• Fashion & Textile Research Journal
• /
• v.11 no.6
• /
• pp.911-917
• /
• 2009

The purpose of this study was to investigate muscle activity of the lower limbs when walking in jeans in order to obtain basic information for development of new jeans patterns with excellent movement adaptability. Using three types of jeans (basic, medium, and slim) with different ease on hip, knee circumference, and crotch length, and two different types of shoes, Electromyogram (EMG) of the lower limbs muscle was measured for four healthy subjects walking on treadmills and stairs. EMG of vastus lateralis, semitendinous, tibialis anterior and medial head of gastrocnemius muscles was measured. The muscle activity was assessed in RMS (Root Mean Square) value of the EMG. On the treadmill in sneakers, only the vastus lateralis muscle showed a significant difference in RMS value depending on patterns. Basic and medium jeans allowed higher muscle activity than trunks of slim jeans did. On the treadmill in high heels and slim jeans, the RMS values of all muscles were significantly smaller than in basic jeans, whereas no significant differences were shown while in trunks or medium jeans. On the stairs either in sneakers or in high heels, no significant differences were shown between all muscle activities for all types of jeans. On the treadmill, greater fatigue was induced in all muscles from walking in high heels than in sneakers for all jeans patterns. When walking on the stairs wearing either type of shoes, however, the effect of jeans pattern on muscle activities was different from muscle to muscle.

• Clinics in Shoulder and Elbow
• /
• v.3 no.2
• /
• pp.87-94
• /
• 2000

Purpose : The purpose of this study was to evaluate the activity of the biceps brachii muscle in the vulnerable abduction and external rotation position of the shoulder in patients with anterior instability. Materials and Methods: This experimental study include a prospective analysis of the electromyographic(EMG) data on a group of patients with traumatic unilateral anterior instability of the shoulder. The EMG data of unstable shoulders was compared with those of opposite shoulders as control. The optimal sample size for the case-control study was calculated using an nQuery Advisor program(nQuery Adviser 3.0, Statisticl solutions Ltd., Ireland). The EMG analyses were conducted in 76 shoulders in 38 patients who had a traumatic anterior instability in one shoulder. The EMG records were obtained at different position of shoulder, which included 0° , 45° , 90° and 120° of shoulder abduction. In each angle of shoulder abduction, the arms were placed in an external rotation as tolerated by the anterior apprehension. The paired-sample T test was used to compare the difference of the root mean square(RMS) voltages between the stable and unstable shoulders in each degree of arm position. Results : The RMS voltage of the biceps muscle was significantly greater in the unstable shoulder than opposite stable shoulder in all position of the arm(p<0.001). The RMS voltage of the biceps was maximal at 90° and 120° of external rotation in the unstable shoulder(p<0.05). The RMS voltage of the supraspinatus muscle revealed no differences in any of the test conditions(p=0.904, 0.506, 0.119 and 0.781 in 0° , 45° , 90° and 120° , respectively) Conclusion: In the vulnerable abduction and external rotation position, the biceps muscle plays an active compensatory role in the unstable shoulder while not in the stable shoulder.

• Journal of the Ergonomics Society of Korea
• /
• v.33 no.6
• /
• pp.565-575
• /
• 2014

Objective: The aim of this study is to evaluate the effect of weight of load and time on the physical workload of repetitive upper-limb tasks with handling light weight loads using EMG and perceived discomfort, and to investigate the relationship between EMG and perceived discomfort for those repetitive tasks of moving light weight loads. Background: Repetitive upper-limb motion is known as one of the main risk factors of musculoskeletal disorders, and a lot of repetitive tasks are carried out while handling light weight loads in the industry. In evaluating the workload of repetitive tasks handling light weight loads, EMG and perceived discomfort can be used, though their relationship in those work conditions are not much investigated. Method: A laboratory experiment with 18 healthy males were conducted to record EMG signals from 5 muscle sites of the right arm and shoulder and rate perceived discomforts for the body parts and the whole body while carrying out repetitive materials-handling tasks for 52min. The subjects were divided into 3 groups which handled the loads of 1kg, 2kg and 3kg, respectively. ANOVAs were conducted to analyze the effects of the weight and time on RMS of EMG amplitude (normalized RMS: NRMS), median frequency of power spectrum of EMG (normalized MDF: NMDF) and perceived discomfort. The correlations between NRMS and NMDF and perceived discomfort were also analyzed. Results: Statistically significant muscular fatigue effects were not found from NRMS and NMDF in most muscles, while there were significant increases of discomfort as the task time elapsed. It was shown that there were an increasing trend of the muscular activity as the weight of load increased and a decreasing trend of median frequency of EMG of upper and lower arms as time elapsed. It was found that there were significant negative correlations between NMDFs from the lower arm and discomfort ratings, though the relationships were weak. Conclusion: It can be concluded that the working conditions adopted in this study were not enough to induce muscular fatigue, while there was significant increase in perceived discomfort. A further study is necessary to integrate the objective and subjective measures for more reliable and sensitive evaluation of workload of repetitive tasks of handling light weight loads. Application: This study can be used as a basic study for the evaluation of workload of repetitive tasks handling light weight loads.

• The Journal of Korean Physical Therapy
• /
• v.13 no.3
• /
• pp.777-789
• /
• 2001

The purpose of this study was to investigate the possibility of using surface electromyographic signals as a measure of muscle fatigue during the wheelchair propulsion. Subjects performed wheelchair exercise tests on a motor-driven treadmill with a constant-velocity of 1.25 m/sec. During each test, the raw EMC signals were acquired from the surface electrodes attached on the belly of five muscle groups: biceps brachii, pectoralis major. deltoid, triceps brachii, and trapezius. The median power frequency(MPF), and the root mean square(RMS) amplitude were calculated for each cyclic contraction in order to quantify muscle fatigue. During the wheelchair propulsion, the MPF decreased and the RMS increased in the trapezius and deltoid. However, the decreasing MPF and the increasing RMS also fluctuated severly during dynamic muscle contractions. Therefore, the MPF and RMS values should be estimated with well-designed methods and used with caution to quantify muscle fatigue during wheelchair propulsion.

• Journal of the Korean Society of Safety
• /
• v.15 no.1
• /
• pp.153-160
• /
• 2000

Occupational cumulative traumas (CTDs) are becoming one of leading ailments in industrialized worl $d^{(1.2)}$. The degree of muscle fatigue is important parameter to understand cause of occupational cumulative trauma disorders. To quantify degree of muscle fatigue, muscle EMG activity was measured during isometric and dynamic contractions(repetitive concentric/eccentric muscle contraction) and its analyzed data, such as RMS, median frequency, and median power were compared when the muscle was fresh and exhausted. When muscle become fatigue, it was observed that median frequency decreased and median power and RMS increased However, based on overall prolonged observation, median frequency increased and median power and RMS decreased. Therefore it was concluded that shifting patterns of RMS, median frequency, and median power values can be used as parameter to evaluate degree of muscle fatigue even in dynamic muscle contraction.

• Korean Journal of Applied Biomechanics
• /
• v.32 no.3
• /
• pp.80-86
• /
• 2022

Objective: The purpose of this study was to investigate the effects of three rotational jump conditions (standing jump, left rotational jump and right rotational jump) on stability through center of pressure (COP) and EMG variables analysis. Method: A total of 16 college students (age: 24.13 ± 7.17 years, height: 169.24 ± 8.23 cm, weight: 65.65 ± 13.88 kg) participated in this study. The study used wireless two COP plates and wireless eight channel EMG. The analyized variables were 11 variables for COP and RMS for EMG, which were analyzed using one-way analysis of variance with repeated measures according to three rotational jump conditions. Results: Among the COP variables, left rotational jump (LRJ) and right rotational jump (RRJ) were larger than standing jump (SJ) for left and right amplitude, area, total displacement, and average velocity for both feet among the variables of COP, and for area of the left foot, RRJ was larger than that of SJ. Among the EMG variables, there was no statistical difference between the muscle activations, but the muscle activity was significantly higher in the order of RRJ, LRJ, and SJ according to direction of rotation. Conclusion: Although the results of COP and EMG were not consistent through this study, it can be expected that the differences in COP was due to the amount of rotation during rotational jump-landing in the left and right directions, and that the EMG is determined by the lateral movements required for rotation.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.3
• /
• pp.143-150
• /
• 2016

In this paper, we propose Korean monophthong recognition method optimizing muscle mixing based on facial surface EMG signals. We observed that EMG signal patterns and muscle activity may vary according to Korean monophthong pronunciation. We use RMS, VAR, MMAV1, MMAV2 which were shown high recognition accuracy in previous study and Cepstral Coefficients as feature extraction algorithm. And we classify Korean monophthong by QDA(Quadratic Discriminant Analysis) and HMM(Hidden Markov Model). Muscle mixing optimized using input data in training phase, optimized result is applied in recognition phase. Then New data are input, finally Korean monophthong are recognized. Experimental results show that the average recognition accuracy is 85.7% in QDA, 75.1% in HMM.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.4
• /
• pp.142-148
• /
• 2016

Recently, human identification using various biological signals has been studied and human identification based on the gait has been actively studied. In this paper, we propose a human identification based on the EMG(Electromyography) signal of the thigh muscles that are used when walking. Various features such as RMS, MAV, VAR, WAMP, ZC, SSC, IEMG, MMAV1, MMAV2, MAVSLP, SSI, WL are extracted from EMG signal data and ANN(Artificial Neural Network) classifier is used for human identification. When we evaluated the recognition ratio per channel and features to select approptiate channels and features for human identification. The experimental results show that the rectus femoris, semitendinous, vastus lateralis are appropriate muscles for human identification and MAV, ZC, IEMG, MMAV1, MAVSLP are adaptable features for human identification. Experimental results also show that the average recognition ratio of method of using all channels and features is 99.7% and that of using selected 3 channels and 5 features is 96%. Therefore, we confirm that the EMG signal can be applied to gait based human identification and EMG signal based human identification using small number of adaptive muscles and features shows good performance.

• Journal of the Korean Academy of Clinical Electrophysiology
• /
• v.6 no.1
• /
• pp.31-42
• /
• 2008

This study performed in order to investigate the effect of isometric resistance exercise for vastus medialis oblique muscle with EMG(electromyography) biofeedback training which are applied to the patello-femoral joint of patients with osteoarthritis on the improve of function. The subjects had no neuromuscular disorders, and they were elder patients with osteoarthritis, 20 women. And the experiment was performed in control group, taping with EMG biofeedback training group respectively, and the measurement was carried out before and after the treatment and 4 weeks after the treatment. Motor unit action potential analysis with surface electromyography showed a significant change in RMS(root mean square) amplitude and MDF(median frequency) in vastus medialis oblique muscle(p<0.05). VMO/VL(vastus medialis oblique/vastus lateralis oblique) MDF ratio showed a significant change between groups(p<0.05). Taping with EMG biofeedback training applied to patello-femoral joint of osteoarthritis patients appeared to be effective for muscle function improvement. However, increase of muscular force in vastus medialis oblique muscle appears to have a positive effect on improve of function along with correction effect on patella malalignment. In conclusion, in case of osteoarthritis patients with loss of patello-femoral joint function, it appears to be effective to practice isometric resistance exercise of vastus medialis oblique muscle selective with taping.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.55 no.7
• /
• pp.344-351
• /
• 2006

The fatigue of back muscle in the repetitive lifting motion was studied using multiple parameters(FFT_MDF, RMS, 2C, NT) in this study. Recent developments in the time-frequency analysis procedures to compute the IMDF(instantaneous median frequency) were utilized to overcome the nonstationarity of EMG signal using Cohen-Posch distribution. But the above method has a lot of computation time because of its complexity. So, in this study, FFT_MDF(median frequency estimation based on FFT) algorithm was used for median frequency estimation of back muscle EMG signal during muscle work in uniform velocity portion of lumbar movement. The analysis period of EMG signal was determined by using the run test and lumbar movement angle in dynamic task, such as lifting. Results showed that FFT_MDF algorithm is well suited for the estimation of back muscle fatigue from the view point of computation time. The negative slope of a regression line fitted to the median frequency values of back muscle EMG signal was taken as an indication of muscle fatigue. The slope of muscle fatigueness with FFT_MDF method shows the similarity of 77.8% comparing with CP_MDF(median frequency estimation based on Cohen Posch distribution) method.