Therefore, the task gait exercise combined with self-observation training should be introduced and actively utilized for the rapid social recovery of stroke patients.

• Physical Therapy Korea
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• v.24 no.4
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• pp.46-53
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• 2017

Background: The MLA is supported by both the abductor hallucis (ABH) and the extrinsic muscles. Insufficient muscular support may lower the MLA when the body's weight is applied to the foot. The short foot exercise (SFE) is effective in increasing the height of the MLA for people with flat feet. Most of the research related to the SFE has simply evaluated the efficiency of the exercise using enhanced ABH electromyography (EMG) activation. Since the tibialis anterior (TA), peroneus longus (PER), and ABH are all involved in supporting the MLA, a new experiment design examining the EMG of the selected muscles during SFE should be applied to clarify its effect. Objects: Therefore, this study aimed to clarify the effect of the SFE in different ankle position on the MLA angle and the activation of both the intrinsic and extrinsic muscles and to determine the optimal position. Methods: 20 healthy subjects and 12 subjects with flat feet were recruited from Yonsei University. The surface EMG and camera were used to collect muscle activation amplitude of TA, PER, and ABH and to capture the image of MLA angle during SFE. The subjects performed the SFE while sitting in three different ankle positions-neutral (N), dorsiflexion (DF) at 30 degrees, and plantar flexion (PF) at 30 degrees. Results: ABH EMG amplitudes were significantly greater in N and DF than in PF (p<.05). Muscle activation ratio of TA to ABH was the lowest in PF (p<.05). MLA angle in both groups significantly decreased in PF (p<.01). The TA and ABH was activated at the highest level in DF. However, in PF, subjects significantly activated the ABH and PER with relatively low activation of TA. Conclusion: Therefore, researchers need to discuss which SFE condition most effectively use the arch support muscle for flat foot.

• Physical Therapy Korea
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• v.11 no.2
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• pp.17-25
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• 2004

The purpose of this study was to assess the effect of applied insole types to lower extremities muscle fatigue during treadmill exercise. The control group and each different insole type group consisted of ten healthy male subjects. In the control group and each different insole type (soft type; 10 shore, semi-rigid type; 33 shore, rigid type; 50 shore) treadmill exercise was performed in twenty-five minutes. The electromyography (EMG) signals of four muscle (tibialis anterior, gastrocnemius medialis, rectus femoris, biceps femoris) were recording at sampling rate of 1024 Hz during treadmill exercise. The localized muscle fatigue (LMF) can be investigated using power spectral analysis. When did data analysis that excepted initial five minutes. The raw EMG signals was processed using the fast Fourier Transformation (FFT) and the median power frequency value was determined in initial ten second period and in last ten second period. Fatigue index was calculated and collected data were statistically analyzed by SPSS version 10.0 two-way using analysis of variance (ANOVA) with repeated measures ($4{\times}4$) was used to determine the main effect and interaction. Post hoc was performed with least significant difference. A level of significance was .05. Muscles fatigue index were significantly decreased in insole types (p<.05) and not significantly different in muscle (p>.05). Post hoc analysis shows that fatigue index in soft insole type, semi-rigid insole type and rigid insole type were lower than that control group (p=.028, p=.146, p=.095). There were no interaction between insole type and muscles (p>.05). The finding of this study can be used as a fundamental data when insole is applied and insole can be used to decreased of a fatigue during the dynamic exercise.