• The Journal of Korean Physical Therapy
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• v.22 no.5
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• pp.33-38
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• 2010

Purpose: This study examined the activation of the rectus abdominis (RA), external abdominal oblique (EO), transversus abdominis, internal abdominal oblique (TrA/IO), and Multifidus (MF) muscles while stabilization exercise was performed in a four-point kneeling position. Methods: Experiments were conducted on 21 healthy male adults (mean age=25.29 years) who voluntarily agreed to participate in the study. Each subject was instructed regarding maximal voluntary contractions (MVC) and stabilization exercise in four-point kneeling. While MVC and stabilization exercise of individual muscles were being performed, activation of the muscles was measured using surface electromyography (EMG). Activation of the muscles while performing stabilization exercise in four-point kneeling was normalized to a percentages of the MVC. Results: Left RA, right TrA/IO, right and left MF muscles showed significant differences among the positions. Conclusion: Selecting an optimal position can aid subjects on physical conditions while performing stabilization exercises in the four-point kneeling position.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.158-161
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• 1989

This paper describes the AR model of EMG signal during maximum voluntary contraction. By comparing the AR coefficients and the reflection coefficients of the AR model with the median frequency of power spectrum, it if proved that muscle fatigue can be measured by the AR and the reflection coefficients. In the estimation procedure of AR model parameter, the auto-correlation method is superior to the covariance method, and it is determined that the optimal order is six. As the muscle becomes fatigue, the median frequency of power spectrum is declined, and the AR coefficient [$a_1$ ] and the reflection coefficient [$k_1$ ] are also decreased. Therefore the muscle fatigue can be measured by the AR parameter.

• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.117-120
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• 2001

Low back pain has been known as the most frequent musuculoskeletal disorders in modern industrial society and cost by low back pain is increasing mon and more. The asymmetric lifting has been identified as a major risk factor of low back pain. In this study, the muscle activity and muscle exertion level during asymmetric load handling (without trunk flexion) was estimated. The results of normalized MVC measurement were decreased about 16％, 24％, 34％ respectively as the asymmetric angle was $30^{\circ}$, $60^{\circ}$, $90^{\circ}$. From the results of EMG measurement contralateral muscles were more active than ipsilateral muscles. RMSEMG values of right erector spinae muscles were decreased as the work posture went to 90$^{\circ}$ and those of left erector spinae muscles were increased until the asymmetric angle was 40$^{\circ}$ but decreased continually over 40$^{\circ}$. And for seven of subjects, activities of left and right latissimus dorsi muscles were maintained constantly, while for remainer, those were irregular.

• Journal of Oral Medicine and Pain
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• v.30 no.4
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• pp.411-426
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• 2005

The purpose of this study was to investigate the effects of occlusal condition and clenching level on the mandibular torque rotational movement. For this study, healthy 14 men without any symptoms and signs of temporomandibular disorders were selected. Mandibular torque rotational movement was observed in each circumstance of combination of three occlusal conditions such as natural dentition, with wafer of 3.6 mm thickness, and wafer with resin stop of 14 mm thickness total during hard biting of bite stick at maximum voluntary contraction(MVC) and 50% of MVC level of surface EMG activity of masseter muscle. Electromyographic activity and mandibular torque rotational movement were observed using BioEMG and BioEGN in $BioPak^{(R)}$ system. Each biting movement in each circumstance was composed of clenching one time and hard biting of wooden stick two times. The observed items were opening distance, velocity and amount of torque rotational movement in mandibular movement, and the data were statistically processed with $SPSS^{(R)}$ windows (ver.10.0). The results of this study were as follows: 1. There were no differences in the mandibular movement distance between those value in both biting sides, and between those in both clenching forces, but the mandibular velocity showed a different results by clenching force. For the amount of torque rotational movement, there were no difference in the value of the frontal plane but some significant difference was in the value of the horizontal plane by biting side. 2. The mandibular movement distance and the mandibular velocity in both planes were higher by maximum voluntary contraction than those by half maximum voluntary contraction, and amount of torque rotational movement in the horizontal plane was also increased by maximum voluntary contraction. 3. The opening distance in both planes were decreased with the increase of vertical dimension of occlusion, namely, by the occlusal appliances, and this pattern was also showed in the mandibular velocity in case of hard biting by maximum voluntary contraction. However, the amount of torque rotational movement were not different by the increase of vertical dimension of occlusion. 4. The value of angle and distance of the torque rotational movement in the hard biting of wooden stick were generally higher than those in the clenching without wooden stick in both planes without regard to occlusal conditions and/or clenching forces.

• Physical Therapy Korea
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• v.16 no.2
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• pp.67-76
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• 2009

In order to prevent upper extremity musculoskeletal disorders, effective keyboard selection is an important consideration. The aim of this study was to compare upper extremity muscle activity according to transverse plane angle changes during vertical keyboard typing. Sixteen healthy men were recruited. All subjects had a similar typing ability (rate of more than 300 keystrokes per minute) and biacromion and forearm-fingertip lengths. Four different types of keyboard (vertical keyboard with a transverse plane angle of $60^{\circ}$, $96^{\circ}$, or $120^{\circ}$, and a standard keyboard) were used with a wrist support. The test order was selected randomly for each subject. Surface electromyography (EMG) was used to measure upper extremity muscle activity during a keyboard typing task. The collected EMG data were normalized using the reference contraction and expressed as a percentage of the reference voluntary contraction (%RVC). In order to analyze the differences in EMG data, a repeated one-way analysis of variance, with a significance level of .05, was used. Bonferroni correction was used for multiple comparisons. There were significant differences in the EMG amplitude of all seven muscles (upper trapezius, middle deltoid, anterior deltoid, extensor carpi radialis, extensor carpi ulnaris, flexor carpi radialis, and flexor carpi ulnaris) assessed during the keyboard typing task. The mean activity of each muscle had a tendency to increase as the transverse plane angle increased. The mean activity recorded during all vertical keyboard typing was lower than that recorded during standard keyboard typing. There was no significant difference in accuracy and error scores; however, there was a significant difference between transverse plane angles of $60^{\circ}$ and $120^{\circ}$ with regard to comfort. In conclusion, a vertical keyboard with a transverse plane angle of $60^{\circ}$ would be effective in reducing muscle activity compared with vertical keyboards with other transverse plane angles.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.3 no.1
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• pp.49-59
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• 2005

This study assigns each 8 of 24 normal persons to control group(Group I), strength increase group(Group II) and endurance increase group(Group III) to analyze differences in changes of strength and endurance with surface electromyography and kinetics according to application modes of neuromuscular electrical stimulation(NMES). Group I had not any treatment, group II performed 15 repeated contraction with 60% intensity of maximal voluntary isometric contraction(MVIC) by setting 10-sec on time and 50-sec off time and group III conducted 30 repeated contraction with 30% intensity of MVIC by setting 10-sec on time and 20-sec off time. For neuromuscular electrical stimulation, 2,500 Hz of Russian current, 35 pps of pulse rate and 200 of pulse width. Neuromuscular electrical stimulation was conducted by five times for total 4 weeks. Before and after experimentmotor unit action potential of vastus medialis, rectus femoris and vastus lateralis were measured with sEMG, median frequency(MDF) was analyzed, and thus the following results were obtained. There was significant difference in the period of measuring vastus medialis and rectus femoris in change of MDF and interaction among groups with analysis of surface electromyography before and after neuromuscular electrical stimulation(p<.001) and in particular, there was a remarkable change among groups according to the period of measurement. In conclusion, NMES influenced changes of strength and endurance according to its application modes and in particular, it was found that strength increment application had a significant influence on strength increment in applying short-time NMES.

• The Journal of Korean Physical Therapy
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• v.27 no.5
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• pp.299-303
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• 2015

Purpose: The objective of this study was to examine the changes in muscle activity on the anterior deltoid muscle depending on the stretch rate of kinesio tape when applying kinesio tape in healthy adult subjects. Methods: This study was a single-blind randomized controlled trial, including 22 healthy participants (male 15, female 7) with no pathology or past history of shoulder who participated voluntarily. Participants applied a different stretch rate of the kinesio tape, and the functional activity was tested. The stretch rate of kinesio tape was 0%, 10%, and 20%. Subjects lifted a weight (5% of their body weight) to their shoulder height. Subjects lifted a weight up to an angle of 90 degrees in the sagittal plane, and muscle activities (biceps brachii, anterior deltoid, middle deltoid, upper trapezius) were assessed using EMG (electromyography). Analysis of muscle activity was divided into two parts (lift weight and keep holding). The EMG activity of each muscle was normalized to the value of reference voluntary contraction (%RVC) and explored using repeated ANOVA. Results: There were no significant differences in muscle activity depending on the ratio of tape stretch when lifting a weight (p>0.05). There were no significant differences in muscle activity depending on the ratio of tape stretch when holding a weight (p>0.05). Conclusion: According to the results of this study, in the case of applying kinesio taping therapy for healthy people, it was found that the stretch rate of the tape does not have an effect on muscle activity.

• The Journal of Advanced Prosthodontics
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• v.4 no.2
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• pp.61-71
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• 2012

PURPOSE. To compare the changes in the occlusal vertical dimension, activity of masseter muscles and biting force after insertion of immediate denture constructed with conventional, tooth-supported and Implant-supported immediate mandibular complete denture. MATERIALS AND METHODS. Patients were selected and treatment was carried out with all the three different concepts i.e, immediate denture constructed with conventional (Group A), tooth-supported (Group B) and Implant-supported (Group C) immediate mandibular complete dentures. Parameters of evaluation and comparison were occlusal vertical dimension measured by radiograph (at three different time intervals), Masseter muscle electromyographic (EMG) measurement by EMG analysis (at three different positions of jaws) and bite force measured by force transducer (at two different time intervals). The obtained data were statistically analyzed by using ANOVA-F test at 5% level of significance. If the F test was significant, Least Significant Difference test was performed to test further significant differences between variables. RESULTS. Comparison between mean differences in occlusal vertical dimension for tested groups showed that it was only statistically significant at 1 year after immediate dentures insertion. Comparison between mean differences in wavelet packet coefficients of the electromyographic signals of masseter muscles for tested groups was not significant at rest position, but significant at initial contact position and maximum voluntary clench position. Comparison between mean differences in maximum biting force for tested groups was not statistically significant at 5% level of significance. CONCLUSION. Immediate complete overdentures whether tooth or implant supported prosthesis is recommended than totally mucosal supported prosthesis.

• Physical Therapy Korea
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• v.11 no.3
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• pp.43-50
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• 2004

This study was designed to determine the effects of different widths in the base of support (BOS) on trunk and lower extremity muscle activation during upper extremity exercise. Twenty-seven healthy male subjects volunteered for this study. Exercises were performed for a total of 10 trials with a load of 10 repetitions maximum (10 RM) for each of the various widths of BOS (10 cm, 32 cm, 45 cm). The width of a BOS is the distance between each medial malleoli when a subject was in a comfortable standing position. Electromyography was used to determine muscle activation. Surface bipolar electrodes were applied over the tibialis anterior, medial gastrocnemius, biceps femoris, rectus femoris, gluteus maximus, upper rectus abdominis, and elector spinae muscle. Electromyographic (EMG) root mean square (RMS) signal intensity was normalized to 5 seconds of EMG obtained with a maximal voluntary isometric contraction (MVIC). The data were analyzed by atwo-factor analysis of variance (ANOVA) with repeated-measures ($3{\times}7$) and Bonferroni post hoc test. The results were as follows: (1) There were significant differences in the width of the BOS (p=.006). (2) The post hoc test showed significant differences with the BOS between 10 cm and 32 cm, between 10 cm and 45 cm and between 32 cm and 35 cm (p=.008, p=.003, p=.011). (3) There was no interaction with the BOS and muscle. (p=.438) There were no significant differences in the muscle activation (p=.215).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2317-2323
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• 2010

When the muscle is contracted by continuous and same, the force takes fatigue and stiffness. The aim of this study was to know how the fatigue and muscle stiffness change during an isometric contraction. Surface Electro myography(EMG) signal monitoring system and ultrasonic transducer set up the same muscle stem, subjects contract his right femoris muscle by submaximal isometric contraction(50% of MVC) until exhaustion. Before and after the test, muscle stiffness was measured and EMG was measured during the contraction. As time goes by, muscle fatigue was increased. and the stiffness was shown strongly after the contraction. These results show if the muscle becomes more and more fatigued, the circulation of muscle is delayed although the contraction doesn't happen. So muscle stiffness is increased.