• Journal of the Ergonomics Society of Korea
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• v.29 no.5
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• pp.789-795
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• 2010

This study aimed to investigate the effect of differing heel height on static balance and muscle activation of ankle joint during standing. Twenty-one young females volunteered to participate in this study. To measure balance function and EMG activity of tibialis anterior and gastrocnemius muscles, the subjects were asked to perform 1-min standing with eyes open and closed state under 3 different heel heights: barefoot, 3cm, and 7cm each. During the standing, postural sway distance and area, and EMG activity of tibialis anterior and gastrocnemius muscles were significantly augmented with increasing heel height (p<0.05). For comparison between eyes open and closed in terms of postural sway area and EMG activity of tibialis anterior muscle, barefoot and 7cm height conditions respectively showed significant differences as well. The findings indicate that high-heeled shoes may have disadvantages in maintaining balance function because of extra-muscular effort of ankle joint. This study provides useful information that will inform future studies on how heel height affects muscle activity around the ankle joint in aspects of static and dynamic balance.

• Journal of the Korean Society of Physical Medicine
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• v.3 no.3
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• pp.151-160
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• 2008

Purpose : The purpose of this study is to know the muscle activation after sub-talar joint mobilition and active exercise, and the low leg muscle activity through the well-balanced interaction of ankle joint around muscle. Methods : For this study 61 experimental subjects are divided into 24 people of supination foot group, pronation foot group 17 people of, 20 people of control group through navicular drop test. Surface EMG was used in order to measure the muscle activities. following is the result of the data analysis about each experiment that has been carried on a week, 2 weeks, 3 weeks, 4 weeks before, and even comparing with pre-experimental state. Results : In electromyogram study, the higher muscle activation there was before the experiment, the more muscle activation increase there was after the experiment in Tibialis Anterior, Peroneus Longus, Peroneus Brevis.(p<.05). Conclusion : This study shows the balanced activation of foot and ankle-around muscle. It shows that foot shape affects the balanced activation recovery of lower leg muscles.

• Journal of the Ergonomics Society of Korea
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• v.30 no.2
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• pp.291-296
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• 2011

This study was designed to investigate the effects of an ankle foot orthosis(AFO) with variable ankle joint angles on balance performance in healthy adults. Eighteen healthy adults were recruited in this repeated measures design with subjects as their own controls. An AFO with four kinds of ankle joint angles(-5, 0, 5, and 10 degree) were used and balance performance was measured during single limb standing. Three trials were obtained and then averaged for data analysis. Foot pressure was measured using an F-scan system and muscle activity was measured using an MP150 system. There were significant differences in balance performance with ankle joint angles. An AFO with -5 degrees was associated with significant increases in postural sway(anterior-posterior), and in muscle activity for the medial gastrocnemius and tibialis anterior compared with other degrees of angle. Findings of this study show that angles of an AFO are related to balance performance and a joint angle of 10 degree is effective for promoting joint stability and postural control. This information can be used by clinicians to prescribe AFOs.

• Korean Journal of Applied Biomechanics
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• v.22 no.1
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• pp.9-16
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• 2012

The purpose of this study was to compare and analyze muscle function and EMG of the trunk and the lower extremity in short and long distance athletes and in order to determine difference in peak torque per unit weight, muscle power per unit weight, endurance ratio, and %MVIC classified by muscle. For that purpose, isokinetic muscle function tests for waist, knee, and ankle joints and EMG measurements for the trunk and the lower extremity muscle with running motion were conducted for 7 short and long distance high school athletes respectively. The study over muscle function of waist, knee, and ankle joints indicates that peak torque per unit weight of short distance athletes is higher than that of long distance athletes in extension and flexion of waist joint, plantar flexion of right ankle joint, and dorsi flexion of left ankle joint. In case of the muscle power per unit weight of short distance athletes is also higher than long distance athletes in waist, knee, and ankle joints. No difference in endurance ratio of waist, knee, and ankle joints between the two groups was founded. The results of the test over EMG of the trunk and the lower extremity show that %MVIC of erector spinae, rectus femoris, vastus medialis, vastus lateralis, and tibialis anterior is higher than that of long distance athletes in support phase. The above results proved to be the same in flight phase except for %MVIC of medial gastrocnemius. In other words, %MVIC of medial gastrocnemius for short distance athletes turned out to be higher than that of long distance athletes in flight phase.

• Physical Therapy Korea
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• v.27 no.2
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• pp.133-139
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• 2020

Background: The gastrocnemius (GCM) is one of the lower extremity muscles that tend to tighten easily. GCM tightness results in limited ankle dorsi-flexion (DF), especially when the knee joint is fully extended. Joint flexibility is determined by the morphological and physiological characteristics of joints, muscles, tendons, and ligaments. Impaired joint flexibility can be attributed to increased susceptibility to muscle injury. High-frequency diathermy is clinically used to reduce pain and muscle tightness and to improve limited range of motion. Objects: This study aimed to investigate the immediate effects of high-frequency therapy in subjects with GCM tightness. Methods: The study was designed as a one-group before-after trial. The subjects included 28 volunteers with GCM tightness (an active ankle DF angle of less than 12°) without any known neurological and musculoskeletal pathologies in the ankle and calf areas. WINBACK Transfer Electrode Capacitive and Resistive Therapy equipment was used to apply high-frequency therapy to the subjects' GCMs for 10-15 minutes. The pennation angle and the fascicle length of the GCM were measured using ultrasonography. The flexibility of the ankle joint, peak torque to the passive ankle DF (Biodex), and soft tissue stiffness (MyotonPRO) were also measured. Results: The pennation angle was significantly decreased following the treatment; however, no significant difference in the fascicle length was found (p < 0.05). The flexibility was significantly increased and both the passive peak torque to passive ankle DF and the soft tissue stiffness significantly decreased (p < 0.05). Conclusion: High-frequency therapy is immediately effective for improving the muscle's architectural properties and functional factors in subjects with GCM tightness. Further longitudinal clinical studies are required to investigate the long-term effects of high-frequency therapy on subjects with GCM tightness from various causes.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.4
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• pp.113-122
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• 2017

PURPOSE: The purpose of this study was to investigate the comparison of muscle activity and mechanical loading according to the angle of ankle joint during a sit-to-stand (STS) task. METHODS: Thirty-four young participants performed the STS in a randomized trial with the ankle joint at a neutral, 15 degrees dorsiflexion and 15 degrees plantarflexion angle in a fixed sitting posture with the knee in 105 degrees flexion. Muscle activity of the tibialis anterior (TA), rectus femoris (RF), biceps femoris (BF), and gastrocnemius medialis (GCM) was measured, and the parameters calculated in relation to mechanical loading were the STS-time, maximum peak, minimum peak, and total sum of mechanical loading. RESULTS: In the dorsiflexion position, the muscle activity of the TA and GCM showed a significant increase (p<.05), and the STS time, maximum peak and total sum of mechanical loading showed a significant difference compared to that in the neutral position (p<.05). In the plantarflexion position, the muscle activity of the RF and GCM showed a significant increase (p<.05), while that of the TA showed a significant decrease (p<.05) compared to that in the neutral position. And the minimum peak was significantly increased than the neutral position (p<.05), and the maximum peak and total sum of mechanical loading were showed significant difference compared with dorsiflexion position (p<.05). CONCLUSION: These results show that there is a difference in muscle activity and mechanical loading when performing the STS movement according to the change in the ankle joint angle.

• Physical Therapy Rehabilitation Science
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• v.6 no.1
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• pp.39-44
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• 2017

Objective: The purpose of this study is to show the effectiveness of performing squat exercises at various angles to show the maximum muscle activity of the Vastus Medialis Oblique (VMO) and Biceps femoris (BF). Design: Cross-sectional study. Methods: A total of seventeen healthy young adults (8 males and 9 females) voluntarily participated in the study. All subjects randomly performed three different squat variations as follows: A squat performed with the ankle joint at $0^{\circ}$ of incline, a squat performed with the ankle joint at $5^{\circ}$ of incline, and a squat performed with the ankle joint at $10^{\circ}$ incline. Muscle activity was measured using surface electromyography. Electrodes were placed on the VMO and BF to measure the muscle activity on the various ankle angles for comparison analysis. Results: There was a significant increase in bilateral VMO muscle activation at $10^{\circ}$ of incline compared to $0^{\circ}$ and $5^{\circ}$ (p<0.05). Greater increases in muscle activation and exercise effect was observed with increasing incline angles of the board. Changes in bilateral BF muscle activity were found; however, none were found to be significant. Conclusions: Bilateral VMO activity was found to be significant when the squats were performed at an ankle angle of $10^{\circ}$ of incline when compared to at an ankle angle of $0^{\circ}$ and $5^{\circ}$ of incline. Squats performed on an incline can be recommended as an effective method to facilitate lower extremity muscle activities.

• The Journal of Korean Physical Therapy
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• v.27 no.6
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• pp.386-391
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• 2015

Purpose: This study investigated whether the strength imbalance between two muscles can affect the score of EMG based biofeedback game, and whether the EMG based biofeedback game score can be used as predictable indicator of the degree of muscle balance alternating the conventional strength measuring equipment. Methods: 40 participated in this study. Biodex was used to measure the peak torque/weight in order to calculate the muscle strength balance index between plantar flexor and dorsiflexor of ankle joint. And muscle balance index (MBI) was calculated. The EMG biofeedback game scores of dorsiflexor and plantar flexor were acquired, so that the EMG electrodes were attached at tibialis anterior and gastrocnemius. The relationship between the game score and the muscle balance index were analyzed. Results: There was negative correlation between the muscle balance index between plantar flexor and dorsiflexor and the peak torque/weight of plantar flexor (r=-0.70). And there was negative correlation between the muscle balance index between plantar flexor and dorsiflexor and the game score of plantar flexor (r=-0.83). Conclusion: The EMG biofeedback game score had significant relationship with muscle imbalance at ankle joint, so it seems that the game score can be used for predicting the degree of muscle imbalance as a parameter.

• Physical Therapy Rehabilitation Science
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• v.12 no.3
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• pp.340-345
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• 2023

Objective: The purpose of this study was to investigate the effect of thoracic spine and ankle joint alignment on trunk and upper limb muscle activity during trunk forward lean exercise using a sling. Methods: 25 subjects participated in this study. All subjects performed trunk forward lean exercise using a sling under four conditions according to the alignment of the thoracic spine and ankle joints. Trials were performed 3 times in each condition. Muscle activity of the trunk and upper extremity was measured using electromyography. Results: In the dorsiflexion, the thoracic kyphosis condition showed significantly higher muscle activity in the pectoralis major, rectus abdominis, latissimus dorsi, transverse abdominis than dorsiflexion(p<0.05). In the plantar flexion, thoracic kyphosis condition showed significantly higher muscle activity in pectoralis major, transverse abdominis, latissimus dorsi muscle activity than dorsiflexion(p<0.05). Conclusions: Regardless of ankle alignment, thoracic kyphosis condition increased the activity of the pectoralis major, transverse abdominis, latissimus dorsi. Therefore, regardless of the alignment of the ankle, it is recommended to perform the trunk forward lean exercise using a sling in thoracic kyphosis.

• Physical Therapy Korea
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• v.12 no.3
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• pp.46-55
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• 2005

The purpose of this study was to evaluate the effect of concurrent and reciprocal isometric contraction and angle of ankle joint on fatigue of concentrically contracting contralateral dorsiflexor and plantar flexor. Seventeen able-bodied subjects participated in the study. Concurrent and reciprocal isometric contraction were performed under three different ankle joint angles (dorsiflexion, neutral position, plantar flexion). During concurrent or reciprocal isometric contraction. fatigue of concentrically contracting contralateral tibialis anterior, gastrocnemius, and soleus was investigated and compared. There was no interaction between different ankle joint angles and direction of isometric contraction (p<.05). No significant differences were found among three different ankle joint angles (p<.05). Contralateral muscle fatigability was lower in reciprocal isometric contraction than that in concurrent isometric contraction (p<.05). Therefore, the findings of this study suggest that reciprocal isometric contraction is more beneficial than concurrent isometric contraction inducing less fatigability during contralateral concentric contraction.