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Effects of Shoe with Flexible Sole on Kinematics and Dynamics of Vertebral Column During Drop Vertical Jump

Mohammadi, Mohammad Mahdi | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56606 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Nourani, Amir
  7. Abstract:
  8. Disorders of the lumbar spine are prevalent within the realm of musculoskeletal issues, emphasizing the importance of investigating contributing factors. This research focuses on assessing how flexible footwear influences the kinematics and dynamics of the vertebral column during drop vertical jump. The study involves mechanical tests on various footwear types, including simple, flexible and re entrant shoes with differing levels of rigidity. Bending tests were performed on simple and flexible shoes with hardness of 50 Asker C and flexible shoes with hardness of 40 Asker C. Additionally, compression tests were carried out on all soles at two different angles. The Bending tests revealed that, by making structure on the outer layer of the shoe sole with a hardness of 50 Asker C, it led to a 37% reduction in the force required for bending, ultimately enhancing sole flexibility. In the compression tests, it was observed that reducing sole hardness increased energy dissipation by up to 26.5%. As a result of the considerable disparities witnessed in the mechanical tests, two pairs of simple and flexible shoes with a hardness of 50 Asker C and two pairs of simple and flexible shoes with a hardness of 40 Asker C were selected for human testing. Nine volunteers were instructed to perform vertical jumps from a 34-cm height using each of the four pairs of shoes and while barefoot. The results from force plate experiments and the coordinates of markers on the volunteers' bodies were employed for biomechanical modeling in the opensim software, enabling the determination of the kinematics and dynamics of the volunteers in various scenarios. The activity of muscles, including the longissimus, Iliocostalis, multifidus, rectus abdominis, and the internal and external obliques, was measured using electromyography electrodes, and the model's validity was confirmed by calculating the correlation coefficient between the muscle activity obtained from the model and electromyography. Upon analyzing the results, it became evident that employing shoes with lower sole hardness and an Flexible during the After landing phase significantly reduced lumbosacral disc pressure (by 8.9%) and decreased the activity of the Iliocostalis muscle (by 14%), resulting in a substantial change in the anteroposterior center of presure (by 6.6 cm). Remarkably, no significant alterations in the kinematics of the mentioned phase were observed due to the rigidity of the shoe's geometry. In light of the findings from this study, it can be concluded that reducing sole hardness and enhancing flexibility can reduce the risk of back pain in individuals exposed to landing and jumping activities
  9. Keywords:
  10. Mechanical Test ; Musculoskeletal System ; Vertical Jump ; Lumbar Spine Portion ; Spine ; Auxetic Shoes ; Flexible Shoes

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