• Korean Journal of Applied Biomechanics
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• v.14 no.1
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• pp.41-50
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• 2004

The objective of the study is to analyze the myoelectrical activity involved in performing the Swallow movement, a D-level technique, in order to use it as the basic research data in helping train gymnasts in how to perform strength-related techniques. To this end, four national representative athletes who participated in the 2002 Busan Asian Games were selected. The results of the comparison analysis of the individual models are summarized as follows. 1) The results of the E.M.G analysis showed that during the Swallow movement, the myoelectrical activity was detected higher in pectorialis major muscle and bicep brachii muscle than in trapezius muscle and deltoid muscle. 2) The results of the E.M.G analysis showed that during the Swallow movement, the myoelectrical activity was measured high in triceps brachii muscle and palmaris longus muscle, while the myoelectrical activity was recorded low in latissimus dorsi muscle and rectus abdominis muscle. 3) In performing the Swallow in the rings, the mean average (%) was found high in the order of erector spinae, pectorialis major muscle, palmaris longus muscle, triceps brachii muscle, deltoid muscle, latissimus dorsi muscle, and trapezius muscle. All taken together, the athletes showed a difference in the distribution of the muscles during the performance of the Swallow. The muscle that showed a constant distribution among the athletes was pectoralis major muscle, which proves that for a stable performance, it is ideal to increase the myoelectrical activity in pectoralis major muscle.

• Journal of the Ergonomics Society of Korea
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• v.14 no.2
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• pp.1-14
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• 1995

Neuromuscular difference between normal subjects and low-back pain patients has been identified in terms of neural excitation signal measured by Electromyography (EMG) under the dynamic flexion/extension trunk motion. Ten healthy subjects and ten low-back pain patients were recruited for this study. New parameters and normalization technique were introduced to quantify the muscle excitation pattern among the flexor-extensor pairs of muscles : rectus abdominis (RA)-erector spinae (ES at L1 and L5 level), external oblique (EO)-internal oblique (IO), rectus femoris (quadricep : QUD)-biceps femoris( hamstring : HAM), and tibialis anterior (TA)-gastrocnemius (GAS). Results indicated that the temporal EMG pattern such as peak timing difference between the hip flexor (QUD) and extensor (HAM) and the duration of coexcitation between ES at L5 and RA muscle pairs showed a statistically significant difference between normal subjects and low-back pain patients. Improtantly, this study presented a new technique to identify the dynamic muscle excitation pattern that canb be least affected by EMG-length-velocity relationship. Further study can performed to validate this method for clinical application to quantitatively identify the low-back pain patients in the future.

• The Journal of Korean Physical Therapy
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• v.34 no.4
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• pp.175-180
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• 2022

Purpose: Leg length discrepancy causes the posture deformation, gait asymmetry, and lower back pain. The purpose of this study is to investigate the correlation among functional leg length discrepancy (FLLD), muscle activity, muscle contraction onset time and vertical ground reaction force (vGRF) during simple lifting task. Methods: Thirty-nine subjects participated in this study. FLLD was measured from the umbilicus to medial malleolus of left and right leg using a tape. The subjects performed to lift a 10 kg box from the floor to chest. The muscle activity and muscle contraction onset time of rectus abdominis, erector spinae and rectus femoris was measured using EMG system and vGRF was measured by two force plate. Pearson correlation was used to fine out the correlation among FDDL, muscle activity, muscle contraction onset time and vGRF during simple lifting task. Results: Correlation between FLLD and difference of muscle activity of short-long side was very high (r>0.9) during simple lifting task. Correlation between FLLD and difference of muscle contraction onset time of short-long side was very high (r>0.9) during simple lifting task. And correlation between FLLD and difference of vGRF of short-long side was high (r>0.7) during simple lifting task. Conclusion: This study suggests that there is high correlation between FLLD and muscle activity, muscle contraction onset time, and ground reaction force during simple lifting task. Therefore, FLLD could negatively affect the postural balance.

• Journal of Korean Physical Therapy Science
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• v.18 no.2
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• pp.51-62
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• 2011

Purpose: The purpose of this study was to investigate the effect of microcurrent on fatigue of muscles in people who were flat-footed during gait. Methods: 10 flat-footed university students volunteered to participate in this study. 10 flat-footed subjects were divided into 2 groups, one group was experimental group of 5subjects(This group put on microcurrent induction shoes but the subjects were not able to feel the current.) and the other group was the control group of 5subjects(This group put on the general shoes which were similar in shape but microcurrent was not induced.) to perform double blind test and random sampling. Their gait muscle fatigue of 6 regions (vastus medialis, gastrocnemius, tibialis anterior, biceps femoris, erector spinae, and rectus abdominis muscle.) was measured by EMG MP150, Delsys Inc Boston, USA during walking and then they carried out the Harvard step with a platform (It was a arbitrarily made wooden platform of 100cm long, 50cm wide, 60cm high. They carried out climbing it for one second and descending it for one second by using the Metronome program, total 5minutes) for 5minutes. Right after that, the subjects walked on a treadmill at a speed of 4km/h for 10minutes and then their gait muscle fatigue of 6regions was assessed while they were walking on the ground as equally as before exercise. Results: The experimental group has resulted in lower average differences in gait muscle fatigue before and after exercise than those of the control group average 12.24Hz(P=0.009) at vastus medialis, average 8.52Hz(P=0.016) at gastrocnemius, average 9.16Hz(P=0.009) at tibialis anterior, average 8.66Hz(P=0.047) at biceps femoris, average 7.53Hz(P=0.016) at erector spinae, and average 7.80Hz(P=0.047) at rectus abdominis. All of the assessments of muscles have shown significant difference statistically. Conclusions: This result has shown that the use of micro current could decrease gait muscle fatigue of flat-footed people. It is recommended to use a microcurrent to reduce their gait muscle fatigue.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.905-913
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• 2018

The purpose of this study is to investigate the difference of muscle activity according to application of a foam roller during pilates. The 8 male subjects were selected and quadruped position, bridge, and core control movement of pilates were randomly assigned to 9 movements on a static mat motion, static foam-roller motion, and dynamic foam-roller actions. This program was conducted once at intervals of 1 week. The muscle activity of erector spinae, rectus abdominis, external oblique, gluteus medius, rectus femoris, and biceps femoris were measured and the collected data was analyzed by one-way ANOVA. First, in the quadruped, the rectus abdominis and external oblique, rectus femoris of the dynamic foam-roller actions showed higher muscle activity than the static mat motion and the static foam-roller motion(p <.001), gluteus medius muscle activity was also significantly higher (p <.05). biceps femoris were significantly higher in static foam-roller motions than in static mat-motion and dynamic foam-roller actions(p <.05). Second, biceps femoris muscle activity was highest in dynamic foam-roller actions than static mat-motion and static foam-roller motions during bridge(p <.001). Third, in the sitting core control, the rectus abdominis and gluteus medius of the dynamic foam-roller actions showed higher muscle activity than the static mat motion and the static foam-roller motion(p <.001). and activity of erector spinae muscle was also significantly higher (p <.01). external oblique were significantly higher in static mat-motion than in static foam-roller motions and dynamic foam-roller actions(p <.05). Considering the muscle activity during pilates exercise, it would be more effective to apply the method and difficulty.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.3
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• pp.323-330
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• 2010

Purpose : The purpose of this study was to evaluate the effects of muscle activation of neck, lumbar and low limb by using baby carrier with arms during walking. Methods : Twenty healthy and young females who brought up infants and had no musculoskeletal disorders of neck, lumbar and low limb were recruited for this study. They were instructed to perform muscle activation of neck, lumbar and low limb using the baby carrier with and without arms during walking. ProComp $infiniti^{TM}$ (Thought Technology Ltd., Canada) was used to measure the muscle activity of neck, lumbar and lower extremity muscles. Results : Activation of neck paraspinalis muscle was significantly increased using baby carrier with arms and there was a significant increase on erector spinae muscle activation by using anterior baby carrier. Conclusion : These results indicate that the muscle activation was changed by arms assist and the position of using baby carrier. Therefore, it could be considered relationship of muscle activation and musculoskeletal demage as carrying baby.

• The Journal of Korean Physical Therapy
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• v.27 no.6
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• pp.400-406
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• 2015

Purpose: The purpose of the present study was to examine joint position senses and muscle activity in subjects with and without chronic low back pain and to determine the effects of different types of bridge exercises on their trunk muscle activity. Methods: Thrity-eight subjects with chronic low back pain and thrity healthy controls participated in the experiment. Joint position senses and trunk muscle activity levels were measured during the different bridge exercise methods. Results: The joint position senses of the healthy group and chronic low back pain group showed significant differences during lumbar flexion, lumbar extension, lumbar lateral flexion, and lumbar rotation. The muscle activity levels of the transversus abdominis (TrA), internal oblique (IO), and external oblique (EO) were highest in the prone bridge exercise (PBE) group, followed by the supine bridge swiss ball exercise (SBSE) group and supine bridge exercise (SBE) group in order of precedence. The muscle activity level of the erector spinae (ES) was highest in the SBSE group, followed by the SBE and PBE groups in order of precedence. Conclusion: Overall, the results suggest that chronic low back pain is associated with declines in joint position senses and that PBEs increase trunk muscle activity more than conventional bridge exercises.

• Journal of the Ergonomics Society of Korea
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• v.21 no.2
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• pp.25-33
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• 2002

The purpose of study is to investigate the relationship between the trunk muscle fatigue and recovery time during repetitive extension by using a surface electromyogram(EMG). Ten healthy subjects particioated in a simulated lifting task with five levels of recovery time and three levels of sub-maximal contraction. EMG signals of the L1(Lumbar 1st Vertebrae) and L3(Lumbar 3rd Vertebrae) level of the erector spinae muscle were recorded. and analyzed in terms of MPF(mean power frequency) parameter to quantify the level of muscle fatigue. It was found that MPF significantly (p<0.05) decreased during repetitive extension task at 50% and 75% sub-maximal contractions. Then it took minutes for the trunk muscle to recover from fatigue during 50% sub-maximal contraction. and it took five minutes during 75% sub-maximal contraction. and it took five minutes during 75% sub-maximal contraction. The recovery time estimated by the maximum force needs to be re-evaluated for the trunk muscle to fully recover from fatigue. In conclusion. the work/rest cycle needs to be studied based upon the information of muscle fatigue in order to prevent workers from musculoskeletal injuries during repetitive lifting task.

• The Korean Journal of Emergency Medical Services
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• v.18 no.3
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• pp.7-18
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• 2014

Purpose: We aimed to investigate trunk angle and muscle activation of the extremity and back to evaluate the effect of chest compression on work-related musculoskeletal disorders in 119 emergency medical technicians (EMTs). Methods: Eighteen 119 EMTs performed 2-minute chest compression without interruption on a cardiopulmonary resuscitation manikin, during which we measured changes in the trunk and shoulder joint angles, muscle activation (triceps brachii, biceps brachii, erector spinae, gluteus maximus, pectoralis major, rectus abdominis, and rectus femoris) and chest compression accuracy. Results: The decrease in trunk angle by trunk muscle activation was the highest in event 2, the major direction of chest compression. Both shoulder joint angles had no significant difference. Muscle activation of the triceps brachii (p < .01), biceps brachii (p < .05), rectus abdominis (p < .05) and rectus femoris (p < .01) significantly increased during the compression phase compared with the decompression phase, with the rectus femoris showing an increase of 19%. Muscle activation of the erector spinae significantly increased in the decompression phase compared with the compression phase (p < .01). Conclusion: 119 EMTs mainly use the triceps brachii, biceps brachii and pectoralis major muscles during chest compression.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.137-140
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• 1996

This study investigated the length-tension and velocity-force relations of the torso erectors. A myoelectric based approach was used wherein a dynamic biomechanical model incorporating active and passive tissue charactreistics provided music kinematic estimates during controlled sagittal plan extension motions. A double linear optimization formulation from the literatured provided muscle tension estimates. The data supported a linear length-tension relation toward full flexion for both the erector spinae and latissimus muscles. Velocity trends agreed with that predicted by Hill's exponential relation. The results have implications for muscle tension estimation in biomechanical torso modeling, and suggest a possible low back pain injury mechanism.