Engineering Mechanics

Proceedings Vol. 24 (2018)

ENGINEERING MECHANICS 2018

Copyright © 2018 Institute of Theoretical and Applied Mechanics of the Cech Academy of Sciences, Prague

 

Nowakowska K., Michnik R., Myśliwiec A., Zadoń H.
pages 617 - 620, full text

This work aimed to determine loads in the musculoskeletal system of the lumbar spine while lifting 10-kg and 20-kg objects off a table. Tests of kinematics of the analyzed actions of lifting were conducted in a group of parents of disabled children. The parents suffered from chronic pain in the lower section of the spine. The action of lifting was divided into 3 positions: 1 – a moment of detachment of the object from the table, 2 – an intermediate stage, 3 – holding the object while adopting an upright posture. The identification of loads exerted on the musculoskeletal system was carried out using a mathematical model of the human body in the Anybody Modeling System. The solution of the inverse dynamics task using the techniques of static optimization was applied. It enabled the determination of the reaction values in the joints of the lumbar spine section as well as the estimation of the values of muscle forces. The obtained results were standardized according to the body weight (BW) of the examined person. The highest values of loads were obtained in segment L5-S1: 2.36 ± 0.44 N/BW for lifting an object of a mass of 10 kg as well as 3.09 ± 0.41 N/BW for lifting a 20-kg object. The increase of the object mass from 10 kg to 20 kg caused the increase of loads in all lumbar segments of the spine by around 31% for position 1 and by 56% for position 3. The most active muscles during the action of lifting were the back extensor muscle and transversus abdominis muscle.

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