• 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.

• Clinics in Shoulder and Elbow
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• v.2 no.2
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• pp.170-177
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• 1999

The electromyographic activity of four muscles(biceps, supraspinatus, infraspinatus and subscapularis) was mea­sured from non-dominant shoulders of 12 volunteers by six different provocative test for the biceps pathology. The provocative tests were Speed, Yergason, Ludington, Heuter, O'Brien and the abduction-extension test. Each test was performed in a force of 30% of maximal voluntary contraction. The levels of activity of the biceps were higher than those of the other rotator cuff muscles only in Speed's test: 28% in the biceps, 26% in the infraspinatus, 25% in the supraspinatus and 21 % in the subscapularis. The levels of activity of the biceps as a percent of MMT(maximal manual test) were higher in Speed's(42%) and O'Brien's test with the arm supinatecl(42%). Speed's test can isolate the activity of biceps better than the other tests but it is a nonspecific test by which the biceps tendon was also activated within other rotator cuff muscles.

• Journal of Oral Medicine and Pain
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• v.30 no.1
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• pp.45-55
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• 2005

As people prefer to use right or left hand, some have preferred chewing side while others do not. Totally, 82 volunteers composed of students and staffs from Dental Hospital College of Dentistry Yonsei University participated in this study for the investigation of influence of preferred chewing habit, that has lasted for more than a year, on electromyographic(EMG) activity of masticatory muscles and bite force. Among the 82 volunteers, 46 had preferred chewing habit while the other 36 did not. Prior to the investigation, those with factors that could affect the study, such as, general disease, irregular dentition and malocclusion, were screened and excluded by questionnaire and clinical examination. The results were as follows: 1. There was no significant difference in EMG activities between chewing side and non-chewing side of preferred chewing subjects at rest as well as maximal voluntary contraction(MCV)(p>0.05). 2. Asymmetrical coefficient of temporal and masseter muscle EMG activities between preferred chewing subjects and non-preferred chewing subjects at rest was not significantly different(p>0.05). 3. Asymmetrical coefficient of masseter EMG activity was significantly higher(p<0.05) than that of non-preferred chewing subjects at MCV, whereas that of anterior temporal muscle showed no difference(p<0.05). 4. In preferred chewing subjects, there was no significant difference in average bite force and occlusal contact area between chewing side and non-chewing side(p>0.05). 5. There was no significant difference in Asymmetrical coefficients of average bite force and occlusal contact area between preferred chewing subjects and non-preferred chewing subjects (p>0.05). Consequently, preferred chewing habit can be considered as physiological asymmetry with normal function rather than to have influence on EMG muscle activity of masticatory muscles, average bite force and occlusal contact area. Objective standardization to differentiate preferred chewing subjects and non-preferred chewing subjects should be established in the further study.

• Physical Therapy Korea
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• v.20 no.1
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• pp.1-9
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• 2013

The purpose of this study was to determine the effect of the pelvic compression belt (PCB) on the electromyography (EMG) activities of trunk muscles during sit-to-stand (SitTS), and stand-to-sit (StandTS) tasks. Twenty healthy subjects (7 men and 13 women) were recruited for this study. The subjects performed SitTS, and StandTS tasks, with and without a PCB. Surface EMG was used to record activity of the internal oblique (IO), external oblique (EO), rectus abdominis (RA), erector spinae (ES), and multifidus (MF) of the dominant limb. EMG activity significantly decreased in the RA (without the PCB, $8.34{\pm}6.04$ %maximal voluntary isometric contraction [%MVIC]; with the PCB, $7.64{\pm}5.11$ %MVIC), EO (without the PCB, $14.83{\pm}11.82$ %MVIC; with the PCB, $11.98{\pm}7.60$ %MVIC), MF (without the PCB, $21.74{\pm}7.76$ %MVIC; with the PCB, $18.50{\pm}8.04$ %MVIC), and ES (without the PCB, $18.39{\pm}7.16$ %MVIC; with the PCB, $16.63{\pm}6.31$ %MVIC) during the SitTS task and in the IO (without the PCB, $20.58{\pm}15.60$ %MVIC; with the PCB, $17.27{\pm}12.32$ %MVIlC), RA (without the PCB, $8.04{\pm}5.68$ %MVIC; with the PCB, $7.40{\pm}4.71$ %MVIC), EO (without the PCB, $13.29{\pm}8.80$ %MVIC; with the PCB, $11.24{\pm}6.14$ %MVIC), MF (without the PCB, $18.59{\pm}7.64$ %MVIC; with the PCB, $15.86{\pm}6.48$ %MVIC), and ES (without the PCB, $17.14{\pm}6.44$ %MVIC; with the PCB, $15.46{\pm}5.62$ %MVIC) during the StandTS task when a PCB was used (p<.05). In men the EMG activity of the MF significantly decreased during the SitTS task when a PCB was used (p<.05): in women, the EMG activity of the RA, EO, MF, and ES during the SitTS task and that of the EO, MF, and ES during the SitTS task significantly decreased when a PCB was used (p<.05). In addition, the rates of change in the EMG activity of each muscle differed significantly during the SitTS and StandTS tasks before and after the use of the PCB. However, the EMG activity did not significantly differ between the male and female subjects. These findings suggest that the PCB may contribute to the modification of activation patterns of the trunk muscles during SitTS, and StandTS tasks.

• Journal of Biomedical Engineering Research
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• v.29 no.4
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• pp.316-322
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• 2008

The purpose of this study was to investigate muscle activation of lower extremity such as rectus femoris, tibialis anterior and soleus according to 0cm(bare foot), 4cm and 7cm heel height of shoe on the rocking surface in older women. 20 older women who did not have any lower musculoskeletal and neurological disorders in the past were participated in this study. Each subject was standing for 15 seconds on the level 8 of Biodex Stability System (BSS) while wearing 4cm and 7cm heel height shoes including bare foot. Electromyography was used to measure muscle activation of lower extremity, and the muscle activation was expressed as a percentage of maximal voluntary isometric contraction (% MVIC). We measured % MVIC of three muscles during 5 seconds except for the first 5 seconds and last 5 seconds. SPSS 12.0 program was used for this study. Repeated one-way analysis of variance(ANOVA) was performed to compare the significant difference among the muscles of lower extremities according to heel heights of shoe on the rocking plate. % MVIC of each muscle such as rectus femoris, tibialis anterior and soleus regarding heel heights of shoe had statistically significant differences (p<0.05). The results of contrast test were as follows; 1) % MVIC of rectus femoris had significant differences between barefoot and 4cm, and barefoot and 7cm. 2) % MVIC of tibialis anterior had significant differences between barefoot and 4cm, barefoot and 7cm, and 4cm and 7cm. 3) % MVIC of soleus had significant differences between barefoot and 7cm, 4cm and 7cm. The results indicate that all commonly responsive muscle on the conditions of barefoot, 4cm, and 7cm shoe height on the rcoking surface is tibialis anterior muscle. We found out that the more heels of shoe high, the more muscle activation increases. High-heeled shoes above 7cm remarkably increase the muscle activation of lower extremity and may result in muscle fatigue. Thus, these shoes may summate risk factors of falls in older women. We can acknowledge that the heels above 4 cm affect each muscle activation in lower extremity on the rocking surface.

• Physical Therapy Korea
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• v.15 no.2
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• pp.54-63
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• 2008

The purpose of this study was to examine the effect of the hip internal rotation on knee extensor and hip abductor electromyographic (EMG) activity during stair up and stair down mobility. Eighteen healthy subjects were recruited. All subjects performed stair up and down movements on a step of 30cm height while maintaining the hip in neutral (condition 1) and hip in internal rotation (condition 2). Surface EMG activity was recorded from five muscles (gluteus maximus, vastus lateralis (VL), vastus medialis oblique (VMO), posterior gluteus medius (Gmed), and tensor fascia latae (TFU)) and hip internal rotation angle was measured using a three dimensional motion analysis system The time period for stair up and down was normalized using the MatLab 6.5 program, and EMG activity was normalized to the value of maximal voluntary isometric contraction (%MVIC). The EMG activities according to the hip rotation (neutral or internal rotation) during the entire time period of stair up and down in each phase were compared using a paired t-test. During the entire period of stair up, the EMG activities of VL and TFL in condition 2 were significantly greater than in condition 1 (p<.05). During the entire period of stair down, the EMG activities of VL and TFL in condition 2 were significantly greater than in condition 1 (p<.05). However, the EMG activities of the other muscles were not significantly different between the conditions (p>.05). These results suggest that the stair up and down maintaining hip internal rotation was could be a contributing factor on patellar lateral tracking.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.19 no.2
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• pp.39-46
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• 2013

Background: The purpose of this study was to realize the relations between gluteus medius, tensor fascia lata of pelvic muscles and functional leg length in women's university students. This study is examined the change of electromyographic activation on gluteus medius and tensor fascia lata according to the leg length discrepancy. Methods: All of the female of freshman and sophomore in 'D'college were gathered and separated fourteen of healthy women in two groups by functional leg length discrepancy. and The subjects divided into two groups that the difference with less than 2cm or more would have structural defects by tapeline. The electromyographic activation on the gluteus medius and tensor fascia lata muscles were recorded by surface electrodes at maximal voluntary isometric contraction (MVIC) during lunge posture. The collected datas were analyzed using Independent t-test with SPSS win19.0. Results: In intergroup comparison of electromyographic activation levels for gluteus medius and tensor fascia lata in short or long leg, the influence of electromyographic activation on tensor fascia lata is shown to be more statically higher than gluteus medius according to functional leg length discrepancy in coeds. Even though both muscles are shown to be statistically higher in comparison of electoromyographic activation levels for tensor fascia lata and gluteus medius between short leg and long leg in Group I, Differences of electoromyographic activation levels for tensor fascia lata is shown to be statistically higher than gluteus medius. Conclusion: Through this study, we realized that tensor fascia lata than the long leg, and also, tensor fascia lata is significantly effective for functional leg length discrepancy than gluteus medius. It leads to pelvic lateral instability. This means that cause tensor fascia lata to have a leg length discrepancy.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.18 no.2
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• pp.41-47
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• 2012

Background: This study was designed to investigate the correlation between electromyography (EMG) activities in the vastus medialis oblique (VMO) vs vastus lateralis (VL) activity ratio and the valgus collapse knee position while stepping down. Methods: Twenty healthy women volunteered to participate in this study. We measured the frontal-plane projections of the knee valgus angle, knee valgus distance, and hip adduction angle by using a digital camcorder. After 3 repetitions of the step down (dominant side) exercise, the findings of the static and dynamic phases were analyzed. EMG activities data of the VMO:VL activity ratio were recorded during the step down exercise and were normalized to the maximal voluntary isometric contraction (MVIC) of the quadriceps. A paired t-test was used to compare the findings of the static and dynamic phases. We analyzed the Spearman's rank order correlation coefficient between the and VMO:VL ratio. Results: Hip adduction angle, knee valgus angle, VMO activity, VL activity, VMO:VL activity ratio were statistically higher in the dynamic phase than in the static phase (p<.05). Frontal-plane projections of knee valgus angle were significantly correlated with hip adduction angle (r=.459, p<.05) and knee valgus distance (r=.505, p<.05). However, the EMG activity ratio of the VMO and the VL did not show a significant change during step down exercise with respect to hip adduction angle (p=.875), knee valgus angle (p=.618), and knee valgus distance (p=.701). Conclusion: The results from this study indicate that frontal-plane projections of knee valgus angle were associated with hip adduction angle and knee valgus distance. On the basis of these results, the knee valgus distance may be used to determine the valgus collapse knee position while stepping down.

• Physical Therapy Korea
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• v.12 no.1
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• pp.1-10
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• 2005

The purpose of this study was to verify the most effective spinal stabilization exercises program by comparing the activities of muscles contributing to spinal stabilization during four types of exercises using a sling and a mat. Twenty healthy males were recruited and each subjects performed four types of exercises. Exercise 1 was performed in a quadruped position with the subjects lifting the left arm and the opposite leg on the mat. Exercise 2 was performed in a prone position while holding a sling with the right hand and the left knee was fully extended while lifting the left arm and right leg. Exercise 3 was performed in quadruped position while holding a sling with one the right hand and lifting the opposite arm and leg. In exercise 4, subjects were instructed to maintain a balance push-up position while holding slings with both hands in 10 cm forward reaching with extended elbows. Electromyographic(EMG) activities were recorded from the multifidus, external oblique, internal oblique, abdominal rectus, and erector spinalis muscles during the exercises. The EMG amplitude of each muscle was normalized to the amplitude in the maximal voluntary isometric contraction (MVIC) of each muscle. Repeated ANOVA and Bonferroni's tests were used to compare the differences in the muscle activity according to the types of exercise. The EMG amplitudes of all the muscles were significantly different according to the types of exercises (p<.05). The highest EMG activities of each muscle was as follow; multifidus was 73.38%MVIC in exercise 3, the erector spinalis was 40.03%MVIC in exercise 3, the external oblique was 135.88%MVIC in exercise 4, the internal oblique was 128.60%MVIC in exercise 4, and the rectus abdominalis was 95.24%MVIC in Exercise 4. The types of exercises showed a significant difference in composition rate of EMG amplitudes of each muscle (p<.05). EMG composition rate of the multifidus was high in exercise 1 and 3. However, EMG composition rates of the external oblique, internal oblique, and the rectus abdominals were high in exercise 2 and 4. These results showed differences in EMG activities of muscles contributing to trunk stabilization during different therapeutic exercises. Therefore, the type of exercise should be carefully selected to effectively strengthen a specific trunk stabilizer.

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.31-41
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• 2006

The primary purpose of a TKA is to restore normal knee function Therefore, ideally, a TKA should: (a) maintain the natural leverage of the knee joint muscles to ensure generating adequate knee muscle moments to accomplish daily tasks such as rising from climbing stairs; (b) provide adequate knee joint stability. A 16-channel MyoResearch XP EMG system was used to collect the differential input surface electromyography signals VM, VL, RF, BF, ST during climbing/descending stair tests. A Peak Motion Measurement System was used to collect the kinematic and kinetic data. AKIN-COM Ill isokinetic dynamometer was used for EMG of VM, VL, RF, BF and ST during maximal voluntary contraction. I Quadriceps EMG results for the VM of the passed 1year group limb demonstrated significant less RMS EMG than that of the passed 3year group limb $60^{\circ}-15^{\circ}$ of knee flexion(p<0.05). The VL of the passed 1year group limb also demonstrated significants less RMS EMG than that of the passed 3year group limb from $60^{\circ}-45^{\circ}$ of knee flexion(p<0.05). Similar to the VM and VL, the RF of the passed 1year group limb showed less RMS EMG than that of the passed 3year group limb from $60^{\circ}-30^{\circ}$ do knee flexion(p<0.05). Hamstring EMG results for the BF of the passed 1year group limb demonstrated less RMS EMG than that of the passed 3year group limb from $75^{\circ}-15^{\circ}$ of knee flexion(p<0.05). The passed 1year group limb tended to have less ADD displacement(p<0.071) than that of the passed 3year group limb. There was no significant difference of the ABD displacement between the passed 1year group and the passed 3year group limbs(p<0.73). The passed 3year group used compensatory adaptation movement strategies to compensate for the strength deficit of passed 3year group limbs. The passed 3year group limb also increased the quadriceps muscle activation level to produce more knee extension moment to compensate for the short quadriceps moment arm. The passe 3year group limb might have an unstable knee joint in the medio-Iateral direction during the climbing/descending by showing a tendency of more ADD displacement and greater hamming co-activation EMG than the passed 1year group limbs. The TKA design was not able to help the knee joint to produce adequate knee extension moment with less quadriceps muscle effort. I think that old man needs continuous exercise for muscle strength.