• PNF and Movement
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• v.14 no.2
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• pp.131-137
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• 2016

Purpose: The purpose of this study was to compare muscle activities in the frontal plane and scapular plane of the middle fiber and lower fiber of the trapezius muscle at different shoulder abduction angles. Methods: Twenty male and female students in their 20s participated in this study. Each subject maintained shoulder abduction at $75^{\circ}$, $90^{\circ}$, $125^{\circ}$, and $160^{\circ}$ in a standing position and repeated motions three times each in the frontal plane and the scapular plane. While maintaining the motions for 10 seconds in each posture, surface electromyography (EMG) was used to measure muscle activity of the middle fiber and lower fiber of the trapezius muscle. The collected EMG data were normalized using maximal voluntary isometric contraction (MVIC). Differences in muscle activity of the middle fiber and lower fiber of the trapezius muscles according to the angles at each plane were statistically processed using repeated measured analysis of variance, and an independent t-test was used to examine the differences between the two planes at each angle. Results: Muscle activity of the middle and lower trapezius during shoulder abduction in the frontal plane and scapular plane significantly increased as the angles increased (p<.05). However, muscle activity of the middle trapezius was significantly lower in the scapular plane than in the frontal plane for all shoulder abduction angles (p<.05). Conclusion: The results of this study suggest that during shoulder abduction, angles should be different according to the goals, and for training during an acute phase or early phase for functional recovery, it is more efficient to perform the training in the scapular plane than in the frontal plane.

• Korean Journal of Applied Biomechanics
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• v.13 no.1
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• pp.95-108
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• 2003

The purposes of this study were to analyze the muscle activities and the characteristics of muscle recruiting patterns of upper trunk for Ssirum dutguri technique using three top-ranked elite Ssirum players. The EMG technique was used to record muscle activities of both right and left sides of latissimus dorsi, biceps brachii, and erector spinae. Six surface electrodes were placed on the surface of the selected muscles and one ground electrode was also attached on the back of neck(C7). One video camera was also used to record the Ssirum motion to define 4 events and 3 phases for further analysis. The raw EMG data were filtered with band pass filter (50-400 Hz) to remove artifacts and then low pass filtered (4 Hz) to find the linear envelope which resemble muscle tension curve. This filtered EMG data were normalized to MVIC for the purpose of comparion between the subjects. The results were indicated that each subject with different physical characteristics showed very different muscle activity patterns. Although Ssirum dutguri is considered as foot technique the player grasped opponent's satba(belt) with both hands when they play. Because of this reason, activities of upper trunk muscles were relatively high. However, direct comparison between upper and lower body muscles was not possible due to the lack of the data in present study. Interestingly, all threes subjects showed that erector spinae muscle activity was comparatively higher than those of latissimus dorsi and biceps brachii. This implies to reinforce back muscle as a routine of training to improve performance or to prevent back injury.

• Physical Therapy Korea
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• v.11 no.4
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• pp.19-29
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• 2004

Many muscles of the trunk and hip are capable of contributing to the stabilization and protection of the lumbar spine. To have optimal effectiveness, a training program should include dynamic back/stomach/hip exercises. This study was designed to assess the L5 level paraspinal, external abdominal oblique, and gluteus maximus muscle activities during various low back stabilization exercises. Participants were 26 healthy adults (13 males, 13 Females), aged 21 to 28 years. The surface electromyography (EMG) was recorded from the L5 level paraspinal, external abdominal oblique, and gluteus maximus muscles. The recorded signal was averaged and normalized to the maximal electromyographic amplitude obtained during the maximal voluntary contraction. The measurements were taken during 3 low back stabilization exercises. One-way analysis of variance with repeated measures was used to examine the difference, and a post hoc test was performed with least significant difference. A level of significance was set at p<.05. The significance of difference between men and women, and between the electromyographic recording sites was evaluated by an independent t-test. The EMG activity for the externus oblique and gluteus maximus muscles had significant differences among 3 exercises (p<.05). In males, the EMG activity for the external abdominal oblique muscle had significantly increased differences during exercises 1 and exercise 2 (p<.05). The gluteus maximus muscle had significantly increased differences during exercise 2 and exercise 3 (p<.05). In females, the multifidus muscle had significantly increased difference during exercise 3 (p<.05), the external abdominal oblique muscle had significantly increased difference during exercise 1 (p<.05). and the gluteus maximus muscle had significantly decreased difference during exercise 3 (p<.05). The results were that the external abdominal oblique muscle was apparently activated during the curl-up exercise in females and males, and the multifidus muscle was apparently activated during the bridging exercise in females and during the sling exercise in males and females.1)In comparison of the %MVC between males and females, exercise 2 and exercise 3 apparently activated of the multifidus and gluteus maximus muscles in both males and females (p<.05). The EMG activity of the gluteus maximus muscle of the males significantly increased during exercise 2 and exercise 3 (p<.05). The EMG activity the multifidus muscle of the females was significantly increased during exercise 2 and exercise 3 (p<.05). More research is needed to understand the nature of motor control problems in the deep muscles in patients with low back pain.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.137-148
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• 2006

The purpose of this study was to compare muscle activity in the lower extremity during walking wearing jogging and roller shoes. Twelve male middle school students (age: 15.0 yrs, height 173.7 cm, weight 587.7 N) who have no known musculoskeletal disorders were recruited as the subjects. Seven pairs of surface electrodes (QEMG8, Laxtha Korea, gain = 1,000, input impedance >$1012{\Omega}$, CMMR >100 dB) were attached to the right-hand side of the body to monitor the rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), and medial (GM) and lateral gastrocnemius (GL) while subjects walked wearing roller and jogging shoes in random order at a speed of 1.1 m/s. An event sync unit with a bright LED light was used to synchronize the video and EMG recordings. EMG data were filtered using a 10 Hz to 350 Hz Butterworth band-passdigital filter and further normalized to the respective maximum voluntary isometric contraction EMG levels. For each trial being analyzed, five critical instants and four phases were identified from the recording. Averaged IEMG and peak IEMG were determined for each trial. For each dependent variable, paired t-test was performed to test if significant difference existed between shoe conditions (p<.05). The VM, TA, BF, and GM activities during the initial double limb stance and the initial single limb stance reduced significantly when going from jogging shoe to roller shoe condition. The decrease in EMG levels in those muscles indicated that the subjects locked the ankle and knee joints in an awkward fashion to compensate for the imbalance. Muscle activity in the GM for the roller shoe condition was significantly greater than the corresponding value for the jogging shoe condition during the terminal double limb stance and the terminal single limb stance. Because the subjects tried to keep their upper body weight in front of the hip to prevent falling backward, the GM activity for the roller shoe condition increased. It seems that there are differences in muscle activity between roller shoe and jogging shoe conditions. The differences in EMG pattern may be caused primarily by the altered position of ankle, knee, and center of mass throughout the walking cycle. Future studies should examine joint kinematics during walking with roller shoes.

• Physical Therapy Korea
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• v.16 no.3
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• pp.9-15
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• 2009

The purpose of this study was to examine contraction of abdominal muscles on surface electromyographic (EMG) activity of superficial cervical flexors, rib cage elevation and angle of craniocervical flexion during deep cervical flexion exercise in supine position. Fifteen healthy subjects were participated for this study. All subjects performed deer cervical flexion exercise with two methods. The positions of two methods were no volitional contraction of abdominal muscles in hook-lying position with 45 degree hip flexion (method 1) and 90 degrees hip and knee flexion with feet off floor for inducing abdominal muscle contraction (method 2). Surface EMG activities were recorded from five muscles (sternocleidmastoid, anterior scaleneus, recuts abdominis, external oblique, internal oblique). And distance of rib cage elevation and angle of craniocervical flexion were measured using a three dimensional motion analysis system. The EMG activity of each muscle was normalized to the value of reference voluntary contraction (%RVC). The EMG activities, distance of rib cage elevation. and angle of craniocervical were compared using a paired t-test between two methods. The results showed that the EMG activities of sternocleidmastoid and anterior scaleneus during deep cervical flexion exercise in method 2 were significantly decreased compared to method 1 (p<.05). Distance of rib cage elevation and angle of craniocervical flexion were significantly decreased in method 2 (p<.05). The findings of this study indicated that deep cervical flexion exercise with contraction of abdominal muscles could be an effective method to prevent substitute motion for rib cage elevation and contraction of superficial neck flexor muscles.

• 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.

• The Journal of the Acoustical Society of Korea
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• v.19 no.8
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• pp.26-34
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• 2000

This paper presents a new adaptive impulse noise cancelling technique based on the adaptive nonlinear suppressing function. The proposed "adaptive threshold algorithm (ATA)" is controlled by the normalized power prior input data term, and this adaptive threshold makes the cancelling system highly robust against additive impulse noise. For the performance evaluation, we have tested the proposed algorithm with the observed signals simulated in various impulsive noise environments and real EMG signals. As a result the proposed algorithm shows superior performance of 51.7% to the available techniques in the points of SNR and MSE.

• 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.

• 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.

• 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.