• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.229-230
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• 2008

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.115-122
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• 2011

Recently, we have proposed a hypothesis that spinal structures have a stress sensor driving feedback mechanism, In the human spine, spinal structure could react to modify muscular action in such a way so as to equalize stress at the disc, therefore reduce the risk of injury, In this analysis, abdominal muscle and abdominal pressure, which were not included in the previous study, were added to identify those effects in spine stability during upright stance posture for the case where the intervertebral disc plays the role of mechanoreceptor, The musculoskeletal FE model was consisted with detailed whole lumbar spine, pelvis, sacrum, coccyx and simplified trunk model. Muscle architecture with 46 local muscles containing paraspinal muscle and 6 rectus abdominal muscles were assigned according to the acting directions. The magnitude of 4kPa was considered for abdominal pressure. Minimization of the nucleus pressure deviation and annulus fiber average tension stress deviation was chosen for cost function. Developed model provide nice coincidence with in-vivo measurement (nucleus pressure). Analysis was conducted according to existence of co-activation of abdominal muscle and abdominal pressure. Antagonistic activity of abdominal muscle produced stability of spinal column with relatively small amount of total muscle force. In contrast to the abdominal muscle, effect of abdominal pressure was not clear that was partly depending on the assumption of constant abdominal pressure.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.130-136
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• 2010

For stability analysis of the lumbar spine, the hypothesis presented is that the disc has stress sensors driving feedback mechanism, which could react to the imposed loads by adjusting the contraction of the muscles. Fusion in the motion segment of the lumbar spinal column is believed to alter the stability of the spinal column. To identify this effect finite element (FE) models combined with optimization technique was applied and quantify the role of each muscle and reaction forces in the spinal column with respect to the fusion level. The musculoskeletal FE model was consisted with detailed whole lumbar spine, pelvis, sacrum, coccyx and simplified trunk model. Vertebral body and pelvis were modeled as a rigid body and the rib cage was constructed with rigid truss element for the computational efficiency. Spinal fusion model was applied to L3-L4, L4-L5, L5-S1 (single level) and L3-L5 (two levels) segments. Muscle architecture with 46 local muscles was used as acting directions. Minimization of the nucleus pressure deviation and annulus fiber average axial stress deviation was selected for cost function. As a result, spinal fusion produced reaction changes at each motion segment as well as contribution of each muscle. Longissimus thoracis and psoas major muscle showed dramatic changes for the cases of L5-S1 and L3-L5 level fusion. Muscle force change at each muscle also generated relatively high nucleus pressure not only at the adjacent level but at another level, which can explain disc degeneration pattern observed in clinical study.

• Physical Therapy Rehabilitation Science
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• v.11 no.1
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• pp.88-96
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• 2022

Objective: Purpose of this study was to compare muscle activity ratio of multifidus to erector spinalis according to various cueing including tactile stimulation to provide an effective strategy to provide verbal and tactile feedback during exercise to provoke multifidus muscle activation. Design: Cross-sectional study. Methods: Participants of this study included 28 healthy adults. Muscle activities of the multifidus and erector spinalis were measured while the participants performed tasks according to the three different methods of verbal cueing and three different tactile stimulation. Surface EMG was used to measure the muscular activity of the muscles during all the tasks. Results: Tactile stimulation to abdomen and lumbar vertebrae showed no significant difference in the muscle activity ratio (p>0.05). However, muscle activity ratio of the multifidus in relation to the erector spinalis was increased when subjects were given verbal instructions to make lumbar curvature with little force and to make lumbar curvature while pulling navel (p<0.05). However, it was decreased when they were provided with verbal instruction to make lumbar curvature with strong force (p<0.05). Conclusions: According to the results, proper verbal instruction was an effective tool to increase the muscular activity of multifidus. This study aimed to find and provide the most appropriate verbal cueing while doing exercises to activate multifidus.