• International journal of advanced smart convergence
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• v.12 no.3
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• pp.211-220
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• 2023

Surface electromyography (sEMG) is a noninvasive method used to capture electrically muscle activity, which can be easily measured even during exercise. The basic unit of muscle activity is the motor unit, and because an sEMG signal is a superposition of motor unit action potentials, analysis of muscle activity using sEMG should ideally be done from the perspective of motor unit activity. However, conventional techniques can only evaluate sEMG signals based on abstract signal features, such as root-mean-square (RMS) and mean-power-frequency (MPF), and cannot detect individual motor unit activities from an sEMG signal. On the other hand, needle EMG can only capture the activity of a few local motor units, making it extremely difficult to grasp the activity of the entire muscle. Therefore, in this study, a method to visualize the activities of motor units in a single-channel sEMG signal by relocating wavelet coefficients obtained by redundant discrete wavelet analysis is proposed. The information obtained through this method resides in between the information obtained through needle EMG and the information obtained through sEMG using conventional techniques.

• Physical Therapy Korea
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• v.22 no.4
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• pp.17-26
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• 2015

The purpose of this study was to investigate the effects of visual electromyography (EMG) biofeedback on the EMG activity of the lower trapezius (LT), serratus anterior (SA), and upper trapezius (UT) muscles, the LT/UT and SA/UT EMG activity ratios, and the scapular upward rotation angle during scapular posterior tilting exercise (SPTE). Twenty-four subjects with round-shoulder posture participated in this study. The EMG activities of the LT, SA, and UT were collected during SPTE both without and with visual EMG biofeedback. The scapular upward rotation angle was measured at the baseline, after SPTE without visual EMG biofeedback, and after SPTE with visual EMG biofeedback. The LT, SA, and UT EMG activities, and the LT/UT and SA/UT EMG activity ratios were analyzed by paired t-test. The scapular upward rotation angle was statistically analyzed using one-way repeated analysis of variance. If a significant difference was found, a Bonferroni correction was performed (p=.05/3=.017). The EMG activities of LT and SA significantly increased, and the EMG activity of UT significantly decreased during SPTE with visual EMG biofeedback compared to SPTE without visual EMG biofeedback (p<.05). In addition, the LT/UT and SA/UT EMG activity ratios significantly increased during SPTE with visual EMG biofeedback compared to SPTE without visual EMG biofeedback (p<.05). Significant increases were found in the scapular upward rotation angle after SPTE without and with visual EMG biofeedback compared to baseline (p<.017), and no significant differences were observed in the scapular upward rotation angle between SPTE without and with visual EMG biofeedback. In conclusion, SPTE using visual EMG biofeedback may be an effective method for increasing LT and SA activities while reducing UT activity.

• Journal of Oral Medicine and Pain
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• v.21 no.1
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• pp.89-101
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• 1996

This study was performed to investigate influence of the changes of head posture on resting electromyographic (EMG) activity in anterior temporalis, masseter, sternocleidomastoid muscle and trapezius, and on status of occlusal contacts. For this study twenty-nine patients with temporomandibular disorders(TMD) and thirty dental students without any masticatory symptoms were selected as patients group and control group, respectively. EMG activity($\mu$V) at rest was observed in four kind of head postures such as natural or normal head posture(NHP), forward head posture(FHP), upward head posture(UHP), downward head posture(DHP), and in NHP and FHP, EMG activity with flat occlusal splint was also checked. BioEMG$^\textregistered$(Bioelectromyograph, Bioresearch Inc., USA) was used to record EMG activity in the above four muscles with eight locations on both sides. The author used T-Scan$^\textregistered$(Tekscan Co., USA) system to investigate the changes of oclusal contats on clenching in the four head postures about number, force, time(duration) and total left-right statistis(TLR, occlusal stability crossing left-right dental arch on clenching). For taking in upward or downward head posture, head was inclined $10^{\circ}$ upward or downward and CROM$^\textregistered$ (cervical-range-of motion, Performance attainment Inc., USA) was used to maintain same posture during the procedure. The results obtained were as follows : 1. For resting EMG activity, anterior temporalis did not show any difference by change of head posture, but masseter and sternocleidomastoid muscle showed higher value of EMG activity in FHP and UHP, and trapezius showed higher value of EMG activity in FHP and DHP. 2. EMG activity of trapezius was higher than that of any other muscles in NHP, FHP, and DHP, but in UHP, the activity was the lowest reversely. 3. Patients group showed higher EMG activity than control group did in all the muscles in NHP. And significant difference between the two groups were also observed in anterior temporalis in FHP, in sternocleidomastoid muscle in UHP, and in sterno-cleidomastoid muscle and trapezius in DHP with higher activity in patients group. 4. There was no change of EMG activity in NHp with splint, but EMG activity in anterior temporalis and masseter was decreased in FHP with splint. 5. In general, status of occlusal contacts was not changed with head posture in all subjects, and difference between patients group and control group was only noted for number and force of tooth contact in UHP and DHP with more value in control group. 6. Correlationship between EMG activity and number ad force of tooth contacts was shown negatively with regard to masseter in NHP, and trapezius in UHP and DHP.

• Journal of Oral Medicine and Pain
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• v.26 no.1
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• pp.75-85
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• 2001

This study was performed to investigate the effect of mandibular midline shift and difference of mandibular height between both sides on the electromyo- graphic(EMG) activity of the masticatory muscles on clenching or gum chewing movement. For this study, 105 patients with temporomandibular disorders(TMD) were selected and panoramic radiograph were taken. Amount and side of the midline shift and height of the mandible from antegonial notch to the top of the condylar head were measured on panoramic view. $BioEMG^{(R)}$ (Bioresearch Inc., Milwaukee, USA) was used for recording of EMG activity(${\mu}V$) of the anterior temporalis and the superficial masseter on clenching or gum chewing movement. EMG activity on clenching during 533msec period were measured for activity of the starting point and the one second-after activity as the early EMG and the maximum EMG, respectively. EMG activity on gum chewing movement were measured for activity of the first and the second chewing stroke. The data collected were analysed by SPSS windows program, and the results of this study were as follows : 1. Height of the mandible was 8.06cm on right side and 8.03cm on left side, and showed no difference by age, but significantly differed by sex with higher in male subjects. 2. Mean value of the midline shift was 0.1mm with range of 0~5mm on both sides. The amount and side of the midline shift did not related with height difference of the mandible and/or the EMG activity of the masticatory muscles on clenching. 3. Prevalence of higher right side and higher left side of the mandible were almost same, and the EMG activity of higher side was not higher than that of the other side. 4. In the subjects with height difference of more than 5mm between both sides of the mandible, the early EMG activity on clenching were differed for the anterior temporalis, but the maximum activity were differed for the superficial masseter. 5. In the subjects with height difference of more than 5mm between both sides of the mandible, EMG activity of the anterior temporalis of the gum chewing side was not higher than that of the other side when chewing on the side of lower height, but in the subjects with height difference of less than 5mm, the EMG activity was higher than that of the other side.

• Journal of Oral Medicine and Pain
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• v.20 no.1
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• pp.171-183
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• 1995

This study was carried out to investigate the relationship between tensed mandibular positions, muscle tenderness and EMG activity, respectively, and between range of motion of the neck and sternocleidomastoid muscle tenderness. Under stressful conditions, most of people take several types of behavioral patterns. Two of them observed frequently are clenching of teeth and grasping of fist. Prolonged clenching or grasping should increase electromyographic activity of associated muscle, especially muscles of mastication and neck muscles and will cause hyperfunction, dysfunction and muscle pain. So it is necessary to relate EMG activity with muscle pain. The author performed routine clinical examination in 47 patients with Temporomandibular Disorders, especially for presence or absence of muscle tenderness. Mandibular rest position was used as a baseline reference position and two more position in which EMG activity was taken were rest postion with grasping of fist and teeth clenching position. BioEMG of Biopak system (Bioresearch Inc, USA) was used for measuring of integrated EMG in masseter, anterior temporalis, anterior belly of digastic muscle and sternocleidomastoid muscle. To measure of the range of neck motion. CROM(Cervical-Range-of Motion, USA) was used. The obtained results were as follows : 1. EMG activity of all muscles except in masseter was higher in grasping of fist than those in rest position and there were significant correlation in EMG activity between the two position except in anterior belly of digastric muscle. 2. When comparing EMG activity between tender and non-tender muscle, all examined muscles did not show any significant difference. From this data, we could conclude that EMG activity was generally not changed with tenderness, of couse, it might be dependent with degree of muscle tenderness. 3. Number of tender points in examined muscles was also not significantly different between in patients with masticatory muscle disorders and in patients with internal derangement. 4. Cervical posture and range of motion of the neck was not differed significantly between in patients with and in patients without tenderness of sternocleidomastoid muscle.

• Physical Therapy Korea
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• v.5 no.1
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• pp.30-43
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• 1998

The purposes of this study were to examine the effect of two different pelvic alignments and the Valsalva maneuver on electromyographic (EMG) activity of the erector spinae during squat lifting and lowering, and to find an efficient method for squat lifting and lowering. Twenty hea1thy men in their twenties lifted and lowered loads using four different methods: 1) anterior pelvic tilt position with the Valsalva maneuver, 2) anterior pelvic tilt position without the Valsalva maneuver, 3) posterior pelvic tilt with the Valsalva maneuver, 4) posterior pelvic tilt without the Valsalva maneuver. The EMG activity of erector spinae was recorded during both lifting and lowering with each method. The EMG activity of each individual was normalized to EMG activity produced by muscle during maximal voluntary contraction. Two-way analysis of variance for repeated measures ($2{\times}2$) was used to analyze the effect of the two factors: 1) pelvic tilt position (anterior pelvic tilt, posterior pelvic tilt), 2) the Valsalva maneuver (with and without). Analysis was performed separately for the lifting and lowering. The results were as follows: 1) EMG activity of erector spinae was greater when the pelvis was tilted anteriorly than when the pelvis was tilted posteriorly during squat lifting and squat lowering. 2) There was no difference between EMG activity of erector spinae with the Valsalva maneuver and EMG activity of erector spinae without the Valsalva maneuver during squat lifting and squat lowering. These results suggest that the greater EMG activity of erector spinae with an anterior pelvic tilt position during squat lifting and squat lowering may ensure optimal muscular support for the spine while handling loads, but the Valsalva maneuver may have less effect on erector spinae.

• The Journal of Korean Physical Therapy
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• v.27 no.4
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• pp.207-213
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• 2015

Purpose: The aim of the current study was to investigate EMG activity on dynamic balance of subjects with functional lumbar instability following fatigue of low back. Methods: The subjects (24 university students) were divided into 2 groups; functional lumbar instability group (6 males and 6 females) and lumbar stable group (7 males and 5 females) who could complete a questionnaire and undergo a prone instability test. All participants were evaluated for distribution of muscle activity using the TeleMyo DTSTM system. Dynamic balance was tested by Y balance test. This study was conducted for measurement of EMG activity on dynamic balance with the difference between FLIG and control group following muscle fatigue. Results: The functional lumbar instability group (FLIG) showed a significantly lower YBT score (%) of anterior, posterolateral direction on Y-balance test (YBT) in dynamic balance than the lumbar stable group (LSG) (p<0.05). The FLIG was significantly lower than the LSG in anterior direction in EMG activity(%) of MF, RA, ES, GMX, GME, RF, and posteromedial direction in EMG activity(%) of IO, ES and then posterolateral direction in EMG activity(%) of IO, ES in dynamic balance (p<0.05). There was significant correlation of MF, RA, and GMX in anterior reach direction (p<0.05) and ES, GME (p<0.01) and IO, ES in posteromedial reach direction (p<0.05) and EO, ES, GMX in posterolateral reach direction (p<0.05) there was positive correlation. Conclusion: This study showed that FLIG effected EMG activity by dynamic balance following muscle fatigue. Further study is needed for measurement of various ages and work with lumbar instability for clinical application.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.1
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• pp.15-21
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• 2009

Purpose : The purpose of this study was to find the effect of ankle joint angle on knee extensor electromyographic activity following knee extension exercise. Methods : Ten male university students participated in the study. The subjects performed isometric maximal voluntary knee extensor contractions (MVC) and knee extensor EMG activity measured in with three different ankle joint angle. The EMG activity of rectus femoris(RF), vastus medialis(VM), vastus lateralis(VL) were measured using surface electromyography. Results : EMG activity of vastus lateralis following the change of ankle joint angle was shown statistically significant difference. Conclusion : Ankle plantar flexion position increase EMG activity of vastus lateralis during knee extension exercise.

• Physical Therapy Korea
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• v.11 no.3
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• pp.51-58
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• 2004

The purpose of this study was to compare the postural muscle activity during wearing a lead apron with and without applying waist belt at working posture. Ten healthy male subjects were recruited for this study. Electromyography using a surface EMG recorded the activity of the splenius capitis, trapezius, and erector spinae. EMG activity was recorded at quiet standing, 45 degrees of neck flexion, 45 degrees of neck flexion with 15 degrees of trunk flexion. The testing order was selected randomly. The subjects were asked to maintain the each posture for 3 minutes. The mean root mean square (RMS) of EMG activity was calculated. EMG activity was normalized using the maximum voluntary isometric contraction (MVIC) elicited using a manual muscle testing technique. Two-factor repeated measures analysis of variance (ANOVA) was used to compare the average RMS value of EMG activity for each condition. The EMG activity of trapezius muscle was significantly decreased with applying waist belt (p<.05). The muscle activity of splenius capitis and erector spinae showed significant difference according to postures (p<.05). These results suggest that applying waist belt during wearing a lead apron will be useful to prevent shoulder pain.

• Journal of The Korean Society of Integrative Medicine
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• v.1 no.4
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• pp.85-92
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• 2013

PURPOSE : The purpose of this study was to determine the effects of the length of the pectoralis minor on muscle activity of trapezius and pectoralis major in subjects in subjects with shortened pectoralis minor muscle. METHOD : The subjects was participated in 36 with shortened pectoralis minor muscle. All subjects was examined the length test of pectoralis minor muscle. we divided by 3 groups. group I(n=12) was for 4~5cm of length of pectoralis minor muscle, group II(n=12) was for 5~6cm, group III(n=12) was for above 6cm. The EMG activity of upper trapezius, middle trapezius, lower trapezius and pectoralis major muscle activity was measured by surface EMG while elevationg the right arm in sitting postion with head to the neutral, shoulder elevation $135^{\circ}$ with scaption. Data were analyed using one-way ANOVA with a Tukey post hoc test. RESULT : The EMG activity differed significantly among the three groups(p<.05). The group III had significantly greater EMG activity of upper trapezius and pectoralis major muscles than group I and II(p<.05). Also, The group III had significantly smaller EMG activity of lower trapezius muscle than group I and II(p<.05). But, these was no significant difference in the EMG activity of the middle trapezius muscle among the groups (p.05). CONCLUSION : Therefore, the result of this study should be suggested that the shortened pectoralis minor muscle was affected the EMG activity of the upper trapezius, lower trapezius and pectoralis major. Ultimately the length of the pectoralis minor muscle leads to the muscle imbalance in shoulder girdle.