• 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.

• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.17-24
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• 2023

Objective: The purpose of this study was to investigate the effects of different frequency on of knee extensors muscle function during electrical muscle stimulation (EMS). Method: In this research, 40 subjects who have no musculoskeletal disorder, and less than a year workout experience were recruited in order to analyze effects of EMS with different stimulus frequency. Forty subjects were randomly divided into four groups of ten subjects in each group. A EMS training program with different frequencies (without EMS [WE], EMS with frequency 30 Hz [E30], EMS with frequency 60 Hz [E60], EMS with frequency 90 Hz [E90]) was assigned to each group. Throughout eight weeks of training, test subjects were simultaneously carried out knee extension exercises such as squat, leg extension, and leg-press while using EMS with different frequency (20 min, pulse width 250 ㎲, on-off ratio 1:1). Isokinetic knee extension strength, muscle activity of the rectus femoris (RF), the vastus medialis (VM), and the vastus lateralis (VL), and the median frequency of the RF, the VM, and the VL were collected and compared between pre and post training in order to find effects of applying EMS with different frequencies. For each dependent variable, a one-way ANOVA was to determine whether there were significant differences among four different conditions (p<.05). When a significant difference was found, post hoc analyses were performed using the contrast procedure. Results: When compared to WE and E90, E30 causes significant increase in isokinetic knee extension strength. No significant differences were found in EMG values across different EMS conditions. However, the median frequency of the VM in E30 was significantly increased than the corresponding value for WE. Conclusion: The results of this study showed that EMS training with 30 Hz frequency had positive effect on knee extensor. Based of the findings of the present study, EMS training with lower frequency may help the performer to focus on developing strength in knee extensor muscles.

• Journal of Korean Academy of Nursing
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• v.20 no.2
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• pp.195-213
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• 1990

The purpose of this study is to assess if EMG biofeedback training with progressive muscle relaxation training is effective in reducing the EMG level in patients with tension headaches. This study which lasted from 23 October to 30 December 1989, was conducted on 10 females who were diagnosed as patients with tension headaches and selected from among volunteers at C. University in Seoul. The process of the study was as follows : First, before the treatment the baseline was measured for two weeks and the level of EMG was measured five times in five minutes. And then EMG biofeedback training was used to six weeks, 12 sessions in at and progressive muscle relaxation was done at home by audio tape over eight weeks. Each session was composed of a 5-minute baseline, two 5-minute EMG biofeedback training periods and a 5-minute self-control stage. Each stage was followed by a five minute rest period. So each session took a total of 40 minutes. The EMG level was measured by EMG biofeedback (Autogenic-Cyborg : M 130 EMG module). The results were as follows : 1. The average age of the subjects was 44.1 years and the average history of headache was 10.6 years(range 6 months-20 yens). 2. The level of EMG was lowest between the third and the fourth week of the training except in Cases I and IV. 3. The patients began to show a nonconciliatory attitude at the first session of the fifth week of the training.

• Journal of The Korean Society of Integrative Medicine
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• v.2 no.3
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• pp.65-73
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• 2014

Purpose: The purpose of this study was to identify the effect of a kinesio tape on inspiratory muscle training(IMT) to improve muscle strength, endurance and pulmonary function. Methods: Healthy 20 males were divided into IMT group (control group) and IMT with tape group (experimental group). The same IMT program was applied to both groups using the Respifit S for four weeks, three times a week, a total 12 times. To exprimental group, kinesio tape was applied on the inspiratory agonist diaphragm and the accessory inspiratory muscle scalene, sternocleidomastoid, pectoralis minor. The inspiratory pulmonary muscle strength was measured by the maximal inspiratory pressure (PI max) and minute volume (MV) using the Respifit S and the pulmonary function were measured peak expiratory flow (PEF), forced vital capacity (FVC), forced expiratory volume in 1sec (FEV1), FEV1/FVC using the Spirometer and compared before and after. Results: Results showed that the PI max in the two groups increased significantly and experimental group increased more effectively than that of control group. However, only MV showed a significant increase in experimental group but was not significantly different between the two groups. PEF and FEV1/FVC are significantly increased in both groups, but they did not make much difference between two groups, and the FVC for the two groups did not increase significantly. FEV1 increased significantly only with control group, but did not make a difference with experimental group. Conclusion: These result show that the PI max value for experimental group increased significantly than that of control group. Therefore kinesio tape maximizes inspiratory muscle exercise effect on muscle strength improvement. However, because of the short experimental period and difficulty in subject control, increase values of the others did not show a significant difference. In other words, kinesio tape did not show maximizing the inspiratory muscle exercise effect to improve endurance and pulmonary function.

• Physical Therapy Korea
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• v.23 no.4
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• pp.27-37
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• 2016

Background: In previous studies regarding flexible pes planus, Foot orthosis, special shoes have been used as interventions for correcting malalignment and intrinsic muscles strengthening exercise have been regarded as interventions for foot function and supporting medial longitudinal arch during walking. However, some recent studies reported that strengthening extrinsic muscles as well as intrinsic muscles is more effective and active intervention for flexible pes planus. In particular, the tibialis posterior muscle of foot extrinsic muscles plays essential roles in maintaining the medial longitudinal arch during dynamic weight bearing and balance. In addition this muscle acts longer than other supination muscles during the stance phase in the gait cycle. Objects: This study aimed to investigate the effect of foot intrinsic muscle and tibialis posterior muscle strengthening exercise for plantar pressure and dynamic balance in adults with flexible pes planus. Methods: 16 young flexible pes planus adults (7 males, 9 females) were recruited and were randomized into two groups. The experimental group performed foot intrinsic muscle and tibialis posterior muscle strengthening training, the control group performed only foot intrinsic muscle strengthening training. All groups received strengthening training for 30 minutes five times a week for six weeks. Results: The experimental group had significantly lower plantar pressure of medial heel area than the control group in stand (p<.05). The experimental group had significantly higher dynamic balance ability than control group (p<.05). Conclusion: The results of this study provide evidence to suggest that foot intrinsic muscle and tibialis posterior muscle of extrinsic muscle strengthening exercises may improve plantar pressure distribution and dynamic balance ability in adults with flexible pes planus.

• Physical Therapy Korea
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• v.9 no.2
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• pp.115-131
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• 2002

Functional electrical stimulation (FES) training of the knee extensors is a useful way to rehabilitate the ability to stand and walk. However, training using FES has not been able to solve the problem of fatigue; clinical application of FES quickly produces muscle fatigue, due to the continuous activation of the muscles of the lower extremity. Therefore, reduction of muscle fatigue is an important factor in increasing the effectiveness of FES training in paraplegia. Intermittent high frequency alternating stimulation is a method that combines the advantages of high frequency (leading to strong muscle contractions) and alternating stimulation (reducing muscle fatigue), thereby continuously strengthening muscles. It is not known whether low frequency simultaneous stimulation results in stronger muscle contraction than high frequency alternating stimulation. This study compared the effectiveness of high frequency alternating stimulation with low frequency synchronized stimulation. Muscle power using FES on the quadriceps of 20 normal subjects were compared. Intermittent high frequency alternating stimulation did not produce more powerful muscle contraction than intermittent low frequency synchronized stimulation, because the muscle characteristics differed individually. Significant individual variation according to muscle characteristics was founded when applying FES. Accordingly, when physical therapists use FES to treat patients, they must be aware of individual variation in muscle characteristics.

• Korean Journal of Exercise Nutrition
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• v.16 no.2
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• pp.65-71
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• 2012

Oxygen is the final acceptor of electron transport from fat and carbohydrate oxidation, which is the rate-limiting factor for cellular ATP production. Under altitude hypoxia condition, energy reliance on anaerobic glycolysis increases to compensate for the shortfall caused by reduced fatty acid oxidation [1]. Therefore, training at altitude is expected to strongly influence the human metabolic system, and has the potential to be designed as a non-pharmacological or recreational intervention regimen for correcting diabetes or related metabolic problems. However, most people cannot accommodate high altitude exposure above 4500 M due to acute mountain sickness (AMS) and insulin resistance corresponding to a increased levels of the stress hormones cortisol and catecholamine [2]. Thus, less stringent conditions were evaluated to determine whether glucose tolerance and insulin sensitivity could be improved by moderate altitude exposure (below 4000 M). In 2003, we and another group in Austria reported that short-term moderate altitude exposure plus endurance-related physical activity significantly improves glucose tolerance (not fasting glucose) in humans [3,4], which is associated with the improvement in the whole-body insulin sensitivity [5]. With daily hiking at an altitude of approximately 4000 M, glucose tolerance can still be improved but fasting glucose was slightly elevated. Individuals vary widely in their response to altitude challenge. In particular, the improvement in glucose tolerance and insulin sensitivity by prolonged altitude hiking activity is not apparent in those individuals with low baseline DHEA-S concentration [6]. In addition, hematopoietic adaptation against altitude hypoxia can also be impaired in individuals with low DHEA-S. In short-lived mammals like rodents, the DHEA-S level is barely detectable since their adrenal cortex does not appear to produce this steroid [7]. In this model, exercise training recovery under prolonged hypoxia exposure (14-15% oxygen, 8 h per day for 6 weeks) can still improve insulin sensitivity, secondary to an effective suppression of adiposity [8]. Genetically obese rats exhibit hyperinsulinemia (sign of insulin resistance) with up-regulated baseline levels of AMP-activated protein kinase and AS160 phosphorylation in skeletal muscle compared to lean rats. After prolonged hypoxia training, this abnormality can be reversed concomitant with an approximately 50% increase in GLUT4 protein expression. Additionally, prolonged moderate hypoxia training results in decreased diffusion distance of muscle fiber (reduced cross-sectional area) without affecting muscle weight. In humans, moderate hypoxia increases postprandial blood distribution towards skeletal muscle during a training recovery. This physiological response plays a role in the redistribution of fuel storage among important energy storage sites and may explain its potent effect on changing body composition. Conclusion: Prolonged moderate altitude hypoxia (rangingfrom 1700 to 2400 M), but not acute high attitude hypoxia (above 4000 M), can effectively improve insulin sensitivity and glucose tolerance for humans and antagonizes the obese phenotype in animals with a genetic defect. In humans, the magnitude of the improvementvaries widely and correlates with baseline plasma DHEA-S levels. Compared to training at sea-level, training at altitude effectively decreases fat mass in parallel with increased muscle mass. This change may be associated with increased perfusion of insulin and fuel towards skeletal muscle that favors muscle competing postprandial fuel in circulation against adipose tissues.

• PNF and Movement
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• v.6 no.1
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• pp.41-51
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• 2008

Purpose : This paper reviews evidence supporting adaptive plasticity in skeletal muscle fibers induced by various exercise training and neuromuscular activity. Result : Skeletal muscle fiber demonstrates a remarkable adaptability and can adjust its physiologic and contractile makeup in response to alterations in functional demands. This adaptive plasticity results from the ability of muscle fibers to adjust their molecular, functional, and contractile properties in response to altered physiological demands, such as changes in exercise patterns and mechanical loading. The process of activity-dependent plasticity in skeletal muscle involves a multitude of signalling mechanisms initiating replication of specific genetic sequences, enabling subsequent translation of the genetic message and ultimately generating a series of myosin heavy chain isoform. Conclusions : Knowledge of the mechanisms and interaction of activity-dependent adaptive pathways in skeletal muscle is important for our understanding of the synthesis of muscle myosin protein, maintenance of metabolic and functional capacity with physical activity, and therapeutic intervention for functional improvement.

• 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.12 no.3
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• pp.94-100
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• 2005

Eccentric muscle contraction is more effective than concentric and iosmetric muscle contraction in increasing muscle strength. Also, eccentric or concentric-eccentric training has greater effective in neural activation and muscle hypertrophy than concentric training. In some study, eccentric exercises have been shown to reduce pain and improve function on Achilles tendinopathy. The purpose of this study was to evaluate the effect of eccentric isokinetic exercise in a patient with dislocation of the tarsometatarsal joint by traffic accident. After eccentric isokinetic training, peak torque, average work, and average power were increased. Also, the patient was fully weightbearing with a pain free normal gait thus making good recovery.