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Effect of Hand-Held Flexible-Bar on Postural Stability and Shoulder Muscle Synergies during Repetitive Planar Hand Exercises

Davoodi, Mehrdad | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50825 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Parnianpour, Mohammad; Hoviattalab, Maryam
  7. Abstract:
  8. Shoulder is one of the most important joints of the body with high degrees of freedom. Synergic analysis of the shoulder muscles shows the joint condition due to applied force or torque. The results of the linear COP parameters and nonlinear analysis indicate the characteristics of subjects postural stability. The flexi-bar is a rehabilitation tool which stimulates the muscles. In this study, the effect of bar on the body has been examined. The modeling is carried out in two horizontal and vertical condition of bar in sixteen separate positions in the upper right side quadrant of the model. Muscle activation and joint stiffness, force and torque were obtained. COP data in AP and ML were recorded with experimental tests on healthy people. With time varying synergy algorithms, five phasic synergies which are effected by muscles movement and speed also five tonic synergies which are impacted by bar position extracted. Each synergy has been actived in special part of space where in each synergies, there are special muscles appropriated for that domain. More muscles were actived for each synergy in horizontal condition. nonlinear analysis was investigated by nonlinear criteria such as Recurrence, Determinism, Antropy, Trend and Lyapunov Exponent and also with assessing of amplitude and velocity standard deviation, linear analysis was obtained. mathematical results were verified by Recurrence. Determinism didn’t show any specific result but three other nonlinear parameters besides linear parameter and joint stiffness, demonstrated CNS effort for determining the instant equilibrium point, which compensate its defect with increase in COP standard deviation and muscles stiffness. Sometimes the CNS decision is optimal for body stability but in contrast in some other times, subject achieved stability by fast increase COP standard deviation or with muscles stiffing. This procedure is accurate in both directions
  9. Keywords:
  10. Muscle Synergy ; Shoulders Joint ; Local Stability ; Flexible Bar ; Postural Stability

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